Specific phosphatidic acid species regulate the circadian period in Arabidopsis thaliana by directly binding key circadian clock transcription factors.
Information
The circadian clock is an internal timekeeper that synchronizes the timing of critical daily processes with the 24-hour cycle through a complex system involving feedback loops of transcription factors and downstream metabolites. Most recently, lipid metabolism was found to be integrated with the circadian clock as many lipids, including phosphatidic acid (PA), cycle diurnally. PA is an important secondary messenger involved in stress responses and its role in regulation of the circadian clock has only just begun to be explored. CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1) and LATE-ELONGATED HYPOCOTYL (LHY) are two key transcription factors that peak in the morning and regulate the expression of genes controlled by the circadian clock. CCA1 and LHY are important for the circadian regulation of lipid metabolism as cca1/lhy double knockout mutants lost diurnal lipid changes and PA directly binds CCA1 and LHY to inhibit the transcriptional regulation of their target genes. Our work characterizes how PA regulates the circadian clock by assessing the physical interaction of PA with clock factors and determining how altered PA levels can influence normal circadian rhythms in Arabidopsis thaliana. We found that circadian clock factors CCA1, LHY, and REVEILLE (RVE) family members can directly bind specific PA species. For CCA1, LHY, and most, but not all, of the RVE family, PA binding then inhibits their ability to bind to their target promoters within the circadian clock. In addition, when background PA levels are increased or decreased in planta, the short period phenotype of cca1/lhy mutants is partially rescued, further highlighting a key role for PA in the complex signaling within the circadian clock.
Equity and Inclusion: As a queer woman in science, I hope to reach other diverse scientists with this proposal to discuss new ideas and build collaborations. The Nusinow and Wang Labs have build great communities that have been especially inclusive of women and people of color where I have felt well-supported, successful, and happy.
