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Kev hloov pauv ntawm cov kab mob me me muaj kev tawm tsam ntawm kev xaiv ntuj, uas ua rau cov kab mob zoo dua, thiab kev hloov pauv caj ces, uas ua rau cov kab mob poob cov noob caj noob ces thiab khaws cov kev hloov pauv tsis zoo. Ntawm no, txhawm rau nkag siab tias qhov kev tawm tsam no tshwm sim li cas ntawm qhov ntsuas ntawm ib qho macromolecule, peb piav qhia txog cov qauv cryo-EM ntawm ribosome ntawm Encephalitozoon cuniculi, ib qho eukaryotic organism nrog ib qho ntawm cov genomes me tshaj plaws hauv xwm. Kev txo qis ntawm rRNA hauv E. cuniculi ribosomes yog nrog los ntawm kev hloov pauv tsis tau muaj dua, xws li kev hloov pauv ntawm cov fused rRNA linkers thiab rRNA tsis muaj bulges. Tsis tas li ntawd, E. cuniculi ribosome tau dim ntawm kev poob ntawm rRNA fragments thiab proteins los ntawm kev tsim lub peev xwm los siv cov molecules me me ua cov qauv mimics ntawm cov rRNA fragments thiab proteins uas lwj. Zuag qhia tag nrho, peb qhia tau hais tias cov qauv molecular ntev xav tias yuav txo qis, degenerate, thiab raug rau kev hloov pauv debilitating muaj ntau lub tshuab them rov qab uas ua rau lawv ua haujlwm txawm tias muaj kev sib cog lus molecular heev.
Vim tias feem ntau cov pab pawg ntawm cov kab mob me me muaj cov cuab yeej tshwj xeeb los siv lawv cov tswv tsev, peb feem ntau yuav tsum tsim cov kev kho mob sib txawv rau cov pab pawg sib txawv ntawm cov kab mob1,2. Txawm li cas los xij, cov pov thawj tshiab qhia tias qee qhov ntawm kev hloov pauv ntawm cov kab mob yog sib sau ua ke thiab feem ntau kwv yees tau, qhia txog lub hauv paus rau kev kho mob dav dav hauv cov kab mob me me3,4,5,6,7,8,9.
Cov haujlwm yav dhau los tau txheeb xyuas qhov sib txawv ntawm kev hloov pauv hauv cov kab mob me me hu ua genome reduction lossis genome decay10,11,12,13. Kev tshawb fawb tam sim no qhia tau hais tias thaum cov kab mob me me tso tseg lawv txoj kev ua neej nyob dawb thiab dhau los ua cov kab mob hauv hlwb (lossis endosymbionts), lawv cov genomes dhau los qeeb tab sis zoo kawg nkaus metamorphoses dhau ntau lab xyoo9,11. Hauv cov txheej txheem hu ua genome decay, cov kab mob me me sau cov kev hloov pauv uas ua rau ntau cov noob tseem ceeb yav dhau los ua pseudogenes, ua rau cov noob poob qeeb thiab kev hloov pauv poob14,15. Qhov kev poob no tuaj yeem rhuav tshem txog li 95% ntawm cov noob hauv cov kab mob hauv hlwb qub tshaj plaws piv rau cov tsiaj txhu uas muaj kev nyob dawb. Yog li, kev hloov pauv ntawm cov kab mob hauv hlwb yog kev sib ntaus sib tua ntawm ob lub zog sib tw: Darwinian natural selection, ua rau kev txhim kho ntawm cov kab mob, thiab kev poob ntawm genome, pov cov kab mob mus rau hauv kev tsis nco qab. Yuav ua li cas tus kab mob tswj kom tawm ntawm qhov kev sib ntaus sib tua no thiab khaws cov haujlwm ntawm nws cov qauv molecular tseem tsis meej.
Txawm hais tias txoj kev ua rau genome lwj tsis tau nkag siab tag nrho, nws zoo li tshwm sim feem ntau yog vim muaj kev hloov pauv ntawm cov noob caj noob ces. Vim tias cov kab mob nyob hauv cov pej xeem me me, tsis muaj poj niam txiv neej, thiab muaj kev txwv ntawm cov noob caj noob ces, lawv tsis tuaj yeem tshem tawm cov kev hloov pauv tsis zoo uas qee zaum tshwm sim thaum lub sijhawm DNA replication. Qhov no ua rau muaj kev sib sau ua ke ntawm cov kev hloov pauv tsis zoo thiab txo qis ntawm cov noob caj noob ces ntawm cov kab mob. Yog li ntawd, cov kab mob tsis yog tsuas yog poob cov noob caj noob ces uas tsis tsim nyog rau nws txoj kev ciaj sia nyob hauv ib puag ncig intracellular. Nws yog qhov tsis muaj peev xwm ntawm cov pej xeem kab mob kom tshem tawm cov kev hloov pauv tsis zoo uas ua rau cov kev hloov pauv no sib sau ua ke thoob plaws hauv genome, suav nrog lawv cov noob caj noob ces tseem ceeb tshaj plaws.
Feem ntau ntawm peb txoj kev nkag siab tam sim no ntawm kev txo qis genome tsuas yog raws li kev sib piv ntawm cov kab ke genome, nrog tsawg dua kev saib xyuas rau kev hloov pauv hauv cov molecules tiag tiag uas ua haujlwm tu vaj tse thiab ua haujlwm ua lub hom phiaj tshuaj. Kev tshawb fawb sib piv tau qhia tias lub nra hnyav ntawm kev hloov pauv microbial intracellular zoo li ua rau cov protein thiab nucleic acids ua rau misfold thiab sib sau ua ke, ua rau lawv nyob ntawm tus chaperone thiab hypersensitive rau cua sov19,20,21,22,23. Tsis tas li ntawd, ntau yam kab mob parasitic - kev hloov pauv ywj pheej qee zaum sib cais los ntawm ntau npaum li 2.5 billion xyoo - tau ntsib kev poob zoo sib xws ntawm cov chaw tswj hwm zoo hauv lawv cov protein synthesis5,6 thiab DNA kho mechanisms24. Txawm li cas los xij, me ntsis paub txog qhov cuam tshuam ntawm kev ua neej nyob hauv intracellular rau txhua yam khoom ntawm cellular macromolecules, suav nrog kev hloov pauv molecular rau kev nce ntxiv ntawm kev hloov pauv deterprise.
Hauv txoj haujlwm no, txhawm rau kom nkag siab zoo dua txog kev hloov pauv ntawm cov protein thiab nucleic acids ntawm cov kab mob hauv lub hlwb, peb tau txiav txim siab cov qauv ntawm ribosomes ntawm tus kab mob hauv lub hlwb Encephalitozoon cuniculi. E. cuniculi yog ib yam kab mob zoo li fungus uas yog ib pawg ntawm cov kab mob microsporidia uas muaj cov genomes eukaryotic me me thiab yog li ntawd siv los ua cov qauv kab mob los kawm txog kev lwj ntawm genome25,26,27,28,29,30. Tsis ntev los no, cov qauv ribosome cryo-EM tau txiav txim siab rau cov genomes txo qis ntawm Microsporidia, Paranosema locustae, thiab Vairimorpha necatrix31,32 (~ 3.2 Mb genome). Cov qauv no qhia tias qee qhov kev poob ntawm rRNA amplification tau them los ntawm kev txhim kho cov kev sib cuag tshiab ntawm cov protein ribosomal nyob sib ze lossis kev tau txais cov protein msL131,32 ribosomal tshiab. Cov tsiaj Encephalitozoon (genome ~ 2.5 lab bp), nrog rau lawv cov txheeb ze ze tshaj plaws Ordospora, qhia txog qib kawg ntawm kev txo qis genome hauv eukaryotes - lawv muaj tsawg dua 2000 cov noob protein-coding, thiab nws xav tias lawv cov ribosomes tsis yog tsuas yog tsis muaj rRNA nthuav dav (rRNA fragments uas sib txawv eukaryotic ribosomes los ntawm cov kab mob ribosomes) kuj muaj plaub cov protein ribosomal vim lawv tsis muaj homologues hauv E. cuniculi genome26,27,28. Yog li ntawd, peb xaus lus tias E. cuniculi ribosome tuaj yeem qhia cov tswv yim tsis paub yav dhau los rau kev hloov pauv molecular rau genome lwj.
