scholarly journals Staurosporine Induces Filamentation in the Human Fungal Pathogen Candida albicans via Signaling through Cyr1 and Protein Kinase A

mSphere ◽  
2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Jinglin L. Xie ◽  
Teresa R. O’Meara ◽  
Elizabeth J. Polvi ◽  
Nicole Robbins ◽  
Leah E. Cowen
Keyword(s):  
Candida Albicans ◽  
Small Molecules ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Bloodstream Infections ◽  
Filamentous Growth ◽  
Genetic Pathways ◽  
Content Type ◽  
Virulence Trait ◽  
The Impact

ABSTRACT The impact of fungal pathogens on human health is devastating. One of the most pervasive fungal pathogens is Candida albicans, which kills ~40% of people suffering from bloodstream infections. Treatment of these infections is extremely difficult, as fungi are closely related to humans, and there are limited drugs that kill the fungus without host toxicity. The capacity of C. albicans to transition between yeast and filamentous forms is a key virulence trait. Thus, understanding the genetic pathways that regulate morphogenesis could provide novel therapeutic targets to treat C. albicans infections. Here, we establish the small molecule staurosporine as an inducer of filamentous growth. We unveil distinct regulatory circuitry required for staurosporine-induced filamentation that appears to be unique to this filament-inducing cue. Thus, this work highlights the fact that small molecules, such as staurosporine, can improve our understanding of the pathways required for key virulence programs, which may lead to the development of novel therapeutics. Protein kinases are key regulators of signal transduction pathways that participate in diverse cellular processes. In fungal pathogens, kinases regulate signaling pathways that govern drug resistance, stress adaptation, and pathogenesis. The impact of kinases on the fungal regulatory circuitry has recently garnered considerable attention in the opportunistic fungal pathogen Candida albicans, which is a leading cause of human morbidity and mortality. Complex regulatory circuitry governs the C. albicans morphogenetic transition between yeast and filamentous growth, which is a key virulence trait. Here, we report that staurosporine, a promiscuous kinase inhibitor that abrogates fungal drug resistance, also influences C. albicans morphogenesis by inducing filamentation in the absence of any other inducing cue. We further establish that staurosporine exerts its effect via the adenylyl cyclase Cyr1 and the cyclic AMP (cAMP)-dependent protein kinase A (PKA). Strikingly, filamentation induced by staurosporine does not require the known upstream regulators of Cyr1, Ras1 or Pkc1, or effectors downstream of PKA, including Efg1. We further demonstrate that Cyr1 is capable of activating PKA to enable filamentation in response to staurosporine through a mechanism that does not require degradation of the transcriptional repressor Nrg1. We establish that staurosporine-induced filamentation is accompanied by a defect in septin ring formation, implicating cell cycle kinases as potential staurosporine targets underpinning this cellular response. Thus, we establish staurosporine as a chemical probe to elucidate the architecture of cellular signaling governing fungal morphogenesis and highlight the existence of novel circuitry through which the Cyr1 and PKA govern a key virulence trait. IMPORTANCE The impact of fungal pathogens on human health is devastating. One of the most pervasive fungal pathogens is Candida albicans, which kills ~40% of people suffering from bloodstream infections. Treatment of these infections is extremely difficult, as fungi are closely related to humans, and there are limited drugs that kill the fungus without host toxicity. The capacity of C. albicans to transition between yeast and filamentous forms is a key virulence trait. Thus, understanding the genetic pathways that regulate morphogenesis could provide novel therapeutic targets to treat C. albicans infections. Here, we establish the small molecule staurosporine as an inducer of filamentous growth. We unveil distinct regulatory circuitry required for staurosporine-induced filamentation that appears to be unique to this filament-inducing cue. Thus, this work highlights the fact that small molecules, such as staurosporine, can improve our understanding of the pathways required for key virulence programs, which may lead to the development of novel therapeutics.

