Peptidyl-prolyl isomerization targets rice Aux/IAAs for proteasomal degradation during auxin signalling

Subjects: Biology >> Biophysics submitted time 2016-05-11

Jing, Hongwei Yang, Xiaolu Zhang, Jian Zheng, Huakun Nian, Jinqiang Feng, Jian Li, Jiayang Zuo, Jianru Jing, Hongwei Yang, Xiaolu Zhang, Jian Zheng, Huakun Nian, Jinqiang Feng, Jian Li, Jiayang Zuo, Jianru Jing, Hongwei Yang, Xiaolu Zheng, Huakun Liu, Xuehui

Abstract： In plants, auxin signalling is initiated by the auxin-promoted interaction between the auxin receptor TIR1, an E3 ubiquitin ligase, and the Aux/IAA transcriptional repressors, which are subsequently degraded by the proteasome. Gain-of-function mutations in the highly conserved domain II of Aux/IAAs abolish the TIR1-Aux/IAA interaction and thus cause an auxin-resistant phenotype. Here we show that peptidyl-prolyl isomerization of rice OsIAA11 catalysed by LATERAL ROOTLESS2 (LRT2), a cyclophilin-type peptidyl-prolyl cis/trans isomerase, directly regulates the stability of OsIAA11. NMR spectroscopy reveals that LRT2 efficiently catalyses the cis/trans isomerization of OsIAA11. The lrt2 mutation reduces OsTIR1-OsIAA11 interaction and consequently causes the accumulation of a higher level of OsIAA11 protein. Moreover, knockdown of the OsIAA11 expression partially rescues the lrt2 mutant phenotype in lateral root development. Together, these results illustrate cyclophilin-catalysed peptidyl-prolyl isomerization promotes Aux/IAA degradation, as a mechanism regulating auxin signalling.

Peer Review Status:Awaiting Review

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