Peb cov qauv cryo-EM sawv cev rau qhov me tshaj plaws eukaryotic cytoplasmic ribosome kom tau piav qhia thiab muab kev nkag siab txog qhov kawg ntawm kev txo qis genome cuam tshuam li cas rau cov qauv, kev sib dhos, thiab kev hloov pauv ntawm cov tshuab molecular uas yog qhov tseem ceeb rau lub cell. Peb pom tias E. cuniculi ribosome ua txhaum ntau lub hauv paus ntsiab lus ntawm RNA folding thiab ribosome sib dhos, thiab nrhiav tau ib qho protein ribosomal tshiab, yav dhau los tsis paub. Tsis tau xav txog, peb qhia tias microsporidia ribosomes tau hloov pauv lub peev xwm los khi cov molecules me me, thiab xav tias qhov kev txiav tawm hauv rRNA thiab cov protein ua rau muaj kev hloov pauv tshiab uas thaum kawg yuav muab cov txiaj ntsig zoo rau ribosome.
Txhawm rau txhim kho peb txoj kev nkag siab txog kev hloov pauv ntawm cov protein thiab nucleic acids hauv cov kab mob hauv lub hlwb, peb tau txiav txim siab cais cov noob E. cuniculi los ntawm cov kab lis kev cai ntawm cov tsiaj txhu uas muaj kab mob kom huv lawv cov ribosomes thiab txiav txim siab cov qauv ntawm cov ribosomes no. Nws nyuaj rau tau txais ntau tus kab mob parasitic microsporidia vim tias microsporidia tsis tuaj yeem cog qoob loo hauv cov khoom noj khoom haus. Hloov chaw, lawv loj hlob thiab rov tsim dua tsuas yog hauv lub cell host. Yog li ntawd, kom tau txais E. cuniculi biomass rau kev ntxuav ribosome, peb tau kis tus kab mob raum cell kab RK13 nrog E. cuniculi spores thiab cog cov hlwb no rau ob peb lub lis piam kom cia E. cuniculi loj hlob thiab ntau ntxiv. Siv cov kab mob cell monolayer ntawm kwv yees li ib nrab square meter, peb tau ntxuav txog 300 mg ntawm Microsporidia spores thiab siv lawv los cais cov ribosomes. Tom qab ntawd peb tau cuam tshuam cov noob purified nrog cov hlaws iav thiab cais cov ribosomes nyoos siv cov kauj ruam polyethylene glycol fractionation ntawm lysates. Qhov no tso cai rau peb kom tau txais kwv yees li 300 µg ntawm cov E. cuniculi ribosomes nyoos rau kev tshuaj xyuas cov qauv.
Tom qab ntawd peb tau sau cov duab cryo-EM siv cov qauv ribosome thiab ua cov duab no siv cov masks sib raug rau ribosomal subunit loj, subunit taub hau me, thiab subunit me. Thaum lub sijhawm no, peb tau sau cov duab ntawm kwv yees li 108,000 ribosomal particles thiab cov duab cryo-EM computed nrog qhov kev daws teeb meem ntawm 2.7 Å (Cov Duab Ntxiv 1-3). Tom qab ntawd peb tau siv cov duab cryoEM los ua qauv rRNA, ribosomal protein, thiab hibernation factor Mdf1 cuam tshuam nrog E. cuniculi ribosomes (Daim Duab 1a, b).
a Cov qauv ntawm E. cuniculi ribosome hauv kev sib xyaw nrog qhov hibernation factor Mdf1 (pdb id 7QEP). b Daim ntawv qhia ntawm qhov hibernation factor Mdf1 cuam tshuam nrog E. cuniculi ribosome. c Daim ntawv qhia qauv theem ob piv rau cov rRNA rov qab tau hauv Microsporidian hom rau cov qauv ribosomal paub. Cov vaj huam sib luag qhia qhov chaw ntawm cov amplified rRNA fragments (ES) thiab ribosome active sites, suav nrog qhov chaw decoding (DC), lub voj voog sarcinicin (SRL), thiab peptidyl transferase center (PTC). d Qhov ceev ntawm electron sib raug rau qhov chaw peptidyl transferase ntawm E. cuniculi ribosome qhia tias qhov chaw catalytic no muaj tib lub qauv hauv E. cuniculi parasite thiab nws cov tswv tsev, suav nrog H. sapiens. e, f Qhov ceev ntawm cov electron sib xws ntawm qhov chaw decoding (e) thiab cov qauv schematic ntawm qhov chaw decoding (f) qhia tias E. cuniculi muaj cov seem U1491 es tsis yog A1491 (E. coli numbering) hauv ntau lwm yam eukaryotes. Qhov kev hloov pauv no qhia tau hais tias E. cuniculi tej zaum yuav rhiab rau cov tshuaj tua kab mob uas tsom mus rau qhov chaw no.
Tsis zoo li cov qauv uas tau tsim ua ntej ntawm V. necatrix thiab P. locustae ribosomes (ob qho qauv sawv cev rau tib tsev neeg microsporidia Nosematidae thiab zoo sib xws heev), 31,32 E. cuniculi ribosomes dhau los ntawm ntau cov txheej txheem ntawm rRNA thiab protein fragmentation. Ntxiv denaturation (Cov Duab Ntxiv 4-6). Hauv rRNA, qhov kev hloov pauv tseem ceeb tshaj plaws suav nrog kev poob tag nrho ntawm amplified 25S rRNA fragment ES12L thiab ib feem ntawm kev puas tsuaj ntawm h39, h41, thiab H18 helices (Daim Duab 1c, Daim Duab Ntxiv 4). Ntawm cov protein ribosomal, qhov kev hloov pauv tseem ceeb tshaj plaws suav nrog kev poob tag nrho ntawm eS30 protein thiab kev luv ntawm eL8, eL13, eL18, eL22, eL29, eL40, uS3, uS9, uS14, uS17, thiab eS7 proteins (Cov Duab Ntxiv 4, 5).
