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Identification of sumoylation targets, combined with inactivation of SMT3, reveals the impact of sumoylation upon growth, morphology, and stress resistance in the pathogen Candida albicans.

Leach MD, Stead DA, Argo E, Brown AJ - Mol. Biol. Cell (2011)

Bottom Line: Smt3/smt3 cells also displayed sensitivity to thermal, oxidative, and cell wall stresses as well as to the antifungal drug caspofungin.Furthermore, signaling via the cell integrity pathway was defective in C. albicans smt3/smt3 cells.Clearly sumoylation plays key roles in fundamental cellular processes that underpin the pathogenicity of this medically important fungus.

View Article: PubMed Central - PubMed

Affiliation: School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.

ABSTRACT
Posttranslational modifications of proteins play critical roles in the control of cellular differentiation, development, and environmental adaptation. In particular, the covalent attachment of the small ubiquitin-like modifier, SUMO, to target proteins (sumoylation) regulates cell cycle progression, transcription, nucleocytoplasmic transport, and stress responses. Here we combine proteomic, molecular, and cellular approaches to examine the roles of sumoylation in the major fungal pathogen of humans, Candida albicans. Using an N-terminally FLAG-tagged SUMO, 31 sumoylated proteins were identified in C. albicans with roles in stress responses (e.g., Hsp60, Hsp70 family members, Hsp104), the cytoskeleton and polarized growth (e.g., Tub1, Cct7, Mlc1), secretion, and endocytosis (e.g., Lsp1, Sec24, Sec7). The output from this proteomic screen was entirely consistent with the phenotypes of C. albicans mutants in which the single SUMO-encoding locus (SMT3) was inactivated or down-regulated. C. albicans smt3/smt3 cells displayed defects in growth, morphology, cell separation, nuclear segregation, and chitin deposition, suggesting important roles for sumoylation in cell cycle control. Smt3/smt3 cells also displayed sensitivity to thermal, oxidative, and cell wall stresses as well as to the antifungal drug caspofungin. Mutation of consensus sumoylation sites in Hsp60 and Hsp104 affected the resistance of C. albicans to thermal stress. Furthermore, signaling via the cell integrity pathway was defective in C. albicans smt3/smt3 cells. These observations provide mechanistic explanations for many of the observed phenotypic effects of Smt3 inactivation upon C. albicans growth and environmental adaptation. Clearly sumoylation plays key roles in fundamental cellular processes that underpin the pathogenicity of this medically important fungus.

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C. albicans smt3 mutants are unable to form hyphae. (A) Light microscopy of C. albicans smt3/smt3 cells grown with 10% serum at 37°C reveals their inability to form true hyphae: SMT3/SMT3 (BWP17), SMT3/smt3 (MLC33), and smt3/smt3 (MLC37). (B) Percentage of true hyphal cells in YPD at 30°C (FCS −) or in YPD plus 10% serum at 37°C (FCS +): SMT3/SMT3 (BWP17), SMT3/smt3 (MLC33), and smt3/smt3 (MLC37). **p < 0.01 (Student’s t test).
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Figure 6: C. albicans smt3 mutants are unable to form hyphae. (A) Light microscopy of C. albicans smt3/smt3 cells grown with 10% serum at 37°C reveals their inability to form true hyphae: SMT3/SMT3 (BWP17), SMT3/smt3 (MLC33), and smt3/smt3 (MLC37). (B) Percentage of true hyphal cells in YPD at 30°C (FCS −) or in YPD plus 10% serum at 37°C (FCS +): SMT3/SMT3 (BWP17), SMT3/smt3 (MLC33), and smt3/smt3 (MLC37). **p < 0.01 (Student’s t test).

Mentions: Yeast–hypha morphogenesis is a major virulence attribute of C. albicans. Smt3/smt3 cells displayed aberrant morphologies under conditions that promote the growth of budding cells (Figure 5A). Therefore we asked whether smt3/smt3 cells could form hyphae following serum stimulation. In contrast to the control strains (SMT3/SMT3 and smt3/SMT3), the smt3/smt3 mutant was unable to form true hyphae, with these cells becoming only slightly elongated in the presence of serum (Figure 6).


