scholarly journals Alternative oxidase induction protects Candida albicans from respiratory stress and promotes hyphal growth

2018 ◽  
Author(s):  
Lucian Duvenage ◽  
Louise A. Walker ◽  
Aleksandra Bojarczuk ◽  
Simon A. Johnston ◽  
Donna M. McCallum ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Candida Albicans ◽  
Fungal Pathogen ◽  
Alternative Oxidase ◽  
Hyphal Growth ◽  
Infection Model ◽  
Human Fungal Pathogen ◽  
Zebrafish Infection

AbstractThe human fungal pathogenCandida albicanspossesses two genes expressing a cyanide-insensitive Alternative Oxidase (Aox) enzymes in addition to classical and parallel electron transfer chains (ETC). In this study, we examine the role of Aox inC.albicansunder conditions of respiratory stress, which may be inflicted during its interaction with the human host or co-colonising bacteria. We find that the level of Aox expression is sufficient to modulate resistance to classical ETC inhibition under respiratory stress and are linked to gene expression changes that can promote both survival and pathogenicity. For example we demonstrate that Aox function is important for the regulation of filamentation inC.albicansand observe that cells lacking Aox function lose virulence in a zebrafish infection model. Our investigations also identify that pyocyanin, a phenazine produced by the co-colonising bacteriumPseudomonas aeruginosa, inhibits Aox-based respiration inC.albicans. These results suggest that Aox plays important roles within respiratory stress response pathways whichC.albicansmay utilise both as a commensal organism and as a pathogen.

scholarly journals MFα1, the Gene Encoding the α Mating Pheromone of Candida albicans

2003 ◽  
Vol 2 (6) ◽  
pp. 1350-1360 ◽  
Author(s):  
Sneh L. Panwar ◽  
Melanie Legrand ◽  
Daniel Dignard ◽  
Malcolm Whiteway ◽  
Paul. T. Magee
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogen ◽  
Null Mutant ◽  
Mating Pheromone ◽  
Gene Encoding ◽  
Human Fungal Pathogen ◽  
Isolation And Characterization ◽  
Α Pheromone

ABSTRACT Candida albicans, the single most frequently isolated human fungal pathogen, was thought to be asexual until the recent discovery of the mating-type-like locus (MTL). Homozygous MTL strains were constructed and shown to mate. Furthermore, it has been demonstrated that opaque-phase cells are more efficient in mating than white-phase cells. The similarity of the genes involved in the mating pathway in Saccharomyces cerevisiae and C. albicans includes at least one gene (KEX2) that is involved in the processing of the α mating pheromone in the two yeasts. Taking into account this similarity, we searched the C. albicans genome for sequences that would encode the α pheromone gene. Here we report the isolation and characterization of the gene MFα1, which codes for the precursor of the α mating pheromone in C. albicans. Two active α-peptides, 13 and 14 amino acids long, would be generated after the precursor molecule is processed in C. albicans. To examine the role of this gene in mating, we constructed an mfα1 null mutant of C. albicans. The mfα1 null mutant fails to mate as MTLα, while MTLa mfα1 cells are still mating competent. Experiments performed with the synthetic α-peptides show that they are capable of inducing growth arrest, as demonstrated by halo tests, and also induce shmooing in MTLa cells of C. albicans. These peptides are also able to complement the mating defect of an MTLα kex2 mutant strain when added exogenously, thereby confirming their roles as α mating pheromones.

scholarly journals Recent advances in understanding Candida albicans hyphal growth

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 700 ◽  
Author(s):  
Robert A. Arkowitz ◽  
Martine Bassilana
Keyword(s):  
Candida Albicans ◽  
Medical Research ◽  
Filamentous Fungi ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Morphological Changes ◽  
Hyphal Growth ◽  
Yeast Form ◽  
Intensive Research ◽  
Human Fungal Pathogen

Morphological changes are critical for the virulence of a range of plant and human fungal pathogens. Candida albicans is a major human fungal pathogen whose ability to switch between different morphological states is associated with its adaptability and pathogenicity. In particular, C. albicans can switch from an oval yeast form to a filamentous hyphal form, which is characteristic of filamentous fungi. What mechanisms underlie hyphal growth and how are they affected by environmental stimuli from the host or resident microbiota? These questions are the focus of intensive research, as understanding C. albicans hyphal growth has broad implications for cell biological and medical research.

scholarly journals A conserved regulator controls asexual sporulation in the fungal pathogen Candida albicans

