Repression of light signaling by Arabidopsis SPA1 involves post‐translational regulation of HFR1 protein accumulation

• DOI: 10.1111/j.1365-313x.2005.02433.x
• Publication Date: 2005-06-15T13:41:30Z
• Authors: Jianping Yang; Rongcheng Lin; Ute Hoecker; Bolin Liu; Ling Xu; Haiyang Wang
• Keywords: Photomorphogenesis; Phytochrome; Phytochrome A; Etiolation

Summary Arabidopsis uses two major classes of photoreceptors to mediate seedling de‐etiolation. The cryptochromes (cry1 and cry2) absorb blue/ultraviolet‐A light, whereas the phytochromes (phyA–phyE) predominantly regulate responses red/far‐red light. COP1 represses light signaling by acting as an E3 ubiquitin ligase in nucleus, is responsible for targeted degradation a number photomorphogenesis‐promoting factors, including HY5, LAF1, phyA, HFR1. Distinct pathways initiated multiple (including both cryptochromes) eventually converge on COP1, causing its inactivation nuclear depletion. SPA1 , which encodes protein structurally related also under various conditions. In this study, we present genetic evidence supporting that HFR1 bHLH transcription factor, acts downstream required different subsets branch controlled We show physically interacts with yeast two‐hybrid assay vitro co‐immunoprecipitation assay. demonstrate higher levels accumulate spa1 mutant background conditions, far‐red, red, blue, white marginal increase transcript level only seen dark‐ far‐red light‐grown spa1‐100 mutants. Together, our data suggest repression likely involves post‐translational regulation accumulation.