Structural basis of a Tn7-like transposase recruitment and DNA loading to CRISPR-Cas surveillance complex
Dear Editor,Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated (Cas) systems confer RNA-guided adaptive immunity against invading genetic elements in prokaryotic cells.1 These systems employ CRISPR RNA (crRNA) containing surveillance complexes for sequence-specific recognition and degradation of foreign DNA or RNA.Several nuclease-deficient type I-F,I-B,and V-K systems have been reported to be evolutionarily and functionally associated with Tn7-like transposons lacking a key gene for DNA targeting,implying a new mode of RNA-guided DNA insertion.2,3 Recent studies characterized CRISPR-associated transposase in type I-F and V-K systems and established genome-wide programmable site-specific DNA transposition in E.coli cells,providing the prospect of genome editing strategy without requirement of double-strand breaks and endogenous DNA repair pathways.4,5 All these CRISPR-associated transposons contain transposase subunits,CRISPR effector,and a CRISPR array.Furthermore,subunit TniQ,a homolog of E.coli TnsD,forms a stable complex with Vibrio cholerae Tn6677 type I-F effector Cascade (also called Csy complex) and plays an essential role during DNA insertion.
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We thank the staff of the BL18U and BL19U1 beamlines of National Center for Protein Science in Shanghai ;We thank the staff of Electron Microscopy facility of NCPSS for technical assistance in data collection;This study was supported by the National Natural Science Foundation of China
2020-06-15（万方平台首次上网日期，不代表论文的发表时间）
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