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Yokonolide B, a novel inhibitor of auxin action, blocks degradation of AUX/IAA factors
被引:49
作者:
Hayashi, K
Jones, AM
Ogino, K
Yamazoe, A
Oono, Y
Inoguchi, M
Kondo, H
Nozaki, H
机构:
[1] Okayama Univ Sci, Dept Biochem, Okayama 7000005, Japan
[2] Univ N Carolina, Dept Biol, Chapel Hill, NC 27599 USA
[3] Japan Atom Energy Res Inst, Dept Ion Beam Appl Biol, Takasaki, Gumma 3701292, Japan
关键词:
D O I:
10.1074/jbc.M300299200
中图分类号:
Q5 [生物化学];
Q7 [分子生物学];
学科分类号:
071010 ;
081704 ;
摘要:
Yokonolide B (YkB; also known as A82548A), a spiroketal-macrolide, was isolated from Streptomyces diastatochromogenes B59 in a screen for inhibitors of beta-glucoronidase expression under the control of an auxin-responsive promoter in Arabidopsis. YkB inhibits the expression of auxin-inducible genes as shown using native and synthetic auxin promoters as well as using expression profiling of 8,300 Arabidopsis gene probes but does not affect expression of an abscisic acid- and a gibberellin A(3)-inducible gene. The mechanism of action of YkB is to block AUX/IAA protein degradation; however, YkB is not a general proteasome inhibitor. YkB blocks auxin-dependent cell division and auxin-regulated epinastic growth mediated by auxin-binding protein 1. Gain of function mutants such as shy2-2, slr1, and axr2-1 encoding AUX/IAA transcriptional repressors and loss of function mutants encoding components of the ubiquitin-proteolytic pathway such as axr1-3 and tir1-1, which display increased AUX/IAAs protein stability, are less sensitive to YkB, although axr1 and tir1 mutants were sensitive to MG132, a general proteasome inhibitor, consistent with a site of action downstream of AXR1 and TIR. YkB-treated seedlings displayed similar phenotypes as dominant AUX/IAA mutants. Taken together, these results indicate that YkB acts to block AUX/IAA protein degradation upstream of AXR and TIR, links a shared element upstream of AUX/IAA protein stability to auxin-induced cell division/elongation and to auxin-binding protein 1, and provides a new tool to dissect auxin signal transduction.
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页码:23797 / 23806
页数:10
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