scholarly journals Morphogenesis, Adhesive Properties, and Antifungal Resistance Depend on the Pmt6 Protein Mannosyltransferase in the Fungal Pathogen Candida albicans

2000 ◽  
Vol 182 (11) ◽  
pp. 3063-3071 ◽  
Author(s):  
Claudia Timpel ◽  
Sigrid Zink ◽  
Sabine Strahl-Bolsinger ◽  
Klaus Schröppel ◽  
Joachim Ernst
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogen ◽  
Systemic Infection ◽  
Iron Chelator ◽  
Secreted Proteins ◽  
Adhesive Properties ◽  
Cell Extracts ◽  
Hydroxyphenylacetic Acid ◽  
Hyphal Formation ◽  
Mutant Phenotypes

ABSTRACT Protein mannosyltransferases (Pmt proteins) initiate O glycosylation of secreted proteins in fungi. We have characterizedPMT6, which encodes the second Pmt protein of the fungal pathogen Candida albicans. The residues of Pmt6p are 21 and 42% identical to those of C. albicans Pmt1p and S. cerevisiae Pmt6p, respectively. Mutants lacking one or twoPMT6 alleles grow normally and contain normal Pmt enzymatic activities in cell extracts but show phenotypes including a partial block of hyphal formation (dimorphism) and a supersensitivity to hygromycin B. The morphogenetic defect can be suppressed by overproduction of known components of signaling pathways, including Cek1p, Cph1p, Tpk2p, and Efg1p, suggesting a specific Pmt6p target protein upstream of these components. Mutants lacking bothPMT1 and PMT6 are viable and showpmt1 mutant phenotypes and an additional sensitivity to the iron chelator ethylenediamine-di(o-hydroxyphenylacetic acid). The lack of Pmt6p significantly reduces adherence to endothelial cells and overall virulence in a mouse model of systemic infection. The results suggest that Pmt6p regulates a more narrow subclass of proteins in C. albicans than Pmt1p, including secreted proteins responsible for morphogenesis and antifungal sensitivities.

scholarly journals The Golgi GDPase of the Fungal Pathogen Candida albicans Affects Morphogenesis, Glycosylation, and Cell Wall Properties

2002 ◽  
Vol 1 (3) ◽  
pp. 420-431 ◽  
Author(s):  
Ana B. Herrero ◽  
Daniela Uccelletti ◽  
Carlos B. Hirschberg ◽  
Angel Dominguez ◽  
Claudia Abeijon
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Fungal Pathogen ◽  
Solid Medium ◽  
Chain Extension ◽  
Wild Type ◽  
Adhesive Properties ◽  
Hyphal Formation ◽  
Cell Wall Properties ◽  
Increased Susceptibility

ABSTRACT Cell wall mannoproteins are largely responsible for the adhesive properties and immunomodulation ability of the fungal pathogen Candida albicans. The outer chain extension of yeast mannoproteins occurs in the lumen of the Golgi apparatus. GDP-mannose must first be transported from the cytosol into the Golgi lumen, where mannose is transferred to mannans. GDP is hydrolyzed by a GDPase, encoded by GDA1, to GMP, which then exits the Golgi lumen in a coupled, equimolar exchange with cytosolic GDP-mannose. We isolated and disrupted the C. albicans homologue of the Saccharomyces cerevisiae GDA1 gene in order to investigate its role in protein mannosylation and pathogenesis. CaGda1p shares four apyrase conserved regions with other nucleoside diphosphatases. Membranes prepared from the C. albicans disrupted gda1/gda1 strain had a 90% decrease in the ability to hydrolyze GDP compared to wild type. The gda1/gda1 mutants showed a severe defect in O-mannosylation and reduced cell wall phosphate content. Other cell wall-related phenotypes are present, such as elevated chitin levels and increased susceptibility to attack by β-1,3-glucanases. Our results show that the C. albicans organism contains β-mannose at their nonreducing end, differing from S. cerevisiae, which has only α-linked mannose residues in its O-glycans. Mutants lacking both alleles of GDA1 grow at the same rate as the wild type but are partially blocked in hyphal formation in Lee solid medium and during induction in liquid by changes in temperature and pH. However, the mutants still form normal hyphae in the presence of serum and N-acetylglucosamine and do not change their adherence to HeLa cells. Taken together, our data are in agreement with the hypothesis that several pathways regulate the yeast-hypha transition. Gda1/gda1 cells offer a model for discriminating among them.

