Genome-scale analysis reveals Sst2 as the principal regulator of mating pheromone signaling in the yeast Saccharomyces cerevisiae.
A common property of G protein-coupled receptors is that they become less responsive with prolonged stimulation. Regulators of G protein signaling (RGS proteins) are well known to accelerate G protein GTPase activity and do so by stabilizing the transition state conformation of the G protein alpha subunit. In the yeast Saccharomyces cerevisiae there are four RGS-homologous proteins (Sst2, Rgs2, Rax1, and Mdm1) and two Galpha proteins (Gpa1 and Gpa2). We show that Sst2 is the only RGS protein that binds selectively to the transition state conformation of Gpa1. The other RGS proteins also bind Gpa1 and modulate pheromone signaling, but to a lesser extent and in a manner clearly distinct from Sst2. To identify other candidate pathway regulators, we compared pheromone responses in 4,349 gene deletion mutants representing nearly all nonessential genes in yeast. A number of mutants produced an increase (sst2, bar1, asc1, and ygl024w) or decrease (cla4) in pheromone sensitivity or resulted in pheromone-independent signaling (sst2, pbs2, gas1, and ygl024w). These findings suggest that Sst2 is the principal regulator of Gpa1-mediated signaling in vivo but that other proteins also contribute in distinct ways to pathway regulation.
Chasse
Scott A
SA
Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260, USA.
Flanary
Paul
P
Parnell
Stephen C
SC
Hao
Nan
N
Cha
Jiyoung Y
JY
Siderovski
David P
DP
Dohlman
Henrik G
HG
D000595:Amino Acid Sequence; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D016681:Genome, Fungal / Q000235:genetics*; D023281:Genomics; D000072235:Mating Factor; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism*; D010675:Pheromones / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020710:RGS Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction
D044385:GTP-Binding Protein alpha Subunits; D020690:GTPase-Activating Proteins; D010455:Peptides; D010675:Pheromones; D020710:RGS Proteins; C094301:SST2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor; D020928:Mitogen-Activated Protein Kinases; C084293:GPA1 protein, S cerevisiae; D043802:GTP-Binding Protein alpha Subunits, Gq-G11