Dataset Information

Molecular and proteomic analyses highlight the importance of ubiquitination for the stress resistance, metabolic adaptation, morphogenetic regulation and virulence of Candida albicans.

ABSTRACT: Post-translational modifications of proteins play key roles in eukaryotic growth, differentiation and environmental adaptation. In model systems the ubiquitination of specific proteins contributes to the control of cell cycle progression, stress adaptation and metabolic reprogramming. We have combined molecular, cellular and proteomic approaches to examine the roles of ubiquitination in Candida albicans, because little is known about ubiquitination in this major fungal pathogen of humans. Independent null (ubi4/ubi4) and conditional (MET3p-UBI4/ubi4) mutations were constructed at the C. albicans polyubiquitin-encoding locus. These mutants displayed morphological and cell cycle defects, as well as sensitivity to thermal, oxidative and cell wall stresses. Furthermore, ubi4/ubi4 cells rapidly lost viability under starvation conditions. Consistent with these phenotypes, proteins with roles in stress responses (Gnd1, Pst2, Ssb1), metabolism (Acs2, Eno1, Fba1, Gpd2, Pdx3, Pgk1, Tkl1) and ubiquitination (Ubi4, Ubi3, Pre1, Pre3, Rpt5) were among the ubiquitination targets we identified, further indicating that ubiquitination plays key roles in growth, stress responses and metabolic adaptation in C. albicans. Clearly ubiquitination plays key roles in the regulation of fundamental cellular processes that underpin the pathogenicity of this medically important fungus. This was confirmed by the observation that the virulence of C. albicans ubi4/ubi4 cells is significantly attenuated.

SUBMITTER: Leach MD

PROVIDER: S-EPMC3084552 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Molecular and proteomic analyses highlight the importance of ubiquitination for the stress resistance, metabolic adaptation, morphogenetic regulation and virulence of Candida albicans.

Leach Michelle D MD Stead David A DA Argo Evelyn E MacCallum Donna M DM Brown Alistair J P AJ

Molecular microbiology 20110126 6

Post-translational modifications of proteins play key roles in eukaryotic growth, differentiation and environmental adaptation. In model systems the ubiquitination of specific proteins contributes to the control of cell cycle progression, stress adaptation and metabolic reprogramming. We have combined molecular, cellular and proteomic approaches to examine the roles of ubiquitination in Candida albicans, because little is known about ubiquitination in this major fungal pathogen of humans. Indepe ...[more]

PMID: 21269335

Similar Datasets

Project description:UnlabelledCandida albicans is the most prevalent fungal pathogen of humans, causing a variety of diseases ranging from superficial mucosal infections to deep-seated systemic invasions. Mucus, the gel that coats all wet epithelial surfaces, accommodates C. albicans as part of the normal microbiota, where C. albicans resides asymptomatically in healthy humans. Through a series of in vitro experiments combined with gene expression analysis, we show that mucin biopolymers, the main gel-forming constituents of mucus, induce a new oval-shaped morphology in C. albicans in which a range of genes related to adhesion, filamentation, and biofilm formation are downregulated. We also show that corresponding traits are suppressed, rendering C. albicans impaired in forming biofilms on a range of different synthetic surfaces and human epithelial cells. Our data suggest that mucins can manipulate C. albicans physiology, and we hypothesize that they are key environmental signals for retaining C. albicans in the host-compatible, commensal state.ImportanceThe yeast Candida albicans causes both superficial infections of the mucosa and life-threatening infections upon entering the bloodstream. However, C. albicans is not always harmful and can exist as part of the normal microbiota without causing disease. Internal body surfaces that are susceptible to infection by C. albicans are coated with mucus, which we hypothesize plays an important role in preventing infections. Here, we show that the main components of mucus, mucin glycoproteins, suppress virulence attributes of C. albicans at the levels of gene expression and the corresponding morphological traits. Specifically, mucins suppress attachment to plastic surfaces and human cells, the transition to cell-penetrating hyphae, and the formation of biofilms (drug-resistant microbial communities). Additionally, exposure to mucins induces an elongated morphology that physically resembles the mating-competent opaque state but is phenotypically distinct. We suggest that mucins are potent antivirulence molecules that have therapeutic potential for suppressing C. albicans infections.

Project description:The dimorphic fungus Candida albicans is one of the most important opportunistic pathogens for humankind. The use of fungicides against Candida could be associated with sub-inhibitory effects, which are referred to as fungal stress responses and are undesirable for the host. In this work, we investigated the antifungal action of 2,4-diacetylphloroglucinol (2,4-DAPG) against Candida albicans ATCC 10231 with a focus on their biofilm-forming ability. We found that 2,4-DAPG was able to reduce the ability of Candida cells to form biofilms, but complete inhibition and eradication effects were not achieved. Furthermore, C. albicans cells in the adherent state were characterized by reduced susceptibility to 2,4-DAPG compared to planktonic cells. The investigation of the mechanisms that could explain the antibiofilm action of 2,4-DAPG revealed a reduction in the cell`s surface hydrophobicity and the inhibition of the yeast-to-hyphae transition. The inhibition of the Candida cells filamentation was accompanied by an increase in the expression of the NRG1 gene, which is a negative regulator of hyphal development. In addition, we microscopically visualized the treated biofilms and revealed numerous channels that were decorated with particles and localized on the hyphae. We assumed that these hyphal structures could be associated with the secretion of aspartyl proteases (Sap). The performed assessments revealed an increase in the activity of Sap, which was accompanied by an increase in the expression of the sap2 and sap4 genes. The antifungal action of 2,4-DAPG is known to be associated with affecting the permeability of cellular structures, which leads to H+ATPase malfunction and the disruption of mitochondrial respiration. The subsequent cytosol acidification and generation of ROS trigger the inhibition of Candida filamentation and activation of Sap production. The introduction of antioxidant Trolox simultaneously with 2,4-DAPG leads to a reduction in Sap production. Collectively, the obtained data indicate new aspects of the interaction of fungal cells with 2,4-DAPG, an antimicrobial metabolite of Pseudomonas spp.

Project description:Small heat shock proteins (sHsps) have multiple cellular functions. However, the biological function of sHsps in pathogenic microorganisms is largely unknown. In the present study we identified and characterized the novel sHsp Hsp21 of the human fungal pathogen Candida albicans. Using a reverse genetics approach we demonstrate the importance of Hsp21 for resistance of C. albicans to specific stresses, including thermal and oxidative stress. Furthermore, a hsp21?/? mutant was defective in invasive growth and formed significantly shorter filaments compared to the wild type under various filament-inducing conditions. Although adhesion to and invasion into human-derived endothelial and oral epithelial cells was unaltered, the hsp21?/? mutant exhibited a strongly reduced capacity to damage both cell lines. Furthermore, Hsp21 was required for resisting killing by human neutrophils. Measurements of intracellular levels of stress protective molecules demonstrated that Hsp21 is involved in both glycerol and glycogen regulation and plays a major role in trehalose homeostasis in response to elevated temperatures. Mutants defective in trehalose and, to a lesser extent, glycerol synthesis phenocopied HSP21 deletion in terms of increased susceptibility to environmental stress, strongly impaired capacity to damage epithelial cells and increased sensitivity to the killing activities of human primary neutrophils. Via systematic analysis of the three main C. albicans stress-responsive kinases (Mkc1, Cek1, Hog1) under a range of stressors, we demonstrate Hsp21-dependent phosphorylation of Cek1 in response to elevated temperatures. Finally, the hsp21?/? mutant displayed strongly attenuated virulence in two in vivo infection models. Taken together, Hsp21 mediates adaptation to specific stresses via fine-tuning homeostasis of compatible solutes and activation of the Cek1 pathway, and is crucial for multiple stages of C. albicans pathogenicity. Hsp21 therefore represents the first reported example of a small heat shock protein functioning as a virulence factor in a eukaryotic pathogen.

Dataset Information

Molecular and proteomic analyses highlight the importance of ubiquitination for the stress resistance, metabolic adaptation, morphogenetic regulation and virulence of Candida albicans.

Publications

Molecular and proteomic analyses highlight the importance of ubiquitination for the stress resistance, metabolic adaptation, morphogenetic regulation and virulence of Candida albicans.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets