Genetic and functional analyses of krs, a locus encoding kurstakin, a lipopeptide produced by Bacillus thuringiensis

• Published in: Research in microbiology Vol. 168; no. 4; pp. 356 - 368
• Main Authors: Gélis-Jeanvoine, Sébastien, Canette, Alexis, Gohar, Michel, Caradec, Thibault, Lemy, Christelle, Gominet, Myriam, Jacques, Philippe, Lereclus, Didier, Slamti, Leyla
• Format: Journal Article Web Resource
• Language: English
• Published: France Elsevier Masson SAS 01.05.2017; Elsevier
• Subjects: Bacillus cereus; Bacillus cereus group; Bacillus thuringiensis; Bacillus thuringiensis - genetics; Bacillus thuringiensis - metabolism; Bacterial Proteins; Bacterial Proteins - genetics; Biofilm; Biofilms; Biofilms - growth & development; Biotechnologie; Biotechnology; chemical elements; DNA; entomopathogenic bacteria; environmental law; Gene Expression Regulation, Bacterial; Life Sciences; ligases; Lipopeptides; Lipopeptides - genetics; Lipopeptides - metabolism; loci; Microbiologie; Microbiology; Operon; Operon - genetics; Peptide Biosynthesis, Nucleic Acid-Independent; Peptide Biosynthesis, Nucleic Acid-Independent - physiology; promoter regions; Promoter Regions, Genetic; Quorum Sensing; Quorum Sensing - genetics; Sciences du vivant; Spo0A; surfactants; transcription (genetics); Transcriptional regulation; Biofilm; Bacillus cereus group; Transcriptional regulation; Spo0A
• ISSN: 0923-2508; 1769-7123; 1769-7123; 0923-2508
• DOI: 10.1016/j.resmic.2016.06.002

Bacteria of the Bacillus genus are able to synthesize several families of lipopeptides. These small molecules are the product of non-ribosomal peptide synthetases. In 2000, it was found that Bacillus thuringiensis, an entomopathogenic bacterium of the Bacillus cereus group, produced a previously unknown lipopeptide: kurstakin. Genomic analyses reveal that the krs locus, encoding the kurstakin synthetases, is specific to the B. cereus group, but is unevenly distributed within this group. Previous work showed that krs transcription requires the necrotrophism quorum-sensor NprR. Here, we demonstrated that the genes of the krs locus form an operon and we defined its transcription start site. Following krs transcription at the population and single-cell levels in multiple culture conditions, we depicted a condition-dependent transcription pattern, indicating that production of kurstakin is subject to environmental regulation. Consistent with this idea, we found krs transcription to be regulated by another master regulator, Spo0A, suggesting that krs expression is fine-tuned by integrating multiple signals. We also reported an unknown DNA palindrome in the krs promoter region that modulates krs expression. Due to their surfactant properties, lipopeptides could play several physiological roles. We showed that the krs locus was required for proper biofilm structuration.