Candida albicans Sun41p, a putative glycosidase, is involved in morphogenesis, cell wall biogenesis, and biofilm formation.

Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstrasse 12, 70569 Stuttgart, Germany.
Eukaryotic Cell (Impact Factor: 3.18). 12/2007; 6(11):2056-65. DOI: 10.1128/EC.00285-07
Source: PubMed

ABSTRACT The SUN gene family has been defined in Saccharomyces cerevisiae and comprises a fungus-specific family of proteins which show high similarity in their C-terminal domains. Genes of this family are involved in different cellular processes, like DNA replication, aging, mitochondrial biogenesis, and cytokinesis. In Candida albicans the SUN family comprises two genes, SUN41 and SIM1. We demonstrate that C. albicans mutants lacking SUN41 show similar defects as found for S. cerevisiae, including defects in cytokinesis. In addition, the SUN41 mutant showed a higher sensitivity towards the cell wall-disturbing agent Congo red, whereas no difference was observed in the presence of calcofluor white. Compared to the wild type, SUN41 deletion strains exhibited a defect in biofilm formation, a reduced adherence on a Caco-2 cell monolayer, and were unable to form hyphae on solid medium under the conditions tested. Interestingly, Sun41p was found to be secreted in the medium of cells growing as blastospores as well as those forming hyphae. Our results support a function of SUN41p as a glycosidase involved in cytokinesis, cell wall biogenesis, adhesion to host tissue, and biofilm formation, indicating an important role in the host-pathogen interaction.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The SUN family is comprised of proteins that are conserved among various yeasts and fungi, but that are absent in mammals and plants. Although the function(s) of these proteins are mostly unknown, they have been linked to various, often unrelated cellular processes such as those connected to mitochondrial and cell wall functions. Here we show that three of the four Saccharomyces cerevisiae SUN family proteins, Uth1p, Sim1p and Sun4p, are efficiently secreted out of the cells in different growth phases and their production is affected by the level of oxygen. The Uth1p, Sim1p, Sun4p and Nca3p are mostly synthesized during the growth phase of both yeast liquid cultures and colonies. Culture transition to slow-growing or stationary phases is linked with a decreased cellular concentration of Sim1p and Sun4p and with their efficient release from the cells. In contrast, Uth1p is released mainly from growing cells. The synthesis of Uth1p and Sim1p, but not of Sun4p, is repressed by anoxia. All four proteins confer cell sensitivity to zymolyase. In addition, Uth1p affects cell sensitivity to compounds influencing cell wall composition and integrity (such as Calcofluor white and Congo red) differently when growing on fermentative versus respiratory carbon sources. In contrast, Uth1p is essential for cell resistance to boric acids irrespective of carbon source. In summary, our novel findings support the hypothesis that SUN family proteins are involved in the remodeling of the yeast cell wall during the various phases of yeast culture development and under various environmental conditions. The finding that Uth1p is involved in cell sensitivity to boric acid, i.e. to a compound that is commonly used as an important antifungal in mycoses, opens up new possibilities of investigating the mechanisms of boric acid's action.
    PLoS ONE 09/2013; 8(9):e73882. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Malassezia species are ubiquitous residents of human skin and are associated with several diseases, such as seborrheic dermatitis, tinea versicolor, folliculitis, atopic dermatitis, and scalp conditions such as dandruff. Host-Malassezia interactions and mechanisms to evade local immune responses remain largely unknown. M. restricta is one of the most predominant yeasts of the healthy human skin and in this paper, its cell wall has been investigated. Polysaccharides in the M. restricta cell wall are almost exclusively alkali-insoluble, showing that they play an essential role in the organization and rigidity of the M. restricta cell wall. Fractionation of cell wall polymers and carbohydrate analyses showed that the polysaccharidic core of the cell wall of M. restricta contained an average of 5% chitin, 20% chitosan, 5% β-(1,3)-glucan and 70% β-(1,6)-glucan. In contrast to other yeasts, chitin and chitosan are relatively abundant and β-(1,3)-glucans constitute a minor cell wall component. The most abundant polymer is β-(1,6)-glucans that are large molecules composed of a linear β-(1,6)-glucan chains with β-(1,3)-glucosyl side chain with an average of 1 branch point every 3.8 glucose unit. Both β-glucans are cross-linked, forming a huge alkali-insoluble complex with chitin and chitosan polymers. Data presented here shows that M. restricta has a polysaccharide organization very different of all fungal species analysed to date.
    Journal of Biological Chemistry 03/2014; · 4.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pichia fermentans DiSAABA 726 is a dimorphic yeast that reversibly shifts from yeast-like to pseudohyphal morphology. This yeast behaves as a promising antagonist of Monilia spp. in the yeast-like form, but becomes a destructive plant pathogen in the pseudohyphal form thus raising the problem of the biological risk associated with the use of dimorphic yeasts as microbial antagonists in the biocontrol of phytopathogenic fungi. Pichia fermentans DiSAABA 726 was grown in urea- and methionine- containing media in order to induce and separate yeast-like and pseudohyphal morphologies. Total RNA was extracted from yeast-like cells and pseudohyphae and retro-transcribed into cDNA. A rapid subtraction hybridization approach was utilized to obtain the cDNA sequences putatively over-expressed during growth on methionine-containing medium and involved in pseudohyphal transition. Five genes that are over-expressed during yeast-like/pseudohyphal dimorphic transition were isolated. One of these, encoding a putative phospholipase C, is involved in P. fermentans filamentation. In fact, while the inhibition of phospholipase C, by means of 1-O-octadecyl-2-O-methyl-rac glycero-3-phosporylcholine (Et-18), is accompanied by a significant reduction of pseudohyphae formation in P. fermentans, the addition of exogenous of cAMP fully restores pseudohyphal growth also in the presence of Et-18. Phospholipase C is part of a putative "methionine sensing machinery" that activates cAMP-PKA signal transduction pathway and controls P. fermentans yeast-like/pseudohyphal dimorphic transition. Phospholipase C is a promising molecular target for further investigations into the link between pseudohyphae formation and pathogenicity in P. fermentans.
    Biochimica et Biophysica Acta 09/2013; · 4.66 Impact Factor

Full-text (2 Sources)

Available from
Jun 5, 2014