Nyob rau hauv kaum xyoo dhau los, cov noob kho cov thev naus laus zis raws li CRISPR tau tsim kho sai, thiab tau ua tiav zoo rau kev kho cov kab mob caj ces thiab mob qog noj ntshav hauv tib neeg kev sim tshuaj.Nyob rau tib lub sijhawm, cov kws tshawb fawb thoob plaws ntiaj teb niaj hnub siv cov cuab yeej tshiab tshiab nrog cov noob kho cov peev txheej los daws cov teeb meem ntawm cov cuab yeej kho cov noob tam sim no thiab txiav txim siab.

Thaum lub Cuaj Hlis 2021, Zhang Feng pab pawg tau luam tawm ib daim ntawv hauv Science journal [1], thiab pom tias ntau yam ntawm cov transposters code RNA coj nucleic acid enzymes thiab hu ua Omega system (xws li ISCB, ISRB, TNP8).Txoj kev tshawb no kuj pom tias Omega system siv ib ntu ntawm RNA los coj cov kev txiav DNA dual saw, uas yog ωRNA.Qhov tseem ceeb tshaj, cov enzymes nucleic acid no tsawg heev, tsuas yog kwv yees li 30% ntawm CAS9, uas txhais tau hais tias lawv yuav raug xa mus rau cov hlwb ntau dua.

Thaum Lub Kaum Hli 12, 2022, Zhang Feng cov pab pawg tau luam tawm nyob rau hauv Nature phau ntawv xov xwm hu ua: Cov qauv ntawm Omega Nickase ISRB hauv Complex nrog ωrna thiab Target DNA [2].

Txoj kev tshawb fawb ntxiv tau txheeb xyuas cov qauv khov electron microscope ntawm ISRB-ωRNA thiab lub hom phiaj DNA complex hauv Omega system.

ISCB yog cov poj koob yawm txwv ntawm CAS9, thiab ISRB yog tib yam khoom ntawm qhov tsis muaj HNH nucleic acid domain ntawm ISCB, yog li qhov loj me me, tsuas yog kwv yees li 350 amino acids.DNA tseem muab lub hauv paus rau kev txhim kho ntxiv thiab kev hloov pauv engineering.

RNA-guided IsrB yog ib tug tswv cuab ntawm tsev neeg OMEGA encoded los ntawm IS200/IS605 superfamily ntawm transposons.Los ntawm kev txheeb xyuas phylogenetic thiab sib koom ua ke tshwj xeeb, IsrB zoo li yuav yog tus thawj coj ntawm IscB, uas yog poj koob yawm txwv ntawm Cas9.

Thaum lub Tsib Hlis 2022, Cornell University's Lovely Dragon Laboratory tau luam tawm ib daim ntawv hauv phau ntawv Journal Science [3], txheeb xyuas cov qauv ntawm IscB-ωRNA thiab nws cov txheej txheem ntawm kev txiav DNA.

Piv nrog IscB thiab Cas9, IsrB tsis muaj HNH nuclease domain, REC lobe, thiab feem ntau ntawm PAM cov kab ke sib cuam tshuam, yog li IsrB tsawg dua li Cas9 (tsuas yog kwv yees li 350 amino acids).Txawm li cas los xij, qhov me me ntawm IsrB yog sib npaug los ntawm cov lus qhia loj RNA (nws omega RNA yog li 300 nt ntev).

Zhang Feng pab pawg tau tshuaj xyuas cov qauv cryo-electron microscope ntawm IsrB (DtIsrB) los ntawm cov kab mob damp-heat anaerobic kab mob Desulfovirgula thermocuniculi thiab nws cov complex ntawm ωRNA thiab lub hom phiaj DNA.Cov qauv kev soj ntsuam pom tau hais tias tag nrho cov qauv ntawm IsrB protein sib koom ua ke cov pob txha caj qaum nrog Cas9 protein.

Tab sis qhov txawv yog tias Cas9 siv REC lobe los pab txhawb lub hom phiaj kev paub, thaum IsrB tso siab rau nws ωRNA, ib feem ntawm cov qauv tsim peb sab uas ua haujlwm zoo li REC.

Txhawm rau kom nkag siab zoo dua cov kev hloov pauv ntawm IsrB thiab Cas9 thaum lub sijhawm hloov pauv los ntawm RuvC, Zhang Feng pab pawg tau sib piv cov hom phiaj DNA-binding qauv ntawm RuvC (TtRuvC), IsrB, CjCas9 thiab SpCas9 los ntawm Thermus thermophilus .

Kev txheeb xyuas cov qauv ntawm IsrB thiab nws ωRNA qhia meej li cas IsrB-ωRNA koom ua ke lees paub thiab tshem tawm lub hom phiaj DNA, thiab tseem muab lub hauv paus rau kev txhim kho ntxiv thiab kev tsim vaj tsev ntawm cov nuclease miniaturized no.Kev sib piv nrog rau lwm cov RNA-kev coj ua qhia txog kev ua haujlwm ntawm cov proteins thiab RNAs, ua rau peb nkag siab txog biology thiab evolution ntawm ntau hom kab ke.

Txuas:

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