Expression and Characterization of the Flocculin Flo11/Muc1, a Saccharomyces cerevisiae Mannoprotein with Homotypic Properties of Adhesion

Abstract

The Flo11/Muc1 flocculin has diverse phenotypic effects. Saccharomyces cerevisiae cells of strain background ⌺1278b require Flo11p to form pseudohyphae, invade agar, adhere to plastic, and develop biofilms, but they do not flocculate. We show that S. cerevisiae var. diastaticus strains, on the other hand, exhibit Flo11-dependent flocculation and biofilm formation but do not invade agar or form pseudohyphae. In order to study the nature of the Flo11p proteins produced by these two types of strains, we examined secreted Flo11p, encoded by a plasmid-borne gene, in which the glycosylphosphatidylinositol anchor sequences had been replaced by a histidine tag. A protein of approximately 196 kDa was secreted from both strains, which upon purification and concentration, aggregated into a form with a very high molecular mass. When secreted Flo11p was covalently attached to microscopic beads, it conferred the ability to specifically bind to S. cerevisiae var. diastaticus cells, which flocculate, but not to ⌺1278b cells, which do not flocculate. This was true for the 196-kDa form as well as the high-molecular-weight form of Flo11p, regardless of the strain source. The coated beads bound to S. cerevisiae var. diastaticus cells expressing FLO11 and failed to bind to cells with a deletion of FLO11, demonstrating a homotypic adhesive mechanism. Flo11p was shown to be a mannoprotein. Bead-to-cell adhesion was inhibited by mannose, which also inhibits Flo11-dependent flocculation in vivo, further suggesting that this in vitro system is a useful model for the study of fungal adhesion.

Sensing of mammalian IL-17A regulates fungal adaptation and virulence

“…Consistently, the TOR inhibitor LPF18 and the downstream orf. 19.4325 gene-an orthologue of Saccharomyces cerevisiae MUC1 coding for an adhesion protein 19 -were upregulated (Fig. 2c).…”

Regulation of Cell Wall Biogenesis in Saccharomyces cerevisiae: The Cell Wall Integrity Signaling Pathway

“…The polysaccharides that provide the mechanical strength of the cell wall also serve as the attachment matrix for a wide variety of glycoproteins (Zlotnick et al 1984;Klis et al 2006). These glycoproteins include sexual agglutination factors important for mating (Cappellaro et al 1994;Zhao et al 2001) and adhesins critical to cell-cell contact during filamentation, invasive growth, and biofilm formation (Reynolds and Fink 2001;Douglas et al 2007). Cellsurface glycoproteins also limit the permeability of the cell wall to macromolecules, thereby protecting the glucan layer from wall-degrading enzymes (Zlotnik et al 1984;De Nobel et al 1990;De Nobel and Barnett 1991;Klis et al 2006).…”

Gene expression associated with vegetative incompatibility in Amylostereum areolatum

“…Cell-cell adhesion and recognition in A. areolatum further appear to be lectin-mediated, because the two glycoprotein-encoding ESTs identified in this study encode a putative mucin and a mannoprotein. By functioning as lectins, these proteins are thought to facilitate cell-cell adhesion by binding to cell surface carbohydrates in fungi (Fukazawa and Kagaya, 1997;Fichtner et al, 2007;Douglas et al, 2007). The fact that transcripts for both these proteins were up-regulated during vegetative compatibility and incompatibility relative to non-interacting mycelia, supports the notion that similar molecular mechanisms underlie hyphal fusion during these interactions.…”