Direct activation of fission yeast adenylyl cyclase by heterotrimeric G protein gpa2.
Genetic studies on Schizosaccharomyces pombe adenylyl cyclase (cyr1) have shown that its activity is positively regulated by a heterotrimetric G protein a subunit gpa2 and that the resulting increase in intracellular cAMP concentration causes inhibition of sexual development including mating and meiosis. However, molecular mechanism underlying this gpa2-dependent regulation of cyr1 remains to be clarified. Here, we show that gpa2 exhibits a direct and GTP-dependent binding to the Ras-associating domain (RAD) of cyr1, which is identified by a computer algorithm-based search of the cyr1 amino acid sequence. Overexpression of this RAD results in acceleration of the sexual development of fission yeast cells presumably by competitive sequestration of gpa2. Furthermore, cyr1 is activated in vitro by the addition of purified gpa2, which is converted to the active state by treatment with AlF4-. These results indicate a crucial role of the RAD as a direct binding site of gpa2 in activation of cyr1. Thus, RADs, which have been defined as a conserved motif shared among the Ras-family small G protein-associating domains, are for the first time shown to exhibit a functional association with a member of the heterotrimeric G proteins.
Ogihara
Hideki
H
Division of Molecular Biology, Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe, Japan.
Shima
Fumi
F
Naito
Kana
K
Asato
Tsuyoshi
T
Kariya
Ken-ichi
K
Kataoka
Tohru
T
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D004789:Enzyme Activation; D044385:GTP-Binding Protein alpha Subunits / Q000502:physiology*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal; D011905:Genes, ras / Q000502:physiology; D008969:Molecular Sequence Data; D012568:Schizosaccharomyces / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029702:Schizosaccharomyces pombe Proteins / Q000502:physiology*; D012733:Sex Differentiation / Q000235:genetics
D044385:GTP-Binding Protein alpha Subunits; D029702:Schizosaccharomyces pombe Proteins; D019205:GTP-Binding Protein alpha Subunits, Gs; C540695:gpa2 protein, S pombe; D000262:Adenylyl Cyclases