Structural highlights
Publication Abstract from PubMedA hallmark of type I CRISPR-Cas systems is the presence of Cas3, which contains both the nuclease and helicase activities required for DNA cleavage during interference. In subtype I-D systems, however, the histidine-aspartate (HD) nuclease domain is encoded as part of a Cas10-like large effector complex subunit and the helicase activity in a separate Cas3' subunit, but the functional and mechanistic consequences of this organisation are not currently understood. Here we show that the Sulfolobus islandicus type I-D Cas10d large subunit exhibits an unusual domain architecture consisting of a Cas3-like HD nuclease domain fused to a degenerate polymerase fold and a C-terminal domain structurally similar to Cas11. Crystal structures of Cas10d both in isolation and bound to S. islandicus rod-shaped virus 3 AcrID1 reveal that the anti-CRISPR protein sequesters the large subunit in a non-functional state unable to form a cleavage-competent effector complex. The architecture of Cas10d suggests that the type I-D effector complex is similar to those found in type III CRISPR-Cas systems and that this feature is specifically exploited by phages for anti-CRISPR defence. Structural basis for inhibition of an archaeal CRISPR-Cas type I-D large subunit by an anti-CRISPR protein.,Manav MC, Van LB, Lin J, Fuglsang A, Peng X, Brodersen DE Nat Commun. 2020 Nov 25;11(1):5993. doi: 10.1038/s41467-020-19847-x. PMID:33239638[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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