ABSTRACT: Systems level analyses establish CodY as a multifaceted metabolic regulator integrating metabolism, motility and virulence in Listeria monocytogenes
Project description:Systems level analyses establish CodY as a multifaceted metabolic regulator integrating metabolism, motility and virulence in Listeria monocytogenes [ChIP-Seq]
Project description:To gain knowledge on L. monocytogenes differential CodY activity, we set on analyzing CodY’s regulon in L. monocytogenes in both rich and minimal growth conditions using genome-wide sequencing techniques. Remarkably, we identified for the first time a global regulatory role for CodY when BCAAs are limited, that are similar to those within the mammalian niche. Furthermore, our data establish CodY as a central regulator that integrates metabolism, motility, stress responses and virulence in L. monocytogenes.
Project description:To gain knowledge on L. monocytogenes differential CodY activity, we set on analyzing CodY’s regulon in L. monocytogenes in both rich and minimal growth conditions using genome wide sequencing techniques. Remarkably, we identified for the first time a global regulatory role for CodY when BCAAs are limited, that are similar to those within the mammalian niche. Furthermore, our data establish CodY as a central regulator that integrates metabolism, motility, stress responses and virulence in L. monocytogenes.
Project description:To gain knowledge on L. monocytogenes differential CodY activity, we set on analyzing CodYâ??s regulon in L. monocytogenes in both rich and minimal growth conditions using genome wide sequencing techniques. Remarkably, we identified for the first time a global regulatory role for CodY when BCAAs are limited, that are similar to those within the mammalian niche. Furthermore, our data establish CodY as a central regulator that integrates metabolism, motility, stress responses and virulence in L. monocytogenes. Examination of CodY regulon in rich and minimal conditions.
Project description:To characterize regulons of alternative sigma factor SigH, SigL, and SigC in Listeria monocytogenes, in-frame mutant strains were created in the 10403S background. Regulons controlled by these 3 alternative sigma factors were characterized by whole-genome microarrays. The L. monocytogenes 10403S wild type and sigma factor null mutation strains were grown at 37 °C to stationary phase (defined in this study as growth to OD600 = 1.0, followed by incubation for an additional 3 h) prior to RNA isolation. Transcriptional profiles of 10403S wild type were compared to those of null mutation strain. In addition to stationary phase condition, SigC regulon was further characterized using heat stress (cultures grown to log phase at OD600 = 0.4, 37 °C and then exposed to heat at 55 °C for 10 min) and a condition with IPTG-inducible expression of sigC (sigC gene is placed under Pspac promoter using pLIV2 vector in wild type 10403S background). Under these conditions, expression profiles were compared between (i) wild type and sigC null mutant for heat stress and (ii) IPTG-inducible sigC strain and sigC null mutant, respectively. Using adjusted P < 0.05 and ≥ 1.5 fold change as cutoff values, microarray analyses identified 169 SigH-dependent, 51 SigL-dependent, and 3 SigC-dependent genes. Keywords: Listeria monocytogenes, alternative sigma factor, SigH, SigL, SigC
Project description:Listeria monocytogenes is a food-borne pathogen which causes listeriosis. It is an intracellular parasite invading the epithelial cells where it escapes from the vacuole into the host cytoplasm to replicate, using actin-based motility to move within and between cells. The intracellular life cycle is well documented whereas the time spent in the lumen of the intestine is poorly understood. The aim of this study was to investigate the mechanism by which L. monocytogenes adapts to the environment of the small intestine prior to invasion. Specifically, to determine if the PrfA regulon, that encodes the virulence factors of L. monocytogenes, is switched on by signals within the intestinal lumen. L. monocytogenes were grown under aerobic or microaerobic conditions with glucose or glycerol as carbon source.
Project description:Information regarding the Alkaline Tolerance Response (AlTR) in Listeria monocytogenes is very limited. In this study, L. monocytogenes was shown to exhibit a significant adaptive alkaline tolerance response (AlTR) following a 1-h exposure to mild alkaline (pH 9.5), which is capable of protecting cells from subsequent lethal alkali stress (pH 12.0). Treatment of adapted cells with protein synthesis inhibitor chloramphenicol has revealed that AlTR is at least partially protein-dependent. In order to gain a more comprehensive perspective on the physiology and regulation of AlTR, we compared differential gene expression and protein content at pH 9.5 using microarray and two-dimensional (2D) gel electrophoresis, (combined with mass spectrometry) respectively. By interfacing the results of both approaches this study showed strong evidence that alkali tolerance response in L. monocytogenes functions as to minimize excess alkalisation and energy expenditures while mobilizing available carbon sources. Adaptive intracellular gene expression involved genes that are associated with virulence, the general stress response, cell division, and changes in cell wall structure and included many genes with unknown functions. The variability observed between results of cDNA arrays and 2D may account for posttranslational modifications. Interestingly, several alkali induced genes/proteins can provide a cross protective overlap to other types of stresses. Alkaline pH provides therefore L. monocytogenes with nonspecific multiple-stress resistance that may be vital for survival in the human gastrointestinal tract as well as within food processing systems where similar alkaline conditions as the ones used in this study prevail. Keywords: Transcriptomic and Proteomic Comparison Study