scholarly journals A CRISPR Interference Platform for Efficient Genetic Repression in Candida albicans

mSphere ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Lauren Wensing ◽  
Jehoshua Sharma ◽  
Deeva Uthayakumar ◽  
Yannic Proteau ◽  
Alejandro Chavez ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Human Disease ◽  
Transcriptional Repression ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Fungal Infections ◽  
Content Type ◽  
Guide Rna ◽  
Crispr Interference ◽  
Functional Genomic Analysis

ABSTRACT Fungal pathogens are emerging as an important cause of human disease, and Candida albicans is among the most common causative agents of fungal infections. Studying this fungal pathogen is of the utmost importance and necessitates the development of molecular technologies to perform comprehensive genetic and functional genomic analysis. Here, we designed and developed a novel clustered regularly interspaced short palindromic repeat interference (CRISPRi) system for targeted genetic repression in C. albicans. We engineered a nuclease-dead Cas9 (dCas9) construct that, paired with a guide RNA targeted to the promoter of an endogenous gene, is capable of targeting that gene for transcriptional repression. We further optimized a favorable promoter locus to achieve repression and demonstrated that fusion of dCas9 to an Mxi1 repressor domain was able to further enhance transcriptional repression. Finally, we demonstrated the application of this CRISPRi system through genetic repression of the essential molecular chaperone HSP90. This is the first demonstration of a functional CRISPRi repression system in C. albicans, and this valuable technology will enable many future applications in this critical fungal pathogen. IMPORTANCE Fungal pathogens are an increasingly important cause of human disease and mortality, and Candida albicans is among the most common causes of fungal disease. Studying this important fungal pathogen requires a comprehensive genetic toolkit to establish how different genetic factors play roles in the biology and virulence of this pathogen. Here, we developed a CRISPR-based genetic regulation platform to achieve targeted repression of C. albicans genes. This CRISPR interference (CRISPRi) technology exploits a nuclease-dead Cas9 protein (dCas9) fused to transcriptional repressors. The dCas9 fusion proteins pair with a guide RNA to target genetic promoter regions and to repress expression from these genes. We demonstrated the functionality of this system for repression in C. albicans and show that we can apply this technology to repress essential genes. Taking the results together, this work presents a new technology for efficient genetic repression in C. albicans, with important applications for genetic analysis in this fungal pathogen.

scholarly journals Epitope Shaving Promotes Fungal Immune Evasion

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Delma S. Childers ◽  
Gabriela Mol Avelar ◽  
Judith M. Bain ◽  
Arnab Pradhan ◽  
Daniel E. Larcombe ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Cell Surface ◽  
Immune Evasion ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Specific Cell ◽  
Immune Recognition ◽  
Content Type ◽  
Evasion Strategy

ABSTRACT The cell wall provides a major physical interface between fungal pathogens and their mammalian host. This extracellular armor is critical for fungal cell homeostasis and survival. Fungus-specific cell wall moieties, such as β-1,3-glucan, are recognized as pathogen-associated molecular patterns (PAMPs) that activate immune-mediated clearance mechanisms. We have reported that the opportunistic human fungal pathogen Candida albicans masks β-1,3-glucan following exposure to lactate, hypoxia, or iron depletion. However, the precise mechanism(s) by which C. albicans masks β-1,3-glucan has remained obscure. Here, we identify a secreted exoglucanase, Xog1, that is induced in response to lactate or hypoxia. Xog1 functions downstream of the lactate-induced β-glucan “masking” pathway to promote β-1,3-glucan “shaving.” Inactivation of XOG1 blocks most but not all β-1,3-glucan masking in response to lactate, suggesting that other activities contribute to this phenomenon. Nevertheless, XOG1 deletion attenuates the lactate-induced reductions in phagocytosis and cytokine stimulation normally observed for wild-type cells. We also demonstrate that the pharmacological inhibition of exoglucanases undermines β-glucan shaving, enhances the immune visibility of the fungus, and attenuates its virulence. Our study establishes a new mechanism underlying environmentally induced PAMP remodeling that can be manipulated pharmacologically to influence immune recognition and infection outcomes. IMPORTANCE The immune system plays a critical role in protecting us against potentially fatal fungal infections. However, some fungal pathogens have evolved evasion strategies that reduce the efficacy of our immune defenses. Previously, we reported that the fungal pathogen Candida albicans exploits specific host-derived signals (such as lactate and hypoxia) to trigger an immune evasion strategy that involves reducing the exposure of β-glucan at its cell surface. Here, we show that this phenomenon is mediated by the induction of a major secreted exoglucanase (Xog1) by the fungus in response to these host signals. Inactivating XOG1-mediated “shaving” of cell surface-exposed β-glucan enhances immune responses against the fungus. Furthermore, inhibiting exoglucanase activity pharmacologically attenuates C. albicans virulence. In addition to revealing the mechanism underlying a key immune evasion strategy in a major fungal pathogen of humans, our work highlights the potential therapeutic value of drugs that block fungal immune evasion.

