Probing the functional conformation of the tridecapeptide mating pheromone of Saccharomyces cerevisiae through study of disulfide-constrained analogs.
Analogs of the Saccharomyces cerevisiae alpha-mating factor, Trp-His-Trp-Leu-Gln-Leu-Lys-Pro-Gly-Gln-Pro-Met-Tyr, where Lys7 and Gln10 were replaced with Cys, Cys(CH3), or Ser, were synthesized using solid-phase procedures on a phenylacetamidomethyl resin. Cyclo7,10[Cys7,X9,Cys10,Nle12]alpha-factor , where X=D-Val, D-Ala, L-Ala and Gly, were prepared by on-resin cyclization using thallic trifluoroacetate in yields of 20-30%. Linear sulfhydryl-containing peptides were generated from their corresponding cyclic peptide by treatment with dithioerythritol in basic solution. In the linear analogs, replacement of both Lys7 and Gln10 with a cysteine residue resulted in an over 100-fold loss of the biological activity when compared with the native pheromone. The corresponding cyclic disulfides were 5-10-fold more active than their sulfhydryl-containing homologs, and cyclo7,10[Cys7,L-Ala9,Cys10,Nle12] alpha-factor was 50-fold more potent than linear analogs containing Ser or Cys(CH3) in positions 7 and 10. Binding competition studies indicated that all analogs had low affinity for the alpha-factor receptor and there was a poor correlation between binding and activity in a growth arrest assay. A cyclic analog in which residues 8 and 9 were replaced by 5-aminopentanoic acid was not biologically active. Based on NMR studies, all cyclic peptides have a higher tendency to form beta-turns spanning residues 7-10 than their less active linear counterparts. The results provide strong evidence that this beta-turn is important for optimal signal transduction by alpha-factor.
Xue
C B
CB
Department of Chemistry, College of Staten Island, City University of New York, USA.
McKinney
A
A
Lu
H F
HF
Jiang
Y
Y
Becker
J M
JM
Naider
F
F
D000595:Amino Acid Sequence; D001667:Binding, Competitive; D002851:Chromatography, High Pressure Liquid; D003553:Cystine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D000072235:Mating Factor; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D010675:Pheromones / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development; D014157:Transcription Factors
D004220:Disulfides; D010455:Peptides; D010675:Pheromones; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide; D014157:Transcription Factors; D003553:Cystine; D000072235:Mating Factor