Yog li, qhov kev txo qis ntawm cov genomes ntawm Encephalotozoon / Ordospora hom tau pom tseeb hauv lawv cov qauv ribosome: E. cuniculi ribosomes ntsib qhov poob qis tshaj plaws ntawm cov protein hauv eukaryotic cytoplasmic ribosomes uas raug rau cov qauv kev ua haujlwm, thiab lawv tsis muaj cov rRNA thiab cov protein fragments uas tau khaws cia dav dav tsis yog hauv eukaryotes, tab sis kuj nyob rau hauv peb qhov chaw ntawm lub neej. Cov qauv ntawm E. cuniculi ribosome muab thawj tus qauv molecular rau cov kev hloov pauv no thiab qhia txog cov xwm txheej evolutionary uas tau raug saib tsis taus los ntawm ob qho tib si sib piv genomics thiab kev tshawb fawb ntawm cov qauv intracellular biomolecular (Supplementary Fig. 7). Hauv qab no, peb piav qhia txog txhua qhov xwm txheej no nrog rau lawv cov keeb kwm evolutionary thiab lawv qhov cuam tshuam rau ribosome ua haujlwm.
Tom qab ntawd peb pom tias, ntxiv rau qhov loj rRNA truncations, E. cuniculi ribosomes muaj rRNA variations ntawm ib qho ntawm lawv cov chaw ua haujlwm. Txawm hais tias lub chaw peptidyl transferase ntawm E. cuniculi ribosome muaj tib lub qauv li lwm cov eukaryotic ribosomes (Daim duab 1d), lub chaw decoding txawv vim yog qhov sib txawv ntawm nucleotide 1491 (E. coli numbering, Daim duab 1e, f). Qhov kev soj ntsuam no tseem ceeb vim tias qhov chaw decoding ntawm eukaryotic ribosomes feem ntau muaj cov residues G1408 thiab A1491 piv rau cov kab mob-hom residues A1408 thiab G1491. Qhov kev hloov pauv no yog qhov sib txawv ntawm cov kab mob thiab eukaryotic ribosomes rau tsev neeg aminoglycoside ntawm ribosomal tshuaj tua kab mob thiab lwm cov molecules me me uas tsom mus rau qhov chaw decoding. Ntawm qhov chaw decoding ntawm E. cuniculi ribosome, residue A1491 tau hloov nrog U1491, tej zaum yuav tsim ib qho kev sib txuas tshwj xeeb rau cov molecule me me uas tsom mus rau qhov chaw nquag no. Tib qho A14901 variant kuj muaj nyob rau hauv lwm yam microsporidia xws li P. locustae thiab V. necatrix, qhia tias nws kis tau dav ntawm cov hom microsporidia (Daim duab 1f).
Vim tias peb cov qauv E. cuniculi ribosome tau rho tawm los ntawm cov noob tsis ua haujlwm hauv lub cev, peb tau sim daim ntawv qhia cryo-EM ntawm E. cuniculi rau kev khi ribosome uas tau piav qhia ua ntej hauv qab kev ntxhov siab lossis kev tshaib plab. Cov yam ntxwv hibernation 31,32,36,37, 38. Peb tau phim cov qauv tsim ua ntej ntawm hibernating ribosome nrog daim ntawv qhia cryo-EM ntawm E. cuniculi ribosome. Rau docking, S. cerevisiae ribosomes tau siv hauv complex nrog hibernation factor Stm138, locust ribosomes hauv complex nrog Lso232 factor, thiab V. necatrix ribosomes hauv complex nrog Mdf1 thiab Mdf231 factors. Tib lub sijhawm, peb pom qhov ceev cryo-EM sib raug rau qhov so factor Mdf1. Zoo ib yam li Mdf1 khi rau V. necatrix ribosome, Mdf1 kuj khi rau E. cuniculi ribosome, qhov twg nws thaiv E qhov chaw ntawm ribosome, tej zaum yuav pab ua rau ribosomes muaj thaum cov kab mob parasite ua haujlwm tsis zoo thaum lub cev tsis ua haujlwm (Daim Duab 2).
Mdf1 thaiv qhov chaw E ntawm ribosome, uas zoo li pab ua kom ribosome tsis ua haujlwm thaum cov noob kab mob ua rau lub cev tsis ua haujlwm. Hauv cov qauv ntawm E. cuniculi ribosome, peb pom tias Mdf1 tsim kev sib cuag tsis paub yav dhau los nrog L1 ribosome qia, ib feem ntawm ribosome uas pab txhawb kev tso tawm ntawm deacylated tRNA los ntawm ribosome thaum lub sijhawm ua cov protein synthesis. Cov kev sib cuag no qhia tias Mdf1 dissociates los ntawm ribosome siv tib lub tshuab li deacetylated tRNA, muab cov lus piav qhia txog yuav ua li cas ribosome tshem tawm Mdf1 kom rov ua kom cov protein synthesis.
Txawm li cas los xij, peb cov qauv tau qhia txog kev sib cuag tsis paub ntawm Mdf1 thiab L1 ribosome ceg (qhov ntawm ribosome uas pab tso tawm deacylated tRNA los ntawm ribosome thaum lub sijhawm tsim cov protein). Tshwj xeeb, Mdf1 siv cov kev sib cuag tib yam li ntu ntawm lub luj tshib ntawm deacylated tRNA molecule (Daim Duab 2). Qhov kev ua qauv molecular tsis paub yav dhau los no tau qhia tias Mdf1 sib cais los ntawm ribosome siv tib lub tshuab li deacetylated tRNA, uas piav qhia txog yuav ua li cas ribosome tshem tawm qhov hibernation factor no kom rov ua kom cov protein synthesis rov ua haujlwm.
Thaum tsim cov qauv rRNA, peb pom tias E. cuniculi ribosome muaj cov rRNA fragments uas tsis zoo li qub, uas peb hu ua fused rRNA (Daim Duab 3). Hauv ribosomes uas hla peb thaj chaw ntawm lub neej, rRNA quav rau hauv cov qauv uas feem ntau rRNA yog lub hauv paus khub thiab quav nrog ib leeg lossis cuam tshuam nrog cov protein ribosomal38,39,40. Txawm li cas los xij, hauv E. cuniculi ribosomes, rRNAs zoo li ua txhaum txoj cai quav no los ntawm kev hloov qee qhov ntawm lawv cov helices mus rau hauv thaj chaw rRNA unfolded.
Cov qauv ntawm H18 25S rRNA helix hauv S. cerevisiae, V. necatrix, thiab E. cuniculi. Feem ntau, hauv ribosomes uas nthuav dav peb lub neej, qhov txuas no coils rau hauv RNA helix uas muaj 24 txog 34 residues. Hauv Microsporidia, qhov sib piv, qhov txuas rRNA no maj mam txo qis rau ob lub txuas uridine-nplua nuj uas muaj tsuas yog 12 residues. Feem ntau ntawm cov residues no raug rau cov kuab tshuaj. Daim duab qhia tau hais tias parasitic microsporidia zoo li ua txhaum cov ntsiab cai dav dav ntawm rRNA folding, qhov twg rRNA bases feem ntau yog txuas nrog lwm lub bases lossis koom nrog rRNA-protein sib cuam tshuam. Hauv microsporidia, qee qhov rRNA fragments noj rau ntawm qhov tsis zoo fold, uas yav dhau los rRNA helix dhau los ua ib qho fragment-stranded elongated yuav luag hauv ib txoj kab ncaj. Qhov muaj cov cheeb tsam txawv txawv no tso cai rau microsporidia rRNA khi cov fragments rRNA deb siv tsawg kawg nkaus ntawm RNA bases.
