Boolean Models of Biosurfactants Production in Pseudomonas fluorescens

• Published in: PloS one Vol. 7; no. 1; p. e24651
• Main Authors: Richard, Adrien, Rossignol, Gaelle, Comet, Jean-Paul, Bernot, Gilles, Guespin-Michel, Jannine, Merieau, Annabelle
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 31.01.2012; Public Library of Science (PLoS)
• Subjects: Analysis; Bacteria; Bacterial Proteins - metabolism; Bioinformatics; Biology; Biosurfactants; Bistability; Boolean algebra; Boolean functions; C gene; Complementation; Computer Science; DNA methylation; Epigenetic inheritance; Epigenetics; Feedback; Gene Regulatory Networks; Genes; Genetic aspects; Genomes; Genomics; Hemolysis; Life Sciences; Lipopeptides - metabolism; Methods; Models, Biological; Mutation; Peptides, Cyclic - metabolism; Phenotypic variations; Phospholipase; Phospholipase C; Proteins; Pseudomonas; Pseudomonas fluorescens; Pseudomonas fluorescens - genetics; Pseudomonas fluorescens - metabolism; Quantitative Methods; Regulation; Signal transduction; Surface-Active Agents - metabolism; Surfactants; Switching theory; Topology; Transcription factors
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0024651

Cyclolipopeptides (CLPs) are biosurfactants produced by numerous Pseudomonas fluorescens strains. CLP production is known to be regulated at least by the GacA/GacS two-component pathway, but the full regulatory network is yet largely unknown. In the clinical strain MFN1032, CLP production is abolished by a mutation in the phospholipase C gene (plcC) and not restored by plcC complementation. Their production is also subject to phenotypic variation. We used a modelling approach with Boolean networks, which takes into account all these observations concerning CLP production without any assumption on the topology of the considered network. Intensive computation yielded numerous models that satisfy these properties. All models minimizing the number of components point to a bistability in CLP production, which requires the presence of a yet unknown key self-inducible regulator. Furthermore, all suggest that a set of yet unexplained phenotypic variants might also be due to this epigenetic switch. The simplest of these Boolean networks was used to propose a biological regulatory network for CLP production. This modelling approach has allowed a possible regulation to be unravelled and an unusual behaviour of CLP production in P. fluorescens to be explained.