Search results for "Sigma factor"
showing 10 items of 11 documents
Roles for RpoS in survival of Escherichia coli during protozoan predation and in reduced moisture conditions highlight its importance in soil environ…
2017
The soil is a complex ecosystem where interactions between biotic and abiotic factors determine the survival and fate of microbial inhabitants of the system. Having previously shown that Escherichia coli requires the general stress response regulator, RpoS, to survive long term in soil, it was important to determine what specific conditions in this environment necessitate a functional RpoS. This study investigated the susceptibility of soil-persistent E. coli to predation by the single-celled eukaryotes Acanthamoeba polyphaga and Tetrahymena pyriformis, and the role RpoS plays in resisting this predation. Strain-specific differences were observed in the predation of E. coli strains, with so…
Transcriptional regulation of theNε‐fructoselysine metabolism inEscherichia coliby global and substrate‐specific cues
2020
Thermally processed food is an important part of the human diet. Heat-treatment, however, promotes the formation of so-called Amadori rearrangement products, such as fructoselysine. The gut microbiota including Escherichia coli can utilize these compounds as a nutrient source. While the degradation route for fructoselysine is well described, regulation of the corresponding pathway genes frlABCD remained poorly understood. Here, we used bioinformatics combined with molecular and biochemical analyses and show that fructoselysine metabolism in E. coli is tightly controlled at the transcriptional level. The global regulator CRP (CAP) as well as the alternative sigma factor σ32 (RpoH) contribute…
CtsR is the master regulator of stress response gene expression in Oenococcus oeni.
2005
ABSTRACT Although many stress response genes have been characterized in Oenococcus oeni , little is known about the regulation of stress response in this malolactic bacterium. The expression of eubacterial stress genes is controlled both positively and negatively at the transcriptional level. Overall, negative regulation of heat shock genes appears to be more widespread among gram-positive bacteria. We recently identified an ortholog of the ctsR gene in O. oeni . In Bacillus subtilis , CtsR negatively regulates expression of the clp genes, which belong to the class III family of heat shock genes. The ctsR gene of O. oeni is cotranscribed with the downstream clpC gene. Sequence analysis of t…
An MLSA approach for the taxonomic update of the Splendidus clade, a lineage containing several fish and shellfish pathogenic Vibrio spp.
2016
A multilocus sequence analysis was undertaken in order to redefine the Splendidus clade of the genus Vibrio, a large group of species containing several pathogenic members that affect fish and shellfish, and are difficult to identify through both phenotypic and genotypic approaches. The study included analysis of partial sequences of recA, gyrB, mreB, rpoD and pyrH genes, as well as the 16S rRNA gene. Seventeen type strain species were included that were complemented with other reference strains and a collection of isolates tentatively identified as members of this clade, as well as a set of other Vibrio species. The clade was well defined and stable in all analyses, and was confirmed to co…
Description of Enterovibrio nigricans sp. nov., reclassification of Vibrio calviensis as Enterovibrio calviensis comb. nov. and emended description o…
2009
Eleven strains of halophilic, facultative anaerobes isolated from healthy and diseased Dentex dentex and Sparus aurata (bony fishes) cultured in Spanish Mediterranean fisheries have been studied by a polyphasic approach that included a wide phenotypic characterization, DNA-DNA hybridization and phylogenetic analysis using 16S rRNA, recA and rpoD gene sequences. All strains were phylogenetically related to Enterovibrio species and Vibrio calviensis. On the basis of sequence analysis and DNA-DNA hybridization data, eight of the strains were identified as Enterovibrio coralii. The remaining three strains formed a tight, independent clade in all sequence analyses and showed less than 70 % DNA-D…
Multilocus sequence analysis of the central clade of the genus Vibrio by using the 16S rRNA, recA, pyrH, rpoD, gyrB, rctB and toxR genes.
2009
The central clade of the genus Vibrio, also called the Vibrio core group, comprises six species that are tightly related (DNA–DNA reassociation values are very close to 70 % for most species pairs). Identification of novel strains to the species level within this group is troublesome and results are quite often dependent on the methodology employed. Therefore, this group represents an excellent framework to test the robustness of multilocus sequence analysis (MLSA) not only for inferring phylogeny but also as an identification tool without the need for DNA–DNA hybridization assays. The genes selected, 16S rRNA, recA, pyrH, rpoD, gyrB, rctB and toxR, were amplified by direct PCR from 44 Vibr…
Transcriptional regulation of theNε-fructoselysine metabolism inEscherichia coliby global and substrate-specific cues
2020
AbstractThermally processed food is an important part of the human diet. Heat-treatment, however, promotes the formation of so-called Amadori rearrangement products (ARPs), such as fructoselysine. The gut microbiota includingEscherichia colican utilize these compounds as a nutrient source. While the degradation route for fructoselysine is well described, regulation of the corresponding pathway genesfrlABCDremained poorly understood. Here we use bioinformatics combined with molecular and biochemical analyses and show that inE. coli, fructoselysine metabolism is tightly controlled at the transcriptional level. The global regulator Crp (CAP), as well as the alternative sigma factor σ32 (RpoH) …
Listeria monocytogenes Differential Transcriptome Analysis Reveals Temperature-Dependent Agr Regulation and Suggests Overlaps with Other Regulons
2012
Listeria monocytogenes is a ubiquitous, opportunistic pathogenic organism. Environmental adaptation requires constant regulation of gene expression. Among transcriptional regulators, AgrA is part of an auto-induction system. Temperature is an environmental cue critical for in vivo adaptation. In order to investigate how temperature may affect AgrA-dependent transcription, we compared the transcriptomes of the parental strain L. monocytogenes EGD-e and its Delta agrA mutant at the saprophytic temperature of 25 degrees C and in vivo temperature of 37 degrees C. Variations of transcriptome were higher at 37 degrees C than at 25 degrees C. Results suggested that AgrA may be involved in the regu…
Investigation of the roles of AgrA and σB regulators in Listeria monocytogenes adaptation to roots and soil
2020
ABSTRACT Little is known about the regulatory mechanisms that ensure the survival of the food-borne bacterial pathogen Listeria monocytogenes in the telluric environment and on roots. Earlier studies have suggested a regulatory overlap between the Agr cell–cell communication system and the general stress response regulator σB. Here, we investigated the contribution of these two systems to root colonisation and survival in sterilised and biotic soil. The ability to colonise the roots of the grass Festuca arundinacea was significantly compromised in the double mutant (∆agrA∆sigB). In sterile soil at 25°C, a significant defect was observed in the double mutant, suggesting some synergy between …
Exploring new roles for the rpoS gene in the survival and virulence of the fire blight pathogen Erwinia amylovora
2014
Erwinia amylovora causes fire blight in economically important plants of the family Rosaceae. This bacterial pathogen spends part of its life cycle coping with starvation and other fluctuating environmental conditions. In many Gram-negative bacteria, starvation and other stress responses are regulated by the sigma factor RpoS. We obtained an E. amylovora rpoS mutant to explore the role of this gene in starvation responses and its potential implication in other processes not yet studied in this pathogen. Results showed that E. amylovora needs rpoS to develop normal starvation survival and viable but nonculturable (VBNC) responses. Furthermore, this gene contributed to stationary phase cross-…