The dual role of amyloid-β-sheet sequences in the cell surface properties of <i>FLO11</i>-encoded flocculins in <i>Saccharomyces cerevisiae</i>.

Abstract

Fungal adhesins (Als) or flocculins are family of cell surface proteins that mediate adhesion to diverse biotic and abiotic surfaces. A striking characteristic of Als proteins originally identified in the pathogenic <i>Candida albicans</i> is to form functional amyloids that mediate <i>cis-</i>interaction leading to the formation of adhesin nanodomains and <i>trans</i>-interaction between amyloid sequences of opposing cells. In this report, we show that flocculins encoded by <i>FLO11</i> in <i>Saccharomyces cerevisiae</i> behave like adhesins in <i>C. albicans</i>. To do so, we show that the formation of nanodomains under an external physical force requires a threshold number of amyloid-forming sequences in the Flo11 protein. Then, using a genome editing approach, we constructed strains expressing variants of the Flo11 protein under the endogenous <i>FLO11</i> promoter, leading to the demonstration that the loss of amyloid-forming sequences strongly reduces cell-cell interaction but has no effect on either plastic adherence or invasive growth in agar, both phenotypes being dependent on the N- and C-terminal ends of Flo11p. Finally, we show that the location of Flo11 is not altered either by the absence of amyloid-forming sequences or by the removal of the N- or C-terminus of the protein.