scholarly journals Phenotypic and Transcriptional Characterization of the Meningococcal PhoPQ System, a Magnesium-Sensing Two-Component Regulatory System That Controls Genes Involved in Remodeling the Meningococcal Cell Surface

2005 ◽  
Vol 187 (14) ◽  
pp. 4967-4975 ◽  
Author(s):  
J. Newcombe ◽  
J. C. Jeynes ◽  
E. Mendoza ◽  
J. Hinds ◽  
G. L. Marsden ◽  
...  
Keyword(s):  
Cell Surface ◽  
Transcriptional Profiling ◽  
Regulatory System ◽  
Host Environment ◽  
Low Magnesium ◽  
System A ◽  
Solid Media ◽  
Two Component ◽  
Pathogenic Process

ABSTRACT We previously identified and characterized a two-component regulatory system in the meningococcus with homology to the phoP-phoQ system in salmonella and showed that allele replacement of the NMB0595 regulator gene led to loss of virulence, sensitivity to antimicrobial peptides, perturbed protein expression, and magnesium-sensitive growth. On the basis of these findings we proposed that the system should be designated the meningococcal PhoPQ system. Here we further characterized the NMB0595 mutant and demonstrated that it had increased membrane permeability and was unable to form colonies on solid media with low magnesium concentrations, features that are consistent with disruption of PhoPQ-mediated modifications to the lipooligosaccharide structure. We examined the transcriptional profiles of wild-type and NMB0595 mutant strains and found that magnesium-regulated changes in gene expression are completely abrogated in the mutant, indicating that, similar to the salmonella PhoPQ system, the meningococcal PhoPQ system is regulated by magnesium. Transcriptional profiling of the mutant indicated that, also similar to the salmonella PhoPQ system, the meningococcal system is involved in control of virulence and remodeling of the bacterial cell surface in response to the host environment. The results are consistent with the hypothesis that the PhoP homologue plays a role in the meningococcus similar to the role played by PhoP in salmonella. Elucidating the role that the PhoPQ system and PhoPQ-regulated genes play in the response of the meningococcus to the host environment may provide new insights into the pathogenic process.

Molecular characterization of lpxACD and pmrA/B two-component regulatory system in the colistin resistance Acinetobacter baumannii clinical isolates

Gene Reports ◽  
2020 ◽  
Vol 21 ◽  
pp. 100952
Author(s):  
Mohammad Reza Kandehkar Ghahraman ◽  
Hossein Hosseini-Nave ◽  
Omid Azizi ◽  
Mohammad Reza Shakibaie ◽  
Hamid Reza Mollaie ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Molecular Characterization ◽  
Regulatory System ◽  
Clinical Isolates ◽  
Colistin Resistance ◽  
Two Component

scholarly journals Succinoglycan Production by Rhizobium meliloti Is Regulated through the ExoS-ChvI Two-Component Regulatory System

1998 ◽  
Vol 180 (1) ◽  
pp. 20-26 ◽  
Author(s):  
Hai-Ping Cheng ◽  
Graham C. Walker
Keyword(s):  
Histidine Kinase ◽  
Cytoplasmic Membrane ◽  
Rhizobium Meliloti ◽  
Response Regulator ◽  
Regulatory System ◽  
Kinase Domain ◽  
Cloning And Sequencing ◽  
System A ◽  
Two Component ◽  
Close Homolog

ABSTRACT The Rhizobium meliloti exoS gene is involved in regulating the production of succinoglycan, which plays a crucial role in the establishment of the symbiosis between R. melilotiRm1021 and its host plant, alfalfa. TheexoS96::Tn5 mutation causes the upregulation of the succinoglycan biosynthetic genes, thereby resulting in the overproduction of succinoglycan. Through cloning and sequencing, we found that the exoS gene is a close homolog of theAgrobacterium tumefaciens chvG gene, which has been proposed to encode the sensor protein of the ChvG-ChvI two-component regulatory system, a member of the EnvZ-OmpR family. Further analyses revealed the existence of a newly discovered A. tumefaciens chvI homolog located just upstream of the R. meliloti exoS gene. R. meliloti ChvI may serve as the response regulator of ExoS in a two-component regulatory system. By using ExoS-specific antibodies, it was found that the ExoS protein cofractionated with membrane proteins, suggesting that it is located in the cytoplasmic membrane. By using the same antibodies, it was shown that the exoS96::Tn5 allele encodes an N-terminal truncated derivative of ExoS. The cytoplasmic histidine kinase domain of ExoS was expressed in Escherichia coli and purified, as was the R. meliloti ChvI protein. The ChvI protein autophosphorylated in the presence of acetylphosphate, and the ExoS cytoplasmic domain fragment autophosphorylated at a histidine residue in the presence of ATP. The ChvI protein was phosphorylated in the presence of ATP only when the histidine kinase domain of ExoS was also present. We propose a model for regulation of succinoglycan production by R. meliloti through the ExoS-ChvI two-component regulatory system.

