scholarly journals Multiple Two-Component Systems Modulate Alkali Generation in Streptococcus gordonii in Response to Environmental Stresses

2009 ◽  
Vol 191 (23) ◽  
pp. 7353-7362 ◽  
Author(s):  
Yaling Liu ◽  
Robert A. Burne
Keyword(s):  
Acid Tolerance ◽  
Low Ph ◽  
Arginine Deiminase ◽  
Streptococcus Gordonii ◽  
Anaerobic Conditions ◽  
Environmental Signals ◽  
Ph Values ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems

ABSTRACT The oral commensal Streptococcus gordonii must adapt to constantly fluctuating and often hostile environmental conditions to persist in the oral cavity. The arginine deiminase system (ADS) of S. gordonii enables cells to produce, ornithine, ammonia, CO2, and ATP from arginine hydrolysis, augmenting the acid tolerance of the organism. The ADS genes are substrate inducible and sensitive to catabolite repression, mediated through ArcR and CcpA, respectively, but the system also requires low pH and anaerobic conditions for optimal activation. Here, we demonstrate that the CiaRH and ComDE two-component systems (TCS) are required for low-pH-dependent expression of ADS genes in S. gordonii. Further, the VicRK TCS is required for optimal ADS gene expression under anaerobic conditions and enhances the sensitivity of the operon to repression by oxygen. The known anaerobic activator of the ADS, Fnr-like protein (Flp), appeared to act independently of the Vic TCS. Mutants of S. gordonii lacking components of the CiaRH, ComDE, or VicRK grew more slowly in acidified media and were more sensitive to killing at lethal pH values and to agents that induce oxidative stress. This study provides the first evidence that TCS can regulate the ADS of bacteria in response to specific environmental signals and reveals some notable differences in the contribution of CiaRH, ComDE, and VicRK to viability and stress tolerance between the oral commensal S. gordonii and the oral pathogen Streptococcus mutans.

scholarly journals Two Component Regulatory Systems and Antibiotic Resistance in Gram-Negative Pathogens

2019 ◽  
Vol 20 (7) ◽  
pp. 1781 ◽  
Author(s):  
Anjali Y. Bhagirath ◽  
Yanqi Li ◽  
Rakesh Patidar ◽  
Katherine Yerex ◽  
Xiaoxue Ma ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Antimicrobial Resistance ◽  
Pathogenic Bacteria ◽  
Current Knowledge ◽  
Regulation Of Gene Expression ◽  
Gram Negative ◽  
Environmental Signals ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems

Gram-negative pathogens such as Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa are the leading cause of nosocomial infections throughout the world. One commonality shared among these pathogens is their ubiquitous presence, robust host-colonization and most importantly, resistance to antibiotics. A significant number of two-component systems (TCSs) exist in these pathogens, which are involved in regulation of gene expression in response to environmental signals such as antibiotic exposure. While the development of antimicrobial resistance is a complex phenomenon, it has been shown that TCSs are involved in sensing antibiotics and regulating genes associated with antibiotic resistance. In this review, we aim to interpret current knowledge about the signaling mechanisms of TCSs in these three pathogenic bacteria. We further attempt to answer questions about the role of TCSs in antimicrobial resistance. We will also briefly discuss how specific two-component systems present in K. pneumoniae, A. baumannii, and P. aeruginosa may serve as potential therapeutic targets.

scholarly journals Global transcriptional analysis of acid-inducible genes in Streptococcus mutans: multiple two-component systems involved in acid adaptation

Microbiology ◽  
2009 ◽  
Vol 155 (10) ◽  
pp. 3322-3332 ◽  
Author(s):  
Yongxing Gong ◽  
Xiao-Lin Tian ◽  
Tara Sutherland ◽  
Gary Sisson ◽  
Junni Mai ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Expression Profiles ◽  
Acid Tolerance ◽  
Transcriptional Analysis ◽  
Acidic Ph ◽  
Acid Adaptation ◽  
Component Systems ◽  
Two Component ◽  
Tolerance Response ◽  
Two Component Systems

Streptococcus mutans in dental biofilms is regularly exposed to cycles of acidic pH during the ingestion of fermentable dietary carbohydrates. The ability of S. mutans to tolerate low pH is crucial for its virulence and pathogenesis in dental caries. To better understand its acid tolerance mechanisms, we performed genome-wide transcriptional analysis of S. mutans in response to an acidic pH signal. The preliminary results showed that adaptation of S. mutans to pH 5.5 induced differential expression of nearly 14 % of the genes in the genome, including 169 upregulated genes and 108 downregulated genes, largely categorized into nine functional groups. One of the most interesting findings was that the genes encoding multiple two-component systems (TCSs), including CiaHR, LevSR, LiaSR, ScnKR, Hk/Rr1037/1038 and ComDE, were upregulated during acid adaptation. Real-time qRT-PCR confirmed the same trend in the expression profiles of these genes at pH 5.5. To determine the roles of these transduction systems in acid adaptation, mutants with a deletion of the histidine-kinase-encoding genes were constructed and assayed for the acid tolerance response (ATR). The results revealed that inactivation of each of these systems resulted in a mutant that was impaired in ATR, since pre-exposure of these mutants to pH 5.5 did not induce the same level of protection against lethal pH levels as the parent did. A competitive fitness assay showed that all the mutants were unable to compete with the parent strain for persistence in dual-strain mixed cultures at acidic pH, although, with the exception of the mutant in liaS, little effect was observed at neutral pH. The evidence from this study suggests that the multiple TCSs are required for S. mutans to orchestrate its signal transduction networks for optimal adaptation to acidic pH.

