FLO11, a yeast gene related to the STA genes, encodes a novel cell surface flocculin

Abstract

We report the characterization of a gene encoding a novel flocculin related to the STA genes of yeast, which encode secreted glucoamylase. The STA genes comprise sequences that are homologous to the sporulationspecific glucoamylase SGA and to two other sequences, S2 and S1. We find that S2 and S1 are part of a single gene which we have named FLO11. The sequence of FLO11 reveals a 4,104-bp open reading frame on chromosome IX whose predicted product is similar in overall structure to the class of yeast serine/threoninerich GPI-anchored cell wall proteins. An amino-terminal domain containing a signal sequence and a carboxyterminal domain with homology to GPI (glycosyl-phosphatidyl-inositol) anchor-containing proteins are separated by a central domain containing a highly repeated threonine-and serine-rich sequence. Yeast cells that express FLO11 aggregate in the calcium-dependent process of flocculation. Flocculation is abolished when FLO11 is disrupted. The product of STA1 also is shown to have flocculating activity. When a green fluorescent protein fusion of FLO11 was expressed from the FLO11 promoter on a single-copy plasmid, fluorescence was observed in vivo at the periphery of cells. We propose that FLO11 encodes a flocculin because of its demonstrated role in flocculation, its structural similarity to other members of the FLO gene family, and the cell surface location of its product. FLO11 gene sequences are present in all yeast strains tested, including all standard laboratory strains, unlike the STA genes which are present only in the variant strain Saccharomyces cerevisiae var. diastaticus. FLO11 differs from all other yeast flocculins in that it is located near a centromere rather than a telomere, and its expression is regulated by mating type. Repression of FLO11-dependent flocculation in diploids is conferred by the mating-type repressor a1/␣2.

The Structural and Functional Role of Med5 in the Yeast Mediator Tail Module

“…The DAN/TIR genes encode homologous mannoproteins, which contribute to the anaerobic remodeling of the cell wall (18,19), whereas ANB1 encodes an anaerobic isoform of translation initiation factor eIF-5A (21). We also noted an up-regulation of MUC1 (FLO11), a cell surface glycoprotein required for diploid pseudohyphal formation and haploid invasive growth (20,21). In agreement with these changes in MUC1 gene transcription, scanning electron microscopy revealed a weak chain-forming phenotype for both the med5⌬ and med16⌬ strains (data not shown).…”

Architecture and Biosynthesis of the Saccharomyces cerevisiae Cell Wall

“…However, activation of individual FLO genes confers the ability to flocculate (Guo et al 2000;Van Mulders et al 2009). Flo11/Muc1, a diverged Flo protein (Lambrechts et al 1996;Lo and Dranginis 1996), is not involved in flocculation, but is required for pseudohypha formation by diploids, invasion of agar by haploids, and biofilm development (Lo and Dranginis 1998;Guo et al 2000;Reynolds and Fink 2001;Dranginis et al 2007;Bojsen et al 2012).…”

Construction of FlocculentKluyveromyces marxianusStrains Suitable for High-Temperature Ethanol Fermentation

“…9,[12][13][14] The five FLO genes, FLO1, FLO5, FLO9, FLO10, and FLO11, have been described in S. cerevisiae thus far. [15][16][17][18][19] The FLO1, 5, 9, and 10 genes confer cell-cell adhesion (flocculation) ability, whereas FLO11 is responsible for substrate adhesion. 20) FLO1, FLO5, and FLO9 are highly similar to each other, but FLO10 has lower similarity.…”