Family

CRISPR-associated protein Cas1 (IPR002729)

Short name: CRISPR-assoc_Cas1

Family relationships

Description

The CRISPR-Cas system is a prokaryotic defense mechanism against foreign genetic elements. The key elements of this defense system are the Cas proteins and the CRISPR RNA.

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) are a family of DNA direct repeats separated by regularly sized non-repetitive spacer sequences that are found in most bacterial and archaeal genomes [PMID: 17442114]. CRISPRs appear to provide acquired resistance 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).

The defense reaction is divided into three stages. In the adaptation stage, the invader DNA is cleaved, and a piece of it is selected to be integrated as a new spacer into the CRISPR locus, where it is stored as an identity tag for future attacks by this invader. During the second stage (the expression stage), the CRISPR RNA (pre-crRNA) is transcribed and subsequently processed into the mature crRNAs. In the third stage (the interference stage), Cas proteins, together with crRNAs, identify and degrade the invader [PMID: 17379808, PMID: 16545108, PMID: 21699496].

The CRISPR-Cas systems have been sorted into three major classes. In CRISPR-Cas types I and III, the mature crRNA is generally generated by a member of the Cas6 protein family. Whereas in system III the Cas6 protein acts alone, in some class I systems it is part of a complex of Cas proteins known as Cascade (CRISPR-associated complex for antiviral defense). The Cas6 protein is an endoribonuclease necessary for crRNA production whereas the additional Cas proteins that form the Cascade complex are needed for crRNA stability [PMID: 24459147].

This entry represents Cas1, which is a metal-dependent DNA-specific endonuclease [PMID: 19523907]. Cas1 may play a role in the recognition, cleavage, and/or integration of foreign nucleic acids into CRISPRs.

GO terms

Biological Process

GO:0051607 defense response to virus
GO:0043571 maintenance of CRISPR repeat elements

Molecular Function

GO:0004519 endonuclease activity
GO:0046872 metal ion binding
GO:0003676 nucleic acid binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
HAMAP
Pfam
TIGRFAMs