Qhov piv txwv tseem ceeb tshaj plaws ntawm qhov kev hloov pauv no tuaj yeem pom hauv H18 25S rRNA helix (Daim Duab 3). Hauv cov tsiaj txhu los ntawm E. coli mus rau tib neeg, lub hauv paus ntawm rRNA helix no muaj 24-32 nucleotides, tsim ib lub helix tsis sib xws me ntsis. Hauv cov qauv ribosomal uas tau txheeb xyuas yav dhau los los ntawm V. necatrix thiab P. locustae,31,32 lub hauv paus ntawm H18 helix yog ib feem uncoiled, tab sis nucleotide base pairing tseem khaws cia. Txawm li cas los xij, hauv E. cuniculi qhov rRNA fragment no dhau los ua cov txuas luv tshaj plaws 228UUUGU232 thiab 301UUUUUUUUUU307. Tsis zoo li cov fragments rRNA ib txwm muaj, cov txuas uridine nplua nuj no tsis coil lossis ua kev sib cuag ntau nrog cov protein ribosomal. Hloov chaw, lawv txais yuav cov qauv qhib thiab qhib tag nrho uas cov rRNA strands tau nthuav dav yuav luag ncaj. Qhov kev sib txuas no piav qhia txog E. cuniculi siv tsuas yog 12 RNA bases los sau qhov sib txawv 33 Å ntawm H16 thiab H18 rRNA helices, thaum lwm hom tsiaj xav tau tsawg kawg yog ob npaug ntawm ntau rRNA bases los sau qhov sib txawv.
Yog li, peb tuaj yeem ua pov thawj tias, los ntawm kev sib sau ua ke tsis zoo, cov kab mob microsporidia tau tsim ib txoj kev los cog lus txawm tias cov rRNA ntu uas tseem khaws cia thoob plaws hauv peb hom tsiaj hauv peb thaj chaw ntawm lub neej. Zoo li, los ntawm kev sib sau ua ke cov kev hloov pauv uas hloov rRNA helices mus rau hauv cov poly-U txuas luv luv, E. cuniculi tuaj yeem tsim cov rRNA tsis tshua muaj uas muaj ob peb nucleotides li sai tau rau kev sib txuas ntawm cov rRNA tawg. Qhov no pab piav qhia tias microsporidia tau ua tiav qhov kev txo qis hauv lawv cov qauv molecular yam tsis poob lawv cov qauv thiab kev ua haujlwm.
Lwm yam tshwj xeeb ntawm E. cuniculi rRNA yog qhov tshwm sim ntawm rRNA yam tsis muaj cov khoom tuab (Daim Duab 4). Cov pob yog cov nucleotides tsis muaj cov khub puag uas ntswj tawm ntawm RNA helix es tsis txhob nkaum hauv nws. Feem ntau cov rRNA protrusions ua haujlwm ua cov nplaum molecular, pab khi cov protein ribosomal uas nyob ib sab lossis lwm cov rRNA fragments. Qee qhov ntawm cov pob ua haujlwm ua cov hinges, tso cai rau rRNA helix kom khoov thiab quav tau zoo tshaj plaws rau kev tsim cov protein tsim tau 41.
a Ib qho rRNA protrusion (S. cerevisiae numbering) tsis muaj nyob rau hauv E. cuniculi ribosome qauv, tab sis muaj nyob rau hauv feem ntau lwm yam eukaryotes b E. coli, S. cerevisiae, H. sapiens, thiab E. cuniculi sab hauv ribosomes. cov kab mob tsis muaj ntau yam ntawm cov rRNA bulges qub, khaws cia zoo heev. Cov thickenings no ruaj khov lub ribosome qauv; yog li ntawd, lawv tsis muaj nyob rau hauv microsporidia qhia txog kev txo qis kev ruaj khov ntawm rRNA folding hauv microsporidia parasites. Kev sib piv nrog P stems (L7/L12 stems hauv cov kab mob) qhia tau hais tias qhov poob ntawm rRNA bumps qee zaum coincides nrog cov tsos ntawm cov bumps tshiab nyob ib sab ntawm cov bumps ploj. Lub H42 helix hauv 23S/28S rRNA muaj ib qho bulge qub (U1206 hauv Saccharomyces cerevisiae) kwv yees tias muaj tsawg kawg yog 3.5 billion xyoo vim nws txoj kev tiv thaiv hauv peb qhov chaw ntawm lub neej. Hauv microsporidia, qhov bulge no raug tshem tawm. Txawm li cas los xij, ib qho pob tshiab tau tshwm sim ib sab ntawm qhov pob uas ploj lawm (A1306 hauv E. cuniculi).
Qhov txaus ntshai, peb pom tias E. cuniculi ribosomes tsis muaj feem ntau ntawm cov rRNA bulges pom muaj nyob rau hauv lwm hom tsiaj, suav nrog ntau dua 30 bulges khaws cia rau hauv lwm eukaryotes (Daim duab 4a). Qhov kev poob no tshem tawm ntau qhov kev sib cuag ntawm ribosomal subunits thiab cov rRNA helices sib ze, qee zaum tsim cov qhov loj loj hauv ribosome, ua rau E. cuniculi ribosome porous ntau dua piv rau cov ribosomes ib txwm muaj (Daim duab 4b). Qhov tseem ceeb, peb pom tias feem ntau ntawm cov bulges no kuj tau ploj mus rau hauv cov qauv ribosome V. necatrix thiab P. locustae uas tau txheeb xyuas ua ntej, uas tau raug saib tsis taus los ntawm cov qauv kev tshuaj xyuas yav dhau los31,32.
Qee zaum qhov poob ntawm rRNA bulges yog nrog los ntawm kev loj hlob ntawm cov bulges tshiab nyob ib sab ntawm qhov poob bulge. Piv txwv li, ribosomal P-stem muaj U1208 bulge (hauv Saccharomyces cerevisiae) uas tau dim ntawm E. coli rau tib neeg thiab yog li ntawd kwv yees tias muaj hnub nyoog 3.5 billion xyoo. Thaum lub sijhawm tsim cov protein, qhov bulge no pab P stem txav mus los ntawm qhov qhib thiab kaw conformations kom ribosome tuaj yeem nrhiav cov yam ntxwv txhais lus thiab xa lawv mus rau qhov chaw nquag. Hauv E. cuniculi ribosomes, qhov thickening no tsis muaj; txawm li cas los xij, qhov thickening tshiab (G883) nyob tsuas yog nyob rau hauv peb lub hauv paus khub tuaj yeem pab txhawb rau kev kho dua tshiab ntawm qhov zoo tshaj plaws ntawm P stem (Daim duab 4c).
Peb cov ntaub ntawv ntawm rRNA tsis muaj bulges qhia tias rRNA minimization tsis txwv rau qhov poob ntawm rRNA cov ntsiab lus ntawm qhov chaw ntawm ribosome, tab sis kuj tseem yuav cuam tshuam rau ribosome nucleus, tsim ib qho parasite tshwj xeeb molecular defect uas tsis tau piav qhia hauv cov hlwb dawb-nyob. cov tsiaj txhu nyob tau pom.
