J Integr Plant Biol. ›› 2019, Vol. 61 ›› Issue (9): 968-973.DOI: 10.1111/jipb.12760

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ESCRT-dependent vacuolar sorting and degradation of the auxin biosynthetic enzyme YUC1 flavin monooxygenase

Chennan Ge1,2,†, Caiji Gao3,4,†, Qingguo Chen2, Liwen Jiang3 and Yunde Zhao2,*   

  1. 1National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China
    2Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093-0116, USA
    3School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
    4Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China

    These authors contributed equally to this article.
    Email: Yunde Zhao (yundezhao@ucsd.edu)
  • Received:2018-09-10 Accepted:2018-12-13 Online:2018-12-19 Published:2019-09-01


YUC flavin monooxygenases catalyze the rate‐limiting step of auxin biosynthesis. Here we report the vacuolar targeting and degradation of GFP‐YUC1. GFP‐YUC1 fusion expressed in Arabidopsis protoplasts or transgenic plants was primarily localized in vacuoles. Surprisingly, we established that GFP‐YUC1, a soluble protein, was sorted to vacuoles through the ESCRT pathway, which has long been recognized for sorting and targeting integral membrane proteins. We further show that GFP‐YUC1 was ubiquitinated and in this form GFP‐YUC1 was targeted for degradation, a process that was also stimulated by elevated auxin levels. Our findings revealed a molecular mechanism of GFP‐YUC1 degradation and demonstrate that the ESCRT pathway can recognize both soluble and integral membrane proteins as cargoes.

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