Glycosyl phosphatidylinositol-dependent cross-linking of alpha-agglutinin and beta 1,6-glucan in the Saccharomyces cerevisiae cell wall.
The cell adhesion protein alpha-agglutinin is bound to the outer surface of the Saccharomyces cerevisiae cell wall and mediates cell-cell contact in mating. alpha-Agglutinin is modified by addition of a glycosyl phosphatidylinositol (GPI) anchor as it traverses the secretory pathway. The presence of a GPI anchor is essential for cross-linking into the wall, but the fatty acid and inositol components of the anchor are lost before cell wall association (Lu, C.-F., J. Kurjan, and P. N. Lipke, 1994. A pathway for cell wall anchorage of Saccharomyces cerevisiae alpha-agglutinin. Mol. Cell. Biol. 14:4825-4833). Cell wall association of alpha-agglutinin was accompanied by an increase in size and a gain in reactivity to antibodies directed against beta 1,6-glucan. Several kre mutants, which have defects in synthesis of cell wall beta 1,6-glucan, had reduced molecular size of cell wall alpha-agglutinin. These findings demonstrate that the cell wall form of alpha-agglutinin is covalently associated with beta 1,6-glucan. The alpha-agglutinin biosynthetic precursors did not react with antibody to beta 1,6-glucan, and the sizes of these forms were unaffected in kre mutants. A COOH-terminal truncated form of alpha-agglutinin, which is not GPI anchored and is secreted into the medium, did not react with the anti-beta 1,6-glucan. We propose that extracellular cross-linkage to beta 1,6-glucan mediates covalent association of alpha-agglutinin with the cell wall in a manner that is dependent on prior addition of a GPI anchor to alpha-agglutinin.
Department of Biological Sciences, Hunter College of the City University of New York, New York 10021.
C F
CF
Lu
R C
RC
Montijn
J L
JL
Brown
F
F
Klis
J
J
Kurjan
H
H
Bussey
P N
PN
Lipke
D000906:Antibodies / Q000276:immunology; D002448:Cell Adhesion; D002473:Cell Wall / Q000378:metabolism; D005936:Glucans / Q000276:immunology / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D000072235:Mating Factor; D009154:Mutation; D010316:Particle Size; D010455:Peptides / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D047071:beta-Glucans
D000906:Antibodies; D005936:Glucans; D017261:Glycosylphosphatidylinositols; D010455:Peptides; D047071:beta-Glucans; C064197:beta-1,6-glucan; D000072235:Mating Factor