scholarly journals The LysR-Type Transcriptional Regulator LeuO Controls Expression of Several Genes in Salmonella enterica Serovar Typhi

2007 ◽  
Vol 190 (5) ◽  
pp. 1658-1670 ◽  
Author(s):  
I. Hernández-Lucas ◽  
A. L. Gallego-Hernández ◽  
S. Encarnación ◽  
M. Fernández-Mora ◽  
A. G. Martínez-Batallar ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Regulatory Protein ◽  
Genomic Analysis ◽  
Stringent Response ◽  
Transcriptional Regulator ◽  
Global Regulator ◽  
Salmonella Enterica Serovar Typhi ◽  
Intergenic Regions ◽  
Positive Effect ◽  
Transcriptional Fusions

ABSTRACT LeuO is a LysR-type transcriptional regulator that has been implicated in the bacterial stringent response and in the virulence of Salmonella. A genomic analysis with Salmonella enterica serovar Typhi revealed that LeuO is a positive regulator of OmpS1, OmpS2, AssT, and STY3070. In contrast, LeuO down-regulated the expression of OmpX, Tpx, and STY1978. Transcriptional fusions supported the positive and negative LeuO regulation. Expression of ompS1, assT, and STY3070 was induced in an hns mutant, consistent with the notion that H-NS represses these genes; transcriptional activity was lower for tpx and STY1978 in an hns background, suggesting that this global regulatory protein has a positive effect. In contrast, ompS2 and ompX expression appeared to be H-NS independent. LeuO specifically bound to the 5′ intergenic regions of ompS2, assT, STY3070, ompX, and tpx, while it was not observed to bind to the promoter region of STY1978, suggesting that LeuO regulates in direct and indirect ways. In this work, a novel set of genes belonging to the LeuO regulon are described; interestingly, these genes are involved in a variety of biological processes, suggesting that LeuO is a global regulator in Salmonella.

scholarly journals The CRISPR/Cas Immune System Is an Operon Regulated by LeuO, H-NS, and Leucine-Responsive Regulatory Protein in Salmonella enterica Serovar Typhi

2011 ◽  
Vol 193 (10) ◽  
pp. 2396-2407 ◽  
Author(s):  
L. Medina-Aparicio ◽  
J. E. Rebollar-Flores ◽  
A. L. Gallego-Hernandez ◽  
A. Vazquez ◽  
L. Olvera ◽  
...  
Keyword(s):  
Immune System ◽  
Salmonella Enterica ◽  
Regulatory Protein ◽  
Salmonella Enterica Serovar Typhi

scholarly journals Low cytoplasmic magnesium increases the specificity of the Lon and ClpAP proteases

2021 ◽  
Author(s):  
Jinki Yeom ◽  
Eduardo A. Groisman
Keyword(s):  
Salmonella Enterica ◽  
Regulatory Protein ◽  
Fundamental Property ◽  
Transcriptional Regulator ◽  
Enterobacter Cloacae ◽  
Enteric Bacteria ◽  
Living Cells ◽  
Acetyl Coa ◽  
Serovar Typhimurium ◽  
Protease Specificity

Proteolysis is a fundamental property of all living cells. In the bacterium Salmonella enterica serovar Typhimurium ( S. Typhimurium), the HspQ protein controls the specificities of the Lon and ClpAP proteases. Upon acetylation, HspQ stops being a Lon substrate and no longer enhances proteolysis of the Lon substrate Hha. The accumulated HspQ protein binds to the protease adaptor ClpS, hindering proteolysis of ClpS-dependent substrates of ClpAP, such as Oat, a promoter of antibiotic persistence. HspQ is acetylated by the protein acetyl transferase Pat from acetyl-CoA bound to the acetyl-CoA binding protein Qad. We now report that low cytoplasmic Mg 2+ promotes qad expression, which protects substrates of Lon and ClpSAP by furthering HspQ amounts. The qad promoter is activated by PhoP, a regulatory protein highly activated in low cytoplasmic Mg 2+ that also represses clpS transcription. Both the qad gene and PhoP repression of the clpS promoter are necessary for antibiotic persistence. PhoP promotes qad transcription also in Escherichia coli , which shares a similar PhoP box in the qad promoter region with S. Typhimurium, S. bongori , and Enterobacter cloacae . Our findings identify cytoplasmic Mg 2+ and the PhoP protein as critical regulators of protease specificity in multiple enteric bacteria. Importance The bacterium Salmonella enterica serovar Typhimurium narrows down the spectrum of substrates degraded by the proteases Lon and ClpAP in response to low cytoplasmic Mg 2+ , a condition that decreases protein synthesis. This control is exerted by PhoP, a transcriptional regulator activated in low cytoplasmic Mg 2+ that governs proteostasis and is conserved in enteric bacteria. The uncovered mechanism enables bacteria to control the abundance of pre-existing proteins.

scholarly journals The Hfq Homolog in Legionella pneumophila Demonstrates Regulation by LetA and RpoS and Interacts with the Global Regulator CsrA

2005 ◽  
Vol 187 (4) ◽  
pp. 1527-1532 ◽  
Author(s):  
Tamara L McNealy ◽  
Vera Forsbach-Birk ◽  
Chunwei Shi ◽  
Reinhard Marre
Keyword(s):  
Legionella Pneumophila ◽  
Transcriptional Regulator ◽  
Exponential Phase ◽  
Ferric Uptake Regulator ◽  
Global Regulator ◽  
Macrophage Infection ◽  
Infection Models ◽  
Significant Homology ◽  
Regulatory Cascades ◽  
Positive Effect

ABSTRACT A gene in Legionella pneumophila that has significant homology to published hfq genes demonstrated regulation by RpoS and the transcriptional regulator LetA. Additionally, Hfq has a positive effect on the presence of transcripts of the genes for CsrA and the ferric uptake regulator Fur. Mutants lacking hfq demonstrate defects in growth and pigmentation and slight defects in virulence in both amoeba and macrophage infection models. Hfq appears to play a major role in exponential-phase regulatory cascades of L. pneumophila.

Sign in / Sign up

Export Citation Format

Share Document