Clp Protease and OR Directly Control the Proteostasis of Phytoene Synthase, the Crucial Enzyme for Carotenoid Biosynthesis in Arabidopsis  

作　　者：Ralf Welsch Xiangjun Zhou Hui Yuan Daniel Alvarez Tianhu Sun Dennis Schlossarek Yong Yang Guoxin Shen Hong Zhang Manuel Rodriguez-Concepcion Theodore W. Thannhauser Li Li 

机构地区：[1]University of Freiburg, Faculty of Biology II, 79104 Freiburg, Germany [2]Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, NY 14853, USA [3]plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA [4]Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China [5]Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA [6]Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain [7]These authors contributed equally to this article.

出　　处：《Molecular Plant》2018年第1期149-162,共14页分子植物（英文版）

摘　　要：Phytoene synthase （PSY） is the crucial plastidial enzyme in the carotenoid biosynthetic pathway. However, its post-translational regulation remains elusive. Likewise, Clp protease constitutes a central part of the plastid protease network, but its substrates for degradation are not well known. In this study, we report that PSY is a substrate of the Clp protease. PSY was uncovered to physically interact with various Clp protease subunits （i.e., ClpS1, CIpC1, and CIpD）. High levels of PSY and several other carotenogenic enzyme proteins overac- cumulate in the clpcl, clpp4, and clprl-2 mutants. The overaccumulated PSY was found to be partially enzy- matically active. Impairment of Clp activity in clpcl results in a reduced rate of PSY protein turnover, further supporting the role of Clp protease in degrading PSY protein. On the other hand, the ORANGE （OR） protein, a major post-translational regulator of PSY with holdase chaperone activity, enhances PSY protein stability and increases the enzymatically active proportion of PSY in clpcl, counterbalancing CIp-mediated proteol- ysis in maintaining PSY protein homeostasis. Collectively, these findings provide novel insights into the qual- ity control of plastid-localized proteins and establish a hitherto unidentified post-translational regulatory mechanism of carotenogenic enzymes in modulating carotenoid biosynthesis in plants.Phytoene synthase （PSY） is the crucial plastidial enzyme in the carotenoid biosynthetic pathway. However, its post-translational regulation remains elusive. Likewise, Clp protease constitutes a central part of the plastid protease network, but its substrates for degradation are not well known. In this study, we report that PSY is a substrate of the Clp protease. PSY was uncovered to physically interact with various Clp protease subunits （i.e., ClpS1, CIpC1, and CIpD）. High levels of PSY and several other carotenogenic enzyme proteins overac- cumulate in the clpcl, clpp4, and clprl-2 mutants. The overaccumulated PSY was found to be partially enzy- matically active. Impairment of Clp activity in clpcl results in a reduced rate of PSY protein turnover, further supporting the role of Clp protease in degrading PSY protein. On the other hand, the ORANGE （OR） protein, a major post-translational regulator of PSY with holdase chaperone activity, enhances PSY protein stability and increases the enzymatically active proportion of PSY in clpcl, counterbalancing CIp-mediated proteol- ysis in maintaining PSY protein homeostasis. Collectively, these findings provide novel insights into the qual- ity control of plastid-localized proteins and establish a hitherto unidentified post-translational regulatory mechanism of carotenogenic enzymes in modulating carotenoid biosynthesis in plants.

关 键 词：CAROTENOID phytoene synthase clp protease OR post-translational regulation ARABIDOPSIS 

分 类 号：Q562[生物学—生物化学] X173[环境科学与工程—环境科学]