| Autor: |
Xiaoqing, Yang, Sungsu, Lee, Jai-Hyun, So, Suni, Dharmasiri, Nihal, Dharmasiri, Lei, Ge, Carolyn, Jensen, Roger, Hangarter, Lawrence, Hobbie, Mark, Estelle |
| Rok vydání: |
2004 |
| Předmět: |
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| Zdroj: |
The Plant journal : for cell and molecular biology. 40(5) |
| ISSN: |
0960-7412 |
| Popis: |
Recent studies of auxin response have focused on the functions of three sets of proteins: the auxin (Aux) response factors (ARFs), the Aux/IAAs, and the F-box protein TIR1. The ARF proteins bind DNA and directly activate or repress transcription of target genes while the Aux/IAA proteins repress ARF function. TIR1 is part of a ubiquitin protein ligase required for degradation of Aux/IAA proteins. Here we report the isolation and characterization of a novel mutant of Arabidopsis called axr5-1. Mutant plants are resistant to auxin and display a variety of auxin-related growth defects including defects in root and shoot tropisms. Further, the axr5-1 mutation results in a decrease in auxin-regulated transcription. The molecular cloning of AXR5 revealed that the gene encodes the IAA1 protein, a member of the Aux/IAA family of proteins. AXR5 is expressed throughout plant development consistent with the pleiotropic mutant phenotype. The axr5-1 mutation results in an amino acid substitution in conserved domain II of the protein, similar to gain-of-function mutations recovered in other members of this gene family. Biochemical studies show that IAA1/AXR5 interacts with TIR1 in an auxin-dependent manner. The mutation prevents this interaction suggesting that the mutant phenotype is caused by the accumulation of IAA1/AXR5. Our results provide further support for a model in which most members of the Aux/IAA family are targeted for degradation by SCFTIR1 in response to auxin. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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