scholarly journals The Fungal Pathogen Candida albicans Autoinduces Hyphal Morphogenesis by Raising Extracellular pH

mBio ◽  
2011 ◽  
Vol 2 (3) ◽  
Author(s):  
Slavena Vylkova ◽  
Aaron J. Carman ◽  
Heather A. Danhof ◽  
John R. Collette ◽  
Huaijin Zhou ◽  
...  
Keyword(s):  
Amino Acids ◽  
Candida Albicans ◽  
Amino Acid ◽  
Carbon Source ◽  
Fungal Pathogen ◽  
Host Cells ◽  
Acid Uptake ◽  
Content Type ◽  
Virulence Trait ◽  
Ph Adaptation

ABSTRACTpH homeostasis is critical for all organisms; in the fungal pathogenCandida albicans, pH adaptation is critical for virulence in distinct host niches. We demonstrate that beyond adaptation,C. albicansactively neutralizes the environment from either acidic or alkaline pHs. Under acidic conditions, this species can raise the pH from 4 to >7 in less than 12 h, resulting in autoinduction of the yeast-hyphal transition, a critical virulence trait. Extracellular alkalinization has been reported to occur in several fungal species, but under the specific conditions that we describe, the phenomenon is more rapid than previously observed. Alkalinization is linked to carbon deprivation, as it occurs in glucose-poor media and requires exogenous amino acids. These conditions are similar to those predicted to exist inside phagocytic cells, and we find a strong correlation between the use of amino acids as a cellular carbon source and the degree of alkalinization. Genetic and genomic approaches indicate an emphasis on amino acid uptake and catabolism in alkalinizing cells. Mutations in four genes,STP2, a transcription factor regulating amino acid permeases,ACH1(acetyl-coenzyme A [acetyl-CoA] hydrolase),DUR1,2(urea amidolyase), andATO5, a putative ammonia transporter, abolish or delay neutralization. The pH changes are the result of the extrusion of ammonia, as observed in other fungi. We propose that nutrient-deprivedC. albicanscells catabolize amino acids as a carbon source, excreting the amino nitrogen as ammonia to raise environmental pH and stimulate morphogenesis, thus directly contributing to pathogenesis.IMPORTANCECandida albicansis the most important fungal pathogen of humans, causing disease at multiple body sites. The ability to switch between multiple morphologies, including a rounded yeast cell and an elongated hyphal cell, is a key virulence trait in this species, as this reversible switch is thought to promote dissemination and tissue invasion in the host. We report here thatC. albicanscan actively alter the pH of its environment and induce its switch to the hyphal form. The change in pH is caused by the release of ammonia from the cells produced during the breakdown of amino acids. This phenomenon is unprecedented in a human pathogen and may substantially impact host physiology by linking morphogenesis, pH adaptation, carbon metabolism, and interactions with host cells, all of which are critical for the ability ofC. albicansto cause disease.

scholarly journals Improved Gene Ontology Annotation for Biofilm Formation, Filamentous Growth, and Phenotypic Switching in Candida albicans