Tom qab ua qauv rau cov protein ribosomal canonical thiab rRNA, peb pom tias cov khoom ribosomal ib txwm tsis tuaj yeem piav qhia peb ntu ntawm daim duab cryo-EM. Ob ntawm cov khoom no yog cov molecule me me hauv qhov loj me (Daim Duab 5, Daim Duab Ntxiv 8). Ntu thawj zaug yog sandwiched ntawm cov protein ribosomal uL15 thiab eL18 hauv qhov chaw feem ntau nyob los ntawm C-terminus ntawm eL18, uas luv dua hauv E. cuniculi. Txawm hais tias peb tsis tuaj yeem txiav txim siab tus kheej ntawm cov molecule no, qhov loj me thiab cov duab ntawm cov kob ceev no tau piav qhia zoo los ntawm qhov muaj cov molecule spermidine. Nws txoj kev khi rau ribosome yog stabilized los ntawm microsporidia-specific mutations hauv cov protein uL15 (Asp51 thiab Arg56), uas zoo li ua rau muaj kev sib raug zoo ntawm ribosome rau cov molecule me me no, vim lawv tso cai rau uL15 qhwv cov molecule me me rau hauv cov qauv ribosomal. Daim Duab Ntxiv 2). 8, cov ntaub ntawv ntxiv 1, 2).
Daim duab Cryo-EM qhia txog qhov muaj cov nucleotides sab nraum cov ribose khi rau E. cuniculi ribosome. Hauv E. cuniculi ribosome, cov nucleotide no nyob rau tib qho chaw li 25S rRNA A3186 nucleotide (Saccharomyces cerevisiae numbering) hauv feem ntau lwm cov eukaryotic ribosomes. b Hauv cov qauv ribosomal ntawm E. cuniculi, cov nucleotide no nyob nruab nrab ntawm cov protein ribosomal uL9 thiab eL20, yog li ua kom kev sib cuag ntawm ob cov protein ruaj khov. cd eL20 kev tshuaj xyuas kev txuag kab ke ntawm cov hom microsporidia. Tsob ntoo phylogenetic ntawm Microsporidia hom (c) thiab ntau qhov sib lawv liag ntawm cov protein eL20 (d) qhia tias cov nucleotide-binding residues F170 thiab K172 raug khaws cia rau hauv feem ntau Microsporidia, tshwj tsis yog S. lophii, tshwj tsis yog Microsporidia ceg thaum ntxov, uas khaws cia ES39L rRNA txuas ntxiv. e Daim duab no qhia tau hais tias cov nucleotide-binding residues F170 thiab K172 tsuas yog muaj nyob rau hauv eL20 ntawm cov microsporidia genome uas txo qis heev, tab sis tsis yog nyob rau hauv lwm cov eukaryotes. Zuag qhia tag nrho, cov ntaub ntawv no qhia tau hais tias Microsporidian ribosomes tau tsim ib qho chaw khi nucleotide uas zoo li khi AMP molecules thiab siv lawv los tswj cov protein-protein sib cuam tshuam hauv cov qauv ribosomal. Kev txuag siab ntawm qhov chaw khi no hauv Microsporidia thiab nws tsis muaj nyob rau hauv lwm cov eukaryotes qhia tau hais tias qhov chaw no yuav muab qhov zoo dua rau kev ciaj sia rau Microsporidia. Yog li, lub hnab tshos khi nucleotide hauv microsporidia ribosome zoo li tsis yog qhov tsis zoo lossis daim ntawv kawg ntawm rRNA degradation raws li tau piav qhia ua ntej, tab sis yog ib qho kev hloov pauv tshiab uas tso cai rau microsporidia ribosome khi cov molecules me me ncaj qha, siv lawv ua cov khoom siv molecular. cov khoom siv rau ribosomes. Qhov kev tshawb pom no ua rau microsporidia ribosome tsuas yog ribosome paub tias siv ib qho nucleotide ua nws cov khoom siv. f Txoj kev hloov pauv hypothetical uas tau los ntawm kev khi nucleotide.
Qhov thib ob qis molecular weight density nyob ntawm qhov interface ntawm ribosomal proteins uL9 thiab eL30 (Daim Duab 5a). Qhov interface no tau piav qhia ua ntej hauv cov qauv ntawm Saccharomyces cerevisiae ribosome ua qhov chaw khi rau 25S nucleotide ntawm rRNA A3186 (ib feem ntawm ES39L rRNA extension)38. Nws tau pom tias hauv degenerate P. locustae ES39L ribosomes, qhov interface no khi ib qho tsis paub nucleotide 31, thiab nws xav tias qhov nucleotide no yog daim ntawv kawg ntawm rRNA, uas qhov ntev ntawm rRNA yog ~ 130-230 lub hauv paus. ES39L raug txo kom ib qho nucleotide 32.43. Peb cov duab cryo-EM txhawb nqa lub tswv yim tias qhov ceev tuaj yeem piav qhia los ntawm nucleotides. Txawm li cas los xij, qhov kev daws teeb meem siab dua ntawm peb cov qauv qhia tau hais tias qhov nucleotide no yog ib qho extraribosomal molecule, tej zaum AMP (Daim Duab 5a, b).
Tom qab ntawd peb nug seb qhov chaw khi nucleotide puas tau tshwm sim hauv E. cuniculi ribosome lossis seb nws puas muaj yav dhau los. Txij li thaum nucleotide khi feem ntau yog los ntawm Phe170 thiab Lys172 residues hauv eL30 ribosomal protein, peb tau soj ntsuam qhov kev txuag ntawm cov residues no hauv 4396 tus sawv cev eukaryotes. Ib yam li hauv rooj plaub ntawm uL15 saum toj no, peb pom tias Phe170 thiab Lys172 residues tsuas yog khaws cia hauv Microsporidia ib txwm muaj, tab sis tsis muaj nyob hauv lwm cov eukaryotes, suav nrog atypical Microsporidia Mitosporidium thiab Amphiamblys, uas ES39L rRNA fragment tsis txo qis 44, 45, 46 (Daim duab 5c). -e).
Thaum muab cov ntaub ntawv no ua ke, txhawb nqa lub tswv yim tias E. cuniculi thiab tej zaum lwm cov kab mob me me uas muaj peev xwm tau tsim kom muaj peev xwm ntes tau cov metabolites me me hauv cov qauv ribosome kom them rau qhov poob qis hauv rRNA thiab cov protein. Thaum ua li ntawd, lawv tau tsim lub peev xwm tshwj xeeb los khi cov nucleotides sab nraum ribosome, qhia tias cov qauv molecular parasitic them rov qab los ntawm kev ntes cov metabolites me me thiab siv lawv ua cov qauv mimics ntawm RNA thiab cov protein fragments uas lwj.
Qhov thib peb tsis tau simulated ntawm peb daim ntawv qhia cryo-EM, pom nyob rau hauv lub ribosomal subunit loj. Qhov kev daws teeb meem siab (2.6 Å) ntawm peb daim ntawv qhia qhia tias qhov ceev no yog rau cov protein nrog kev sib xyaw ua ke ntawm cov saw hlau loj, uas tso cai rau peb txheeb xyuas qhov ceev no ua ib qho protein ribosomal tsis paub yav dhau los uas peb tau txheeb xyuas tias nws tau raug hu ua msL2 (Microsporidia- tshwj xeeb protein L2) (cov txheej txheem, daim duab 6). Peb qhov kev tshawb nrhiav homology qhia tau hais tias msL2 tau khaws cia hauv Microsporidia clade ntawm genus Encephaliter thiab Orosporidium, tab sis tsis muaj nyob rau hauv lwm hom tsiaj, suav nrog lwm Microsporidia. Hauv cov qauv ribosomal, msL2 nyob hauv qhov sib txawv tsim los ntawm kev poob ntawm ES31L rRNA txuas ntxiv. Hauv qhov khoob no, msL2 pab tswj rRNA folding thiab tuaj yeem them rau qhov poob ntawm ES31L (Daim duab 6).