scholarly journals Multiple Two-Component Systems of Streptococcus mutans Regulate Agmatine Deiminase Gene Expression and Stress Tolerance

2009 ◽  
Vol 191 (23) ◽  
pp. 7363-7366 ◽  
Author(s):  
Yaling Liu ◽  
Robert A. Burne
Keyword(s):  
Gene Expression ◽  
Stress Tolerance ◽  
Streptococcus Mutans ◽  
Thermal Stresses ◽  
Low Ph ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Agmatine Deiminase

ABSTRACT Induction of the agmatine deiminase system (AgDS) of Streptococcus mutans requires agmatine and is optimal at low pH. We show here that the VicRK, ComDE, and CiaRH two-component systems influence AgDS gene expression in response to acidic and thermal stresses.

scholarly journals Unlimited multistability and Boolean logic in microbial signalling

2015 ◽  
Vol 12 (108) ◽  
pp. 20150234 ◽  
Author(s):  
Varun B. Kothamachu ◽  
Elisenda Feliu ◽  
Luca Cardelli ◽  
Orkun S. Soyer
Keyword(s):  
Response Regulator ◽  
Reaction Rates ◽  
Boolean Logic ◽  
Mathematical Framework ◽  
Core Network ◽  
Environmental Signals ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Logic Functions

The ability to map environmental signals onto distinct internal physiological states or programmes is critical for single-celled microbes. A crucial systems dynamics feature underpinning such ability is multistability. While unlimited multistability is known to arise from multi-site phosphorylation seen in the signalling networks of eukaryotic cells, a similarly universal mechanism has not been identified in microbial signalling systems. These systems are generally known as two-component systems comprising histidine kinase (HK) receptors and response regulator proteins engaging in phosphotransfer reactions. We develop a mathematical framework for analysing microbial systems with multi-domain HK receptors known as hybrid and unorthodox HKs. We show that these systems embed a simple core network that exhibits multistability, thereby unveiling a novel biochemical mechanism for multistability. We further prove that sharing of downstream components allows a system with n multi-domain hybrid HKs to attain 3 n steady states. We find that such systems, when sensing distinct signals, can readily implement Boolean logic functions on these signals. Using two experimentally studied examples of two-component systems implementing hybrid HKs, we show that bistability and implementation of logic functions are possible under biologically feasible reaction rates. Furthermore, we show that all sequenced microbial genomes contain significant numbers of hybrid and unorthodox HKs, and some genomes have a larger fraction of these proteins compared with regular HKs. Microbial cells are thus theoretically unbounded in mapping distinct environmental signals onto distinct physiological states and perform complex computations on them. These findings facilitate the understanding of natural two-component systems and allow their engineering through synthetic biology.

scholarly journals Global Chromosome Topology and the Two-Component Systems in Concerted Manner Regulate Transcription in Streptomyces

mSystems ◽  
2021 ◽  
Author(s):  
Martyna Gongerowska-Jac ◽  
Marcin J. Szafran ◽  
Jakub Mikołajczyk ◽  
Justyna Szymczak ◽  
Magdalena Bartyńska ◽  
...  
Keyword(s):  
Soil Bacteria ◽  
Biologically Active ◽  
Complex Life Cycle ◽  
Regulation Mechanism ◽  
Environmental Signals ◽  
Component Systems ◽  
Chromosome Topology ◽  
Two Component ◽  
Two Component Systems ◽  
Transcriptional Regulation Mechanism

Streptomyces microbes, soil bacteria with complex life cycle, are the producers of a broad range of biologically active compounds (e.g., antibiotics). Streptomyces bacteria respond to various environmental signals using a complex transcriptional regulation mechanism. Understanding regulation of their gene expression is crucial for Streptomyces application as industrial organisms.

scholarly journals Osmosensing by the bacterial PhoQ/PhoP two-component system

2017 ◽  
Vol 114 (50) ◽  
pp. E10792-E10798 ◽  
Author(s):  
Jing Yuan ◽  
Fan Jin ◽  
Timo Glatter ◽  
Victor Sourjik
Keyword(s):  
Essential Role ◽  
Lateral Pressure ◽  
Low Ph ◽  
Membrane Thickness ◽  
Two Component System ◽  
Component System ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Tm Domain

The PhoQ/PhoP two-component system plays an essential role in the response of enterobacteria to the environment of their mammalian hosts. It is known to sense several stimuli that are potentially associated with the host, including extracellular magnesium limitation, low pH, and the presence of cationic antimicrobial peptides. Here, we show that the PhoQ/PhoP two-component systems ofEscherichia coliandSalmonellacan also perceive an osmotic upshift, another key stimulus to which bacteria become exposed within the host. In contrast to most previously established stimuli of PhoQ, the detection of osmotic upshift does not require its periplasmic sensor domain. Instead, we show that the activity of PhoQ is affected by the length of the transmembrane (TM) helix as well as by membrane lateral pressure. We therefore propose that osmosensing relies on a conformational change within the TM domain of PhoQ induced by a perturbation in cell membrane thickness and lateral pressure under hyperosmotic conditions. Furthermore, the response mediated by the PhoQ/PhoP two-component system was found to improve bacterial growth recovery under hyperosmotic stress, partly through stabilization of the sigma factor RpoS. Our findings directly link the PhoQ/PhoP two-component system to bacterial osmosensing, suggesting that this system can mediate a concerted response to most of the established host-related cues.

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.

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