2012 ◽  
Vol 12 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Diane O. Inglis ◽  
Marek S. Skrzypek ◽  
Martha B. Arnaud ◽  
Jonathan Binkley ◽  
Prachi Shah ◽  
...  
Keyword(s):  
Gene Ontology ◽  
Candida Albicans ◽  
Gene Product ◽  
Fungal Pathogen ◽  
Biofilm Formation ◽  
Filamentous Growth ◽  
Phenotypic Switching ◽  
Gene Products ◽  
Content Type ◽  
Opportunistic Fungal Pathogen

ABSTRACTThe opportunistic fungal pathogenCandida albicansis a significant medical threat, especially for immunocompromised patients. Experimental research has focused on specific areas ofC. albicansbiology, with the goal of understanding the multiple factors that contribute to its pathogenic potential. Some of these factors include cell adhesion, invasive or filamentous growth, and the formation of drug-resistant biofilms. The Gene Ontology (GO) (www.geneontology.org) is a standardized vocabulary that theCandidaGenome Database (CGD) (www.candidagenome.org) and other groups use to describe the functions of gene products. To improve the breadth and accuracy of pathogenicity-related gene product descriptions and to facilitate the description of as yet uncharacterized but potentially pathogenicity-related genes inCandidaspecies, CGD undertook a three-part project: first, the addition of terms to the biological process branch of the GO to improve the description of fungus-related processes; second, manual recuration of gene product annotations in CGD to use the improved GO vocabulary; and third, computational ortholog-based transfer of GO annotations from experimentally characterized gene products, using these new terms, to uncharacterized orthologs in otherCandidaspecies. Through genome annotation and analysis, we identified candidate pathogenicity genes in seven non-C. albicans Candidaspecies and in one additionalC. albicansstrain, WO-1. We also defined a set ofC. albicansgenes at the intersection of biofilm formation, filamentous growth, pathogenesis, and phenotypic switching of this opportunistic fungal pathogen, which provides a compelling list of candidates for further experimentation.

scholarly journals Genetic Analysis of Candida auris Implicates Hsp90 in Morphogenesis and Azole Tolerance and Cdr1 in Azole Resistance

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. e02529-18 ◽  
Author(s):  
Sang Hu Kim ◽  
Kali R. Iyer ◽  
Lakhansing Pardeshi ◽  
José F. Muñoz ◽  
Nicole Robbins ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Filamentous Growth ◽  
Antifungal Drugs ◽  
Clinical Isolates ◽  
Azole Resistance ◽  
Candida Auris ◽  
Content Type ◽  
Insight Into

ABSTRACT Candida auris is an emerging fungal pathogen and a serious global health threat as the majority of clinical isolates display elevated resistance to currently available antifungal drugs. Despite the increased prevalence of C. auris infections, the mechanisms governing drug resistance remain largely elusive. In diverse fungi, the evolution of drug resistance is enabled by the essential molecular chaperone Hsp90, which stabilizes key regulators of cellular responses to drug-induced stress. Hsp90 also orchestrates temperature-dependent morphogenesis in Candida albicans, a key virulence trait. However, the role of Hsp90 in the pathobiology of C. auris remains unknown. In order to study regulatory functions of Hsp90 in C. auris, we placed HSP90 under the control of a doxycycline-repressible promoter to enable transcriptional repression. We found that Hsp90 is essential for growth in C. auris and that it enables tolerance of clinical isolates with respect to the azoles, which inhibit biosynthesis of the membrane sterol ergosterol. High-level azole resistance was independent of Hsp90 but dependent on the ABC transporter CDR1, deletion of which resulted in abrogated resistance. Strikingly, we discovered that C. auris undergoes a morphogenetic transition from yeast to filamentous growth in response to HSP90 depletion or cell cycle arrest but not in response to other cues that induce C. albicans filamentation. Finally, we observed that this developmental transition is associated with global transcriptional changes, including the induction of cell wall-related genes. Overall, this report provides a novel insight into mechanisms of drug tolerance and resistance in C. auris and describes a developmental transition in response to perturbation of a core regulator of protein homeostasis. IMPORTANCE Fungal pathogens pose a serious threat to public health. Candida auris is an emerging fungal pathogen that is often resistant to commonly used antifungal drugs. However, the mechanisms governing drug resistance and virulence in this organism remain largely unexplored. In this study, we adapted a conditional expression system to modulate the transcription of an essential gene, HSP90, which regulates antifungal resistance and virulence in diverse fungal pathogens. We showed that Hsp90 is essential for growth in C. auris and is important for tolerance of the clinically important azole antifungals, which block ergosterol biosynthesis. Further, we established that the Cdr1 efflux transporter regulates azole resistance. Finally, we discovered that C. auris transitions from yeast to filamentous growth in response to Hsp90 inhibition, accompanied by global transcriptional remodeling. Overall, this work provides a novel insight into mechanisms regulating azole resistance in C. auris and uncovers a distinct developmental program regulated by Hsp90.

