Binding of fluorinated phenylalanine alpha-factor analogues to Ste2p: evidence for a cation-pi binding interaction between a peptide ligand and its cognate G protein-coupled receptor.
Ste2p, a G protein-coupled receptor (GPCR), binds alpha-factor, WHWLQLKPGQPMY, a tridecapeptide pheromone secreted by yeast cells. Upon alpha-factor binding, Ste2p undergoes conformational changes activating a signal transduction system through its associated heterotrimeric G protein leading to the arrest of cell growth in the G1 phase to prepare cells for mating. Previous studies have indicated that Tyr at position 13 of alpha-factor interacts with Arg58 on transmembrane one (TM1) of Ste2p. This observation prompted this investigation to determine whether a cation-pi type of interaction occurred between these residues. Tyrosine at position 13 of alpha-factor was systematically substituted with analogous amino acids with varying cation-pi binding energies using solid-phase peptide synthesis, and these analogues were modified by derivatization of their Lys(7) residue with the fluorescent group 7-nitrobenz-2-oxa-1,3-diazole (NBD) to serve as a useful probe for binding determination. Saturation binding of these peptides to Ste2p was assayed using whole yeast cells and a flow cytometer. In parallel the biological activities of the peptides were determined using a growth arrest assay. The data provide evidence for the presence of a cation-pi interaction between Arg58 of Ste2p and Tyr(13) of alpha-factor.
Tantry
Subramanyam
S
Department of Chemistry, College of Staten Island of the City University of New York, Staten Island, New York 10314, USA.
Ding
Fa-Xiang
FX
Dumont
Mark
M
Becker
Jeffrey M
JM
Naider
Fred
F
D001667:Binding, Competitive; D005461:Fluorine; D000072235:Mating Factor; D010455:Peptides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D010649:Phenylalanine / Q000737:chemistry*; D010675:Pheromones / Q000378:metabolism*; D051964:Receptors, Mating Factor / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013816:Thermodynamics
D010455:Peptides; D010675:Pheromones; D051964:Receptors, Mating Factor; C498031:STE2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D005461:Fluorine; D010649:Phenylalanine; D000072235:Mating Factor