scholarly journals Contributions of the Response Regulators Ssk1p and Skn7p in the Pseudohyphal Development, Stress Adaptation, and Drug Sensitivity of the Opportunistic Yeast Candida lusitaniae

2008 ◽  
Vol 7 (6) ◽  
pp. 1071-1074 ◽  
Author(s):  
Gwenaël Ruprich-Robert ◽  
Florence Chapeland-Leclerc ◽  
Stéphanie Boisnard ◽  
Martine Florent ◽  
Gaël Bories ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Functional Analysis ◽  
Histidine Kinase ◽  
Drug Sensitivity ◽  
Stress Adaptation ◽  
Response Regulators ◽  
Candida Lusitaniae

ABSTRACT We recently characterized the histidine kinase receptor genes of Candida lusitaniae. For the present study, we have further investigated the role of SSK1 and SKN7, encoding response regulators. The results of functional analysis of mutants indicated that Ssk1p is involved in osmotolerance and pseudohyphal development, whereas Skn7p appears crucial for oxidative stress adaptation.

scholarly journals The Phosphoarginine Phosphatase PtpB from Staphylococcus aureus Is Involved in Bacterial Stress Adaptation during Infection

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 645
Author(s):  
Mohamed Ibrahem Elhawy ◽  
Sylvaine Huc-Brandt ◽  
Linda Pätzold ◽  
Laila Gannoun-Zaki ◽  
Ahmed Mohamed Mostafa Abdrabou ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Staphylococcus Aureus ◽  
Treatment Strategies ◽  
Physiological Role ◽  
Aureus Strain ◽  
Stress Adaptation ◽  
Cellular Mechanisms ◽  
Host Interaction ◽  
Liver And Kidney

Staphylococcus aureus continues to be a public health threat, especially in hospital settings. Studies aimed at deciphering the molecular and cellular mechanisms that underlie pathogenesis, host adaptation, and virulence are required to develop effective treatment strategies. Numerous host-pathogen interactions were found to be dependent on phosphatases-mediated regulation. This study focused on the analysis of the role of the low-molecular weight phosphatase PtpB, in particular, during infection. Deletion of ptpB in S. aureus strain SA564 significantly reduced the capacity of the mutant to withstand intracellular killing by THP-1 macrophages. When injected into normoglycemic C57BL/6 mice, the SA564 ΔptpB mutant displayed markedly reduced bacterial loads in liver and kidney tissues in a murine S. aureus abscess model when compared to the wild type. We also observed that PtpB phosphatase-activity was sensitive to oxidative stress. Our quantitative transcript analyses revealed that PtpB affects the transcription of various genes involved in oxidative stress adaptation and infectivity. Thus, this study disclosed first insights into the physiological role of PtpB during host interaction allowing us to link phosphatase-dependent regulation to oxidative bacterial stress adaptation during infection.

scholarly journals Differential Involvement of Histidine Kinase Receptors in Pseudohyphal Development, Stress Adaptation, and Drug Sensitivity of the Opportunistic Yeast Candida lusitaniae

2007 ◽  
Vol 6 (10) ◽  
pp. 1782-1794 ◽  
Author(s):  
Florence Chapeland-Leclerc ◽  
Paméla Paccallet ◽  
Gwenaël Ruprich-Robert ◽  
David Reboutier ◽  
Christiane Chastin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Histidine Kinase ◽  
High Sensitivity ◽  
Triple Mutant ◽  
Mating Ability ◽  
Reverse Transcription Pcr ◽  
Moderate Sensitivity ◽  
Candida Lusitaniae ◽  
High Level

