Phosphorylation of WRINKLED1 by KIN10 Results in Its Proteasomal Degradation, Providing a Link between Energy Homeostasis and Lipid Biosynthesis.
WRINKLED1 (WRI1), a member of the APETALA2 (AP2) class of transcription factors, positively regulates glycolysis and lipid biosynthesis inArabidopsis thalianaHere, we identify mechanistic links between KIN10, the major SUCROSE NON-FERMENTATION1-RELATED KINASE1 involved in sugar/energy homeostasis, and the posttranslational regulation of WRI1. Transient expression ofWRI1withOLEOSIN1inNicotiana benthamianastimulates triacylglycerol accumulation, but their coexpression withKIN10abrogates this effect by inducing proteasomal degradation of WRI1. While WRI1 lacks canonical KIN10 target sequences, we demonstrated direct KIN10-dependent phosphorylation of WRI1 using purifiedEscherichia coli-expressed components. The resulting phosphorylated WRI1 was more rapidly degraded than native WRI1 in cell-free degradation assays. WRI1 phosphorylation was localized to two variants of the canonical KIN10 recognition sequence, one in each of its two AP2 DNA binding domains. Conversion of the phosphorylation sites at Thr-70 and Ser-166 to Ala resulted in a loss of KIN10-dependent phosphorylation, and when coexpressed with KIN10 the WRI1 double mutant accumulated to 2- to 3-fold higher levels than native WRI1. KIN10-dependent degradation of WRI1 provides a homeostatic mechanism that favors lipid biosynthesis when intracellular sugar levels are elevated and KIN10 is inhibited; conversely, glycolysis and lipid biosynthesis are curtailed as sugar levels decrease and KIN10 regains activity.
Biology Department, Brookhaven National Laboratory, Upton, New York 11973.
Zhiyang
http://orcid.org/0000-0003-3181-1773
Z
Zhai
Biology Department, Brookhaven National Laboratory, Upton, New York 11973.
Hui
H
Liu
Biology Department, Brookhaven National Laboratory, Upton, New York 11973 shanklin@bnl.gov.
John
http://orcid.org/0000-0002-6774-8043
J
Shanklin
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D004734:Energy Metabolism / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D050356:Lipid Metabolism / Q000235:genetics / Q000502:physiology; D010766:Phosphorylation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases
D029681:Arabidopsis Proteins; D010940:Plant Proteins; D014157:Transcription Factors; C495665:WRINKLED1 protein, Arabidopsis; C531469:At3g01090 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases