|Mutations in the TIR1 auxin receptor that increase affinity for auxin/indole-3-acetic acid proteins result in auxin hypersensitivity.
|Year of Publication
|Yu H, Moss BL, Jang SS, Prigge M, Klavins E, Nemhauser JL, Estelle M
|2,4-Dichlorophenoxyacetic Acid, Amino Acid Substitution, arabidopsis, Arabidopsis Proteins, Saccharomyces cerevisiae, F-Box Proteins, Gene Expression Regulation, Plant, Genes, Reporter, Indoleacetic Acids, Mutation, Reproductive Isolation, Plant Growth Regulators, Plant Roots, Receptors, Cell Surface, Recombinant Fusion Proteins, Seedling, Signal Transduction, SKP Cullin F-Box Protein Ligases, Two-Hybrid System Techniques
<p>The phytohormone auxin regulates virtually every aspect of plant development. The hormone directly mediates the interaction between the two members of the auxin coreceptor complex, a TRANSPORT INHIBITOR RESPONSE (TIR1)/AUXIN SIGNALING F-BOX protein and an AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) transcriptional repressor. To learn more about the interaction between these proteins, a mutant screen was performed using the yeast (Saccharomyces cerevisiae) two-hybrid system in Arabidopsis (Arabidopsis thaliana). Two tir1 mutations were identified that increased interaction with Aux/IAAs. The D170E and M473L mutations increase affinity between TIR1 and the degron motif of Aux/IAAs and enhance the activity of the SCF(TIR1) complex. This resulted in faster degradation of Aux/IAAs and increased transcription of auxin-responsive genes in the plant. Plants carrying the pTIR1:tir1 D170E/M473L-Myc transgene exhibit diverse developmental defects during plant growth and display an auxin-hypersensitive phenotype. This work demonstrates that changes in the leucine-rich repeat domain of the TIR1 auxin coreceptor can alter the properties of SCF(TIR1).</p>