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

• DOI: 10.1038/srep43670
• Publication Date: 2017-03-02T10:13:02Z
• Authors: Annabelle Mouammine; Sylvie Pages; Anne Lanois; Sophie Gaudriault; Gregory Jubelin; Maurine Bonabaud; Stéphane Cruveiller; Emeric Dubois; David Roche; Ludovic Legrand; Julien Brillard; Alain Givaudan
• Keywords: 570; Insecta; [SDV]Life Sciences [q-bio]; salmonella; peptide antimicrobien; Article; 03 medical and health sciences; inhomogeneity; Disk Diffusion Antimicrobial Tests; Drug Resistance, Bacterial; Gene Order; Operon; hétérogénéité; Animals; photorhabdus luminescens; bactérie; 0303 health sciences; Virulence; Gene Expression Profiling; Enterobacteriaceae Infections; bacterium; virulence; Gene Expression Regulation; Genes, Bacterial; Mutation; Photorhabdus; Antimicrobial Cationic Peptides

AbstractSome 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 bacteriumPhotorhabdus 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 ofpbgPE,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 inP. 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 ofP. luminescensis based on a bet-hedging strategy to cope with the diverse environmental conditions experienced during the lifecycle.