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Arturo Hernández-Cervantes ◽  
Sadri Znaidi ◽  
Lasse van Wijlick ◽  
Iryna Denega ◽  
Virginia Basso ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Chromatin Immunoprecipitation ◽  
Fungal Pathogen ◽  
Hyphal Growth ◽  
Second Phase ◽  
Asexual Sporulation ◽  
Expression Of Genes ◽  
Genome Wide ◽  
Genome Wide Expression

AbstractTranscription factor Rme1 is conserved among ascomycetes and regulates meiosis and pseudohyphal growth in Saccharomyces cerevisiae. The genome of the meiosis-defective pathogen Candida albicans encodes an Rme1 homolog that is part of a transcriptional circuitry controlling hyphal growth. Here, we use chromatin immunoprecipitation and genome-wide expression analyses to study a possible role of Rme1 in C. albicans morphogenesis. We find that Rme1 binds upstream and activates the expression of genes that are upregulated during chlamydosporulation, an asexual process leading to formation of large, spherical, thick-walled cells during nutrient starvation. RME1 deletion abolishes chlamydosporulation in three Candida species, whereas its overexpression bypasses the requirement for chlamydosporulation cues and regulators. RME1 expression levels correlate with chlamydosporulation efficiency across clinical isolates. Interestingly, RME1 displays a biphasic pattern of expression, with a first phase independent of Rme1 function and dependent on chlamydospore-inducing cues, and a second phase dependent on Rme1 function and independent of chlamydospore-inducing cues. Our results indicate that Rme1 plays a central role in chlamydospore development in Candida species.

scholarly journals Hyphal growth inCandida albicansdoes not require induction of hyphal-specific gene expression

2015 ◽  
Vol 26 (6) ◽  
pp. 1174-1187 ◽  
Author(s):  
Shamoon Naseem ◽  
Esteban Araya ◽  
James B. Konopka
Keyword(s):  
Gene Expression ◽  
Fungal Pathogen ◽  
Hyphal Growth ◽  
Specific Gene ◽  
Ph Sensing ◽  
Triple Mutant ◽  
Transcriptional Responses ◽  
Hyphal Morphogenesis ◽  
Transcriptional Induction

Various stimuli, including N-acetylglucosamine (GlcNAc), induce the fungal pathogen Candida albicans to switch from budding to hyphal growth. Previous studies suggested that hyphal morphogenesis is stimulated by transcriptional induction of a set of genes that includes known virulence factors. To better understand hyphal development, we examined the role of GlcNAc metabolism using a triple mutant lacking the genes required to metabolize exogenous GlcNAc ( hxk1Δ nag1Δ dac1Δ). Surprisingly, at low ambient pH (∼pH 4), GlcNAc stimulated this mutant to form hyphae without obvious induction of hyphal genes. This indicates that GlcNAc can stimulate a separate signal to induce hyphae that is independent of transcriptional responses. Of interest, GlcNAc could induce the triple mutant to express hyphal genes when the medium was buffered to a higher pH (>pH 5), which normally occurs after GlcNAc catabolism. Catabolism of GlcNAc raises the ambient pH rather than acidifying it, as occurs after dextrose catabolism. This synergy between alkalinization and GlcNAc to induce hyphal genes involves the Rim101 pH-sensing pathway; GlcNAc induced rim101Δ and dfg16Δ mutants to form hyphae, but hyphal gene expression was partially defective. These results demonstrate that hyphal morphogenesis and gene expression can be regulated independently, which likely contributes to pathogenesis at different host sites.

scholarly journals Farnesol and Cyclic AMP Signaling Effects on the Hypha-to-Yeast Transition in Candida albicans

2012 ◽  
Vol 11 (10) ◽  
pp. 1219-1225 ◽  
Author(s):  
Allia K. Lindsay ◽  
Aurélie Deveau ◽  
Amy E. Piispanen ◽  
Deborah A. Hogan
Keyword(s):  
Candida Albicans ◽  
Cyclic Amp ◽  
Fungal Pathogen ◽  
Hyphal Growth ◽  
Morphological Plasticity ◽  
Camp Signaling ◽  
Environmental Cues ◽  
Transcriptional Repressors ◽  
Content Type

ABSTRACTCandida albicans, a fungal pathogen of humans, regulates its morphology in response to many environmental cues and this morphological plasticity contributes to virulence. Farnesol, an autoregulatory molecule produced byC. albicans, inhibits the induction of hyphal growth by inhibiting adenylate cyclase (Cyr1). The role of farnesol and Cyr1 in controlling the maintenance of hyphal growth has been less clear. Here, we demonstrate that preformed hyphae transition to growth as yeast in response to farnesol and that strains with increased cyclic AMP (cAMP) signaling exhibit more resistance to farnesol. Exogenous farnesol did not induce the hypha-to-yeast transition in mutants lacking the Tup1 or Nrg1 transcriptional repressors in embedded conditions. Although body temperature is not required for embedded hyphal growth, we found that the effect of farnesol on the hypha-to-yeast transition varies inversely with temperature. Our model of Cyr1 activity being required for filamentation is also supported by our liquid assay data, which show increased yeast formation when preformed filaments are treated with farnesol. Together, these data suggest that farnesol can modulate morphology in preformed hyphal cells and that the repression of hyphal growth maintenance likely occurs through the inhibition of cAMP signaling.

