Alternative sigma factor σ^Hactivates competence gene expression in <it>Lactobacillus sakei</it>

• Main Authors: Schmid Solveig, Bevilacqua Claudia, Crutz-Le Coq Anne-Marie
• Format: Article
• Language: English
• Published: BMC 2012-03-01
• Series: BMC Microbiology
• Online Access: http://www.biomedcentral.com/1471-2180/12/32

<p>Abstract</p> <p>Background</p> <p>Alternative sigma factors trigger various adaptive responses. <it>Lactobacillus sakei</it>, a non-sporulating meat-borne bacterium, carries an alternative sigma factor seemingly orthologous to σ^Hof <it>Bacillus subtilis</it>, best known for its contribution to the initiation of a large starvation response ultimately leading to sporulation. As the role of σ^H-like factors has been little studied in non-sporulating bacteria, we investigated the function of σ^Hin <it>L. sakei</it>.</p> <p>Results</p> <p>Transcription of <it>sigH </it>coding for σ^Hwas hardly affected by entry into stationary phase in our laboratory conditions. Twenty-five genes potentially regulated by σ^Hin <it>L. sakei </it>23 K were revealed by genome-wide transcriptomic profiling of <it>sigH </it>overexpression and/or quantitative PCR analysis. More than half of them are involved in the synthesis of a DNA uptake machinery linked to genetic competence, and in DNA metabolism; however, σ^Hoverproduction did not allow detectable genetic transformation. σ^Hwas found to be conserved in the <it>L. sakei </it>species.</p> <p>Conclusion</p> <p>Our results are indicative of the existence of a genetic competence state activated by σ^Hin <it>L. sakei</it>, and sustain the hypothesis that σ^H-like factors in non sporulating Firmicutes share this common function with the well-known ComX of naturally transformable streptococci.</p>