Transcriptional regulation of sdiA by cAMP-receptor protein, LeuO, and environmental signals in Salmonella enterica serovar Typhimurium

2012 ◽  
Vol 58 (1) ◽  
pp. 10-22 ◽  
Author(s):  
Amy L. Turnbull ◽  
Wook Kim ◽  
Michael G. Surette
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Receptor Protein ◽  
Camp Receptor Protein ◽  
Late Stationary Phase ◽  
Environmental Signals ◽  
Serovar Typhimurium ◽  
Elevated Expression ◽  
Transcriptional Changes ◽  
Camp Receptor

The sdiA gene encodes for a LuxR-type transcription factor, which is active when bound to N-acyl homoserine lactones (AHLs). Because Salmonella enterica serovar Typhimurium does not produce AHLs, SdiA senses signals produced by other organisms. SdiA is not expressed constitutively, and response is limited to conditions in which elevated expression occurs, but little is known about the regulation of sdiA expression. Here we map the sdiA promoter and define several regulators that directly or indirectly act on the promoter. The major activator of sdiA expression is cAMP-receptor protein (CRP), and we define the CRP operator in the sdiA promoter using promoter and crp mutants. LeuO activates sdiA expression to a lesser extent than does CRP. We demonstrate that LeuO directly binds the sdiA promoter and the Rcs phosphorelay represses sdiA expression. In this study, NhaR, IlvY, and Fur affected sdiA expression indirectly and weakly. Expression in late-stationary phase depended on RpoS. AHL-dependent expression of the SdiA-regulated gene rck correlated to the observed sdiA transcriptional changes in regulator mutants. The data demonstrate that regulation of sdiA involves integration of multiple environmental and metabolic signals.

Influence of RpoS, cAMP-receptor protein, and ppGpp on expression of the opgGH operon and osmoregulated periplasmic glucan content of Salmonella enterica serovar Typhimurium

2009 ◽  
Vol 55 (11) ◽  
pp. 1284-1293 ◽  
Author(s):  
Cristina S. Costa ◽  
Ramón A. Pizarro ◽  
Dora N. Antón
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Receptor Protein ◽  
Transcriptional Level ◽  
Camp Receptor Protein ◽  
High Osmolarity ◽  
Serovar Typhimurium ◽  
Camp Receptor ◽  
Periplasmic Glucan

A transcriptional fusion (opgG1::MudJ) to the opgGH operon of Salmonella enterica serovar Typhimurium (S. Typhimurium) LT2, isolated by resistance to mecillinam, was used to study the influence of global regulators RpoS, ppGpp, and cAMP/cAMP-receptor protein (CRP) on expression of the opgGH operon and osmoregulated periplasmic glucan (OPG) content. Neither high growth medium osmolarity nor absence of ppGpp or CRP had important effects on opgG1::MudJ expression in exponential cultures. However, under the same conditions, OPG content was strongly decreased by high osmolarity or cAMP/CRP defectiveness, and reduced to a half by lack of ppGpp. In stationary cultures, high osmolarity as well as CRP loss caused significant descents in opgG1::MudJ expression that were compensated by inactivation of RpoS σ factor. No effect of RpoS inactivation on OPG content was observed. It is concluded that opgGH expression in S. Typhimurium is only slightly affected by high osmolarity, but is inversely modulated by RpoS level. On the other hand, osmolarity and the cAMP/CRP global regulatory system appear to control OPG content, either directly or indirectly, mainly at the post-transcriptional level.

scholarly journals The Yersinia enterocoliticaPhospholipase Gene yplA Is Part of the Flagellar Regulon

2000 ◽  
Vol 182 (8) ◽  
pp. 2314-2320 ◽  
Author(s):  
Deborah H. Schmiel ◽  
Glenn M. Young ◽  
Virginia L. Miller
Keyword(s):  
Virulence Genes ◽  
Receptor Protein ◽  
Camp Receptor Protein ◽  
Transcriptional Fusion ◽  
Logarithmic Growth Phase ◽  
Environmental Signals ◽  
Flagellar Regulon ◽  
Camp Receptor ◽  
Logarithmic Growth ◽  
Regulatory Sites

ABSTRACT Yersinia enterocolitica yplA encodes a phospholipase required for virulence. Virulence genes are often regulated in response to environmental signals; therefore, yplA expression was examined using a yplA::lacZYtranscriptional fusion. Maximal yplA expression occurred between pH 6.5 and pH 7.5 and was induced in the mid-logarithmic growth phase. Potential Fnr, cyclic AMP (cAMP)-cAMP receptor protein (Crp), and ςF regulatory sites were identified in the nucleotide sequence. Reduction of yplA expression by aeration, addition of glucose and sucrose, and application of high temperature and salt is consistent with Fnr-, cAMP-Crp-, and ςF-mediated regulation, respectively. Expression ofyplA was reduced in flhDC and fliAnull strains, indicating that yplA is part of the flagellar regulon.

