Circadian clock factors regulate the first condensation reaction of fatty acid synthesis in Arabidopsis

• Published in: Cell reports (Cambridge) 2023-12, Vol.42 (12), p.113483-113483, Article 113483
• Main Authors: Kim, Sang-Chul, Edgeworth, Kristen N., Nusinow, Dmitri A., Wang, Xuemin
• Format: Article
• Language: English
• Subjects: Arabidopsis; b-ketoacyl-ACP synthase III (KASIII); circadian clock; Clock regulation of lipid metabolism; CP: Plants; fatty acid synthesis; LHY/CCA1; lipid signaling; Lipid-clock interconnection; phosphatidic acid; seed oil; transcriptional regulation
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2023.113483

The circadian clock regulates temporal metabolic activities, but how it affects lipid metabolism is poorly understood. Here, we show that the central clock regulators LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) regulate the initial step of fatty acid (FA) biosynthesis in Arabidopsis. Triacylglycerol (TAG) accumulation in seeds was increased in LHY-overexpressing (LHY-OE) and decreased in lhycca1 plants. Metabolic tracking of lipids in developing seeds indicated that LHY enhanced FA synthesis. Transcript analysis revealed that the expression of genes involved in FA synthesis, including the one encoding β-ketoacyl-ACP synthase III (KASIII), was oppositely changed in developing seeds of LHY/CCA1-OEs and lhycca1. Chromatin immunoprecipitation, electrophoretic mobility shift, and transactivation assays indicated that LHY bound and activated the promoter of KASIII. Furthermore, phosphatidic acid, a metabolic precursor to TAG, inhibited LHY binding to KASIII promoter elements. Our data show a regulatory mechanism for plant lipid biosynthesis by the molecular clock. [Display omitted] •LHY/CCA1 bind to KASIII promoter mediating the first FA condensation reaction•LHY/CCA1 enhance KASIII expression and FA synthesis in Arabidopsis•PA inhibits LHY/CCA1’s interaction with KASIII•The results show an interconnection between the molecular clock and lipid metabolism Kim et al. show that Arabidopsis clock regulators LHY/CCA1 enhance expression of KASIII, which encodes KASIII, catalyzing the first condensation of FA biosynthesis. LHY/CCA1 bind to KASIII’s promoter, whereas PA inhibits the binding, potentially acting as a retrograde modulator of the clock regulation of lipid production.