5xh7
From Proteopedia
Crystal structure of the Acidaminococcus sp. BV3L6 Cpf1 RR variant in complex with crRNA and target DNA (TCCA PAM)
Structural highlights
FunctionCS12A_ACISB 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. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). Recognizes a short motif in the CRISPR repeat sequences (the 5' PAM or protospacer adjacent motif, TTTN in this organism) to help distinguish self versus nonself, as targets within the bacterial CRISPR locus do not have PAMs (PubMed:26422227). Has dsDNA endonuclease activity, results in staggered 4-base 5' overhangs 19 and 22 bases downstream of the PAM on the non-targeted and targeted strand respectively (PubMed:26422227). Non-target strand cleavage by the RuvC domain is probably a prerequisite of target strand cleavage by the Nuc domain (PubMed:27114038). In this CRISPR system correct processing of pre-crRNA requires only this protein and the CRISPR locus (By similarity).[UniProtKB:A0Q7Q2][1] [2] Publication Abstract from PubMedThe RNA-guided Cpf1 nuclease cleaves double-stranded DNA targets complementary to the CRISPR RNA (crRNA), and it has been harnessed for genome editing technologies. Recently, Acidaminococcus sp. BV3L6 (AsCpf1) was engineered to recognize altered DNA sequences as the protospacer adjacent motif (PAM), thereby expanding the target range of Cpf1-mediated genome editing. Whereas wild-type AsCpf1 recognizes the TTTV PAM, the RVR (S542R/K548V/N552R) and RR (S542R/K607R) variants can efficiently recognize the TATV and TYCV PAMs, respectively. However, their PAM recognition mechanisms remained unknown. Here we present the 2.0 A resolution crystal structures of the RVR and RR variants bound to a crRNA and its target DNA. The structures revealed that the RVR and RR variants primarily recognize the PAM-complementary nucleotides via the substituted residues. Our high-resolution structures delineated the altered PAM recognition mechanisms of the AsCpf1 variants, providing a basis for the further engineering of CRISPR-Cpf1. Structural Basis for the Altered PAM Recognition by Engineered CRISPR-Cpf1.,Nishimasu H, Yamano T, Gao L, Zhang F, Ishitani R, Nureki O Mol Cell. 2017 Jul 6;67(1):139-147.e2. doi: 10.1016/j.molcel.2017.04.019. Epub, 2017 Jun 6. PMID:28595896[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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