Title: Phosphorylation of WRINKLED1 by KIN10 Results in its Proteasomal Degradation, Providing a Link Between Energy Homeostasis and Lipid Biosynthesis

Abstract

WRINKLED1 (WRI1), a member of the APETALA2 (AP2) class of transcription factors, positively regulates glycolysis and lipid biosynthesis in Arabidopsis thaliana. Here we identify mechanistic links between KIN10, the major SUCROSE NON-FERMENTATION-1 (SNF1)-RELATED KINASE 1 (SnRK1) involved in sugar/energy homeostasis and the posttranslational regulation of WRI1. Transient expression of WRI1 with OLEOSIN1 (OLE1) in Nicotiana benthamiana stimulates triacylglycerol (TAG) accumulation, but their coexpression with KIN10 abrogates this effect by inducing proteasomal degradation of WRI1. While WRI1 lacks canonical KIN10 target sequences, we demonstrated direct KIN10-dependent phosphorylation of WRI1 using purified E. 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 T70 and S166 to Ala resulted in a loss of KIN10-dependent phosphorylation, and when coexpressed with KIN10 the WRI1 double mutant accumulated to 2-3 fold higher levels than native WRI1. In conclusion, 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 levelsmore » decrease and KIN10 regains activity.« less

Authors:

Zhai, Zhiyang; Liu, Hui; Shanklin, John

Publication Date:

Fri Mar 17 00:00:00 EDT 2017

Research Org.:

Brookhaven National Laboratory (BNL), Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1348294

Report Number(s):

BNL-113680-2017-JA
Journal ID: ISSN 1040-4651

Grant/Contract Number:  

SC0012704

Resource Type:

Accepted Manuscript

Journal Name:

The Plant Cell

Additional Journal Information:

Journal Volume: 29; Journal Issue: 4; Journal ID: ISSN 1040-4651

Publisher:

American Society of Plant Biologists

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; Sugar sensing; fatty acids; TAG; protein proteasomal degradation