Evolution and classification of the CRISPR-Cas systems
2011 (English)In: Nature Reviews Microbiology, ISSN 1740-1526, E-ISSN 1740-1534, Vol. 9, no 6, 467-477 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
Nature Publishing Group , 2011. Vol. 9, no 6, 467-477 p.
IdentifiersURN: urn:nbn:se:umu:diva-45507DOI: 10.1038/nrmicro2577PubMedID: 21552286OAI: oai:DiVA.org:umu-45507DiVA: diva2:430076