title: A mannose-binding protein from the cell surface of flocculent Saccharomyces cerevisiae (NCIM 3528): its role in flocculation.
abstract: A cell surface lectin was isolated and purified to homogeneity from the cell walls of a highly flocculent strain of Saccharomyces cerevisiae (NCIM 3528) by chromatography on DEAE-cellulose, phenyl Sepharose and Sephacryl S-300. It showed a molecular mass of 40 kDa on SDS-PAGE. It is an acidic protein with a pI of 4.0 and contains 44% hydrophobic amino acids. The N-terminal sequence up to 10 amino acid residues showed at least 70% homology with the predicted N-terminal sequence of the putative FLO1 as well as FLO5 gene products. The mannose-binding nature of the lectin was indicated by its high affinity and specificity towards the branched trisaccharide of mannose, a ligand which also inhibits the flocculation of yeast cells. Immunofluorescence studies confirmed the presence of lectin on the yeast cell surface and lectin-specific IgGs prevented flocculation of the cells. This cell surface mannose-specific lectin probably plays an important role in flocculation, with the branched trimannoside on the cell wall being the apparent carbohydrate receptor. The N-terminal sequence data gives a primary indication that the lectin could be a product of one of the FLO genes.
authors.affiliation: Division of Biochemical Sciences, National Chemical Laboratory, Pune-411 008, India.
authors.forename: V S
authors.initials: VS
authors.lastname: Javadekar
authors.forename: H
authors.initials: H
authors.lastname: Sivaraman
authors.forename: S R
authors.initials: SR
authors.lastname: Sainkar
authors.forename: M I
authors.initials: MI
authors.lastname: Khan
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000737:chemistry / Q000494:pharmacology; D002352:Carrier Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D002473:Cell Wall / Q000737:chemistry*; D037222:Collectins; D005427:Flocculation; D005455:Fluorescent Antibody Technique; D006385:Hemagglutination Inhibition Tests; D006863:Hydrogen-Ion Concentration; D037102:Lectins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D008670:Metals / Q000494:pharmacology; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013696:Temperature
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D002352:Carrier Proteins; D037222:Collectins; C087578:FLO1 protein, S cerevisiae; D037102:Lectins; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D008670:Metals; D029701:Saccharomyces cerevisiae Proteins