Molecular characterisation of GTP1, a Saccharomyces cerevisiae gene encoding a small GTP-binding protein

The RHO1 gene encodes a homolog of the mammalian RhoA small GTP-binding protein in the yeast Saccharomyces cerevisiae. Rho1p is localized at the growth site and is required for bud formation. The RHO1(G22S, D125N) mutation is a temperature-sensitive and dominant negative mutation of RHO1, and a multicopy suppressor of RHO1(G22S, D125N), ROM7, was isolated. Nucleotide sequencing of ROM7 revealed that it is identical to the BEM4 gene (GenBank accession number L27816), although its physiological function has not yet been reported. Disruption of BEM4 resulted in the cold- and temperature-sensitive growth phenotypes, and cells of the deltabem4 mutant showed abnormal morphology, suggesting that BEM4 is involved in the budding process. The temperature-sensitive growth phenotype was suppressed by overexpression of RHO1, ROM2, which encodes a Rho1p-specific GDP/GTP exchange factor, or PKC1, which encodes a target of Rho1p. Moreover, glucan synthase activity, which is activated by Rho1p, was significantly reduced in the deltabem4 mutant. Two-hybrid and biochemical experiments revealed that Bem4p directly interacts with the nucleotide-free form of Rho1p and, to lesser extents, with the GDP- and GTP-bound forms of Rho1p, although Bem4p showed neither GDP/GTP exchange factor, GDP dissociation inhibitor, nor GTPase-activating protein activity toward Rho1p. These results indicate that Bem4p is a novel protein directly interacting with Rho1p and is involved in the RHO1-mediated signaling pathway.

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Identification and characterization of mouse GTPBP3 gene encoding a mitochondrial GTP-binding protein involved in tRNA modification

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2003.10.187 ◽

2003 ◽

Vol 312 (3) ◽

pp. 747-754 ◽

Cited By ~ 5

Author(s):

Xiaoming Li ◽

Min-Xin Guan

Keyword(s):

Binding Protein ◽

Trna Modification ◽

Gtp Binding Protein ◽

Gene Encoding ◽

Gtp Binding ◽

Identification And Characterization

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A hemopoietic specific gene encoding a small GTP binding protein is overexpressed during T cell activation

Biochemical and Biophysical Research Communications ◽

10.1016/0006-291x(91)91585-z ◽

1991 ◽

Vol 175 (2) ◽

pp. 451-458 ◽

Cited By ~ 36

Author(s):

L. Reibel ◽

O. Dorseuil ◽

R. Stancou ◽

J. Bertoglio ◽

G. Gacon

Keyword(s):

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Binding Protein ◽

Specific Gene ◽

Gtp Binding Protein ◽

Gene Encoding ◽

Gtp Binding

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Characterization of GTPase Activity of TrmE, a Member of a Novel GTPase Superfamily, from Thermotoga maritima

Journal of Bacteriology ◽

10.1128/jb.182.24.7078-7082.2000 ◽

2000 ◽

Vol 182 (24) ◽

pp. 7078-7082 ◽

Cited By ~ 40

Author(s):

Kunitoshi Yamanaka ◽

Jihwan Hwang ◽

Masayori Inouye

Keyword(s):

Thermotoga Maritima ◽

Binding Protein ◽

Protein A ◽

Hydrolysis Rate ◽

Gtpase Activity ◽

Gtp Binding Protein ◽

Gene Encoding ◽

Gtp Hydrolysis ◽

Gtp Binding

ABSTRACT A gene encoding a putative GTP-binding protein, a TrmE homologue that is highly conserved in both prokaryotes and eukaryotes, was cloned from Thermotoga maritima, a hyperthermophilic bacterium.T. maritima TrmE was overexpressed in Escherichia coli and purified. TrmE has a GTPase activity but no ATPase activity. The GTPase activity can be competed with GTP, GDP, and dGTP but not with GMP, ATP, CTP, or UTP. Km andk cat at 70°C were 833 μM and 9.3 min−1, respectively. Our results indicate that TrmE is a GTP-binding protein with a very high intrinsic GTP hydrolysis rate. We also propose that TrmE homologues constitute a novel subfamily of the GTPase superfamily.

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