Role of glycine‐82 as a pivot point during the transition from the inactive to the active form of the yeast Ras2 protein

FEBS Letters

Crechet, Jean Bernard²  De Vendittis, Emmanuele¹  Di Blasi, Francesco³  Bozopoulos, Anastasios⁴  Fasano, Ottavio³  Parmeggiani, Andrea²  Verrotti, Arturo C.³  Tsernoglou, Demetrios⁴  Zahn, Regina³  Kavounis, Constantin³ 

[1] Dipartimento di Biochimica e Biotecnologie Mediche, Università de Napoli, via S. Pansini 5, I-80131 Napoli, Italy;Laboratoire de Biochimie, Ecole Polytechnique, F-91128 Palaiseau-Cedex, France;Differentiation Structures Programme, European Molecular Biology Laboratory, Meyerhofstrasse 1, D-6900 Heidelberg, Germany;Biological Structures Programme, European Molecular Biology Laboratory, Meyerhofstrasse 1, D-6900 Heidelberg, Germany

关键词: S. cerevisae;    Ras;    Point mutation;    Guanosine diphosphate;    Guanosine triphosphate;    PAGE;    polyacrylamide gel electrophoresis;    Gpp(NH)p;    guanyl-5′-yl imidodiphosphate;    GDP-βS;    guanosine-5′-O-(2-thiodiphosphate);    EDTA;    [ethylenedinitrilo]tetraacetic acid;    SDS;    sodium dodecyl sulfate;   

DOI  :  10.1016/0014-5793(91)80401-N

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Ras proteins bind either GDP or GTP with high affinity. However, only the GTP-bound form of the yeast Ras2 protein is able to stimulate adenylyl cyclase. To identify amino acid residues that play a role in the conversion from the GDP-bound to the GTP-bound state of Ras proteins, we have searched for single amino acid substitutions that selectively affected the binding of one of the two nucleotides. We have found that the replacement of glycine-82 of the Ras2 protein by serine resulted in an increased rate of dissociation of Gpp(NH)p, a nonhydrolysable analog of GTP, while the GDP dissociation rate was not significantly modified. Glycine-82 resides in a region that is highly conserved between the yeast and human proteins. However, this residue is structurally distant from residues that participate in the binding of the nucleotide, as determined from the crystal structure of the human H-ras gene product. Therefore, the ability of the nucleotide binding site to discriminate between GDP and GTP is dependent not only on residues that are spatially close to the nucleotide, but also on distant amino acids. This is in agreement with the role of glycine-82 as a pivot point during the transition from the GDP- to the GTP-bound form of the Ras proteins.

【 授权许可】

Unknown