Excision-reintegration at a pneumococcal phase-variable restriction-modification locus drives within- and between-strain epigenetic differentiation and inhibits gene acquisition.

ABSTRACT: Phase-variation of Type I restriction-modification systems can rapidly alter the sequence motifs they target, diversifying both the epigenetic patterns and endonuclease activity within clonally descended populations. Here, we characterize the Streptococcus pneumoniae SpnIV phase-variable Type I RMS, encoded by the translocating variable restriction (tvr) locus, to identify its target motifs, mechanism and regulation of phase variation, and effects on exchange of sequence through transformation. The specificity-determining hsdS genes were shuffled through a recombinase-mediated excision-reintegration mechanism involving circular intermediate molecules, guided by two types of direct repeat. The rate of rearrangements was limited by an attenuator and toxin-antitoxin system homologs that inhib

SUBMITTER: Kwun MJ 

PROVIDER: S-EPMC6265443 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature