On the Origin and Evolutionary Relationships of the Reverse Transcriptases Associated With Type III CRISPR-Cas Systems.

ABSTRACT: Reverse transcriptases (RTs) closely related to those encoded by group II introns but lacking the intron RNA structure have been found associated with type III clustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems, a prokaryotic immune system against invading viruses and foreign genetic elements. Two models have been proposed to explain the origin and evolutionary relationships of these RTs: (i) the "single point of origin" model, according to which these RTs originated from a single acquisition event in bacterial, with the various protein domains (RT, RT-Cas1, and Cas6-RT-Cas1 fusions) corresponding to single points in evolution; and (ii) the "various origins" model, according to which, independent acquisition events in different evolutionary episodes led to these

SUBMITTER: Toro N 

PROVIDER: S-EPMC6013744 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature