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type I-F variant CRISPR-associated protein Cas5 (Cas5fv) Cas5fv is one of the CRISPR-associated (Cas) proteins of type I-F variant CRISPR-Cas system. CRISPR (clustered regularly interspaced short palindromic repeats)-Cas modules are adaptive immune systems found in archaea and bacteria against foreign nucleic acids such as phages and plasmids via RNA-guided endonucleases. CRISPR-Cas systems are classified based on Cas protein content and arrangement in CRISPR-Cas loci into two main classes (1 and 2) and at least six types (I, II, III, IV, V, VI). Class 1 systems utilize multiple Cas proteins and CRISPR RNA (crRNA) to form an effector complex while class 2 systems employ a large, single effector with crRNA to mediate interference. Type I CRISPR-Cas systems are most widespread in nature and the Cas protein composition of the employed Cascade interference complexes differ between seven subtypes (A-F, U). Type I-F variant (I-Fv) is a subtype that rely on a minimal set of five Cas proteins and has structural differences with I-F and I-E Cascades. Double strand DNA recruitment and recognition in the type I-Fv Cascade is facilitated from the major groove side by Cas5fv instead of the large subunit Cas8 and the finger domain of Cas7fv. |
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