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Kwiminyaka elishumi edlulileyo, iteknoloji yokuhlela i-gene esekelwe kwi-CRISPR iye yaphuhliswa ngokukhawuleza, kwaye isetyenziswe ngempumelelo kunyango lwezifo zofuzo kunye nomhlaza kwizilingo zeklinikhi zabantu.Kwangaxeshanye, izazinzulu kwihlabathi liphela zihlala zicofa izixhobo ezitsha ezinokuthi zikwazi ukusombulula iingxaki zezixhobo esele zikho zokuhlela imfuza kunye nezigqibo.

NgoSeptemba 2021, iqela likaZhang Feng lapapasha iphepha kwijenali yeSayensi [1], kwaye yafumanisa ukuba uluhlu olubanzi lwee-transposters ezinekhowudi ye-RNA ekhokela i-nucleic acid enzymes kwaye yayithiya i-Omega system (kubandakanywa ne-ISCB, ISRB, TNP8).Uphononongo luphinde lwafumanisa ukuba inkqubo ye-Omega isebenzisa icandelo le-RNA ukukhokela i-DNA yokusika i-chain chain, eyi-ωRNA.Okubaluleke ngakumbi, ezi enzymes ze-nucleic acid zincinci kakhulu, kuphela malunga ne-30% ye-CAS9, okuthetha ukuba kunokwenzeka ukuba zisiwe kwiiseli.

ISRB1

Ngo-Okthobha we-12, i-2022, iqela likaZhang Feng lapapashwa kwijenali yeNdalo enesihloko esithi: Ulwakhiwo lwe-Omega Nickase ISRB kwi-Complex ene-ωrna kunye ne-Target DNA [2].

Uphononongo luphinde lwahlalutya ubume be-electron microscope ekhenkcezisiweyo ye-ISRB-ωRNA kunye ne-DNA ekujoliswe kuyo kwinkqubo ye-Omega.

I-ISCB ingukhokho we-CAS9, kwaye i-ISRB yinto efanayo yokungabikho kwe-HNH nucleic acid domain ye-ISCB, ngoko ubungakanani buncinci, kuphela malunga ne-350 amino acids.I-DNA ikwabonelela ngesiseko sophuhliso olongezelelweyo kunye nenguqu yobunjineli.

ISRB2

I-IsrB ekhokelwa yi-RNA lilungu losapho lwe-OMEGA olufakwe ngekhowudi yi-IS200/IS605 superfamily of transposons.Ukususela kuhlalutyo lwe-phylogenetic kunye neendawo ezizodwa ezabelwana ngazo, i-IsrB inokuthi ibe yi-precursor ye-IscB, engukhokho we-Cas9.

NgoMeyi ka-2022, iYunivesithi yaseCornell iLovely Dragon Laboratory yapapasha iphepha kwijenali yeSayensi [3], ihlalutya ubume be-IscB-ωRNA kunye nendlela yayo yokusika iDNA.

ISRB3

Xa kuthelekiswa ne-IscB kunye ne-Cas9, i-IsrB ayinayo i-nuclease domain ye-HNH, i-REC lobe, kunye neninzi ye-PAM ye-sequence-interacting domains, ngoko i-IsrB incinci kakhulu kune-Cas9 (kuphela malunga ne-350 amino acids).Nangona kunjalo, ubungakanani obuncinci be-IsrB bulungelelaniswa yi-RNA yesikhokelo esikhulu (i-omega RNA yayo imalunga ne-300 nt ubude).

Iqela likaZhang Feng lihlalutye i-cryo-electron microscope structure ye-IsrB (DtIsrB) ukusuka kwibhaktheriya efumileyo yobushushu be-anaerobic i-Desulfovirgula thermocuniculi kunye ne-complex ye-ωRNA kunye ne-DNA ekujoliswe kuyo.Uhlalutyo lwezakhiwo lubonise ukuba ulwakhiwo olupheleleyo lweprotheyini ye-IsrB yabelana ngesakhiwo somqolo kunye neprotheni ye-Cas9.

Kodwa umahluko kukuba i-Cas9 isebenzisa i-REC lobe ukuququzelela ukuqondwa kwethagethi, ngelixa i-IsrB ixhomekeke kwi-ωRNA yayo, inxalenye yayo eyenza isakhiwo esiyinkimbinkimbi se-dimensional emithathu esebenza njenge-REC.

ISRB4

Ukuqonda ngcono utshintsho lwesakhiwo se-IsrB kunye ne-Cas9 ngexesha lokuziphendukela kwemvelo kwi-RuvC, iqela likaZhang Feng lithelekisa i-DNA-binding ekujoliswe kuyo ye-RuvC (TtRuvC), i-IsrB, i-CjCas9 kunye ne-SpCas9 esuka kwi-Thermus thermophilus.

ISRB5

Uhlalutyo lwesakhiwo se-IsrB kunye ne-ωRNA yayo icacisa indlela i-IsrB-ωRNA eyamkela ngayo ngokudibeneyo kwaye icande i-DNA ekujoliswe kuyo, kwaye ikwabonelela ngesiseko sophuhliso olongezelelweyo kunye nobunjineli bale nuclease encinci.Ukuthelekiswa nezinye iinkqubo ezikhokelwa yi-RNA zigxininisa intsebenziswano esebenzayo phakathi kweeprotheyini kunye nee-RNAs, ukuqhubela phambili ukuqonda kwethu ibhayoloji kunye nokuvela kwezi nkqubo zahlukeneyo.

Unxulumano:

1.https://www.science.org/doi/10.1126/science.abj6856

2.https://www.science.org/doi/10.1126/science.abq7220

3.https://www.nature.com/articles/s41586-022-05324-6


Ixesha lokuposa: Oct-14-2022