July 7, 2019  |  

An antimicrobial peptide-resistant minor subpopulation of Photorhabdus luminescens is responsible for virulence.

Authors: Mouammine, Annabelle and Pages, Sylvie and Lanois, Anne and Gaudriault, Sophie and Jubelin, Gregory and Bonabaud, Maurine and Cruveiller, Stéphane and Dubois, Emeric and Roche, David and Legrand, Ludovic and Brillard, Julien and Givaudan, Alain

Some of the bacterial cells in isogenic populations behave differently from others. We describe here how a new type of phenotypic heterogeneity relating to resistance to cationic antimicrobial peptides (CAMPs) is determinant for the pathogenic infection process of the entomopathogenic bacterium Photorhabdus luminescens. We demonstrate that the resistant subpopulation, which accounts for only 0.5% of the wild-type population, causes septicemia in insects. Bacterial heterogeneity is driven by the PhoPQ two-component regulatory system and expression of pbgPE, an operon encoding proteins involved in lipopolysaccharide (LPS) modifications. We also report the characterization of a core regulon controlled by the DNA-binding PhoP protein, which governs virulence in P. luminescens. Comparative RNAseq analysis revealed an upregulation of marker genes for resistance, virulence and bacterial antagonism in the pre-existing resistant subpopulation, suggesting a greater ability to infect insect prey and to survive in cadavers. Finally, we suggest that the infection process of P. luminescens is based on a bet-hedging strategy to cope with the diverse environmental conditions experienced during the lifecycle.

Journal: Scientific reports
DOI: 10.1038/srep43670
Year: 2017

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