0000000000698971
AUTHOR
Conor O'byrne
Frequent emergence of sigB mutant alleles in Listeria monocytogenes is likely to be linked to a growth advantage at elevated temperatures
International audience; Background: The food-borne pathogen Listeria monocytogenes is a Gram-positive bacteria and highly resistant to a variety of stresses. Such resistance is determinate by the activation of the alternative sigma factor B (σB). Genes within sigB operon encode for the signal transduction that controls σB activity. Mutations within this operon generally result on reduced σB activation. Objectives: Characterize the impact of secondary mutations within L. monocytogenes sigB operon, and identify laboratory conditions that promote the selection of such mutations among wild type (WT) populations. Methods: Transposon mutants (Tms) that lost the ability to form rings in response t…
σB and agrA regulation in Listeria monocytogenes: Effect on survival in soil/rhizosphere under biotic and abiotic conditions
International audience; Abstract -250 words Backgrounds: Listeria monocytogenes is the agent of listeriosis, a life-threatening condition in at-risk people. Complex transmission routes between outdoor environments and the food chain result in foodstuff contamination. Sensing of environmental changes can trigger regulation of gene expression, allowing bacteria to adapt their physiology and survive. The Agr cell-cell communication system transcription regulator AgrA is triggered during several environmental conditions including soil, an important reservoir of L. monocytogenes. The RNA polymerase σB factor aids survival in several stress conditions and may be required for L. monocytogenes surv…
Sigma B-dependent regulatory sRNA Rli47 represses isoleucine biosynthesis in Listeria monocytogenes
International audience; Background: Small regulatory RNAs (sRNAs) can influence cellular processes by targeting mRNAs, leading to translation inhibition and mRNA degradation. Previous studies have shown that the σB-dependent sRNA Rli47 is induced in L. monocytogenes stationary phase cells, in the intestinal lumen and macrophages, but its function has remained elusive. Objectives: This study aimed to comprehensively characterize Rli47 and determine its biological function in L. monocytogenes. Methods: Besides in silico predictions, several molecular approaches such as DMS-MaPseq, northern blotting, EMSAs, RTqPCR, RNA-seq and phenotypic experiments were applied. Results: Rli47 was shown to ba…