A covalently constrained congener of the Saccharomyces cerevisiae tridecapeptide mating pheromone is an agonist.
An analog of alpha-factor, the Saccharomyces cerevisiae tridecapeptide mating pheromone (Trp-His-Trp-Leu-Gln-Leu-Lys-Pro-Gly-Gln-Pro-Met-Tyr), in which the side chains of Lys7 and Gln10 were covalently linked, was synthesized using solid phase methodologies. The yield of the purified cyclic analog cyclo7,10[Nle12]alpha-factor was 30%, and its structure was verified by amino acid analysis, peptide sequencing, fast atom bombardment-mass spectrometry, and proton nuclear magnetic resonance spectroscopy. Cyclo7,10[Nle12]alpha-factor caused growth arrest and morphological alterations in S. cerevisiae MATa cells qualitatively identical to those induced by linear pheromone and was one-fourth to one-twentieth as active as the linear alpha-factor depending upon the S. cerevisiae strain tested. Consistent with the relative activities of the linear and cyclic peptides, binding competition studies indicated that cyclo7,10[Nle12]alpha-factor had approximately 20-40-fold less affinity for the alpha-factor receptor. Hydrolysis of the cyclic peptide by the target cells did not lead to opening of the ring and was less rapid than that of linear alpha-factor. The alpha-factor antagonist des-Trp1-[Ala3,Nle12]alpha-factor reversed the activity of the cyclic analog, and cyclo7,10[Nle12]alpha-factor was not active at the restrictive temperature in a temperature-sensitive receptor mutant. These results support the conclusion that the cyclic alpha-factor occupies the same binding site within the receptor as is occupied by the natural pheromone. The cyclic alpha-factor represents a rare example of an agonist among covalently constrained congeners of small linear peptide messengers.
Xue
C B
CB
Department of Chemistry, College of Staten Island, City University of New York 10301.
Eriotou-Bargiota
E
E
Miller
D
D
Becker
J M
JM
Naider
F
F
D000595:Amino Acid Sequence; D007202:Indicators and Reagents; D013058:Mass Spectrometry; D000072235:Mating Factor; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis* / Q000378:metabolism / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000138:chemical synthesis / Q000494:pharmacology; D010675:Pheromones / Q000138:chemical synthesis*; D011485:Protein Binding; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000254:growth & development*; D013329:Structure-Activity Relationship
D007202:Indicators and Reagents; D010455:Peptides; D010456:Peptides, Cyclic; D010675:Pheromones; D000072235:Mating Factor