scholarly journals Two-Component Histidine Phosphotransfer Protein Ypd1 Is Not Essential for Viability in Candida albicans

2014 ◽  
Vol 13 (4) ◽  
pp. 452-460 ◽  
Author(s):  
John Mavrianos ◽  
Chirayu Desai ◽  
Neeraj Chauhan
Keyword(s):  
Candida Albicans ◽  
Fluorescent Protein ◽  
Mapk Pathway ◽  
Response Regulator ◽  
Pathogenic Fungi ◽  
Mitogen Activated Protein Kinase ◽  
Wild Type ◽  
Signaling Mechanism ◽  
Content Type ◽  
Two Component

ABSTRACTProkaryotes and lower eukaryotes, such as yeasts, utilize two-component signal transduction pathways to adapt cells to environmental stress and to regulate the expression of genes associated with virulence. One of the central proteins in this type of signaling mechanism is the phosphohistidine intermediate protein Ypd1. Ypd1 is reported to be essential for viability in the model yeastSaccharomyces cerevisiae. We present data here showing that this is not the case forCandida albicans. Disruption ofYPD1causes cells to flocculate and filament constitutively under conditions that favor growth in yeast form. To determine the function of Ypd1 in the Hog1 mitogen-activated protein kinase (MAPK) pathway, we measured phosphorylation of Hog1 MAPK inypd1Δ/Δ and wild-type strains ofC. albicans. Constitutive phosphorylation of Hog1 was observed in theypd1Δ/Δ strain compared to the wild-type strain. Furthermore, fluorescence microscopy revealed that green fluorescent protein (GFP)-tagged Ypd1 is localized to both the nucleus and the cytoplasm. The subcellular segregation of GFP-tagged Ypd1 hints at an important role(s) of Ypd1 in regulation of Ssk1 (cytosolic) and Skn7 (nuclear) response regulator proteins via phosphorylation inC. albicans. Overall, our findings have profound implications for a mechanistic understanding of two-component signaling pathways inC. albicans, and perhaps in other pathogenic fungi.

scholarly journals Mitochondrial Two-Component Signaling Systems in Candida albicans

2013 ◽  
Vol 12 (6) ◽  
pp. 913-922 ◽  
Author(s):  
John Mavrianos ◽  
Elizabeth L. Berkow ◽  
Chirayu Desai ◽  
Alok Pandey ◽  
Mona Batish ◽  
...  
Keyword(s):  
Cell Death ◽  
Candida Albicans ◽  
Response Regulator ◽  
Wild Type ◽  
Content Type ◽  
Cell Death Pathway ◽  
Regulator Protein ◽  
Two Component ◽  
In The Wild ◽  
Response Regulator Protein

ABSTRACTTwo-component signal transduction pathways are one of the primary means by which microorganisms respond to environmental signals. These signaling cascades originated in prokaryotes and were inherited by eukaryotes via endosymbiotic lateral gene transfer from ancestral cyanobacteria. We report here that the nuclear genome of the pathogenic fungusCandida albicanscontains elements of a two-component signaling pathway that seem to be targeted to the mitochondria. TheC. albicanstwo-component response regulator protein Srr1 (stressresponseregulator 1) contains a mitochondrial targeting sequence at the N terminus, and fluorescence microscopy reveals mitochondrial localization of green fluorescent protein-tagged Srr1. Moreover, phylogenetic analysis indicates thatC. albicansSrr1 is more closely related to histidine kinases and response regulators found in marine bacteria than are other two-component proteins present in the fungi. These data suggest conservation of this protein during the evolutionary transition from endosymbiont to a subcellular organelle. We used microarray analysis to determine whether the phenotypes observed with asrr1Δ/Δmutant could be correlated with gene transcriptional changes. The expression of mitochondrial genes was altered in thesrr1Δ/Δnull mutant in comparison to their expression in the wild type. Furthermore, apoptosis increased significantly in thesrr1Δ/Δmutant strain compared to the level of apoptosis in the wild type, suggesting the activation of a mitochondrion-dependent apoptotic cell death pathway in thesrr1Δ/Δmutant. Collectively, this study shows for the first time that a lower eukaryote likeC. albicanspossesses a two-component response regulator protein that has survived in mitochondria and regulates a subset of genes whose functions are associated with the oxidative stress response and programmed cell death (apoptosis).

scholarly journals Multiple Roles of Ypd1 Phosphotransfer Protein in Viability, Stress Response, and Virulence Factor Regulation in Cryptococcus neoformans

2011 ◽  
Vol 10 (7) ◽  
pp. 998-1002 ◽  
Author(s):  
Jang-Won Lee ◽  
Young-Joon Ko ◽  
Seo-Young Kim ◽  
Yong-Sun Bahn
Keyword(s):  
Cryptococcus Neoformans ◽  
Mapk Pathway ◽  
Multiple Roles ◽  
Mitogen Activated Protein Kinase ◽  
Independent Manner ◽  
Content Type ◽  
Component Systems ◽  
Two Component ◽  
Mitogen Activated Protein ◽  
Two Component Systems

