R&D Scientist Academia Sinica Taipei, Taipei, Taiwan (Republic of China)
Body of Abstract: Light-regulated WD proteins (LWDs) contribute to circadian clock maintenance, photoperiodic flowering, and light responses in Arabidopsis. Despite lacking a DNA-binding domain, LWDs are crucial for activating the morning gene CCA1 expression at dawn by interacting with TCP20 and TCP22. Together with the molecular evidence indicating multiple entry points for LWD1 in Arabidopsis circadian clock, we proposed that LWDs act as scaffold proteins, dynamically interacting with different transcriptional regulators to orchestrate circadian clock gene expressions. To explore this hypothesis, we used the TurboID proximity labeling strategy to identify LWD1-interacting protein partners for clock regulation at three time points, ZT 0, 9, and 16. After LC-MS/MS identification and label-free quantification analyses, 257 proteins were identified as potential LWD1 protein partners. Protein-protein interaction network and gene ontology analyses of these proteins revealed enrichment of biological functions related to RNA splicing, epigenetic regulation of gene expression, and circadian rhythm. Several candidate proteins were selected to confirm their formation of protein complexes with LWD1. We also experimentally verified that a few epigenetic regulators found are new regulators of the Arabidopsis circadian clock, flowering time control, and responses to light-induced inhibition of hypocotyl elongation.