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 Clathrin- and Arp2/3-Independent Endocytosis in the Fungal Pathogen Candida albicans

mBio ◽  
2013 ◽  
Vol 4 (5) ◽  
Author(s):  
Elias Epp ◽  
Elena Nazarova ◽  
Hannah Regan ◽  
Lois M. Douglas ◽  
James B. Konopka ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Membrane Proteins ◽  
Fungal Pathogen ◽  
Mammalian Cells ◽  
Fluid Phase ◽  
Fungal Species ◽  
Endocytic Pathway ◽  
Dependent Manner ◽  
Content Type ◽  
Actin Cables

ABSTRACT Clathrin-mediated endocytosis (CME) is conserved among eukaryotes and has been extensively analyzed at a molecular level. Here, we present an analysis of CME in the human fungal pathogen Candida albicans that shows the same modular structure as those in other fungi and mammalian cells. Intriguingly, C. albicans is perfectly viable in the absence of Arp2/3, an essential component of CME in other systems. In C. albicans, Arp2/3 function remains essential for CME as all 15 proteins tested that participate in CME, including clathrin, lose their characteristic dynamics observed in wild-type (WT) cells. However, since arp2/3 cells are still able to endocytose lipids and fluid-phase markers, but not the Ste2 and Mup1 plasma membrane proteins, there must be an alternate clathrin-independent pathway we term Arp2/3-independent endocytosis (AIE). Characterization of AIE shows that endocytosis in arp2 mutants relies on actin cables and other Arp2/3-independent actin structures, as inhibition of actin functions prevented cargo uptake in arp2/3 mutants. Transmission electron microscopy (TEM) showed that arp2/3 mutants still formed invaginating tubules, cell structures whose proper functions are believed to heavily rely on Arp2/3. Finally, Prk1 and Sjl2, two proteins involved in patch disassembly during CME, were not correctly localized to sites of endocytosis in arp2 mutants, implying a role of Arp2/3 in CME patch disassembly. Overall, C. albicans contains an alternative endocytic pathway (AIE) that relies on actin cable function to permit clathrin-independent endocytosis (CIE) and provides a system to further explore alternate endocytic routes that likely exist in fungal species. IMPORTANCE There is a well-established process of endocytosis that is generally used by eukaryotic cells termed clathrin-mediated endocytosis (CME). Although the details are somewhat different between lower and higher eukaryotes, CME appears to be the dominant endocytic process in all eukaryotes. While fungi such as Saccharomyces cerevisiae have proven excellent models for dissecting the molecular details of endocytosis, loss of CME is so detrimental that it has been difficult to study alternate pathways functioning in its absence. Although the fungal pathogen Candida albicans has a CME pathway that functions similarly to that of S. cerevisiae, inactivation of this pathway does not compromise growth of yeast-form C. albicans. In these cells, lipids and fluid-phase molecules are still endocytosed in an actin-dependent manner, but membrane proteins are not. Thus, C. albicans provides a powerful model for the analysis of CME-independent endocytosis in lower eukaryotes.

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 Oxidative Stress Responses in the Human Fungal Pathogen, Candida albicans

Biomolecules ◽  
2015 ◽  
Vol 5 (1) ◽  
pp. 142-165 ◽  
Author(s):  
Alessandra Dantas ◽  
Alison Day ◽  
Mélanie Ikeh ◽  
Iaroslava Kos ◽  
Beatrice Achan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Candida Albicans ◽  
Stress Responses ◽  
Fungal Pathogen ◽  
Human Fungal Pathogen ◽  
Oxidative Stress Responses

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 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 A novel Hsp90 phospho-switch modulates virulence in the major human fungal pathogen Candida albicans

2020 ◽  
Author(s):  
Leenah Alaalm ◽  
Julia L. Crunden ◽  
Mark Butcher ◽  
Ulrike Obst ◽  
Ryann Whealy ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Stress Responses ◽  
Fungal Pathogen ◽  
Drug Targets ◽  
Fungal Infections ◽  
Pathogenic Fungi ◽  
First Record ◽  
Drug Susceptibility ◽  
Phosphorylation Sites ◽  
Fungal Virulence