ABSTRACT Ypd1 is a key phosphorelay protein that controls eukaryotic two-component systems, but its function in Cryptococcus neoformans is not known. Here, we report that Ypd1 is required for the viability of C. neoformans via the Hog1 mitogen-activated protein kinase (MAPK) pathway but plays multiple cellular roles in both a Hog1-dependent and -independent manner.

scholarly journals Histidine Phosphotransfer Proteins in Fungal Two-Component Signal Transduction Pathways

2013 ◽  
Vol 12 (8) ◽  
pp. 1052-1060 ◽  
Author(s):  
Jan S. Fassler ◽  
Ann H. West
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Single Gene ◽  
Signal Transduction Pathway ◽  
Pathogenic Fungi ◽  
Kinase Gene ◽  
Content Type ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Histidine Phosphotransfer

ABSTRACTThe histidine phosphotransfer (HPt) protein Ypd1 is an important participant in theSaccharomyces cerevisiaemultistep two-component signal transduction pathway and, unlike the expanded histidine kinase gene family, is encoded by a single gene in nearly all model and pathogenic fungi. Ypd1 is essential for viability in bothS. cerevisiaeand inCryptococcus neoformans. These and other aspects of Ypd1 biology, combined with the availability of structural and mutational data inS. cerevisiae, suggest that the essential interactions between Ypd1 and response regulator domains would be a good target for antifungal drug development. The goal of this minireview is to summarize the wealth of data onS. cerevisiaeYpd1 and to consider the potential benefits of conducting related studies in pathogenic fungi.

scholarly journals Deletion of the SSK1 Response Regulator Gene in Candida albicans Contributes to Enhanced Killing by Human Polymorphonuclear Neutrophils

2005 ◽  
Vol 73 (2) ◽  
pp. 865-871 ◽  
Author(s):  
Chen Du ◽  
Richard Calderone ◽  
John Richert ◽  
Dongmei Li
Keyword(s):  
Candida Albicans ◽  
Inflammatory Response ◽  
Response Regulator ◽  
Functional Characterization ◽  
Interleukin 2 ◽  
Polymorphonuclear Neutrophils ◽  
Mitogen Activated Protein Kinase ◽  
Human Neutrophils ◽  
Wild Type ◽  
Mitogen Activated Protein

ABSTRACT The isolation and partial functional characterization of the two-component response regulator SSK1 gene of Candida albicans was previously reported. Compared to wild-type (CAF2-1) and gene-reconstituted (SSK23) strains, the ssk1 null strain (SSK21) was avirulent in a murine model of hematogenously disseminated candidiasis and less able to adhere to human esophageal cells. More recent data indicate that SSK21 is sensitive to 4 to 8 mM H2O2 in vitro than CAF2-1 and SSK23. Furthermore, microarray studies indicate that the regulation of two classes of genes, those encoding cell wall functions and stress adaptation, are altered in the ssk1 mutant. In the present study, the susceptibility of strains CAF2-1, SSK21, and SSK23 to killing by human polymorphonuclear neutrophils (PMNs) was assessed. Results are also described for a newly constructed ssk1 mutant (SSK24) in which the URA3 gene is integrated into its native locus. Our results indicate that killing of SSK21 and SSK24 was significantly greater than that of CAF2-1 and SSK23 (P < 0.01). In order to determine why Ssk1p at least partially protects the organism against the killing activity of human PMNs, we compared the signal transduction activity and the inflammatory response gene profiles of PMNs infected with either the wild type or the ssk1 mutant. Phosphorylation of the mitogen-activated protein kinases p42/44 and p38 from neutrophils infected with either CAF2-1 (wild type) or SSK21 (ssk1/ssk1) was similar, while expression and phosphorylation of the JNK mitogen-activated protein kinase was not observed following infection with either strain. On the other hand, we observed an upregulation of seven inflammatory response genes in PMNs infected with the SSK21 mutant only, while an increase in interleukin-10 expression was measured in PMNs infected with either strain. Downregulation of interleukin-2 was observed in PMNs infected with either strain. Verification of the transcriptional profiling was obtained by reverse transcription-PCR for three of the genes that were upregulated in neutrophils infected with the ssk1 mutant. Also, the sensitivity of strain SSK21 to human defensin-1, one of the nonoxidative, antimicrobial peptides of PMNs, was greater than that of CAF2-1, demonstrating that nonoxidative killing in PMNs may contribute to the increased susceptibility of the ssk1 mutant. Our results indicate that the Ssk1p response regulator protein may provide at least partial adaptive functions for the survival of C. albicans following its encounter with human neutrophils.

