8j12
Cryo-EM structure of the AsCas12f-sgRNA-target DNA ternary complex
Structural highlights
FunctionCS12F_SULT2 CRISPR (clustered regularly interspaced short palindromic repeat), is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain sequences complementary to antecedent mobile elements and target invading nucleic acids (Probable). CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA), which requires a trans-encoded small RNA (tracrRNA), but not this protein (By similarity). Recognizes a short motif in the CRISPR repeat sequences (the 5' PAM or protospacer adjacent motif, YTT in this organism) to help distinguish self versus nonself, as targets within the CRISPR locus do not have PAMs. Has dsDNA endonuclease activity upon expression in E.coli of this protein, a mini CRISPR array and the probable tracrRNA. Plasmid cleavage is centered around positions 19-24 base pairs 3' of PAM. The mini system protects E.coli against transformation by foreign plasmids (PubMed:32246713).[UniProtKB:A0A482D308][1] [2] Publication Abstract from PubMedSpCas9 and AsCas12a are widely utilized as genome-editing tools in human cells. However, their relatively large size poses a limitation for delivery by cargo-size-limited adeno-associated virus (AAV) vectors. The type V-F Cas12f from Acidibacillus sulfuroxidans is exceptionally compact (422 amino acids) and has been harnessed as a compact genome-editing tool. Here, we developed an approach, combining deep mutational scanning and structure-informed design, to successfully generate two AsCas12f activity-enhanced (enAsCas12f) variants. Remarkably, the enAsCas12f variants exhibited genome-editing activities in human cells comparable with those of SpCas9 and AsCas12a. The cryoelectron microscopy (cryo-EM) structures revealed that the mutations stabilize the dimer formation and reinforce interactions with nucleic acids to enhance their DNA cleavage activities. Moreover, enAsCas12f packaged with partner genes in an all-in-one AAV vector exhibited efficient knock-in/knock-out activities and transcriptional activation in mice. Taken together, enAsCas12f variants could offer a minimal genome-editing platform for in vivo gene therapy. An AsCas12f-based compact genome-editing tool derived by deep mutational scanning and structural analysis.,Hino T, Omura SN, Nakagawa R, Togashi T, Takeda SN, Hiramoto T, Tasaka S, Hirano H, Tokuyama T, Uosaki H, Ishiguro S, Kagieva M, Yamano H, Ozaki Y, Motooka D, Mori H, Kirita Y, Kise Y, Itoh Y, Matoba S, Aburatani H, Yachie N, Karvelis T, Siksnys V, Ohmori T, Hoshino A, Nureki O Cell. 2023 Oct 26;186(22):4920-4935.e23. doi: 10.1016/j.cell.2023.08.031. Epub , 2023 Sep 29. PMID:37776859[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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