scholarly journals Thioredoxin Regulates Multiple Hydrogen Peroxide-Induced Signaling Pathways in Candida albicans

2010 ◽  
Vol 30 (19) ◽  
pp. 4550-4563 ◽  
Author(s):  
Alessandra da Silva Dantas ◽  
Miranda J. Patterson ◽  
Deborah A. Smith ◽  
Donna M. MacCallum ◽  
Lars P. Erwig ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Candida Albicans ◽  
Intracellular Signaling ◽  
Fungal Pathogen ◽  
Systemic Infection ◽  
Host Immune System ◽  
Oxygen Species ◽  
Signaling Mechanisms ◽  
Bud Growth ◽  
Sense And Respond

ABSTRACT The ability of the major systemic fungal pathogen of humans, Candida albicans, to sense and respond to reactive oxygen species (ROS), such as H2O2 generated by the host immune system, is required for survival in the host. However, the intracellular signaling mechanisms underlying such responses are poorly understood. Here, we show that thioredoxin (Trx1), in addition to its antioxidant activity, plays a central role in coordinating the response of C. albicans to ROS by regulating multiple pathways. In particular, Trx1 function is important for H2O2-induced phosphorylation of the Hog1 stress-activated protein kinase and to reverse H2O2-induced oxidation and activation of the AP-1 like transcription factor Cap1. Furthermore, Trx1 regulates H2O2-induced hyperpolarized bud growth in a mechanism that involves activation of the Rad53 checkpoint kinase. Consistent with its key roles in responses to ROS, cells lacking Trx1 displayed significantly attenuated virulence in a murine model of C. albicans systemic infection. Collectively, our data indicate that Trx1 has a multifaceted role in H2O2 signaling and promotes C. albicans survival in the host.

scholarly journals Protection from Systemic Candida albicans Infection by Inactivation of the Sts Phosphatases

2014 ◽  
Vol 83 (2) ◽  
pp. 637-645 ◽  
Author(s):  
Shamoon Naseem ◽  
David Frank ◽  
James B. Konopka ◽  
Nick Carpino
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogen ◽  
Fungal Growth ◽  
Systemic Infection ◽  
Content Type ◽  
Host Immune Responses ◽  
Human Fungal Pathogen ◽  
Rapid Induction ◽  
Inflammatory Damage ◽  
Functional Inactivation

The human fungal pathogenCandida albicanscauses invasive candidiasis, characterized by fatal organ failure due to disseminated fungal growth and inflammatory damage. Thesuppressor ofTCRsignaling 1 (Sts-1) and Sts-2 are two homologous phosphatases that negatively regulate signaling pathways in a number of hematopoietic cell lineages, including T lymphocytes, mast cells, and platelets. Functional inactivation of both Sts enzymes leads to profound resistance to systemic infection byC. albicans, such that greater than 80% of mice lacking Sts-1 and -2 survive a dose ofC. albicans(2.5 × 105CFU/mouse) that is uniformly lethal to wild-type mice within 10 days. Restriction of fungal growth within the kidney occurs by 24 h postinfection in the mutant mice. This occurs without induction of a hyperinflammatory response, as evidenced by the decreased presence of leukocytes and inflammatory cytokines that normally accompany the antifungal immune response. Instead, the absence of the Sts phosphatases leads to the rapid induction of a unique immunological environment within the kidney, as indicated by the early induction of a proinflammatory cytokine (CXL10). Mice lacking either Sts enzyme individually display an intermediate lethality phenotype. These observations identify an opportunity to optimize host immune responses toward a deadly fungal pathogen.