scholarly journals Reconfiguration of Transcriptional Control of Lysine Biosynthesis in Candida albicans Involves a Central Role for the Gcn4 Transcriptional Activator

mSphere ◽  
2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Yumnam Priyadarshini ◽  
Krishnamurthy Natarajan
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Candida Albicans ◽  
Fungal Pathogen ◽  
Biosynthetic Pathway ◽  
Transcriptional Regulator ◽  
Lysine Biosynthesis ◽  
Content Type ◽  
Human Fungal Pathogen ◽  
Starvation Conditions

ABSTRACT Microbes evolve rapidly so as to reconfigure their gene expression to adapt to the metabolic demands in diverse environmental niches. Here, we explored how conditions of nutrient deprivation regulate lysine biosynthesis in the human fungal pathogen Candida albicans. We show that although both Saccharomyces cerevisiae and C. albicans respond to lysine deprivation by transcriptional upregulation of lysine biosynthesis, the regulatory factors required for this control have been reconfigured in these species. We found that Gcn4 is an essential and direct transcriptional regulator of the expression of lysine biosynthetic genes under lysine starvation conditions in C. albicans. Our results therefore suggest that the regulation of the lysine biosynthetic pathway in Candida clade genomes involves gain of function by the master transcriptional regulator Gcn4, coincident with the neofunctionalization of the S. cerevisiae pathway-specific regulator Lys14. Evolution of transcriptional control is essential for organisms to cope with diversification into a spectrum of environments, including environments with limited nutrients. Lysine biosynthesis in fungi occurs in eight enzymatic steps. In Saccharomyces cerevisiae, amino acid starvation elicits the induction of LYS gene expression, mediated by the master regulator Gcn4 and the pathway-specific transcriptional regulator Lys14. Here, we have shown that the activation of LYS gene expression in the human fungal pathogen Candida albicans is predominantly controlled by Gcn4 under amino acid starvation conditions. Multiple lines of study showed that the four C. albicans LYS14-like genes have no role in the regulation of lysine biosynthesis. Whereas Gcn4 is dispensable for the growth of S. cerevisiae under lysine deprivation conditions, it is an essential regulator required for the growth of C. albicans under these conditions, as gcn4 deletion caused lysine auxotrophy. Gcn4 is required for the induction of increased LYS2 and LYS9 mRNA but not for the induction of increased LYS4 mRNA. Under lysine or isoleucine-valine deprivation conditions, Gcn4 recruitment to LYS2 and LYS9 promoters was induced in C. albicans. Indeed, in contrast to the S. cerevisiae LYS gene promoters, all LYS gene promoters in C. albicans harbored a Gcn4 binding site but not all harbored the S. cerevisiae Lys14 binding site, indicating the evolutionary divergence of cis-regulatory motifs. Thus, the transcriptional rewiring of the lysine biosynthetic pathway in C. albicans involves not only neofunctionalization of the four LYS14-like genes but the attendant strengthening of control by Gcn4, indicating a coordinated response with a much broader scope for control of amino acid biosynthesis in this human pathogen. IMPORTANCE Microbes evolve rapidly so as to reconfigure their gene expression to adapt to the metabolic demands in diverse environmental niches. Here, we explored how conditions of nutrient deprivation regulate lysine biosynthesis in the human fungal pathogen Candida albicans. We show that although both Saccharomyces cerevisiae and C. albicans respond to lysine deprivation by transcriptional upregulation of lysine biosynthesis, the regulatory factors required for this control have been reconfigured in these species. We found that Gcn4 is an essential and direct transcriptional regulator of the expression of lysine biosynthetic genes under lysine starvation conditions in C. albicans. Our results therefore suggest that the regulation of the lysine biosynthetic pathway in Candida clade genomes involves gain of function by the master transcriptional regulator Gcn4, coincident with the neofunctionalization of the S. cerevisiae pathway-specific regulator Lys14.

scholarly journals The role of aneuploidy in the emergence of echinocandin resistance in human fungal pathogen Candida albicans