Identification of sumoylation targets, combined with inactivation of SMT3, reveals the impact of sumoylation upon growth, morphology, and stress resistance in the pathogen Candida albicans.

Leach MD, Stead DA, Argo E, Brown AJ - Mol. Biol. Cell (2011)

C. albicans smt3 mutants are unable to form hyphae. (A) Light microscopy of C. albicans smt3/smt3 cells grown with 10% serum at 37°C reveals their inability to form true hyphae: SMT3/SMT3 (BWP17), SMT3/smt3 (MLC33), and smt3/smt3 (MLC37). (B) Percentage of true hyphal cells in YPD at 30°C (FCS −) or in YPD plus 10% serum at 37°C (FCS +): SMT3/SMT3 (BWP17), SMT3/smt3 (MLC33), and smt3/smt3 (MLC37). **p < 0.01 (Student’s t test).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3046064&req=5

Figure 6: C. albicans smt3 mutants are unable to form hyphae. (A) Light microscopy of C. albicans smt3/smt3 cells grown with 10% serum at 37°C reveals their inability to form true hyphae: SMT3/SMT3 (BWP17), SMT3/smt3 (MLC33), and smt3/smt3 (MLC37). (B) Percentage of true hyphal cells in YPD at 30°C (FCS −) or in YPD plus 10% serum at 37°C (FCS +): SMT3/SMT3 (BWP17), SMT3/smt3 (MLC33), and smt3/smt3 (MLC37). **p < 0.01 (Student’s t test).
Mentions: Yeast–hypha morphogenesis is a major virulence attribute of C. albicans. Smt3/smt3 cells displayed aberrant morphologies under conditions that promote the growth of budding cells (Figure 5A). Therefore we asked whether smt3/smt3 cells could form hyphae following serum stimulation. In contrast to the control strains (SMT3/SMT3 and smt3/SMT3), the smt3/smt3 mutant was unable to form true hyphae, with these cells becoming only slightly elongated in the presence of serum (Figure 6).

Bottom Line: Smt3/smt3 cells also displayed sensitivity to thermal, oxidative, and cell wall stresses as well as to the antifungal drug caspofungin.Furthermore, signaling via the cell integrity pathway was defective in C. albicans smt3/smt3 cells.Clearly sumoylation plays key roles in fundamental cellular processes that underpin the pathogenicity of this medically important fungus.

View Article: PubMed Central - PubMed

Affiliation: School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.

ABSTRACT
Posttranslational modifications of proteins play critical roles in the control of cellular differentiation, development, and environmental adaptation. In particular, the covalent attachment of the small ubiquitin-like modifier, SUMO, to target proteins (sumoylation) regulates cell cycle progression, transcription, nucleocytoplasmic transport, and stress responses. Here we combine proteomic, molecular, and cellular approaches to examine the roles of sumoylation in the major fungal pathogen of humans, Candida albicans. Using an N-terminally FLAG-tagged SUMO, 31 sumoylated proteins were identified in C. albicans with roles in stress responses (e.g., Hsp60, Hsp70 family members, Hsp104), the cytoskeleton and polarized growth (e.g., Tub1, Cct7, Mlc1), secretion, and endocytosis (e.g., Lsp1, Sec24, Sec7). The output from this proteomic screen was entirely consistent with the phenotypes of C. albicans mutants in which the single SUMO-encoding locus (SMT3) was inactivated or down-regulated. C. albicans smt3/smt3 cells displayed defects in growth, morphology, cell separation, nuclear segregation, and chitin deposition, suggesting important roles for sumoylation in cell cycle control. Smt3/smt3 cells also displayed sensitivity to thermal, oxidative, and cell wall stresses as well as to the antifungal drug caspofungin. Mutation of consensus sumoylation sites in Hsp60 and Hsp104 affected the resistance of C. albicans to thermal stress. Furthermore, signaling via the cell integrity pathway was defective in C. albicans smt3/smt3 cells. These observations provide mechanistic explanations for many of the observed phenotypic effects of Smt3 inactivation upon C. albicans growth and environmental adaptation. Clearly sumoylation plays key roles in fundamental cellular processes that underpin the pathogenicity of this medically important fungus.

Show MeSH
Related in: MedlinePlus