The ubiquitous molecular chaperone Hsp90 is a key regulator of cellular proteostasis and environmental stress responses. Hsp90 also regulates cellular morphogenesis, drug resistance, and virulence in human pathogenic fungi, which kill more than 1.6 million patients each year worldwide. Invasive fungal infections are difficult to treat due to the lack of effective antifungal therapies, resulting in mortality rates of up to 95%. As a key regulator of fungal virulence, Hsp90 is an attractive therapeutic target. However, fungal and animal homologs are highly conserved, impeding fungal-specific targeting. Thus, understanding the factors that regulate Hsp90 could provide an alternative strategy aimed at exclusively targeting this regulator of fungal virulence. Here, we demonstrate how CK2-mediated phosphorylation of two Hsp90 residues modulates virulence in a major fungal pathogen of humans, Candida albicans. We combined proteomics, molecular evolution and structural modelling with molecular biology to identify and characterize two Hsp90 phosphorylation sites. Phosphorylation negatively affects thermal stress response, morphogenesis, drug susceptibility and fungal virulence. Our results provide the first record of specific Hsp90 phosphorylation sites acting as modulators of fungal virulence. Post-translational modifications of Hsp90 could prove valuable in future exploitation as antifungal drug targets.

scholarly journals RNA Enrichment Method for Quantitative Transcriptional Analysis of Pathogens In Vivo Applied to the Fungus Candida albicans

mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
Sara Amorim-Vaz ◽  
Van Du T. Tran ◽  
Sylvain Pradervand ◽  
Marco Pagni ◽  
Alix T. Coste ◽  
...  
Keyword(s):  
Candida Albicans ◽  
High Resolution ◽  
Galleria Mellonella ◽  
Iron Acquisition ◽  
Transcriptional Response ◽  
Systemic Infection ◽  
Microbial Pathogens ◽  
Transcriptional Analysis ◽  
Content Type

ABSTRACT In vivo transcriptional analyses of microbial pathogens are often hampered by low proportions of pathogen biomass in host organs, hindering the coverage of full pathogen transcriptome. We aimed to address the transcriptome profiles of Candida albicans, the most prevalent fungal pathogen in systemically infected immunocompromised patients, during systemic infection in different hosts. We developed a strategy for high-resolution quantitative analysis of the C. albicans transcriptome directly from early and late stages of systemic infection in two different host models, mouse and the insect Galleria mellonella. Our results show that transcriptome sequencing (RNA-seq) libraries were enriched for fungal transcripts up to 1,600-fold using biotinylated bait probes to capture C. albicans sequences. This enrichment biased the read counts of only ~3% of the genes, which can be identified and removed based on a priori criteria. This allowed an unprecedented resolution of C. albicans transcriptome in vivo, with detection of over 86% of its genes. The transcriptional response of the fungus was surprisingly similar during infection of the two hosts and at the two time points, although some host- and time point-specific genes could be identified. Genes that were highly induced during infection were involved, for instance, in stress response, adhesion, iron acquisition, and biofilm formation. Of the in vivo-regulated genes, 10% are still of unknown function, and their future study will be of great interest. The fungal RNA enrichment procedure used here will help a better characterization of the C. albicans response in infected hosts and may be applied to other microbial pathogens. IMPORTANCE Understanding the mechanisms utilized by pathogens to infect and cause disease in their hosts is crucial for rational drug development. Transcriptomic studies may help investigations of these mechanisms by determining which genes are expressed specifically during infection. This task has been difficult so far, since the proportion of microbial biomass in infected tissues is often extremely low, thus limiting the depth of sequencing and comprehensive transcriptome analysis. Here, we adapted a technology to capture and enrich C. albicans RNA, which was next used for deep RNA sequencing directly from infected tissues from two different host organisms. The high-resolution transcriptome revealed a large number of genes that were so far unknown to participate in infection, which will likely constitute a focus of study in the future. More importantly, this method may be adapted to perform transcript profiling of any other microbes during host infection or colonization.

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.

Histone acetylation/deacetylation in Candida albicans and their potential as antifungal targets

2020 ◽  
Vol 15 (11) ◽  
pp. 1075-1090
Author(s):  
Shan Su ◽  
Xiuyun Li ◽  
Xinmei Yang ◽  
Yiman Li ◽  
Xueqi Chen ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Candida Albicans ◽  
Histone Acetylation ◽  
Stress Responses ◽  
Histone Deacetylases ◽  
Fungal Pathogen ◽  
Antifungal Agents ◽  
Fungal Infections ◽  
Histone Acetyltransferases ◽  
Opportunistic Fungal Pathogen

Recently, the incidence of invasive fungal infections has significantly increased. Candida albicans (C. albicans) is the most common opportunistic fungal pathogen that infects humans. The limited number of available antifungal agents and the emergence of drug resistance pose difficulties to treatment, thus new antifungals are urgently needed. Through their functions in DNA replication, DNA repair and transcription, histone acetyltransferases (HATs) and histone deacetylases (HDACs) perform essential functions relating to growth, virulence, drug resistance and stress responses of C. albicans. Here, we summarize the physiological and pathological functions of HATs/HDACs, potential antifungal targets and underlying antifungal compounds that impact histone acetylation and deacetylation. We anticipate this review will stimulate the identification of new HAT/HDAC-related antifungal targets and antifungal agents.

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