a Qhov ceev ntawm Electron thiab qauv ntawm Microsporidia-specific ribosomal protein msL2 pom muaj nyob rau hauv E. cuniculi ribosomes. b Feem ntau eukaryotic ribosomes, suav nrog 80S ribosome ntawm Saccharomyces cerevisiae, muaj ES19L rRNA amplification poob rau hauv feem ntau Microsporidian hom. Cov qauv tsim ua ntej ntawm V. necatrix microsporidia ribosome qhia tias qhov poob ntawm ES19L hauv cov kab mob no tau them los ntawm kev hloov pauv ntawm cov protein msL1 ribosomal tshiab. Hauv kev tshawb fawb no, peb pom tias E. cuniculi ribosome kuj tau tsim cov protein ribosomal RNA ntxiv ua qhov kev them nyiaj rau qhov poob ntawm ES19L. Txawm li cas los xij, msL2 (tam sim no tau sau tseg ua cov protein hypothetical ECU06_1135) thiab msL1 muaj cov qauv sib txawv thiab keeb kwm hloov pauv. c Qhov kev tshawb pom no ntawm kev tsim cov protein msL1 thiab msL2 ribosomal uas tsis muaj feem cuam tshuam qhia tias yog tias ribosomes sib sau ua ke cov kev hloov pauv tsis zoo hauv lawv cov rRNA, lawv tuaj yeem ua tiav qib tsis tau muaj dua ntawm kev sib txawv ntawm cov khoom sib xyaw txawm tias yog ib pawg me me ntawm cov tsiaj txhu uas muaj feem cuam tshuam ze. Qhov kev tshawb pom no tuaj yeem pab qhia meej txog keeb kwm thiab kev hloov pauv ntawm mitochondrial ribosome, uas paub txog nws cov rRNA txo qis heev thiab kev hloov pauv tsis zoo hauv cov protein sib xyaw thoob plaws cov tsiaj txhu.
Tom qab ntawd peb piv cov protein msL2 nrog cov protein msL1 uas tau piav qhia ua ntej, tsuas yog cov protein ribosomal uas paub txog microsporidia uas pom muaj nyob hauv V. necatrix ribosome. Peb xav sim seb msL1 thiab msL2 puas muaj feem cuam tshuam nrog kev hloov pauv. Peb qhov kev tshuaj xyuas qhia tau tias msL1 thiab msL2 nyob hauv tib lub qhov hauv cov qauv ribosomal, tab sis muaj cov qauv thawj thiab theem peb sib txawv, uas qhia txog lawv keeb kwm kev hloov pauv ywj pheej (Daim Duab 6). Yog li, peb qhov kev tshawb pom ntawm msL2 muab pov thawj tias cov pab pawg ntawm cov hom eukaryotic compact tuaj yeem hloov pauv ywj pheej ntawm cov protein ribosomal sib txawv los them rau qhov poob ntawm rRNA fragments. Qhov kev tshawb pom no yog qhov tseem ceeb hauv qhov feem ntau cytoplasmic eukaryotic ribosomes muaj cov protein tsis hloov pauv, suav nrog tib tsev neeg ntawm 81 ribosomal proteins. Qhov tshwm sim ntawm msL1 thiab msL2 hauv ntau pawg ntawm microsporidia teb rau qhov poob ntawm cov ntu rRNA ntev qhia tau hais tias kev puas tsuaj ntawm cov qauv molecular ntawm tus kab mob ua rau cov kab mob nrhiav kev hloov pauv, uas thaum kawg yuav ua rau lawv tau txais hauv cov pej xeem kab mob sib txawv.
Thaum kawg, thaum peb tus qauv tiav lawm, peb tau piv cov khoom sib xyaw ntawm E. cuniculi ribosome nrog qhov kwv yees los ntawm cov kab ke genome. Ntau cov protein ribosomal, suav nrog eL14, eL38, eL41, thiab eS30, yav dhau los tau xav tias ploj ntawm E. cuniculi genome vim tsis muaj lawv cov homologues los ntawm E. cuniculi genome. Kev poob ntawm ntau cov protein ribosomal kuj tau kwv yees hauv feem ntau lwm cov kab mob hauv lub hlwb thiab endosymbionts uas txo qis heev. Piv txwv li, txawm hais tias feem ntau cov kab mob uas muaj sia nyob dawb muaj tib tsev neeg ntawm 54 cov protein ribosomal, tsuas yog 11 ntawm cov tsev neeg protein no muaj cov homologues pom tau hauv txhua lub genome uas tau soj ntsuam ntawm cov kab mob uas txwv tsis pub tus tswv tsev. Txhawm rau txhawb nqa lub tswv yim no, kev poob ntawm cov protein ribosomal tau pom los ntawm kev sim hauv V. necatrix thiab P. locustae microsporidia, uas tsis muaj cov protein eL38 thiab eL4131,32.
Txawm li cas los xij, peb cov qauv qhia tau tias tsuas yog eL38, eL41, thiab eS30 xwb thiaj li ploj mus hauv E. cuniculi ribosome. Cov protein eL14 tau khaws cia thiab peb cov qauv qhia tau tias vim li cas cov protein no thiaj li tsis pom hauv kev tshawb nrhiav homology (Daim Duab 7). Hauv E. cuniculi ribosomes, feem ntau ntawm qhov chaw khi eL14 ploj mus vim yog kev puas tsuaj ntawm rRNA-amplified ES39L. Yog tsis muaj ES39L, eL14 poob feem ntau ntawm nws cov qauv theem nrab, thiab tsuas yog 18% ntawm cov kab ke eL14 zoo ib yam hauv E. cuniculi thiab S. cerevisiae. Qhov kev khaws cia tsis zoo no yog qhov zoo kawg nkaus vim tias txawm tias Saccharomyces cerevisiae thiab Homo sapiens - cov kab mob uas tau hloov zuj zus 1.5 billion xyoo sib nrug - sib koom ntau dua 51% ntawm cov seem zoo ib yam hauv eL14. Qhov kev poob qis ntawm kev txuag no piav qhia vim li cas E. cuniculi eL14 tam sim no tau sau tseg tias yog cov protein M970_061160 thiab tsis yog cov protein ribosomal eL1427.
thiab Microsporidia ribosome poob qhov ES39L rRNA extension, uas ib feem tshem tawm qhov chaw khi eL14 ribosomal protein. Yog tsis muaj ES39L, eL14 microspore protein raug poob ntawm cov qauv theem ob, uas qhov qub rRNA-binding α-helix degenerates mus rau hauv lub voj voog ntev tsawg kawg nkaus. b Ntau qhov kev sib phim ua ke qhia tau hais tias eL14 protein raug khaws cia zoo heev hauv cov tsiaj eukaryotic (57% qhov sib piv ntawm cov poov xab thiab tib neeg homologues), tab sis tsis zoo khaws cia thiab sib txawv hauv microsporidia (uas tsis pub ntau tshaj 24% ntawm cov seem zoo ib yam li eL14 homologue). los ntawm S. cerevisiae lossis H. sapiens). Qhov kev khaws cia tsis zoo no thiab qhov sib txawv ntawm cov qauv theem ob piav qhia vim li cas eL14 homologue yeej tsis tau pom hauv E. cuniculi thiab vim li cas cov protein no xav tias tau ploj hauv E. cuniculi. Nyob rau hauv kev sib piv, E. cuniculi eL14 tau raug sau tseg ua ib qho protein M970_061160. Qhov kev soj ntsuam no qhia tau hais tias qhov sib txawv ntawm microsporidia genome tam sim no raug kwv yees ntau dhau: qee cov noob caj noob ces tam sim no xav tias ploj hauv microsporidia qhov tseeb tau khaws cia, txawm hais tias nyob rau hauv cov ntawv sib txawv heev; hloov chaw, qee qhov xav tias yuav code rau microsporidia noob caj noob ces rau cov protein tshwj xeeb rau cov kab mob (piv txwv li, cov protein hypothetical M970_061160) qhov tseeb codes rau cov protein sib txawv heev pom nyob rau hauv lwm cov eukaryotes.