scholarly journals SKN7 of Candida albicans: Mutant Construction and Phenotype Analysis

2004 ◽  
Vol 72 (4) ◽  
pp. 2390-2394 ◽  
Author(s):  
Praveen Singh ◽  
Neeraj Chauhan ◽  
Anup Ghosh ◽  
Freddie Dixon ◽  
Richard Calderone
Keyword(s):  
Candida Albicans ◽  
Response Regulator ◽  
Regulator Gene ◽  
Wild Type ◽  
Response Regulators ◽  
Two Component ◽  
Phenotype Analysis

ABSTRACT The SKN7 two-component response regulator gene of Candida albicans was deleted, and the phenotype of the mutant was established. This mutant exhibited impaired growth on Spider agar and 10% serum agar compared to wild-type and gene-reconstituted strains. The skn7 mutant was sensitive to H2O2 in vitro, but its virulence was only mildly attenuated. A comparison of the Skn7p and Ssk1p response regulators of C. albicans is discussed.

scholarly journals MrSkn7 Controls Sporulation, Cell Wall Integrity, Autolysis, and Virulence in Metarhizium robertsii

2015 ◽  
Vol 14 (4) ◽  
pp. 396-405 ◽  
Author(s):  
Yanfang Shang ◽  
Peilin Chen ◽  
Yixiong Chen ◽  
Yuzhen Lu ◽  
Chengshu Wang
Keyword(s):  
Cell Wall ◽  
Target Genes ◽  
Response Regulator ◽  
Pathogenic Fungus ◽  
Functional Divergence ◽  
Pathogenic Fungi ◽  
Wild Type ◽  
Metarhizium Robertsii ◽  
Content Type ◽  
Cell Autolysis

ABSTRACT Two-component signaling pathways generally include sensor histidine kinases and response regulators. We identified an ortholog of the response regulator protein Skn7 in the insect-pathogenic fungus Metarhizium robertsii , which we named MrSkn7. Gene deletion assays and functional characterizations indicated that MrSkn7 functions as a transcription factor. The MrSkn7 null mutant of M. robertsii lost the ability to sporulate and had defects in cell wall biosynthesis but was not sensitive to oxidative and osmotic stresses compared to the wild type. However, the mutant was able to produce spores under salt stress. Insect bioassays using these spores showed that the virulence of the mutant was significantly impaired compared to that of the wild type due to the failures to form the infection structure appressorium and evade host immunity. In particular, deletion of MrSkn7 triggered cell autolysis with typical features such as cell vacuolization, downregulation of repressor genes, and upregulation of autolysis-related genes such as extracellular chitinases and proteases. Promoter binding assays confirmed that MrSkn7 could directly or indirectly control different putative target genes. Taken together, the results of this study help us understand the functional divergence of Skn7 orthologs as well as the mechanisms underlying the development and control of virulence in insect-pathogenic fungi.

scholarly journals Candida albicans SRR1 , a Putative Two-Component Response Regulator Gene, Is Required for Stress Adaptation, Morphogenesis, and Virulence

2011 ◽  
Vol 10 (10) ◽  
pp. 1370-1374 ◽  
Author(s):  
Chirayu Desai ◽  
John Mavrianos ◽  
Neeraj Chauhan
Keyword(s):  
Candida Albicans ◽  
Response Regulator ◽  
Stress Adaptation ◽  
Regulator Gene ◽  
Content Type ◽  
Virulence Attenuation ◽  
Two Component ◽  
Resistance To Stress ◽  
Identification And Characterization

ABSTRACT We report here the identification and characterization of a previously uncharacterized, two-component response regulator gene (orf19.5843) from Candida albicans . Because of its apparent functions in stress adaptation, we have named this gene SRR1 ( s tress r esponse r egulator 1). Disruption of SRR1 causes defects in hyphal development, reduced resistance to stress, and severe virulence attenuation in the mouse model of disseminated candidiasis.

scholarly journals Diverse Hap43-Independent Functions of the Candida albicans CCAAT-Binding Complex

2013 ◽  
Vol 12 (6) ◽  
pp. 804-815 ◽  
Author(s):  
Po-Chen Hsu ◽  
Chun-Cheih Chao ◽  
Cheng-Yao Yang ◽  
Ya-Ling Ye ◽  
Fu-Chen Liu ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Protein Kinase ◽  
Ribosome Biogenesis ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Content Type ◽  
Virulence Traits ◽  
Wide Range ◽  
Independent Functions ◽  
Low Nitrogen