scholarly journals An Efficient, Rapid, and Recyclable System for CRISPR-Mediated Genome Editing in Candida albicans

mSphere ◽  
2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Namkha Nguyen ◽  
Morgan M. F. Quail ◽  
Aaron D. Hernday
Keyword(s):  
Candida Albicans ◽  
Genome Editing ◽  
Fungal Pathogen ◽  
Gene Knockout ◽  
Strain Engineering ◽  
Molecular Genetic Analysis ◽  
Content Type ◽  
Highly Efficient ◽  
Discovery Research ◽  
Gene Knockouts

ABSTRACT Candida albicans is the most common fungal pathogen of humans. Historically, molecular genetic analysis of this important pathogen has been hampered by the lack of stable plasmids or meiotic cell division, limited selectable markers, and inefficient methods for generating gene knockouts. The recent development of clustered regularly interspaced short palindromic repeat(s) (CRISPR)-based tools for use with C. albicans has opened the door to more efficient genome editing; however, previously reported systems have specific limitations. We report the development of an optimized CRISPR-based genome editing system for use with C. albicans. Our system is highly efficient, does not require molecular cloning, does not leave permanent markers in the genome, and supports rapid, precise genome editing in C. albicans. We also demonstrate the utility of our system for generating two independent homozygous gene knockouts in a single transformation and present a method for generating homozygous wild-type gene addbacks at the native locus. Furthermore, each step of our protocol is compatible with high-throughput strain engineering approaches, thus opening the door to the generation of a complete C. albicans gene knockout library. IMPORTANCE Candida albicans is the major fungal pathogen of humans and is the subject of intense biomedical and discovery research. Until recently, the pace of research in this field has been hampered by the lack of efficient methods for genome editing. We report the development of a highly efficient and flexible genome editing system for use with C. albicans. This system improves upon previously published C. albicans CRISPR systems and enables rapid, precise genome editing without the use of permanent markers. This new tool kit promises to expedite the pace of research on this important fungal pathogen.

Nanoscale adhesion forces between the fungal pathogen Candida albicans and macrophages

2016 ◽  
Vol 1 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Sofiane El-Kirat-Chatel ◽  
Yves F. Dufrêne
Keyword(s):  
Atomic Force Microscopy ◽  
Candida Albicans ◽  
Immune Cells ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Adhesion Forces ◽  
Force Microscopy ◽  
Atomic Force

We establish atomic force microscopy as a new nanoscopy platform for quantifying the forces between fungal pathogens and immune cells.

scholarly journals Kinesin-5 Is Dispensable for Bipolar Spindle Formation and Elongation in Candida albicans, but Simultaneous Loss of Kinesin-14 Activity Is Lethal

mSphere ◽  
2019 ◽  
Vol 4 (6) ◽  
Author(s):  
Irsa Shoukat ◽  
Corey Frazer ◽  
John S. Allingham
Keyword(s):  
Candida Albicans ◽  
Mitotic Spindle ◽  
Fungal Pathogens ◽  
Spindle Assembly ◽  
Spindle Pole ◽  
Content Type ◽  
Bipolar Spindle ◽  
Spindle Elongation ◽  
Simultaneous Loss ◽  
Bipolar Spindles