Qhov kev tshawb pom no qhia tau hais tias rRNA denaturation tuaj yeem ua rau muaj kev poob qis ntawm kev khaws cia cov kab ke hauv cov protein ribosomal uas nyob ib sab, ua rau cov protein no tsis pom kev rau kev tshawb nrhiav homology. Yog li, peb yuav kwv yees qhov tseeb ntawm kev puas tsuaj ntawm cov molecular hauv cov kab mob me me genome, vim tias qee cov protein uas xav tias ploj lawm yeej tseem nyob, txawm tias nyob rau hauv cov ntawv hloov pauv heev.
Cov kab mob parasitic yuav ua li cas thiaj li khaws tau lawv cov tshuab molecular hauv qab cov xwm txheej ntawm kev txo qis genome heev? Peb txoj kev tshawb fawb teb cov lus nug no los ntawm kev piav qhia txog cov qauv molecular nyuaj (ribosome) ntawm E. cuniculi, ib yam kab mob uas muaj ib qho ntawm cov genomes eukaryotic me tshaj plaws.
Nws tau paub txog yuav luag ob xyoo caum lawm tias cov protein thiab RNA molecules hauv cov kab mob me me feem ntau txawv ntawm lawv cov molecules zoo sib xws hauv cov tsiaj txhu uas muaj sia nyob dawb vim tias lawv tsis muaj cov chaw tswj xyuas zoo, raug txo kom txog 50% ntawm lawv qhov loj me hauv cov kab mob me me uas muaj sia nyob dawb, thiab lwm yam. ntau qhov kev hloov pauv uas ua rau lub cev tsis zoo uas ua rau lub cev tsis yooj yim thiab ua haujlwm. Piv txwv li, cov ribosomes ntawm cov kab mob me me genome, suav nrog ntau cov kab mob intracellular thiab endosymbionts, xav tias yuav tsis muaj ntau cov protein ribosomal thiab txog li ib feem peb ntawm rRNA nucleotides piv rau cov tsiaj txhu uas muaj sia nyob dawb 27, 29, 30, 49. Txawm li cas los xij, txoj kev uas cov molecules no ua haujlwm hauv cov kab mob tseem yog qhov paub tsis meej, kawm feem ntau los ntawm kev sib piv genomics.
Peb txoj kev tshawb fawb qhia tau hais tias cov qauv ntawm macromolecules tuaj yeem qhia ntau yam ntawm kev hloov pauv uas nyuaj rau rho tawm los ntawm kev tshawb fawb sib piv genomic ntawm cov kab mob hauv lub hlwb thiab lwm yam kab mob txwv tsis pub tus tswv tsev (Supplementary Fig. 7). Piv txwv li, piv txwv ntawm eL14 protein qhia tau hais tias peb tuaj yeem kwv yees qhov tseeb ntawm kev puas tsuaj ntawm cov khoom siv molecular hauv cov kab mob parasitic. Encephalitic parasites tam sim no ntseeg tias muaj ntau pua tus microsporidia-specific genes. Txawm li cas los xij, peb cov txiaj ntsig qhia tau hais tias qee cov noob caj noob ces tshwj xeeb no tsuas yog cov noob caj noob ces sib txawv heev uas muaj nyob rau hauv lwm cov eukaryotes. Ntxiv mus, piv txwv ntawm msL2 protein qhia tau hais tias peb tsis quav ntsej txog cov protein ribosomal tshiab thiab tsis quav ntsej txog cov ntsiab lus ntawm cov tshuab molecular parasitic. Piv txwv ntawm cov molecules me me qhia tau hais tias peb tuaj yeem tsis quav ntsej txog cov kev hloov pauv tshiab tshaj plaws hauv cov qauv molecular parasitic uas tuaj yeem muab rau lawv cov haujlwm tshiab.
Thaum muab cov txiaj ntsig no ua ke, peb nkag siab zoo dua txog qhov sib txawv ntawm cov qauv molecular ntawm cov kab mob uas raug txwv los ntawm tus tswv tsev thiab lawv cov neeg sib tw hauv cov kab mob uas muaj sia nyob dawb. Peb qhia tau tias cov tshuab molecular, uas tau xav tias yuav raug txo qis, lwj, thiab raug rau ntau yam kev hloov pauv uas ua rau lub cev tsis muaj zog, hloov chaw muaj cov yam ntxwv tsis zoo uas tsis tau saib xyuas.
Ntawm qhov tod tes, cov rRNA uas tsis loj thiab cov khoom sib xyaw uas peb pom hauv ribosomes ntawm E. cuniculi qhia tias kev txo qis genome tuaj yeem hloov pauv txawm tias cov khoom ntawm cov tshuab molecular yooj yim uas tau khaws cia rau hauv peb thaj chaw ntawm lub neej - tom qab yuav luag 3.5 billion xyoo. kev hloov pauv ywj pheej ntawm cov tsiaj.
Cov khoom tawg rRNA uas tsis muaj bulge thiab fused hauv E. cuniculi ribosomes yog qhov txaus siab tshwj xeeb hauv lub teeb ntawm kev tshawb fawb yav dhau los ntawm RNA molecules hauv cov kab mob endosymbiotic. Piv txwv li, hauv aphid endosymbiont Buchnera aphidicola, rRNA thiab tRNA molecules tau pom tias muaj cov qauv kub-sensitive vim yog A + T composition bias thiab feem ntau ntawm cov khub tsis-canonical base 20,50. Cov kev hloov pauv no hauv RNA, nrog rau kev hloov pauv hauv cov protein molecules, tam sim no xav tias yog lub luag haujlwm rau kev vam khom ntawm endosymbionts ntawm cov neeg koom tes thiab tsis muaj peev xwm ntawm endosymbionts hloov cua sov 21, 23. Txawm hais tias parasitic microsporidia rRNA muaj kev hloov pauv sib txawv, qhov xwm txheej ntawm cov kev hloov pauv no qhia tias kev ruaj khov thermal txo qis thiab kev vam khom ntau dua rau cov protein chaperone tej zaum yuav yog cov yam ntxwv ntawm RNA molecules hauv cov kab mob uas muaj genomes txo qis.
