Ethylene regulates monomeric GTP-binding protein gene expression and activity in Arabidopsis.
Ethylene rapidly and transiently up-regulates the activity of several monomeric GTP-binding proteins (monomeric G proteins) in leaves of Arabidopsis as determined by two-dimensional gel electrophoresis and autoradiographic analyses. The activation is suppressed by the receptor-directed inhibitor 1-methylcyclopropene. In the etr1-1 mutant, constitutive activity of all the monomeric G proteins activated by ethylene is down-regulated relative to wild type, and ethylene treatment has no effect on the levels of activity. Conversely, in the ctr1-1 mutant, several of the monomeric G proteins activated by ethylene are constitutively up-regulated. However, the activation profile of ctr1-1 does not exactly mimic that of ethylene-treated wild type. Biochemical and molecular evidence suggested that some of these monomeric G proteins are of the Rab class. Expression of the genes for a number of monomeric G proteins in response to ethylene was investigated by reverse transcriptase-PCR. Rab8 and Ara3 expression was increased within 10 min of ethylene treatment, although levels fell back significantly by 40 min. In the etr1-1 mutant, expression of Rab8 was lower than wild type and unaffected by ethylene; in ctr1-1, expression of Rab8 was much higher than wild type and comparable with that seen in ethylene treatments. Expression in ctr1-1 was also unaffected by ethylene. Thus, the data indicate a role for monomeric G proteins in ethylene signal transduction.
Moshkov
Igor E
IE
Timiryazev Institute of Plant Physiology Russian Academy of Sciences, Botanicheskaya 35, Moscow, Russia.
Mur
Luis A J
LA
Novikova
Galina V
GV
Smith
Aileen R
AR
Hall
Michael A
MA
D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D003521:Cyclopropanes / Q000494:pharmacology; D005030:Ethylenes / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017343:Genes, Plant / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
D029681:Arabidopsis Proteins; D003521:Cyclopropanes; D005030:Ethylenes; D010937:Plant Growth Regulators; C036216:ethylene; D020559:Monomeric GTP-Binding Proteins; C412563:1-methylcyclopropene