scholarly journals cAMP Receptor Protein Positively Regulates the Expression of Genes Involved in the Biosynthesis of Klebsiella oxytoca Tilivalline Cytotoxin

2021 ◽  
Vol 12 ◽  
Author(s):  
Diana Rodríguez-Valverde ◽  
Nancy León-Montes ◽  
Jorge Soria-Bustos ◽  
Jessica Martínez-Cruz ◽  
Ricardo González-Ugalde ◽  
...  
Keyword(s):  
Gene Expression ◽  
Metabolic Regulation ◽  
Divalent Cations ◽  
Klebsiella Oxytoca ◽  
Carbon Sources ◽  
Enteric Bacteria ◽  
Receptor Protein ◽  
Camp Receptor Protein ◽  
Environmental Signals ◽  
Camp Receptor

Klebsiella oxytoca is a resident of the human gut. However, certain K. oxytoca toxigenic strains exist that secrete the nonribosomal peptide tilivalline (TV) cytotoxin. TV is a pyrrolobenzodiazepine that causes antibiotic-associated hemorrhagic colitis (AAHC). The biosynthesis of TV is driven by enzymes encoded by the aroX and NRPS operons. In this study, we determined the effect of environmental signals such as carbon sources, osmolarity, and divalent cations on the transcription of both TV biosynthetic operons. Gene expression was enhanced when bacteria were cultivated in tryptone lactose broth. Glucose, high osmolarity, and depletion of calcium and magnesium diminished gene expression, whereas glycerol increased transcription of both TV biosynthetic operons. The cAMP receptor protein (CRP) is a major transcriptional regulator in bacteria that plays a key role in metabolic regulation. To investigate the role of CRP on the cytotoxicity of K. oxytoca, we compared levels of expression of TV biosynthetic operons and synthesis of TV in wild-type strain MIT 09-7231 and a Δcrp isogenic mutant. In summary, we found that CRP directly activates the transcription of the aroX and NRPS operons and that the absence of CRP reduced cytotoxicity of K. oxytoca on HeLa cells, due to a significant reduction in TV production. This study highlights the importance of the CRP protein in the regulation of virulence genes in enteric bacteria and broadens our knowledge on the regulatory mechanisms of the TV cytotoxin.

scholarly journals The sRNA MicC downregulates hilD translation to control the SPI1 T3SS in Salmonella enterica serovar Typhimurium

2021 ◽  
Author(s):  
Fatih Cakar ◽  
Yekaterina Golubeva ◽  
Carin K Vanderpool ◽  
James M Slauch
Keyword(s):  
Protein Function ◽  
Regulatory Network ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Mrna Translation ◽  
Two Component System ◽  
Environmental Signals ◽  
Serovar Typhimurium ◽  
Inflammatory Diarrhea ◽  
Regulatory Loop

Salmonella enterica serovar Typhimurium invades the intestinal epithelium and induces inflammatory diarrhea using the Salmonella pathogenicity island 1 (SPI1) type III secretion system (T3SS). Expression of the SPI1 T3SS is controlled by three AraC-like regulators, HilD, HilC and RtsA, which form a feed-forward regulatory loop that leads to activation of hilA, encoding the main transcriptional regulator of the T3SS structural genes. This complex system is affected by numerous regulatory proteins and environmental signals, many of which act at the level of hilD mRNA translation or HilD protein function. Here, we show that the sRNA MicC blocks translation of the hilD mRNA by base pairing near the ribosome binding site. This binding blocks translation but does not induce degradation of the hilD message. Our data indicate that micC is transcriptionally activated by SlyA, and SlyA feeds into the SPI1 regulatory network solely through MicC. Transcription of micC is negatively regulated by the OmpR/EnvZ two-component system, but this regulation is dependent on SlyA. OmpR/EnvZ control SPI1 expression partially through MicC, but also affect expression through other mechanisms. MicC-mediated regulation plays a role during infection, as evidenced by an increase in Salmonella fitness in the intestine in the micC deletion mutant that is dependent on the SPI1 T3SS. These results further elucidate the complex regulatory network controlling SPI1 expression and add to the list of sRNAs that control this primary virulence factor.

scholarly journals cAMP receptor protein (CRP) positively regulates the yihU–yshA operon in Salmonella enterica serovar Typhi

