Structure-activity relationships in the dodecapeptide .alpha.-factor of Saccharomyces cerevisiae: position 6 analogs are poor inducers of agglutinability

Abstract

Five des-Trp1,Cha3,X6 analogues of alpha-factor, where X = Ala, Val, Ile, Nle, or D-Leu and X = Leu in the natural alpha-factor sequence, were prepared by solution-phase techniques utilizing isobutyl chloroformate or 1-hydroxybenzotriazole accelerated active esters as the coupling agents. Purification to 98% or greater homogeneity was accomplished by high-performance liquid chromatography on a reversed-phase muBondapak C18 column with methanol/water/trifluoroacetic acid as the mobile phase. Three of the synthesized analogues (X6 = Val, Ile, Nle) induced morphogenesis and increased agglutinability in a cells. These substitutions demonstrate that a gamma-branched side chain at position 6 is not essential for biological activity. All of the active analogues induced morphogenesis at lower concentrations than they induced enhanced agglutinability. These results and other structure-activity relationships [Baffi, R. A., Shenbagamurthi, P., Terrance, K., Becker, J. M., Naider, F., & Lipke, P. (1984) J. Bacteriol. 158, 1152-1156] indicate that the agglutination and morphological responses to alpha-factor can be varied independently. Replacement of Leu6 with Ala or D-Leu resulted in inactive analogues that were not antagonistic for alpha-factor activity. Cell-mediated hydrolysis experiments indicated that the biological activities of the alpha-factor analogues are independent of their rates of degradation. All position 6 analogues were hydrolyzed more slowly than the parent compound, suggesting that the enzyme which degrades alpha-factor is highly specific for the native structure.

Synthesis and biological activity of amino terminus extended analogues of the .alpha. mating factor of Saccharomyces cerevisiae

“…4 Concentrations adjusted to that of a-factor by using absorbance at 289 nm. assay (Baffi et al, 1985). At these low cell densities the minimum concentration of pheromone that caused aberrant cell formation was 5-10-fold greater for the heptadecapeptide than it was for the tridecapeptide a-factor.…”

Sexual agglutination in budding yeasts: structure, function, and regulation of adhesion glycoproteins.

“…Jackson and Hartwell have shown that a cell can choose between mating partners and will mate preferentially with the cell that produces the higher level of pheromone (34,35). This choice may be dependent on pheromone concentrations much higher than those necessary to induce increased expression of genes (3,4,34,35). Induced a-agglutinin and, to a lesser extent, a-agglutinin have been shown to localize to the region of the cell called the shmoo tip, which is the region of cellular elongation that is induced by prolonged exposure to pheromone (98,104).…”

Saccharomyces cerevisiae mata mutant cells defective in pointed projection formation in response to α‐factor at high concentrations

“…There is also a report that a-factor has two actions on MATa cells with different K, values, and that an apparent threshold concentration of a-factor is necessary for the action with the high K, value (Moore, 1983). Evidence for these two types of actions has also been obtained using synthetic a-factor analogs (Baffi et al, 1984(Baffi et al, , 1985. Treatment of MATa cells with a-factor at high concentrations induces pointed p+rojection formation (Moore, 1983) and also Ca uptake by the cells (Ohsumi and Anraku, 1985).…”