ABSTRACTThe CCAAT motif is ubiquitous in promoters of eukaryotic genomes. The CCAAT-binding complex (CBC) is conserved across a wide range of organisms, specifically recognizes the CCAAT motif, and modulates transcription directly or in cooperation with other transcription factors. InCandida albicans, CBC is known to interact with the repressor Hap43 to negatively regulate iron utilization genes in response to iron deprivation. However, the extent of additional functions of CBC is unclear. In this study, we explored new roles of CBC inC. albicansand found that CBC pleiotropically regulates many virulence traitsin vitro, including negative control of genes responsible for ribosome biogenesis and translation and positive regulation of low-nitrogen-induced filamentation. In addition,C. albicansCBC is involved in utilization of host proteins as nitrogen sources and in repression of cellular flocculation and adhesin gene expression. Moreover, our epistasis analyses suggest that CBC acts as a downstream effector of Rhb1-TOR signaling and controls low-nitrogen-induced filamentation via the Mep2-Ras1-protein kinase A (PKA)/mitogen-activated protein kinase (MAPK) pathway. Importantly, the phenotypes identified here are all independent of Hap43. Finally, deletion of genes encoding CBC components slightly attenuatedC. albicansvirulence in both zebrafish and murine models of infection. Our results thus highlight new roles ofC. albicansCBC in regulating multiple virulence traits in response to environmental perturbations and, finally, suggest potential targets for antifungal therapies as well as extending our understanding of the pathogenesis of other fungal pathogens.

scholarly journals The Ssk1p Response Regulator and Chk1p Histidine Kinase Mutants of Candida albicans Are Hypersensitive to Fluconazole and Voriconazole

2007 ◽  
Vol 51 (10) ◽  
pp. 3747-3751 ◽  
Author(s):  
Neeraj Chauhan ◽  
Michael Kruppa ◽  
Richard Calderone
Keyword(s):  
Signal Transduction ◽  
Candida Albicans ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Wild Type ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Signal Transduction Proteins

ABSTRACT Hypersensitivity to the triazoles fluconazole and voriconazole associated with two-component signal transduction proteins has not been reported in Candida albicans. Herein, we show that strains of C. albicans lacking the response regulator Ssk1p or the Chk1p histidine kinase signal transduction proteins are hypersensitive to fluconazole and voriconazole compared to wild-type (wt) as well as gene-reconstituted strains, reflecting an increased hypersensitivity to these drugs of about 16- to 500-fold. In comparison to wt cells, both mutants had elevated levels of fluconazole accumulation and reduced viability upon incubation with either drug, suggesting that in the absence of Ssk1p or Chk1p, fluconazole and voriconazole have significantly increased fungicidal effects on C. albicans.

scholarly journals The 14-3-3 Proteins Rad24 and Rad25 Negatively Regulate Byr2 by Affecting Its Localization in Schizosaccharomyces pombe

2002 ◽  
Vol 22 (20) ◽  
pp. 7105-7119 ◽  
Author(s):  
Fumiyo Ozoe ◽  
Rumi Kurokawa ◽  
Yasuyo Kobayashi ◽  
Hee Tae Jeong ◽  
Katsunori Tanaka ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Cellular Localization ◽  
Fluorescent Protein ◽  
Mapk Pathway ◽  
Mrna Level ◽  
Mitogen Activated Protein Kinase ◽  
Wild Type ◽  
Sporulation Efficiency ◽  
Diploid Cells

ABSTRACT In Schizosaccharomyces pombe, rad24 and rad25 have been identified to be homologous to mammalian 14-3-3 genes and found to be involved in many cellular events, including checkpoint and meiosis. In the present study, we present evidences that Rad24 and Rad25 act as negative regulators of Byr2 (mitogen-activated protein kinase [MAPK] kinase kinase). Overexpression of rad24 or rad25 reduced mating and sporulation in homothallic wild-type cells. In contrast, the mating and sporulation efficiency of rad24- or rad25-null cells was higher than that of wild-type cells. Deletion of rad24 or rad25 increased sporulation efficiency in ras1-null diploid cells but not in byr2-, ste4-, byr1-, and spk1-null cells. Rad24 and Rad25 had no effect on the activity of constitutively active Byr1S214DT218D. Rad24 and Rad25 bound to both the N-terminal and the C-terminal domains of Byr2 when these bacterially expressed proteins were examined. The formation of complexes in vivo between Byr2 and either Rad24 or Rad25 was also confirmed by immunocoprecipitation. Furthermore, we showed negative regulation of Byr2 by Rad25, by monitoring the mRNA level of mam2, which is regulated by both the Ras1/MAPK pathway and ste11, in various combinations of mutants. In addition, the cellular localization of Byr2 in living cells was observed by using fusion to green fluorescent protein. Byr2 was mainly localized in the cytoplasm during vegetative growth and then concentrated at the plasma membrane in response to nitrogen starvation. Deletion of rad24 or rad25 fastened the timing of Byr2 translocation. Our results are consistent with the hypothesis that one of the roles of 14-3-3 is to keep Byr2 in the cytoplasm and to affect the timing of Byr2 translocation in response to sexual developmental signal.

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