scholarly journals Role of PhoP-PhoQ Two-Component System in Biofilm Formation of the Phytopathogen Dickeya dadantii Strain 3937

2010 ◽  
pp. 108-117
Author(s):  
Md Manjurul Haque ◽  
Shinji Tsuyumu
Keyword(s):  
Biofilm Formation ◽  
Transcriptional Control ◽  
Test Tube ◽  
Luria Bertani ◽  
High Concentration ◽  
Two Component System ◽  
Dickeya Dadantii ◽  
Component System ◽  
Two Component

To elucidate the role of PhoP-PhoQ two-component system in biofilm formation by the phytopathogen Dickeya dadantii (formerly Erwinia chrysanthemi) strain 3937, we used marker-exchanged mutants deficient in both phoP and phoQ. A biofilm-inducing medium, salt-optimized broth plus glycerol (SOBG) which contains salt-optimized broth (SOB) plus 2% of glycerol, supported biofilm formation by D. dadantii strain 3937 to a greater extent than either M63 glycerol minimal medium or yeast extract peptone (YP) medium or Luria-Bertani (LB) medium. In addition, magnesium greatly induced biofilm formation. It was found that both the phoP and phoQ mutants exhibited enhanced ability to form a biofilm on the surface of the glass test tube as compared to the wild-type strain in SOBG medium containing high concentration of magnesium. In addition, under high magnesium condition, both the mutants produced elevated level of exopolysaccharide. Accordingly, genes responsible for exopolysaccharide production (weaP, wza and wzc) were derepressed in the mutants. These results suggest that the PhoP-PhoQ two-component system may regulate formation of biofilm, at least in part, by transcriptional control of genes responsible for exopolysaccharide biosynthesis of D. dadantii strain 3937. Since biofilm-associated bacteria showed more tolerance to acidic pH and high osmotic stress, it is apparent that the formation of biofilm may be an important factor for the survival of D. dadantii strain 3937 in unfavorable environment.

scholarly journals Effects of Oxygen on Biofilm Formation and the AtlA Autolysin of Streptococcus mutans

2007 ◽  
Vol 189 (17) ◽  
pp. 6293-6302 ◽  
Author(s):  
Sang-Joon Ahn ◽  
Robert A. Burne
Keyword(s):  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Normal Cell ◽  
Surface Protein ◽  
Two Component System ◽  
Component System ◽  
Oxidative Stress Tolerance ◽  
Two Component ◽  
Causative Agents

ABSTRACT The Streptococcus mutans atlA gene encodes an autolysin required for biofilm maturation and biogenesis of a normal cell surface. We found that the capacity to form biofilms by S. mutans, one of the principal causative agents of dental caries, was dramatically impaired by growth of the organism in an aerated environment and that cells exposed to oxygen displayed marked changes in surface protein profiles. Inactivation of the atlA gene alleviated repression of biofilm formation in the presence of oxygen. Also, the formation of long chains, a characteristic of AtlA-deficient strains, was less evident in cells grown with aeration. The SMu0629 gene is immediately upstream of atlA and encodes a product that contains a C-X-X-C motif, a characteristic of thiol-disulfide oxidoreductases. Inactivation of SMu0629 significantly reduced the levels of AtlA protein and led to resistance to autolysis. The SMu0629 mutant also displayed an enhanced capacity to form biofilms in the presence of oxygen compared to that of the parental strain. The expression of SMu0629 was shown to be under the control of the VicRK two-component system, which influences oxidative stress tolerance in S. mutans. Disruption of vicK also led to inhibition of processing of AtlA, and the mutant was hyperresistant to autolysis. When grown under aerobic conditions, the vicK mutant also showed significantly increased biofilm formation compared to strain UA159. This study illustrates the central role of AtlA and VicK in orchestrating growth on surfaces and envelope biogenesis in response to redox conditions.

The role of PhoP/PhoQ two component system in regulating stress adaptation in Cronobacter sakazakii

2021 ◽  
pp. 103851
Author(s):  
Yan Ma ◽  
Yingying Zhang ◽  
Ke Chen ◽  
Lingzhu Zhang ◽  
Yibei Zhang ◽  
...  
Keyword(s):  
Stress Adaptation ◽  
Cronobacter Sakazakii ◽  
Two Component System ◽  
Component System ◽  
Two Component

scholarly journals Regulatory Role of the MisR/S Two-Component System in Hemoglobin Utilization in Neisseria meningitidis

2009 ◽  
Vol 78 (3) ◽  
pp. 1109-1122 ◽  
Author(s):  
Shuming Zhao ◽  
Grisselle E. Montanez ◽  
Pradeep Kumar ◽  
Soma Sannigrahi ◽  
Yih-Ling Tzeng
Keyword(s):  
Posttranscriptional Regulation ◽  
Regulatory Mechanisms ◽  
Two Component System ◽  
Gene Encoding ◽  
Positive Role ◽  
Upstream Gene ◽  
Component System ◽  
Two Component ◽  
Major Surface

