title: Molecular determinants of bioactivity of the Saccharomyces cerevisiae lipopeptide mating pheromone.
abstract: The a-factor of Saccharomyces cerevisiae (YIIKGVF-WDPAC(Farnesyl)-OCH3) is a peptide pheromone in which post-translational modification with a farnesyl isoprenoid and carboxyl methyl group is required for export and bioactivity. Truncated and carboxyl-terminal modified analogs of the a-factor were synthesized in order to determine the effect of such modifications on bioactivity. Bioactivity studies on carboxyl-terminal analogs in which the chirality, the cysteine thioether, and the carboxyl ester were varied in an attempt to study the influence of topology on a-factor activity indicate that the hydrophobicity conferred by the farnesyl moiety and not its specific spatial orientation is a key determinant of a-factor potency. Analyses on truncated a-factors suggest that sequential removal of NH2-terminal residues leads to a gradient of potency loss, with some amino acids exhibiting a slightly greater contribution to bioactivity than others. Random oligonucleotide-targeted mutagenesis of the gene encoding a-factor was coupled to a biological screen to identify altered a-factor peptides which are secreted yet exhibit a loss of a-factor bioactivity. Transformants exhibiting this phenotype were examined to identify codon changes presumably responsible for the altered phenotype, thus indicating residues that may contribute significantly to a-factor bioactivity.
authors.affiliation: Program in Cellular, Molecular, and Developmental Biology, University of Knoxville 37996-0845.
authors.forename: G A
authors.initials: GA
authors.lastname: Caldwell
authors.forename: S H
authors.initials: SH
authors.lastname: Wang
authors.forename: C B
authors.initials: CB
authors.lastname: Xue
authors.forename: Y
authors.initials: Y
authors.lastname: Jiang
authors.forename: H F
authors.initials: HF
authors.lastname: Lu
authors.forename: F
authors.initials: F
authors.lastname: Naider
authors.forename: J M
authors.initials: JM
authors.lastname: Becker
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D000072235:Mating Factor; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D010455:Peptides; D000072235:Mating Factor