Structure of Saccharomyces cerevisiae alpha-agglutinin. Evidence for a yeast cell wall protein with multiple immunoglobulin-like domains with atypical disulfides.
alpha-Agglutinin of Saccharomyces cerevisiae is a cell wall-associated protein that mediates cell interaction in mating. Although the mature protein includes about 610 residues, the NH2-terminal half of the protein is sufficient for binding to its ligand a-agglutinin. alpha-Agglutinin20-351, a fully active fragment of the protein, has been purified and analyzed. Circular dichroism spectroscopy, together with sequence alignments, suggest that alpha-agglutinin20-351 consists of three immunoglobulin variable-like domains: domain I, residues 20-104; domain II, residues 105-199; and domain III, residues 200-326. Peptide sequencing data established the arrangement of the disulfide bonds in alpha-agglutinin20-351. Cys97 is disulfide-bonded to Cys114, forming an interdomain bond between domains I and II. Cys202 is bonded to Cys300, in an atypical intradomain disulfide bond between the A and F strands of domain III. Cys227 and Cys256 have free sulfhydryls. Sequencing also showed that at least two of three potential N-glycosylation sites with sequence Asn-Xaa-Thr are glycosylated. At least one of three Asn-Xaa-Ser sequences is not glycosylated. No residues NH2-terminal to Ser282 were O-glycosylated, whereas Ser282, and all hydroxy amino acid residues COOH-terminal to this position were modified. Therefore O-glycosylated Ser and Thr residues cluster in the COOH-terminal region of domain III, and the O-glycosylation continues into a Ser/Thr-rich sequence that extends from domain III to the COOH-terminal of the full-length protein.
Chen
M H
MH
Department of Biological Sciences, Hunter College of the City University of New York, New York 10021, USA.
Shen
Z M
ZM
Bobin
S
S
Kahn
P C
PC
Lipke
P N
PN
D000373:Agglutinins / Q000737:chemistry; D000595:Amino Acid Sequence; D001483:Base Sequence; D002942:Circular Dichroism; D016384:Consensus Sequence; D017931:DNA Primers; D007135:Immunoglobulin Variable Region / Q000737:chemistry; D007136:Immunoglobulins / Q000737:chemistry; D000072235:Mating Factor; D008969:Molecular Sequence Data; D010452:Peptide Biosynthesis; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000378:metabolism*; D012697:Serine Endopeptidases; D014357:Trypsin
D000373:Agglutinins; D017931:DNA Primers; D007135:Immunoglobulin Variable Region; D007136:Immunoglobulins; D010446:Peptide Fragments; D010455:Peptides; D011994:Recombinant Proteins; D000072235:Mating Factor; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D014357:Trypsin