TY - JOUR
T1 - Clp Protease and OR Directly Control the Proteostasis of Phytoene Synthase, the Crucial Enzyme for Carotenoid Biosynthesis in Arabidopsis
AU - Welsch, Ralf
AU - Zhou, Xiangjun
AU - Yuan, Hui
AU - Álvarez, Daniel
AU - Sun, Tianhu
AU - Schlossarek, Dennis
AU - Yang, Yong
AU - Shen, Guoxin
AU - Zhang, Hong
AU - Rodriguez-Concepcion, Manuel
AU - Thannhauser, Theodore W.
AU - Li, Li
N1 - Publisher Copyright:
© 2017 The Author
PY - 2018
Y1 - 2018
N2 - 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, ClpC1, and ClpD). High levels of PSY and several other carotenogenic enzyme proteins overaccumulate in the clpc1, clpp4, and clpr1-2 mutants. The overaccumulated PSY was found to be partially enzymatically active. Impairment of Clp activity in clpc1 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 clpc1, counterbalancing Clp-mediated proteolysis in maintaining PSY protein homeostasis. Collectively, these findings provide novel insights into the quality control of plastid-localized proteins and establish a hitherto unidentified post-translational regulatory mechanism of carotenogenic enzymes in modulating carotenoid biosynthesis in plants. We reveal that PSY, the crucial enzyme in the carotenoid biosynthetic pathway, is a substrate of the Clp protease in chloroplasts. The PSY protein homeostasis is maintained by Clp protease for degradation and OR protein for stabilization to modulate carotenoid biosynthesis in plants. This study demonstrates a new post-translational control mechanism of carotenogenic enzymes.
AB - 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, ClpC1, and ClpD). High levels of PSY and several other carotenogenic enzyme proteins overaccumulate in the clpc1, clpp4, and clpr1-2 mutants. The overaccumulated PSY was found to be partially enzymatically active. Impairment of Clp activity in clpc1 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 clpc1, counterbalancing Clp-mediated proteolysis in maintaining PSY protein homeostasis. Collectively, these findings provide novel insights into the quality control of plastid-localized proteins and establish a hitherto unidentified post-translational regulatory mechanism of carotenogenic enzymes in modulating carotenoid biosynthesis in plants. We reveal that PSY, the crucial enzyme in the carotenoid biosynthetic pathway, is a substrate of the Clp protease in chloroplasts. The PSY protein homeostasis is maintained by Clp protease for degradation and OR protein for stabilization to modulate carotenoid biosynthesis in plants. This study demonstrates a new post-translational control mechanism of carotenogenic enzymes.
KW - Arabidopsis
KW - OR
KW - carotenoid
KW - clp protease
KW - phytoene synthase
KW - post-translational regulation
UR - http://www.scopus.com/inward/record.url?scp=85039043638&partnerID=8YFLogxK
U2 - 10.1016/j.molp.2017.11.003
DO - 10.1016/j.molp.2017.11.003
M3 - Article
C2 - 29155321
AN - SCOPUS:85039043638
SN - 1674-2052
VL - 11
SP - 149
EP - 162
JO - Molecular Plant
JF - Molecular Plant
IS - 1
ER -