T2056 Characterization of a Two-Component Regulatory System in a Type IV Pili of Etec

2009 ◽  
Vol 136 (5) ◽  
pp. A-630
Author(s):  
Bharani Pandrangi ◽  
Oscar Gomez
Keyword(s):  
Regulatory System ◽  
Type Iv Pili ◽  
Type Iv ◽  
Two Component

scholarly journals Heterologous Inducible Expression ofEnterococcus faecalis pCF10 Aggregation Substance Asc10 inLactococcus lactis and Streptococcus gordonii Contributes to Cell Hydrophobicity and Adhesion to Fibrin

2000 ◽  
Vol 182 (8) ◽  
pp. 2299-2306 ◽  
Author(s):  
Helmut Hirt ◽  
Stanley L. Erlandsen ◽  
Gary M. Dunny
Keyword(s):  
Cell Surface ◽  
Cell Surface Hydrophobicity ◽  
Regulatory System ◽  
Surface Hydrophobicity ◽  
Bacterial Cells ◽  
Streptococcus Gordonii ◽  
Cell Surfaces ◽  
Gene Encoding ◽  
Aggregation Substance

ABSTRACT Aggregation substance proteins encoded by the sex pheromone plasmid family of Enterococcus faecalis have been shown previously to contribute to the formation of a stable mating complex between donor and recipient cells and have been implicated in the virulence of this increasingly important nosocomial pathogen. In an effort to characterize the protein further, prgB, the gene encoding the aggregation substance Asc10 on pCF10, was cloned in a vector containing the nisin-inducible nisA promoter and its two-component regulatory system. Expression of aggregation substance after nisin addition to cultures of E. faecalis and the heterologous bacteria Lactococcus lactis andStreptococcus gordonii was demonstrated. Electron microscopy revealed that Asc10 was presented on the cell surfaces ofE. faecalis and L. lactis but not on that ofS. gordonii. The protein was also found in the cell culture supernatants of all three species. Characterization of Asc10 on the cell surfaces of E. faecalis and L. lactisrevealed a significant increase in cell surface hydrophobicity upon expression of the protein. Heterologous expression of Asc10 on L. lactis also allowed the recognition of its binding ligand (EBS) on the enterococcal cell surface, as indicated by increased transfer of a conjugative transposon. We also found that adhesion of Asc10-expressing bacterial cells to fibrin was elevated, consistent with a role for the protein in the pathogenesis of enterococcal endocarditis. The data demonstrate that Asc10 expressed under the control of the nisA promoter in heterologous species will be an useful tool in the detailed characterization of this important enterococcal conjugation protein and virulence factor.

scholarly journals Identification and characterization of the two-component NtrY/NtrX regulatory system in Azospirillum brasilense

2002 ◽  
Vol 35 (6) ◽  
pp. 651-661 ◽  
Author(s):  
M.L. Ishida ◽  
M.C. Assumpção ◽  
H.B. Machado ◽  
E.M. Benelli ◽  
E.M. Souza ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Regulatory System ◽  
Two Component ◽  
Identification And Characterization

scholarly journals Identification of CsrC and Characterization of Its Role in Epithelial Cell Invasion in Salmonella enterica Serovar Typhimurium

2006 ◽  
Vol 74 (1) ◽  
pp. 331-339 ◽  
Author(s):  
Doreen R. Fortune ◽  
Mitsu Suyemoto ◽  
Craig Altier
Keyword(s):  
Cell Invasion ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Regulatory Rna ◽  
Two Component ◽  
Serovar Typhimurium ◽  
Regulatory Rnas ◽  
The Stability

ABSTRACT The csr regulatory system of Salmonella regulates the expression of the genes of Salmonella pathogenicity island 1 (SPI1) required for the invasion of epithelial cells. This system consists of the posttranscriptional regulator CsrA and an untranslated regulatory RNA, CsrB, that opposes the action of CsrA. Here we identify and characterize the role of a second regulatory RNA, CsrC, whose ortholog was discovered previously in Escherichia coli. We show that a mutant of csrC has only mild defects in invasion and the expression of SPI1 genes, as does a mutant of csrB, but that a double csrB csrC mutant is markedly deficient in these properties, suggesting that the two regulatory RNAs play redundant roles in the control of invasion. We further show that CsrC, like CsrB, is controlled by the BarA/SirA two-component regulator but that a csrB csrC mutant exhibits a loss of invasion equivalent to that of a barA or sirA mutant, indicating that much of the effect of BarA/SirA on invasion functions through its control of CsrB and CsrC. In addition to their control by BarA/SirA, each regulatory RNA is also controlled by other components of the csr system. The loss of csrB was found to increase the level of CsrC by sevenfold, while the loss of csrC increased CsrB by nearly twofold. Similarly, the overexpression of csrA increased CsrC by nearly 11-fold and CsrB by 3-fold and also significantly increased the stability of both RNAs.

scholarly journals Characterization of Amino Acid Substitutions in the Two-Component Regulatory System AdeRS Identified in Multidrug-Resistant Acinetobacter baumannii

mSphere ◽  
2021 ◽  
Author(s):  
K. Lucaßen ◽  
K. Xanthopoulou ◽  
J. Wille ◽  
T. Wille ◽  
Y. Wen ◽  
...  
Keyword(s):  
Amino Acid ◽  
Antimicrobial Resistance ◽  
Acinetobacter Baumannii ◽  
Regulatory System ◽  
Efflux Pumps ◽  
Multidrug Resistant ◽  
Amino Acid Substitutions ◽  
Active Efflux ◽  
Two Component

The active efflux of antimicrobials by bacteria can lead to antimicrobial resistance and persistence and can affect multiple different classes of antimicrobials. Efflux pumps are tightly regulated, and their overexpression can be mediated by changes in their regulators.

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