title: Alternative sigma factor σH activates competence gene expression in Lactobacillus sakei.
abstract: BACKGROUND
  Alternative sigma factors trigger various adaptive responses. Lactobacillus sakei, a non-sporulating meat-borne bacterium, carries an alternative sigma factor seemingly orthologous to σ(H) of Bacillus subtilis, 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(H) in L. sakei.
  
  
  RESULTS
  Transcription of sigH coding for σ(H) was hardly affected by entry into stationary phase in our laboratory conditions. Twenty-five genes potentially regulated by σ(H) in L. sakei 23 K were revealed by genome-wide transcriptomic profiling of sigH 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(H) overproduction did not allow detectable genetic transformation. σ(H) was found to be conserved in the L. sakei species.
  
  
  CONCLUSIONS
  Our results are indicative of the existence of a genetic competence state activated by σ(H) in L. sakei, 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.
authors.affiliation: UMR Micalis, INRA F, Jouy-en-Josas, France.
authors.forename: Solveig
authors.initials: S
authors.lastname: Schmid
authors.forename: Claudia
authors.initials: C
authors.lastname: Bevilacqua
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Crutz-Le Coq
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D017124:Conserved Sequence; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D007778:Lactobacillus / Q000235:genetics* / Q000378:metabolism; D050296:Microbial Viability; D020411:Oligonucleotide Array Sequence Analysis; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D059467:Transcriptome; D014169:Transformation, Bacterial
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C120328:SigH protein, bacteria; D012808:Sigma Factor