2021 ◽  
Vol 17 (5) ◽  
pp. e1009564
Author(s):  
Sudisht Kumar Sah ◽  
Jeffrey Joseph Hayes ◽  
Elena Rustchenko
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogen ◽  
Human Fungal Pathogen ◽  
Echinocandin Resistance

scholarly journals Imaging and Quantification of mRNA Molecules at Single-Cell Resolution in the Human Fungal Pathogen Candida albicans

mSphere ◽  
2021 ◽  
Author(s):  
Sergio D. Moreno-Velásquez ◽  
J. Christian Pérez
Keyword(s):  
Gene Expression ◽  
Candida Albicans ◽  
Single Cell ◽  
Fungal Pathogen ◽  
Spatiotemporal Patterns ◽  
Animal Cells ◽  
Microbial Cells ◽  
Human Fungal Pathogen ◽  
Accurate Quantification

Tools to visualize and quantify transcripts at single-cell resolution have enabled the dissection of spatiotemporal patterns of gene expression in animal cells and tissues. Yet the accurate quantification of transcripts at single-cell resolution remains challenging for the much smaller microbial cells.

scholarly journals Pseudohyphal Regulation by the Transcription Factor Rfg1p in Candida albicans

2010 ◽  
Vol 9 (9) ◽  
pp. 1363-1373 ◽  
Author(s):  
Ian A. Cleary ◽  
Priyadarshini Mulabagal ◽  
Sara M. Reinhard ◽  
Nishant P. Yadev ◽  
Craig Murdoch ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Hyphal Growth ◽  
Growth Conditions ◽  
Pcr Analysis ◽  
Yeast Growth ◽  
Content Type ◽  
Human Fungal Pathogen ◽  
Hypha Formation

ABSTRACT The opportunistic human fungal pathogen Candida albicans is a major cause of nosocomial infections. One of the fundamental features of C. albicans pathogenesis is the yeast-to-hypha transition. Hypha formation is controlled positively by transcription factors such as Efg1p and Cph1p, which are required for hyphal growth, and negatively by Tup1p, Rfg1p, and Nrg1p. Previous work by our group has shown that modulating NRG1 gene expression, hence altering morphology, is intimately linked to the capacity of C. albicans to cause disease. To further dissect these virulence mechanisms, we employed the same strategy to analyze the role of Rfg1p in filamentation and virulence. Studies using a tet-RFG1 strain revealed that RFG1 overexpression does not inhibit hypha formation in vitro or in the mouse model of hematogenously disseminated candidiasis. Interestingly, RFG1 overexpression drives formation of pseudohyphae under yeast growth conditions—a phenotype similar to that of C. albicans strains with mutations in one of several mitotic regulatory genes. Complementation assays and real-time PCR analysis indicate that, although the morphology of the tet-RFG1 strain resembles that of the mitotic regulator mutants, Rfg1p overexpression does not impact expression of these genes.

scholarly journals Genetic analysis of sirtuin deacetylases in hyphal growth of Candida albicans

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Guolei Zhao ◽  
Laura Rusche
Keyword(s):  
Candida Albicans ◽  
Nuclear Localization ◽  
Fungal Pathogen ◽  
Environmental Changes ◽  
Hyphal Growth ◽  
Morphological Plasticity ◽  
Environmental Cues ◽  
Wild Type ◽  
Human Fungal Pathogen ◽  
Redundant Role

Candida albicans is a major human fungal pathogen that encounters varied host environments during infection. In response to environmental cues, C. albicans switches between ovoid yeast and elongated hyphal growth forms, and this morphological plasticity contributes to virulence. Environmental changes that alter the cell’s metabolic state could be sensed by sirtuins, which are NAD+-dependent deacetylases. Here we studied the roles of three sirtuin deacetylases, Sir2, Hst1, and Hst2, in hyphal growth of C. albicans. We made single, double, and triple sirtuin knockout strains and tested their ability to switch from yeast to hyphae. We found that true hyphae formation was significantly reduced by the deletion of SIR2 but not HST1 or HST2. Moreover, the expression of hyphal-specific genes HWP1, ALS3, and ECE1 decreased in the sir2Δ/Δ mutant compared to wild-type. This regulation of hyphae formation was dependent on the deacetylase activity of Sir2, as a point mutant lacking deacetylase activity had a similar defect in hyphae formation as the sir2Δ/Δ mutant. Finally, we found that Sir2 and Hst1 were localized to the nucleus, with Sir2 specifically focused in the nucleolus. This nuclear localization suggests a role for Sir2 and Hst1 in regulating gene expression. In contrast, Hst2 was localized to the cytoplasm. In conclusion, our results suggest that Sir2 plays a critical and non-redundant role in hyphal growth of C. albicans.

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