ABSTRACT Outer membrane iron receptors are some of the major surface entities that are critical for meningococcal pathogenesis. The gene encoding the meningococcal hemoglobin receptor, HmbR, is both independently transcribed and transcriptionally linked to the upstream gene hemO, which encodes a heme oxygenase. The MisR/S two-component system was previously determined to regulate hmbR transcription, and its hemO and hmbR regulatory mechanisms were characterized further here. The expression of hemO and hmbR was downregulated in misR/S mutants under both iron-replete and iron-restricted conditions, and the downregulation could be reversed by complementation. No significant changes in expression of other iron receptors were detected, suggesting that the MisR/S system specifically regulates hmbR. When hemoglobin was the sole iron source, growth defects were detected in the mutants. Primer extension analysis identified a promoter upstream of the hemO-associated Correia element (CE) and another promoter at the proximal end of CE, and processed transcripts previously identified for other cotranscribed CEs were also detected, suggesting that there may be posttranscriptional regulation. MisR directly interacts with sequences upstream of the CE and upstream of the hmbR Fur binding site and thus independently regulates hemO and hmbR. Analysis of transcriptional reporters of hemO and hmbR further demonstrated the positive role of the MisR/S system and showed that the transcription of hmbR initiated from hemO was significantly reduced. A comparison of the effects of the misS mutation under iron-replete and iron-depleted conditions suggested that activation by the MisR/S system and iron-mediated repression by Fur act independently. Thus, the expression of hemO and hmbR is coordinately controlled by multiple independent regulatory mechanisms, including the MisR/S two-component system.

scholarly journals The Staphylococcus aureus KdpDE Two-Component System Couples Extracellular K+Sensing and Agr Signaling to Infection Programming

2011 ◽  
Vol 79 (6) ◽  
pp. 2154-2167 ◽  
Author(s):  
Ting Xue ◽  
Yibo You ◽  
De Hong ◽  
Haipeng Sun ◽  
Baolin Sun
Keyword(s):  
Staphylococcus Aureus ◽  
Uptake System ◽  
Main Function ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Two Component ◽  
Virulence Regulator ◽  
External K

ABSTRACTThe Kdp system is widely distributed among bacteria. InEscherichia coli, the Kdp-ATPase is a high-affinity K+uptake system and its expression is activated by the KdpDE two-component system in response to K+limitation or salt stress. However, information about the role of this system in many bacteria still remains obscure. Here we demonstrate that KdpFABC inStaphylococcus aureusis not a major K+transporter and that the main function of KdpDE is not associated with K+transport but that instead it regulates transcription for a series of virulence factors through sensing external K+concentrations, indicating that this bacterium might modulate its infectious status through sensing specific external K+stimuli in different environments. Our results further reveal thatS. aureusKdpDE is upregulated by the Agr/RNAIII system, which suggests that KdpDE may be an important virulence regulator coordinating the external K+sensing and Agr signaling during pathogenesis in this bacterium.

scholarly journals The CasKR Two-Component System Is Required for the Growth of Mesophilic and Psychrotolerant Bacillus cereus Strains at Low Temperatures

2014 ◽  
Vol 80 (8) ◽  
pp. 2493-2503 ◽  
Author(s):  
Sara Esther Diomandé ◽  
Stéphanie Chamot ◽  
Vera Antolinos ◽  
Florian Vasai ◽  
Marie-Hélène Guinebretière ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Food Poisoning ◽  
Two Component System ◽  
Diverse Range ◽  
Component System ◽  
Content Type ◽  
Two Component ◽  
Temperature Ranges ◽  
Different Strains

ABSTRACTThe different strains ofBacillus cereuscan grow at temperatures covering a very diverse range. SomeB. cereusstrains can grow in chilled food and consequently cause food poisoning. We have identified a new sensor/regulator mechanism involved in low-temperatureB. cereusgrowth. Construction of a mutant of this two-component system enabled us to show that this system, called CasKR, is required for growth at the minimal temperature (Tmin). CasKR was also involved in optimal cold growth aboveTminand in cell survival belowTmin. Microscopic observation showed that CasKR plays a key role in cell shape during cold growth. Introducing thecasKRgenes in a ΔcasKRmutant restored its ability to grow atTmin. Although it was first identified in the ATCC 14579 model strain, this mechanism has been conserved in most strains of theB. cereusgroup. We show that the role of CasKR in cold growth is similar in otherB. cereus sensu latostrains with different growth temperature ranges, including psychrotolerant strains.

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