Ntawm qhov tod tes, peb cov qauv qhia tau hais tias cov kab mob microsporidia tau tsim muaj peev xwm tshwj xeeb los tiv thaiv cov rRNA thiab cov protein fragments uas tau khaws cia dav dav, tsim kom muaj peev xwm siv cov metabolites me me thiab yooj yim muaj raws li cov qauv mimics ntawm degenerate rRNA thiab cov protein fragments. Kev puas tsuaj ntawm cov qauv molecular. . Lub tswv yim no tau txhawb nqa los ntawm qhov tseeb tias cov molecules me me uas them rau qhov poob ntawm cov protein fragments hauv rRNA thiab ribosomes ntawm E. cuniculi khi rau microsporidia-specific residues hauv uL15 thiab eL30 proteins. Qhov no qhia tau hais tias kev khi ntawm cov molecules me me rau ribosomes yuav yog cov khoom ntawm kev xaiv zoo, uas Microsporidia-specific mutations hauv ribosomal proteins tau raug xaiv rau lawv lub peev xwm los ua kom muaj kev sib raug zoo ntawm ribosomes rau cov molecules me me, uas yuav ua rau cov kab mob ribosomal ua haujlwm zoo dua. Qhov kev tshawb pom qhia txog kev tsim kho tshiab hauv cov qauv molecular ntawm cov kab mob microbial thiab muab rau peb nkag siab zoo dua txog yuav ua li cas cov qauv molecular parasite tswj lawv txoj haujlwm txawm tias muaj kev hloov pauv tsawg.
Tam sim no, kev txheeb xyuas cov molecule me me no tseem tsis meej. Nws tsis meej vim li cas qhov tsos ntawm cov molecule me me no hauv cov qauv ribosomal txawv ntawm microsporidia hom. Tshwj xeeb, nws tsis meej vim li cas nucleotide khi tau pom nyob rau hauv ribosomes ntawm E. cuniculi thiab P. locustae, thiab tsis nyob rau hauv ribosomes ntawm V. necatrix, txawm tias muaj F170 residue hauv eL20 thiab K172 proteins ntawm V. necatrix. Qhov kev rho tawm no yuav tshwm sim los ntawm residue 43 uL6 (nyob ib sab ntawm lub hnab tshos khi nucleotide), uas yog tyrosine hauv V. necatrix thiab tsis yog threonine hauv E. cuniculi thiab P. locustae. Lub bulky aromatic sab saw ntawm Tyr43 tuaj yeem cuam tshuam nrog nucleotide khi vim steric overlap. Xwb, qhov pom tseeb nucleotide deletion yuav yog vim qhov kev daws teeb meem qis ntawm cryo-EM imaging, uas cuam tshuam rau kev ua qauv ntawm V. necatrix ribosomal fragments.
Ntawm qhov tod tes, peb txoj haujlwm qhia tau hais tias cov txheej txheem ntawm kev lwj ntawm genome tej zaum yuav yog lub zog tsim kho tshiab. Tshwj xeeb, cov qauv ntawm E. cuniculi ribosome qhia tau hais tias qhov poob ntawm rRNA thiab cov protein fragments hauv microsporidia ribosome tsim kev nyuaj siab uas txhawb kev hloov pauv hauv cov qauv ribosome. Cov variants no tshwm sim deb ntawm qhov chaw nquag ntawm ribosome thiab zoo li pab tswj (lossis rov qab kho) qhov zoo tshaj plaws ribosome sib dhos uas yuav raug cuam tshuam los ntawm txo qis rRNA. Qhov no qhia tau hais tias qhov kev hloov pauv tseem ceeb ntawm microsporidia ribosome zoo li tau hloov pauv mus rau qhov xav tau buffer gene drift.
Tej zaum qhov no yog qhov zoo tshaj plaws los ntawm kev khi nucleotide, uas yeej tsis tau pom dua hauv lwm yam kab mob txog tam sim no. Qhov tseeb tias cov seem khi nucleotide muaj nyob rau hauv cov microsporidia ib txwm muaj, tab sis tsis yog nyob rau hauv lwm cov eukaryotes, qhia tias cov chaw khi nucleotide tsis yog tsuas yog cov khoom seem tos kom ploj mus, lossis qhov chaw kawg rau rRNA kom rov qab los ua daim ntawv ntawm cov nucleotides ib leeg. Hloov chaw, qhov chaw no zoo li yog ib qho tseem ceeb uas yuav tau hloov pauv ntau qhov kev xaiv zoo. Cov chaw khi nucleotide tej zaum yuav yog cov khoom lag luam ntawm kev xaiv ntuj: thaum ES39L raug rhuav tshem, microsporidia raug yuam kom nrhiav kev them nyiaj los rov qab kho qhov zoo tshaj plaws ribosome biogenesis hauv qhov tsis muaj ES39L. Txij li thaum nucleotide no tuaj yeem ua raws li cov kev sib cuag molecular ntawm A3186 nucleotide hauv ES39L, lub molecule nucleotide dhau los ua lub tsev thaiv ntawm ribosome, qhov kev khi ntawm uas tau txhim kho ntxiv los ntawm kev hloov pauv ntawm eL30 kab lus.
Hais txog kev hloov pauv ntawm cov kab mob hauv lub hlwb, peb txoj kev tshawb fawb qhia tau hais tias lub zog ntawm Darwinian kev xaiv ntuj thiab kev hloov pauv ntawm cov noob caj noob ces tsis ua haujlwm sib luag, tab sis oscillate. Ua ntej, kev hloov pauv ntawm cov noob caj noob ces tshem tawm cov yam ntxwv tseem ceeb ntawm biomolecules, ua rau kev them nyiaj xav tau heev. Tsuas yog thaum cov kab mob ua tiav qhov kev xav tau no los ntawm Darwinian kev xaiv ntuj yuav lawv cov macromolecules muaj lub sijhawm los tsim lawv cov yam ntxwv zoo tshaj plaws thiab tshiab. Qhov tseem ceeb, kev hloov pauv ntawm nucleotide khi qhov chaw hauv E. cuniculi ribosome qhia tias qhov kev poob-rau-nce ntawm cov qauv kev hloov pauv molecular tsis yog tsuas yog amortizes deleterious mutations, tab sis qee zaum muab cov haujlwm tshiab rau cov kab mob macromolecules.
Lub tswv yim no yog sib xws nrog Sewell Wright txoj kev xav txog kev sib npaug ntawm kev txav mus los, uas hais tias ib qho kev xaiv ntuj tsim txwv tsis pub cov kab mob muaj peev xwm tsim kho tshiab51,52,53. Txawm li cas los xij, yog tias kev hloov pauv ntawm cov noob caj noob ces cuam tshuam kev xaiv ntuj tsim, cov kev hloov pauv no tuaj yeem tsim cov kev hloov pauv uas tsis yog lawv tus kheej hloov kho (lossis txawm tias ua rau puas tsuaj) tab sis ua rau muaj kev hloov pauv ntxiv uas muab kev noj qab haus huv zoo dua lossis kev ua haujlwm tshiab ntawm cov kab mob. Peb lub moj khaum txhawb nqa lub tswv yim no los ntawm kev piav qhia tias tib hom kev hloov pauv uas txo qhov quav thiab kev ua haujlwm ntawm biomolecule zoo li yog qhov ua rau nws txhim kho. Nyob rau hauv kab nrog tus qauv kev hloov pauv yeej-yeej, peb txoj kev tshawb fawb qhia tau hais tias kev lwj ntawm genome, ib txwm pom tias yog cov txheej txheem degenerative, kuj yog tus tsav tsheb tseem ceeb ntawm kev tsim kho tshiab, qee zaum thiab tej zaum txawm tias feem ntau tso cai rau macromolecules kom tau txais cov haujlwm parasitic tshiab. tuaj yeem siv lawv.