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S taphylococcus aureus competence genes: mapping of the SigH , ComK 1 and ComK 2 regulons by transcriptome sequencing
Author(s) -
Fagerlund Annette,
Granum Per Einar,
Håvarstein Leiv Sigve
Publication year - 2014
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12767
Subject(s) - regulon , biology , gene , sigma factor , transcriptome , horizontal gene transfer , genetics , virulence , lytic cycle , staphylococcus aureus , mobile genetic elements , microbiology and biotechnology , regulation of gene expression , computational biology , bacteria , promoter , gene expression , plasmid , genome , virus
Summary S taphylococcus aureus is a major human pathogen. Hospital infections caused by methicillin‐resistant strains ( MRSA ), which have acquired resistance to a broad spectrum of antibiotics through horizontal gene transfer ( HGT ), are of particular concern. In S. aureus , virulence and antibiotic resistance genes are often encoded on mobile genetic elements that are disseminated by HGT . Conjugation and phage transduction have long been known to mediate HGT in this species, but it is unclear whether natural genetic transformation contributes significantly to the process. Recently, it was reported that expression of the alternative sigma factor SigH induces the competent state in S . aureus . The transformation efficiency obtained, however, was extremely low, indicating that the optimal conditions for competence development had not been found. We therefore used transcriptome sequencing to determine whether the full set of genes known to be required for competence in other naturally transformable bacteria is part of the SigH regulon. Our results show that several essential competence genes are not controlled by SigH . This presumably explains the low transformation efficiency previously reported, and demonstrates that additional regulating mechanisms must be involved. We found that one such mechanism involves ComK1 , a transcriptional activator that acts synergistically with SigH .