E. Gueguen - A Single Mutation in ArcZ RNA of Dickeya solani Disables Antimicrobial Activity and Affects Virulence

Abstract

The emergence of the necrotrophic plant pathogenic bacterium Dickeya solani in the European potato agrosystem has prompted extensive research into its genetic and pathogenic profile. All isolated strains of D. solani harbor several large polyketide synthase/non-ribosomal peptide synthetase (PKS/NRPS) gene clusters. Comparative analysis with analogous genes in other bacteria indicates that the clusters ooc and zms are responsible for the production of secondary metabolites from the oocydin and zeamine families, respectively. Additionally, a third cluster, designated sol, produces a novel antibiotic named solanimycin, which exhibits potent antifungal activity against various yeasts, including the human pathogen Candida albicans.

In this study, we investigated the antimicrobial properties of these three PKS/NRPS clusters across different wild-type D. solani isolates. Through phenotyping and comparative genomics, we discovered that the small regulatory RNA ArcZ is crucial in regulating the sol and zms clusters. Notably, a single-point mutation, conserved in some wild-type strains of D. solani, including the type strain IPO 2222, disrupts ArcZ function by hindering its maturation into an active form. This mutation, which is also conserved across other Dickeya species, significantly impacts the virulence of D. solani in plants.

Our findings demonstrate that single-nucleotide polymorphisms (SNPs) in sRNA-encoding genes can profoundly affect bacterial phenotypes. These insights underscore the importance of considering allele diversity in sRNA genes when studying bacterial pathogenicity and regulatory mechanisms. This research advances our understanding of bacterial regulation and pathogenesis, highlighting the intricate genetic factors that influence the behavior and impact of plant pathogens like Dickeya solani.

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Erwan Gueguen est Maitre de conférence à l’université Claude Bernard de Lyon, rattaché au laboratoire MAP, équipe « Trafic et signalisation membranaires chez les bactéries »). Ses recherches se concentrent sur les mécanismes de signalisation et d'adaptation chez les bactéries. Il encadre des projets de biotechnologie innovante, notamment dans le cadre du concours international iGEM, où il a supervisé des équipes étudiantes sur des projets d'agriculture durable et de biologie synthétique. En parallèle, il est également impliqué dans des initiatives visant à réduire l'utilisation de produits pétrochimiques dans les pratiques agricoles​.

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