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Crystal structure of the Type I-B CRISPR-associated protein, Csh2 from Thermobaculum terrenumCrystal structure of the Type I-B CRISPR-associated protein, Csh2 from Thermobaculum terrenum
Structural highlights
FunctionPublication Abstract from PubMedClustered regularly interspaced short palindromic repeats (CRISPR) in many prokaryotes functions as an adaptive immune system against mobile genetic elements. A heterologous ribonucleoprotein silencing complex composed of CRISPR-associated (Cas) proteins and a CRISPR RNA (crRNA) neutralizes the incoming mobile genetic elements. The type I and III silencing complexes commonly include a protein-helical backbone of several copies of identical subunits, for example, Cas7 in the type I silencing complex. In this study, we structurally characterized type I-B Cas7 (Csh2 from Thermobaculum terrenum; TterCsh2). The revealed crystal structure of TterCsh2 shows a typical glove-like architecture of Cas7, which consists of a palm, a thumb, and a finger domain. Csh2 proteins have 5 conserved sequence motifs that are arranged to form a presumable crRNA-binding site in the TterCsh2 structure. This crRNA binding site of TterCsh2 is structurally and potentially comparable to those observed in helix-forming Cas7 structures in other sub-types. Analysis of the reported Cas7 structures and their sequences suggests that Cas7s can be divided into at least two sub-classes. These data will broaden our understanding on the Cascade complex of CRISPR/Cas systems. Structural characterization of the type I-B CRISPR Cas7 from Thermobaculum terrenum.,Seo PW, Gu DH, Kim JW, Kim JH, Park SY, Kim JS Biochim Biophys Acta Proteins Proteom. 2023 May 1;1871(3):140900. doi: , 10.1016/j.bbapap.2023.140900. Epub 2023 Jan 20. PMID:36682394[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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