HSP90 Stabilizes Auxin-Responsive Phenotypes by Masking a Mutation in the Auxin Receptor TIR1.
Heat shock protein 90 (HSP90) is a molecular chaperone that is required for the function of various substrate proteins, also known as client proteins. It is proposed that HSP90 buffers or hides phenotypic variations in animals and plants by masking mutations in some of its client proteins. However, none of the client proteins with cryptic mutations has been identified to date. Here, we identify the first client protein example by which HSP90 buffers a mutation: the auxin receptor transport inhibitor response 1 (TIR1). TIR1 interacts with HSP90 in the nucleus. An HSP90-specific inhibitor abolished the nuclear localization of TIR1 and the auxin-induced degradation of a TIR1-substrate, indicating that TIR1 is an HSP90 client protein. Plants with a null mutation in the TIR1 gene had a defect in auxin response, whereas plants with a point mutation in the TIR1 gene responded to auxin treatment in young seedlings, but a cryptic defect in its auxin response was exposed with HSP90 inhibitor treatment. These results demonstrate that HSP90 masks a point mutation in the auxin receptor TIR1 and thereby buffers auxin-responsive phenotypes.
Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585 Japan.|Present address: Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, 020-8550 Japan.
Etsuko
E
Watanabe
Department of Evolutionary Biology and Biodiversity, National Institute for Basic Biology, Okazaki, 444-8585 Japan.|Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8585 Japan.
Shoji
S
Mano
Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602 Japan.
Mika
M
Nomoto
Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602 Japan.|Center for Gene Research, Nagoya University, Nagoya, 464-8602 Japan.
Yasuomi
Y
Tada
Department of Botany; Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan.|Present address: Faculty of Science and Engineering, Konan University, Kobe, 658-0073 Japan.
Ikuko
I
Hara-Nishimura
Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585 Japan.
Mikio
M
Nishimura
Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585 Japan kenji.yamada@uj.edu.pl.|Department of Botany; Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan.|Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, 30-387, Poland.
Kenji
K
Yamada
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D044783:F-Box Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000494:pharmacology*; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D011485:Protein Binding / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D029681:Arabidopsis Proteins; D044783:F-Box Proteins; D018841:HSP90 Heat-Shock Proteins; C466978:Hsp90-1 protein, Arabidopsis; C521946:IAA7 protein, Arabidopsis; D007210:Indoleacetic Acids; D011956:Receptors, Cell Surface; C501405:TIR1 protein, Arabidopsis; D014157:Transcription Factors
Auxin receptor; Buffering; HSP90; Phenotypic variation; TIR1