M'zaka khumi zapitazi, teknoloji yokonza jini yochokera ku CRISPR yakula mofulumira, ndipo yagwiritsidwa ntchito bwino pochiza matenda a chibadwa ndi khansa m'mayesero a anthu.Nthawi yomweyo, asayansi padziko lonse lapansi amangogwiritsa ntchito zida zatsopano zomwe zimatha kusintha jini kuti athetse mavuto a zida zosinthira ma gene ndi zosankha.

Mu Seputembala 2021, gulu la Zhang Feng lidasindikiza pepala mu nyuzipepala ya Science [1], ndipo idapeza kuti ma transposters angapo adalemba ma enzymes a RNA owongolera ma nucleic acid ndikuutcha Omega system (kuphatikiza ISCB, ISRB, TNP8).Kafukufukuyu adapezanso kuti dongosolo la Omega limagwiritsa ntchito gawo la RNA kuwongolera unyolo wapawiri wa DNA, womwe ndi ωRNA.Chofunika kwambiri, ma enzymes a nucleic acid ndi ochepa kwambiri, pafupifupi 30% ya CAS9, zomwe zikutanthauza kuti atha kuperekedwa kumaselo.

Pa Okutobala 12, 2022, gulu la Zhang Feng lidasindikiza mu Nature magazine yotchedwa: Structure of the Omega Nickase ISRB in Complex with ωrna and Target DNA [2].

Kafukufukuyu adasanthulanso mawonekedwe a ma electron microscope a ISRB-ωRNA ndi chandamale cha DNA mu dongosolo la Omega.

ISCB ndi kholo la CAS9, ndipo ISRB ndi chinthu chomwecho cha kusowa kwa HNH nucleic acid domain ya ISCB, kotero kukula kwake ndi kochepa, pafupifupi 350 amino acid.DNA imaperekanso maziko opititsa patsogolo chitukuko ndi kusintha kwa uinjiniya.

IsrB yotsogoleredwa ndi RNA ndi membala wa banja la OMEGA losungidwa ndi IS200/IS605 superfamily of transposons.Kuchokera kusanthula kwa phylogenetic ndikugawana madera apadera, IsrB ikuyenera kukhala kalambulabwalo wa IscB, yemwe ndi kholo la Cas9.

Mu Meyi 2022, University of Cornell's Lovely Dragon Laboratory idasindikiza pepala mu nyuzipepala Science [3], kusanthula kapangidwe ka IscB-ωRNA ndi momwe amacheka DNA.

Poyerekeza ndi IscB ndi Cas9, IsrB ilibe dera la HNH nuclease, REC lobe, ndi madera ambiri a PAM omwe amayenderana, kotero IsrB ndi yaying'ono kwambiri kuposa Cas9 (zokha za 350 amino acids).Komabe, kukula kochepa kwa IsrB kumayenderana ndi kalozera wamkulu wa RNA (omega RNA yake ndi pafupifupi 300 nt kutalika).

Gulu la Zhang Feng lidasanthula mawonekedwe a cryo-electron maikulosikopu a IsrB (DtIsrB) kuchokera ku bakiteriya yonyowa-kutentha ya anaerobic Desulfovirgula thermocuniculi ndi zovuta zake za ωRNA ndi DNA ya chandamale.Kusanthula kwamapangidwe kunawonetsa kuti mawonekedwe onse a protein ya IsrB adagawana kapangidwe ka msana ndi mapuloteni a Cas9.

Koma kusiyana kwake ndikuti Cas9 imagwiritsa ntchito lobe ya REC kuti ithandizire kuzindikira chandamale, pomwe IsrB imadalira ωRNA yake, gawo lomwe limapanga mawonekedwe ovuta atatu omwe amakhala ngati REC.

Kuti mumvetse bwino kusintha kwa kamangidwe ka IsrB ndi Cas9 panthawi yachisinthiko kuchokera ku RuvC, gulu la Zhang Feng linayerekezera zomwe mukufuna DNA-binding nyumba za RuvC (TtRuvC), IsrB, CjCas9 ndi SpCas9 kuchokera ku Thermus thermophilus.

Kusanthula kwadongosolo kwa IsrB ndi ωRNA yake kumamveketsa bwino momwe IsrB-ωRNA imazindikirira pamodzi ndikudula DNA chandamale, komanso imapereka maziko opititsa patsogolo chitukuko ndi uinjiniya wa nyukiliya yaying'ono iyi.Kuyerekeza ndi machitidwe ena otsogozedwa ndi RNA amawonetsa kuyanjana kwa magwiridwe antchito pakati pa mapuloteni ndi ma RNA, kupititsa patsogolo kumvetsetsa kwathu kwa biology ndi kusinthika kwa machitidwe osiyanasiyanawa.

Maulalo:

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