Regulation of the Homologous Two-Component Systems KvgAS and KvhAS in Klebsiella pneumoniae CG43

2006 ◽  
Vol 140 (5) ◽  
pp. 639-648 ◽  
Author(s):  
Ching-Ting Lin ◽  
Hwei-Ling Peng
Keyword(s):  
Klebsiella Pneumoniae ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems

scholarly journals Effects of Regulatory Network Organization and Environment on PmrD Connector Activity and Polymyxin Resistance in Klebsiella pneumoniae and Escherichia coli

2020 ◽  
Vol 65 (3) ◽  
Author(s):  
Annie I. Chen ◽  
Francisco Javier Albicoro ◽  
Jun Zhu ◽  
Mark Goulian
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Critical Role ◽  
Negative Regulator ◽  
Network Organization ◽  
Content Type ◽  
Resistance Pathway ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems

ABSTRACT Polymyxins are a class of cyclic peptides with antimicrobial activity against Gram-negative bacteria. In Enterobacteriaceae, the PhoQ/PhoP and PmrB/PmrA two-component systems regulate many genes that confer resistance to both polymyxins and host antimicrobial peptides. The activities of these two-component systems are modulated by additional proteins that are conserved across Enterobacteriaceae, such as MgrB, a negative regulator of PhoQ, and PmrD, a “connector” protein that activates PmrB/PmrA in response to PhoQ/PhoP stimulation. Despite the conservation of many protein components of the PhoQ/PhoP-PmrD-PmrB/PmrA network, the specific molecular interactions and regulatory mechanisms vary across different genera. Here, we explore the role of PmrD in modulating this signaling network in Klebsiella pneumoniae and Escherichia coli. We show that in K. pneumoniae, PmrD is not required for polymyxin resistance arising from mutation of mgrB—the most common cause of spontaneous polymyxin resistance in this bacterium—suggesting that direct activation of polymyxin resistance genes by PhoQ/PhoP plays a critical role in this resistance pathway. However, for conditions of low pH or intermediate iron concentrations, both of which stimulate PmrB/PmrA, we find that PmrD does contribute to resistance. We further show that in E. coli, PmrD functions as a connector between PhoQ/PhoP and PmrB/PmrA, in contrast with previous reports. In this case, activity also depends on PmrB/PmrA stimulation, or on very high activation of PhoQ/PhoP. Our results indicate that the importance of the PmrD connector in modulating the polymyxin resistance network depends on both the network organization and on the environmental conditions associated with PmrB stimulation.

Diffusive layering during film growth in two-component systems with limited mutual solubility

2000 ◽  
Author(s):  
Grigory V. Merkulov ◽  
Valentin M. Ievlev ◽  
Evgeny V. Shvedov ◽  
Vadim P. Ampilogov
Keyword(s):  
Film Growth ◽  
Mutual Solubility ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems

scholarly journals Regulation of virulence and β-lactamase gene expression in Staphylococcus aureus isolates: cooperation of two-component systems in bloodstream superbugs

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Sanaz Dehbashi ◽  
Hamed Tahmasebi ◽  
Behrouz Zeyni ◽  
Mohammad Reza Arabestani
Keyword(s):  
Staphylococcus Aureus ◽  
Real Time ◽  
Real Time Pcr ◽  
Quantitative Real Time Pcr ◽  
Gene Expressions ◽  
Resistance Development ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Lactamase Gene

Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA)-bloodstream infections (BSI) are predominantly seen in the hospital or healthcare-associated host. Nevertheless, the interactions of virulence factor (VFs) regulators and β-lactam resistance in MRSA-BSI are unclear. This study aims to characterize the molecular relationship of two-component systems of VFs and the expression of the β-lactamase gene in MRSA-BSI isolates. In this study, 639 samples were collected from BSI and identified by phenotypic methods. We performed extensive molecular characterization, including SCCmec type, agr type, VFs gene profiles determinations, and MLST on isolates. Also, a quantitative real-time PCR (q-RT PCR) assay was developed for identifying the gene expressions. Results Ninety-one (91) S. aureus and 61 MRSA (67.0%) strains were detected in BSI samples. The presence of VFs and SCCmec genes in MRSA isolates were as follows: tst (31.4%), etA (18.0%), etB (8.19%), lukS-PVL (31.4%), lukF-PV (18.0%), lukE-lukD (16.3%), edin (3.2%), hla (16.3%), hlb (18.0%), hld (14.7%), hlg (22.9%), SCCmecI (16.3%), SCCmecII (22.9%), SCCmecIII (36.0%), SCCmecIV (21.3%), and SCCmecV (16.3%). Quantitative real-time PCR showed overexpression of mecRI and mecI in the toxigenic isolates. Moreover, RNAIII and sarA genes were the highest expressions of MRSA strains. The multi-locus sequence typing data confirmed a high prevalence of CC5, CC8, and CC30. However, ST30, ST22, and ST5 were the most prevalent in the resistant and toxigenic strains. Conclusion We demonstrated that although regulation of β-lactamase gene expressions is a significant contributor to resistance development, two-component systems also influence antibiotic resistance development in MRSA-BSI isolates. This indicates that resistant strains might have pathogenic potential. We also confirmed that some MLST types are more successful colonizers with a potential for MRSA-BSI.

Monte Carlo Simulation of Electronic Excitation Migrationand Trappingin Disordered Two-Component Systems. A Comparison with Analytical Theories

1989 ◽  
Vol 44 (4) ◽  
pp. 257-261 ◽  
Author(s):  
Sławomir Błonski ◽  
Czesław Bojarski
Keyword(s):  
Monte Carlo ◽  
Electronic Excitation ◽  
Two Component System ◽  
Component System ◽  
Steady State Fluorescence ◽  
Donor And Acceptor ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Viscous Solution

Abstract Monte Carlo simulations of quantum yield and anisotropy of fluorescence in two-component systems have been conducted with various donor and acceptor concentrations and Förster radii ratios RDAO/RDDO. The influence of excitation migration and trapping on the fluorescence of the viscous solution has been considered. The results of the simulations have shown that steady-state fluorescence of a two-component system depends on the RDAO/RDDO ratio as predicted in LAF theory.

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