ABSTRACT Mitotic spindles assume a bipolar architecture through the concerted actions of microtubules, motors, and cross-linking proteins. In most eukaryotes, kinesin-5 motors are essential to this process, and cells will fail to form a bipolar spindle without kinesin-5 activity. Remarkably, inactivation of kinesin-14 motors can rescue this kinesin-5 deficiency by reestablishing the balance of antagonistic forces needed to drive spindle pole separation and spindle assembly. We show that the yeast form of the opportunistic fungus Candida albicans assembles bipolar spindles in the absence of its sole kinesin-5, CaKip1, even though this motor exhibits stereotypical cell-cycle-dependent localization patterns within the mitotic spindle. However, cells lacking CaKip1 function have shorter metaphase spindles and longer and more numerous astral microtubules. They also show defective hyphal development. Interestingly, a small population of CaKip1-deficient spindles break apart and reform two bipolar spindles in a single nucleus. These spindles then separate, dividing the nucleus, and then elongate simultaneously in the mother and bud or across the bud neck, resulting in multinucleate cells. These data suggest that kinesin-5-independent mechanisms drive assembly and elongation of the mitotic spindle in C. albicans and that CaKip1 is important for bipolar spindle integrity. We also found that simultaneous loss of kinesin-5 and kinesin-14 (CaKar3Cik1) activity is lethal. This implies a divergence from the antagonistic force paradigm that has been ascribed to these motors, which could be linked to the high mitotic error rate that C. albicans experiences and often exploits as a generator of diversity. IMPORTANCE Candida albicans is one of the most prevalent fungal pathogens of humans and can infect a broad range of niches within its host. This organism frequently acquires resistance to antifungal agents through rapid generation of genetic diversity, with aneuploidy serving as a particularly important adaptive mechanism. This paper describes an investigation of the sole kinesin-5 in C. albicans, which is a major regulator of chromosome segregation. Contrary to other eukaryotes studied thus far, C. albicans does not require kinesin-5 function for bipolar spindle assembly or spindle elongation. Rather, this motor protein associates with the spindle throughout mitosis to maintain spindle integrity. Furthermore, kinesin-5 loss is synthetically lethal with loss of kinesin-14—canonically an opposing force producer to kinesin-5 in spindle assembly and anaphase. These results suggest a significant evolutionary rewiring of microtubule motor functions in the C. albicans mitotic spindle, which may have implications in the genetic instability of this pathogen.

scholarly journals Melanin Externalization in Candida albicans Depends on Cell Wall Chitin Structures

2010 ◽  
Vol 9 (9) ◽  
pp. 1329-1342 ◽  
Author(s):  
Claire A. Walker ◽  
Beatriz L. Gómez ◽  
Héctor M. Mora-Montes ◽  
Kevin S. Mackenzie ◽  
Carol A. Munro ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Fungal Pathogen ◽  
Cell Walls ◽  
Chitin Synthesis ◽  
Melanin Production ◽  
Content Type ◽  
Encoding Gene ◽  
Chitinase Genes