scholarly journals Identification and Characterization of a Candida albicans Mating Pheromone

2003 ◽  
Vol 23 (22) ◽  
pp. 8189-8201 ◽  
Author(s):  
Richard J. Bennett ◽  
M. Andrew Uhl ◽  
Mathew G. Miller ◽  
Alexander D. Johnson
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogen ◽  
Cell Communication ◽  
Secreted Proteins ◽  
Pheromone Response ◽  
Mating Pheromone ◽  
A Cells ◽  
Bona Fide ◽  
Identification And Characterization

ABSTRACT Candida albicans, the most prevalent fungal pathogen of humans, has recently been shown to undergo mating. Here we describe a mating pheromone produced by C. albicans α cells and show that the gene which encodes it (MFα) is required for α cells, but not a cells, to mate. We also identify the receptor for this mating pheromone as the product of the STE2 gene and show that this gene is required for the mating of a cells, but not α cells. Cells of the a mating type respond to the α mating pheromone by producing long polarized projections, similar to those observed in bona fide mating mixtures of C. albicans a and α cells. During this process, transcription of approximately 62 genes is induced. Although some of these genes correspond to those induced in Saccharomyces cerevisiae by S. cerevisiae α-factor, most are specific to the C. albicans pheromone response. The most surprising class encode cell surface and secreted proteins previously implicated in virulence of C. albicans in a mouse model of disseminated candidiasis. This observation suggests that aspects of cell-cell communication in mating may have been evolutionarily adopted for host-pathogen interactions in C. albicans.

scholarly journals High Resistance to Oxidative Stress in the Fungal Pathogen Candida glabrata Is Mediated by a Single Catalase, Cta1p, and Is Controlled by the Transcription Factors Yap1p, Skn7p, Msn2p, and Msn4p

2008 ◽  
Vol 7 (5) ◽  
pp. 814-825 ◽  
Author(s):  
Mayra Cuéllar-Cruz ◽  
Marcela Briones-Martin-del-Campo ◽  
Israel Cañas-Villamar ◽  
Javier Montalvo-Arredondo ◽  
Lina Riego-Ruiz ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Saccharomyces Cerevisiae ◽  
Candida Albicans ◽  
Transcription Factors ◽  
Adaptive Response ◽  
Fungal Pathogen ◽  
Candida Glabrata ◽  
Systemic Infection ◽  
Oxidative Stress Response

ABSTRACT We characterized the oxidative stress response of Candida glabrata to better understand the virulence of this fungal pathogen. C. glabrata could withstand higher concentrations of H2O2 than Saccharomyces cerevisiae and even Candida albicans. Stationary-phase cells were extremely resistant to oxidative stress, and this resistance was dependent on the concerted roles of stress-related transcription factors Yap1p, Skn7p, and Msn4p. We showed that growing cells of C. glabrata were able to adapt to high levels of H2O2 and that this adaptive response was dependent on Yap1p and Skn7p and partially on the general stress transcription factors Msn2p and Msn4p. C. glabrata has a single catalase gene, CTA1, which was absolutely required for resistance to H2O2 in vitro. However, in a mouse model of systemic infection, a strain lacking CTA1 showed no effect on virulence.

scholarly journals A synthetic system that senses Candida albicans and inhibits virulence factors

2018 ◽  
Author(s):  
Michael Tscherner ◽  
Tobias W. Giessen ◽  
Laura Markey ◽  
Carol A. Kumamoto ◽  
Pamela A. Silver
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogen ◽  
Fungal Infections ◽  
E Coli ◽  
Hospital Acquired Infections ◽  
Hypha Formation ◽  
Factor Expression ◽  
Hydroxyphenylacetic Acid ◽  
Sense And Respond ◽  
Hospital Acquired

