Competence for Genetic Transformation in Streptococcus pneumoniae: Mutations in σA Bypass the comW Requirement.

J Bacteriol. 2014 Aug 11. pii: JB.01933-14. [Epub ahead of print]

Competence for Genetic Transformation in Streptococcus pneumoniae: Mutations in σA Bypass the comW Requirement.

Tovpeko Y1, Morrison DA2.

Author information

Abstract

Competence for genetic transformation in the genus streptococcus depends on an alternative sigma factor, σX, for coordinated synthesis of 23 proteins, which together establish the X state by permitting lysis of incompetent streptococci, uptake of DNA fragments, and integration of strands of that DNA into the resident genome. Initiation of transient accumulation of high levels of σX is coordinated between cells by transcription factors linked to peptide pheromone signals. In S. pneumoniae, elevated σX is insufficient for development of full competence without co-expression of a second competence-specific protein, ComW. ComW, shared by six species in the mitis and anginosus groups, is regulated by the same pheromone circuit that controls σX, but its role in expression of the σX regulon is unknown. Using the strong, but not absolute, dependence of transformation on comW as a selective tool, we collected 27 independent comW bypass mutations and mapped them to ten single-base transitions, all within rpoD, encoding the primary sigma factor subunit of RNA polymerase, σA. Eight mapped to sites in rpoD region 4 that are implicated in interaction with the core β subunit, indicating that ComW may act to facilitate competition of the alternative sigma factor σX for access to core polymerase.

Copyright © 2014, American Society for Microbiology. All Rights Reserved.

PMID: 25112479 [PubMed - as supplied by publisher]