Microbiology ◽  
2011 ◽  
Vol 157 (3) ◽  
pp. 636-647 ◽  
Author(s):  
J. M. Villarreal ◽  
I. Hernández-Lucas ◽  
F. Gil ◽  
I. L. Calderón ◽  
E. Calva ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Salmonella Enterica ◽  
Regulatory Region ◽  
Enteric Bacteria ◽  
Transcriptional Unit ◽  
Receptor Protein ◽  
Camp Receptor Protein ◽  
Salmonella Enterica Serovar Typhi ◽  
Genetic Components ◽  
Camp Receptor

Salmonella enterica serovar Typhi (S. Typhi) is the aetiological agent of typhoid fever in humans. This bacterium is also able to persist in its host, causing a chronic disease by colonizing the spleen, liver and gallbladder, in the last of which the pathogen forms biofilms in order to survive the bile. Several genetic components, including the yihU–yshA genes, have been suggested to be involved in the survival of Salmonella in the gallbladder. In this work we describe how the yihU–yshA gene cluster forms a transcriptional unit regulated positively by the cAMP receptor global regulator CRP (cAMP receptor protein). The results obtained show that two CRP-binding sites on the regulatory region of the yihU–yshA operon are required to promote transcriptional activation. In this work we also demonstrate that the yihU–yshA transcriptional unit is carbon catabolite-repressed in Salmonella, indicating that it forms part of the CRP regulon in enteric bacteria.

scholarly journals The ATP-Dependent Lon Protease of Salmonella enterica Serovar Typhimurium Regulates Invasion and Expression of Genes Carried on Salmonella Pathogenicity Island 1

2002 ◽  
Vol 184 (1) ◽  
pp. 224-232 ◽  
Author(s):  
Akiko Takaya ◽  
Toshifumi Tomoyasu ◽  
Akane Tokumitsu ◽  
Mizue Morioka ◽  
Tomoko Yamamoto
Keyword(s):  
Gene Expression ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Pathogenicity Island ◽  
Lon Protease ◽  
Environmental Signals ◽  
Regulatory Systems ◽  
Expression Of Genes ◽  
Serovar Typhimurium ◽  
Complex Manner

ABSTRACT An early step in the pathogenesis of Salmonella enterica serovar Typhimurium infection is bacterial penetration of the intestinal epithelium. Penetration requires the expression of invasion genes found in Salmonella pathogenicity island 1 (SPI1). These genes are controlled in a complex manner by regulators in SPI1, including HilA and InvF, and those outside SPI1, such as two-component regulatory systems and small DNA-binding proteins. We report here that the expression of invasion genes and the invasive phenotype of S. enterica serovar Typhimurium are negatively regulated by the ATP-dependent Lon protease, which is known to be a major contributor to proteolysis in Escherichia coli. A disrupted mutant of lon was able to efficiently invade cultured epithelial cells and showed increased production and secretion of three identified SPI1 proteins, SipA, SipC, and SipD. The lon mutant also showed a dramatic enhancement in transcription of the SPI1 genes hilA, invF, sipA, and sipC. The increases ranged from 10-fold to almost 40-fold. It is well known that the expression of SPI1 genes is also regulated in response to several environmental conditions. We found that the disruption of lon does not abolish the repression of hilA and sipC expression by high-oxygen or low-osmolarity conditions, suggesting that Lon represses SPI1 gene expression by a regulatory pathway independent of these environmental signals. Since HilA is thought to function as a central regulator of SPI1 gene expression, it is speculated that Lon may regulate SPI1 gene expression by proteolysis of putative factors required for activation of hilA expression.

scholarly journals Environmental Signals Controlling Production of Hemagglutinin/Protease in Vibrio cholerae

2001 ◽  
Vol 69 (10) ◽  
pp. 6549-6553 ◽  
Author(s):  
Jorge A. Benitez ◽  
Anisia J. Silva ◽  
Richard A. Finkelstein
Keyword(s):  
Vibrio Cholerae ◽  
Deletion Mutant ◽  
Receptor Protein ◽  
Intracellular Camp ◽  
Wild Type ◽  
Camp Receptor Protein ◽  
Environmental Signals ◽  
Camp Receptor ◽  
Camp Levels

ABSTRACT Vibrio cholerae hemagglutinin/protease (Hap) was induced upon nutrient limitation and strongly repressed by glucose. Hap was not produced in a mutant defective in the cyclic AMP (cAMP) receptor protein, suggesting that intracellular cAMP levels mediate Hap expression. No difference was found in Hap production between anrpoS deletion mutant and its isogenic wild-type precursor, indicating that the alternate ςs factor is not essential for Hap expression. Based on these and previous results, we discuss the role of Hap in the pathogenesis of cholera.

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