AbstractDue to a limited set of antifungals available and problems in early diagnosis invasive fungal infections caused by Candida species are among the most common hospital-acquired infections with staggering mortality rates. Here, we describe an engineered system able to sense and respond to the fungal pathogen Candida albicans, the most common cause of candidemia. In doing so, we identified hydroxyphenylacetic acid (HPA) as a novel molecule secreted by C. albicans. Furthermore, we engineered E. coli to be able to sense HPA produced by C. albicans. Finally, we constructed a sense-and-respond system by coupling the C. albicans sensor to the production of an inhibitor of hypha formation thereby reducing filamentation, virulence factor expression and fungal-induced epithelial damage. This system could be used as a basis for the development of novel prophylactic approaches to prevent fungal infections.

scholarly journals Functional analysis of the phospholipase C gene CaPLC1 and two unusual phospholipase C genes, CaPLC2 and CaPLC3, of Candida albicans

Microbiology ◽  
2005 ◽  
Vol 151 (10) ◽  
pp. 3381-3394 ◽  
Author(s):  
Donika Kunze ◽  
Inga Melzer ◽  
Désirée Bennett ◽  
Dominique Sanglard ◽  
Donna MacCallum ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Phospholipase C ◽  
Essential Gene ◽  
Pathogenic Fungus ◽  
Systemic Infection ◽  
Cellular Processes ◽  
Solid Media ◽  
Transcriptional Pattern ◽  
Human Pathogenic Fungus ◽  
Hyphal Formation

Phospholipases C are known to be important regulators of cellular processes but may also act as virulence factors of pathogenic microbes. At least three genes in the genome of the human-pathogenic fungus Candida albicans encode phospholipases with conserved phospholipase C (Plc) motifs. None of the deduced protein sequences contain N-terminal signal peptides, suggesting that these phospholipases are not secreted. In contrast to its orthologue in Sacharomyces cerevisiae, CaPLC1 seems to be an essential gene. However, a conditional mutant with reduced transcript levels of CaPLC1 had phenotypes similar to Plc1p-deficient mutants in S. cerevisiae, including reduced growth on media causing increased osmotic stress, on media with a non-glucose carbon source, or at elevated or lower temperatures, suggesting that CaPlc1p, like the Plc1p counterpart in S. cerevisiae, may be involved in multiple cellular processes. Furthermore, phenotypic screening of the heterozygous ΔCaplc1/CaPLC1 mutant showed additional defects in hyphal formation. The loss of CaPLC1 cannot be compensated by two additional PLC genes of C. albicans (CaPLC2 and CaPLC3) encoding two almost identical phospholipases C with no counterpart in S. cerevisiae but containing structural elements found in bacterial phospholipases C. Although the promoter sequences of CaPLC2 and CaPLC3 differed dramatically, the transcriptional pattern of both genes was similar. In contrast to CaPLC1, CaPLC2 and CaPLC3 are not essential. Although Caplc2/3 mutants had reduced abilities to produce hyphae on solid media, these mutants were as virulent as the wild-type in a model of systemic infection. These data suggest that C. albicans contains two different classes of phospholipases C which are involved in cellular processes but which have no specific functions in pathogenicity.

scholarly journals Trans-cellular tunnels induced by the fungal pathogen Candida albicans facilitate invasion through successive epithelial cells without host damage

2021 ◽  
Author(s):  
Joy Lachat ◽  
Alice Pascault ◽  
Delphine Thibaut ◽  
Rémi Le Borgne ◽  
Jean-Marc Verbavatz ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogen ◽  
Single Cell Analysis ◽  
Three Dimensional ◽  
Systemic Infection ◽  
Host Cells ◽  
Galectin 3 ◽  
Opportunistic Fungal Pathogen ◽  
Epithelial Layers

