Atypical organizations and epistatic interactions of CRISPRs and cas clusters in genomes and their mobile genetic elements.

ABSTRACT: Prokaryotes use CRISPR-Cas systems for adaptive immunity, but the reasons for the frequent existence of multiple CRISPRs and cas clusters remain poorly understood. Here, we analysed the joint distribution of CRISPR and cas genes in a large set of fully sequenced bacterial genomes and their mobile genetic elements. Our analysis suggests few negative and many positive epistatic interactions between Cas subtypes. The latter often result in complex genetic organizations, where a locus has a single adaptation module and diverse interference mechanisms that might provide more effective immunity. We typed CRISPRs that could not be unambiguously associated with a cas cluster and found that such complex loci tend to have unique type I repeats in multiple CRISPRs. Many chromosomal CRISPRs lack a nei

SUBMITTER: Bernheim A 

PROVIDER: S-EPMC7145637 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature