An Arabidopsis gene isolated by a novel method for detecting genetic interaction in yeast encodes the GDP dissociation inhibitor of Ara4 GTPase.
The Arabidopsis Ara proteins belong to the Rab/Ypt family of small GTPases, which are implicated in intracellular vesicular traffic. To understand their specific roles in the cell, it is imperative to identify molecules that regulate the GTPase cycle. Such molecules have been found and characterized in animals and yeasts but not in plants. Using a yeast system, we developed a novel method of functional screening to detect interactions between foreign genes and identified this Rab regulator in plants. We found that the expression of the ARA4 gene in yeast ypt mutants causes exaggeration of the mutant phenotype. By introducing an Arabidopsis cDNA library into the ypt1 mutant, we isolated a clone whose coexpression overcame the deleterious effect of ARA4. This gene encodes an Arabidopsis homolog of the Rab GDP dissociation inhibitor (GDI) and was named AtGDI1. The expression of AtGDI1 complemented the yeast sec19-1 (gdi1) mutation. AtGDI1 is expressed almost ubiquitously in Arabidopsis tissues. The method described here indicates the physiological interaction of two plant molecules, Ara4 and GDI, in yeast and should be applicable to other foreign genes.
Ueda
T
T
Institute of Molecular and Cellular Biosciences, University of Tokyo, Japan.
Matsuda
N
N
Anai
T
T
Tsukaya
H
H
Uchimiya
H
H
Nakano
A
A
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D001483:Base Sequence; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics*; D016153:Genes, Suppressor; D020730:Guanine Nucleotide Dissociation Inhibitors; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D020691:rab GTP-Binding Proteins; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors
C100340:ARA4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D020730:Guanine Nucleotide Dissociation Inhibitors; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020691:rab GTP-Binding Proteins