ABSTRACT The fungal pathogen Candida albicans produces dark-pigmented melanin after 3 to 4 days of incubation in medium containing l-3,4-dihydroxyphenylalanine (l-DOPA) as a substrate. Expression profiling of C. albicans revealed very few genes significantly up- or downregulated by growth in l-DOPA. We were unable to determine a possible role for melanin in the virulence of C. albicans. However, we showed that melanin was externalized from the fungal cells in the form of electron-dense melanosomes that were free or often loosely bound to the cell wall exterior. Melanin production was boosted by the addition of N-acetylglucosamine to the medium, indicating a possible association between melanin production and chitin synthesis. Melanin externalization was blocked in a mutant specifically disrupted in the chitin synthase-encoding gene CHS2. Melanosomes remained within the outermost cell wall layers in chs3Δ and chs2Δ chs3Δ mutants but were fully externalized in chs8Δ and chs2Δ chs8Δ mutants. All the CHS mutants synthesized dark pigment at equivalent rates from mixed membrane fractions in vitro, suggesting it was the form of chitin structure produced by the enzymes, not the enzymes themselves, that was involved in the melanin externalization process. Mutants with single and double disruptions of the chitinase genes CHT2 and CHT3 and the chitin pathway regulator ECM33 also showed impaired melanin externalization. We hypothesize that the chitin product of Chs3 forms a scaffold essential for normal externalization of melanosomes, while the Chs8 chitin product, probably produced in cell walls in greater quantity in the absence of CHS2, impedes externalization.

scholarly journals Chromatin Profiling of the Repetitive and Nonrepetitive Genomes of the Human Fungal Pathogen Candida albicans

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Robert Jordan Price ◽  
Esther Weindling ◽  
Judith Berman ◽  
Alessia Buscaino
Keyword(s):  
Gene Expression ◽  
Candida Albicans ◽  
Histone Modifications ◽  
Chromatin Structure ◽  
Fungal Pathogen ◽  
Histone H3 ◽  
Content Type ◽  
Chromatin States ◽  
Genome Wide ◽  
Chromatin Profiling

ABSTRACT Eukaryotic genomes are packaged into chromatin structures that play pivotal roles in regulating all DNA-associated processes. Histone posttranslational modifications modulate chromatin structure and function, leading to rapid regulation of gene expression and genome stability, key steps in environmental adaptation. Candida albicans, a prevalent fungal pathogen in humans, can rapidly adapt and thrive in diverse host niches. The contribution of chromatin to C. albicans biology is largely unexplored. Here, we generated the first comprehensive chromatin profile of histone modifications (histone H3 trimethylated on lysine 4 [H3K4me3], histone H3 acetylated on lysine 9 [H3K9Ac], acetylated lysine 16 on histone H4 [H4K16Ac], and γH2A) across the C. albicans genome and investigated its relationship to gene expression by harnessing genome-wide sequencing approaches. We demonstrated that gene-rich nonrepetitive regions are packaged into canonical euchromatin in association with histone modifications that mirror their transcriptional activity. In contrast, repetitive regions are assembled into distinct chromatin states; subtelomeric regions and the ribosomal DNA (rDNA) locus are assembled into heterochromatin, while major repeat sequences and transposons are packaged in chromatin that bears features of euchromatin and heterochromatin. Genome-wide mapping of γH2A, a marker of genome instability, identified potential recombination-prone genomic loci. Finally, we present the first quantitative chromatin profiling in C. albicans to delineate the role of the chromatin modifiers Sir2 and Set1 in controlling chromatin structure and gene expression. This report presents the first genome-wide chromatin profiling of histone modifications associated with the C. albicans genome. These epigenomic maps provide an invaluable resource to understand the contribution of chromatin to C. albicans biology and identify aspects of C. albicans chromatin organization that differ from that of other yeasts. IMPORTANCE The fungus Candida albicans is an opportunistic pathogen that normally lives on the human body without causing any harm. However, C. albicans is also a dangerous pathogen responsible for millions of infections annually. C. albicans is such a successful pathogen because it can adapt to and thrive in different environments. Chemical modifications of chromatin, the structure that packages DNA into cells, can allow environmental adaptation by regulating gene expression and genome organization. Surprisingly, the contribution of chromatin modification to C. albicans biology is still largely unknown. For the first time, we analyzed C. albicans chromatin modifications on a genome-wide basis. We demonstrate that specific chromatin states are associated with distinct regions of the C. albicans genome and identify the roles of the chromatin modifiers Sir2 and Set1 in shaping C. albicans chromatin and gene expression.

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