SummaryThe opportunistic fungal pathogen Candida albicans is normally commensal, residing in the mucosa of most healthy individuals. In susceptible hosts, its filamentous hyphal form can invade epithelial layers leading to superficial or severe systemic infection. Invasion is mainly intracellular, though it causes no apparent damage to host cells. We investigated the invasive lifestyle of C. albicans in vitro using live-cell imaging and the damage-sensitive reporter galectin-3. Quantitative single cell analysis showed that invasion can result in host membrane breaching at different stages of invasion and cell death, or in traversal of host cells without membrane breaching. Membrane labelling and three-dimensional “volume” electron microscopy revealed that hyphae can traverse several host cells within trans-cellular tunnels that are progressively remodelled and may undergo ‘inflations’ linked to host glycogen stores, possibly during nutrient uptake. Thus, C. albicans invade epithelial tissues by either inflicting or avoiding host damage, the latter facilitated by trans-cellular tunnelling.

scholarly journals The RSC (Remodels the Structure of Chromatin) complex of Candida albicans shows compositional divergence with distinct roles in regulating pathogenic traits

PLoS Genetics ◽  
2020 ◽  
Vol 16 (11) ◽  
pp. e1009071
Author(s):  
Vinutha K. Balachandra ◽  
Jiyoti Verma ◽  
Madhu Shankar ◽  
Timothy M. Tucey ◽  
Ana Traven ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Stress Responses ◽  
Fungal Pathogen ◽  
Regulation Of Gene Expression ◽  
Systemic Infection ◽  
Fungal Species ◽  
Microbial Pathogens ◽  
Proteomic Profiling ◽  
Environmental Signals ◽  
Distinct Features

Regulation of gene expression programs is crucial for the survival of microbial pathogens in host environments and for their ability to cause disease. Here we investigated the epigenetic regulator RSC (Remodels the Structure of Chromatin) in the most prevalent human fungal pathogen Candida albicans. Biochemical analysis showed that CaRSC comprises 13 subunits and contains two novel non-essential members, which we named Nri1 and Nri2 (Novel RSC Interactors) that are exclusive to the CTG clade of Saccharomycotina. Genetic analysis showed distinct essentiality of C. albicans RSC subunits compared to model fungal species suggesting functional and structural divergence of RSC functions in this fungal pathogen. Transcriptomic and proteomic profiling of a conditional mutant of the essential catalytic subunit gene STH1 demonstrated global roles of RSC in C. albicans biology, with the majority of growth-related processes affected, as well as mis-regulation of genes involved in morphotype switching, host-pathogen interaction and adaptive fitness. We further assessed the functions of non-essential CaRSC subunits, showing that the novel subunit Nri1 and the bromodomain subunit Rsc4 play roles in filamentation and stress responses; and also interacted at the genetic level to regulate cell viability. Consistent with these roles, Rsc4 is required for full virulence of C. albicans in the murine model of systemic infection. Taken together, our data builds the first comprehensive study of the composition and roles of RSC in C. albicans, showing both conserved and distinct features compared to model fungal systems. The study illuminates how C. albicans uses RSC-dependent transcriptional regulation to respond to environmental signals and drive survival fitness and virulence in mammals.

scholarly journals The Role of Secretory Pathways in Candida albicans Pathogenesis

2020 ◽  
Vol 6 (1) ◽  
pp. 26 ◽  
Author(s):  
Christiane Rollenhagen ◽  
Sahil Mamtani ◽  
Dakota Ma ◽  
Reva Dixit ◽  
Susan Eszterhas ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Membrane Trafficking ◽  
Fungal Pathogen ◽  
Biofilm Formation ◽  
Secretory Pathways ◽  
Associated Proteins ◽  
Normal Human ◽  
Opportunistic Fungal Pathogen ◽  
Hyphal Formation

Candida albicans is a fungus that is a commensal organism and a member of the normal human microbiota. It has the ability to transition into an opportunistic invasive pathogen. Attributes that support pathogenesis include secretion of virulence-associated proteins, hyphal formation, and biofilm formation. These processes are supported by secretion, as defined in the broad context of membrane trafficking. In this review, we examine the role of secretory pathways in Candida virulence, with a focus on the model opportunistic fungal pathogen, Candida albicans.

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