ABSTRACT Fungal histidine kinase receptors (HKRs) sense and transduce many extracellular signals. We investigated the role of HKRs in morphogenetic transition, osmotolerance, oxidative stress response, and mating ability in the opportunistic yeast Candida lusitaniae. We isolated three genes, SLN1, NIK1, and CHK1, potentially encoding HKRs of classes VI, III, and X, respectively. These genes were disrupted by a transformation system based upon the “URA3 blaster” strategy. Functional analysis of disruptants was undertaken, except for the sln1 nik1 double mutant and the sln1 nik1 chk1 triple mutant, which are not viable in C. lusitaniae. The sln1 mutant revealed a high sensitivity to oxidative stress, whereas both the nik1 and chk1 mutants exhibited a more moderate sensitivity to peroxide. We also showed that the NIK1 gene was implicated in phenylpyrrole and dicarboximide compound susceptibility while HKRs seem not to be involved in resistance toward antifungals of clinical relevance. Concerning mating ability, all disruptants were still able to reproduce sexually in vitro in unilateral or bilateral crosses. The most important result of this study was that the sln1 mutant displayed a global defect of pseudohyphal differentiation, especially in high-osmolarity and oxidative-stress conditions. Thus, the SLN1 gene could be crucial for the C. lusitaniae yeast-to-pseudohypha morphogenetic transition. This implication is strengthened by a high level of SLN1 mRNAs revealed by semiquantitative reverse transcription-PCR when the yeast develops pseudohyphae. Our findings highlight a differential contribution of the three HKRs in osmotic and oxidant adaptation during the morphological transition in C. lusitaniae.

scholarly journals Helicobacter pylori Possesses Two CheY Response Regulators and a Histidine Kinase Sensor, CheA, Which Are Essential for Chemotaxis and Colonization of the Gastric Mucosa

2000 ◽  
Vol 68 (4) ◽  
pp. 2016-2023 ◽  
Author(s):  
Susan Foynes ◽  
Nick Dorrell ◽  
Stephen J. Ward ◽  
Richard A. Stabler ◽  
Andy A. McColm ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Histidine Kinase ◽  
Regulatory System ◽  
Enteric Bacteria ◽  
Video Tracking ◽  
Response Regulators ◽  
Separate Protein ◽  
H Pylori ◽  
Gnotobiotic Piglets

ABSTRACT Infection of the mucous layer of the human stomach byHelicobacter pylori requires the bacterium to be motile and presumably chemotactic. Previous studies have shown that fully functional flagella are essential for motility and colonization, but the role of chemotaxis remains unclear. The two-component regulatory system CheA/CheY has been shown to play a major role in chemotaxis in other enteric bacteria. Scrutiny of the 26695 genome sequence suggests that H. pylori has two CheY response regulators: one a separate protein (CheY1) and the other (CheY2) fused to the histidine kinase sensor CheA. Defined deletion mutations were introduced intocheY1, cheY2, and cheA in H. pylori strains N6 and SS1. Video tracking revealed that the wild-type H. pylori strain moves in short runs with frequent direction changes, in contrast to movement ofcheY2, cheAY2, and cheAY2 cheY1mutants, whose motion was more linear. The cheY1 mutant demonstrated a different motility phenotype of rapid tumbling. All mutants had impaired swarming and greatly reduced chemotactic responses to hog gastric mucin. Neither cheY1 nor cheAY2mutants were able to colonize mice, but they generated a significant antibody response, suggesting that despite impaired chemotaxis, these mutants were able to survive in the stomach long enough to induce an immune response before being removed by gastric flow. Additionally, we demonstrated that cheY1 failed to colonize gnotobiotic piglets. This study demonstrates the importance of the roles ofcheY1, cheY2, and cheA in motility and virulence of H. pylori.

792: Role of Oxidative Stress in Tumorigenic Potential of Bladder Cancer Cells

2005 ◽  
Vol 173 (4S) ◽  
pp. 214-215 ◽  
Author(s):  
Daniel Cho ◽  
Xiao Fang Ha ◽  
J. Andre Melendez ◽  
Louis J. Giorgi ◽  
Badar M. Mian
Keyword(s):  
Oxidative Stress ◽  
Bladder Cancer ◽  
Cancer Cells ◽  
Tumorigenic Potential ◽  
Bladder Cancer Cells
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