Overexpression of PRA2, a Rab/Ypt-family small GTPase from Pea Pisum sativum, aggravates the growth defect of yeast ypt mutants.
A large number of Rab/Ypt-family small GTPases have been identified from higher plants. While some of them can complement yeast ypt mutants, the expression of Arabidopsis Ara4 protein aggravated the growth defect of a subset of ypt mutants, probably because of the titration of common regulator(s) of yeast Ypt proteins [Ueda, T. et al. (1996) Plant Cell, 8: 2079-20911. PRA2 from pea Pisum sativum encodes an interesting Rab GTPase whose expression is regulated by light [Yoshida, K. et al. (1993) Proc. Natl. Acad. Sci. USA, 90: 6636-6640]. We examined whether PRA2 complements any of the yeast ypt mutants and found again that PRA2 does not complement but rather confers the growth defect to some of the ypt mutants. No growth defect was observed when PRA2 was expressed in the wild-type yeast cells. Unlike the case of Ara4, neither Arabidopsis nor yeast GDI remedied the growth defect by Pra2, indicating that the mechanism of the exacerbation is different. Mutational analysis of PRA2 suggests that the growth inhibition can be ascribed to unidentified factor(s) which prefers the GTP-bound form of Pra2. This yeast system will be useful for identifying such putative regulatory factor(s) from yeast and plants and analyzing their interactions with Pra2.
Matsuda
N
N
Molecular Membrane Biology Laboratory, RIKEN, Wako, Saitama, Japan.
Ueda
T
T
Sasaki
Y
Y
Nakano
A
A
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006131:Growth Inhibitors / Q000096:biosynthesis* / Q000235:genetics; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000235:genetics / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors; D016296:Mutagenesis; D018532:Pisum sativum; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D020691:rab GTP-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C079548:DSS4 protein, S cerevisiae; D005656:Fungal Proteins; C086796:GDP dissociation inhibitor 1; D006131:Growth Inhibitors; D020730:Guanine Nucleotide Dissociation Inhibitors; D020662:Guanine Nucleotide Exchange Factors; C092439:MRS6 protein, S cerevisiae; D010940:Plant Proteins; D029701:Saccharomyces cerevisiae Proteins; C087905:YPT31 protein, S cerevisiae; C094510:PRA2 protein, Pisum sativum; C060755:YPT1 protein, S cerevisiae; C121633:YPT32 protein, S cerevisiae; C064320:SEC4 protein, S cerevisiae; D020691:rab GTP-Binding Proteins