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Analysis of σL dependent traits based on phenotypic and transcriptomic evaluation of the Listeria monocytogenes EGDe strain

ABSTRACT: The phenotypic and gene expression traits conferred by the alternative sigma factor protein σL in the food-borne pathogen L. monocytogenes were investigated. σL was shown to be important for the efficient growth of this pathogen exposed to food preservative measures such as low storage temperatures, elevated osmolarity and acidity. Based on high throughput phenotypic analysis, σL function was also found to be protective in L. monocytogenes EGDe cells exposed to several antimicrobial compounds including some of the antibiotics currently applied in listeriosis treatment. The expression of flagella genes and motility were significantly compromized upon loss of σL function. A comparative transcriptome analysis of exponential growth EGDe wild type and sigL null cells unveiled 394 genes that are positively controlled through σL dependent transcriptional regulation mechanisms in this bacterium during growth at low (3°C) and optimized (37°C) temperature conditions. Genes identified indicate that σL is a pleitropic transcription regulator mediating positive expression control of genes involved in diverse cellular processes including protein synthesis, molecular transport, energy metabolism, respiration, transcription regulation, metabolite biosynthesis, and cell envelope composition modification. Overall our observations have revealed that the loss of σL function leads to extensive gene expression defects in L. monocytogenes EGDe cells, and these are consistent with compromized nutrient assimilation, energy metabolism, protein synthesis, and metabolite biosynthesis processes as well as altered cell envelope composition and motility. Numerous gene expression changes imposed by σL loss in EGDe are thus also consistent with pleiotropic phenotypic defects detected in the L. monocytogenes EGDe ∆sigL strain.

ORGANISM(S): Listeria monocytogenes Listeria monocytogenes EGD-e

PROVIDER: GSE32434 | GEO | 2012/01/01

SECONDARY ACCESSION(S): PRJNA147893

REPOSITORIES: GEO

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Project description:The phenotypic and gene expression traits conferred by the alternative sigma factor protein M-OM-^CL in the food-borne pathogen L. monocytogenes were investigated. M-OM-^CL was shown to be important for the efficient growth of this pathogen exposed to food preservative measures such as low storage temperatures, elevated osmolarity and acidity. Based on high throughput phenotypic analysis, M-OM-^CL function was also found to be protective in L. monocytogenes EGDe cells exposed to several antimicrobial compounds including some of the antibiotics currently applied in listeriosis treatment. The expression of flagella genes and motility were significantly compromized upon loss of M-OM-^CL function. A comparative transcriptome analysis of exponential growth EGDe wild type and sigL null cells unveiled 394 genes that are positively controlled through M-OM-^CL dependent transcriptional regulation mechanisms in this bacterium during growth at low (3M-BM-0C) and optimized (37M-BM-0C) temperature conditions. Genes identified indicate that M-OM-^CL is a pleitropic transcription regulator mediating positive expression control of genes involved in diverse cellular processes including protein synthesis, molecular transport, energy metabolism, respiration, transcription regulation, metabolite biosynthesis, and cell envelope composition modification. Overall our observations have revealed that the loss of M-OM-^CL function leads to extensive gene expression defects in L. monocytogenes EGDe cells, and these are consistent with compromized nutrient assimilation, energy metabolism, protein synthesis, and metabolite biosynthesis processes as well as altered cell envelope composition and motility. Numerous gene expression changes imposed by M-OM-^CL loss in EGDe are thus also consistent with pleiotropic phenotypic defects detected in the L. monocytogenes EGDe M-bM-^HM-^FsigL strain. Gene expression DNA-microarray. Two-color hybridizations on 8*15K Agilent arrays. Wild type and three KO mutants in three temperatures, three biological replicates in each condition.

Project description:The foodborne pathogen Listeria monocytogenes has the ability to develop biofilm in food-processing environment, which becomes a major concern for the food safety. PrfA, a key transcriptional activator that regulates most of the known listerial virulence gene expression, has been shown to promote L. monocytogenes biofilm formation. In this study, the whole genome microarray was used to identify differentially expressed genes associated with the putative interaction between biofilm formation and PrfA in L. monocytogenes. Comparative transcriptome analyses indicated over 21.9% of the L. monocytogenes EGDe genes (627 out of 2857 predicted) were altered in their expression in biofilm cells relative to planktonic cell populations. These genes were classed into different functional categories which cover most of the biochemical functions encountered in bacterial cells, especially involved in ion transport, DNA repair, and cell wall biosynthesis based on significant enrichment of GO terms. Among them, 185 genes were identified to be associated with PrfA and biofilm formation by comparison of the whole gene expression profiles of L. monocytogenes EGDe and its M-NM-^TprfA mutant. The expression tendency of these PrfA-associated and biofilm-specific genes were mainly opposite in M-NM-^TprfA biofilm, and most of them are involved in phage-related function, membrane bioenergetics, and cell wall. Our results indicated that L. monocytogenes biofilm formation is probably controlled by the complex regulation network involved variable genes required for the different biological pathways. This regulatory network is modified in the prfA deletion mutant in order to maintain its stable biofilm lifestyle. Gene expression of planktonic cells and biofilm cells in Listeria monocytogenes EGDe and prfA isogenic deletion strain EGDeM-NM-^TprfA with cultivated in MEM and BHI for 48 hours, were mesasued using Agilent Listeria monocytogenes customized whole-genome microarray 8x15 array. Three replicates.

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Analysis of σL dependent traits based on phenotypic and transcriptomic evaluation of the Listeria monocytogenes EGDe strain

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