Format

Send to:

Choose Destination
See comment in PubMed Commons below
Nat Rev Microbiol. 2011 Jun;9(6):467-77. doi: 10.1038/nrmicro2577. Epub 2011 May 9.

Evolution and classification of the CRISPR-Cas systems.

Author information

  • 1National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, 8600 Rockville Pike, Bethesda, Maryland 20894, USA.

Abstract

The CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated proteins) modules are adaptive immunity systems that are present in many archaea and bacteria. These defence systems are encoded by operons that have an extraordinarily diverse architecture and a high rate of evolution for both the cas genes and the unique spacer content. Here, we provide an updated analysis of the evolutionary relationships between CRISPR-Cas systems and Cas proteins. Three major types of CRISPR-Cas system are delineated, with a further division into several subtypes and a few chimeric variants. Given the complexity of the genomic architectures and the extremely dynamic evolution of the CRISPR-Cas systems, a unified classification of these systems should be based on multiple criteria. Accordingly, we propose a 'polythetic' classification that integrates the phylogenies of the most common cas genes, the sequence and organization of the CRISPR repeats and the architecture of the CRISPR-cas loci.

PMID:
21552286
[PubMed - indexed for MEDLINE]
PMCID:
PMC3380444
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Nature Publishing Group Icon for PubMed Central
    Loading ...
    Write to the Help Desk