Structural highlights
FunctionPublication Abstract from PubMedCertain CRISPR-Cas elements integrate into Tn7-like transposons, forming CRISPR-associated transposon (CAST) systems. How the activity of these systems is controlled in situ has remained largely unknown. Here we characterize the MerR-type transcriptional regulator Alr3614 that is encoded by one of the CAST (AnCAST) system genes in the genome of cyanobacterium Anabaena sp. PCC 7120. We identify a number of Alr3614 homologs across cyanobacteria and suggest naming these regulators CvkR for Cas V-K repressors. Alr3614/CvkR is translated from leaderless mRNA and represses the AnCAST core modules cas12k and tnsB directly, and indirectly the abundance of the tracr-CRISPR RNA. We identify a widely conserved CvkR binding motif 5'-AnnACATnATGTnnT-3'. Crystal structure of CvkR at 1.6 A resolution reveals that it comprises distinct dimerization and potential effector-binding domains and that it assembles into a homodimer, representing a discrete structural subfamily of MerR regulators. CvkR repressors are at the core of a widely conserved regulatory mechanism that controls type V-K CAST systems. CvkR is a MerR-type transcriptional repressor of class 2 type V-K CRISPR-associated transposase systems.,Ziemann M, Reimann V, Liang Y, Shi Y, Ma H, Xie Y, Li H, Zhu T, Lu X, Hess WR Nat Commun. 2023 Feb 18;14(1):924. doi: 10.1038/s41467-023-36542-9. PMID:36801863[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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