The Arabidopsis B-box protein BZS1/BBX20 interacts with HY5 and mediates strigolactone regulation of photomorphogenesis

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• 作者：Chuang-Qi Wei^a ; ^b ; Chih-Wei Chien^b ; Lian-Feng Ai^c ; Jun Zhao^a ; Zhenzhen Zhang^a ; ^d ; Kathy H. Li^e ; Alma L. Burlingame^e ; Yu Sun^a ; ^{yusun05@hebtu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Zhi-Yong Wang^b ; ^{zywang24@stanford.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Light signaling ; Immunoprecipitation ; Mass spectrometry ; Strigolactone ; BZS1/BBX20 ; HY5 ; COP1
• 刊名：Journal of Genetics and Genomics
• 出版年：2016
• 出版时间：20 September 2016
• 年：2016
• 卷：43
• 期：9
• 页码：555-563
• 全文大小：980 K

文摘

Plant growth is controlled by integration of hormonal and light-signaling pathways. BZS1 is a B-box zinc finger protein previously characterized as a negative regulator in the brassinosteroid (BR)-signaling pathway and a positive regulator in the light-signaling pathway. However, the mechanisms by which BZS1/BBX20 integrates light and hormonal pathways are not fully understood. Here, using a quantitative proteomic workflow, we identified several BZS1-associated proteins, including light-signaling components COP1 and HY5. Direct interactions of BZS1 with COP1 and HY5 were verified by yeast two-hybrid and co-immunoprecipitation assays. Overexpression of BZS1 causes a dwarf phenotype that is suppressed by the hy5 mutation, while overexpression of BZS1 fused with the SRDX transcription repressor domain (BZS1-SRDX) causes a long-hypocotyl phenotype similar to hy5, indicating that BZS1's function requires HY5. BZS1 positively regulates HY5 expression, whereas HY5 negatively regulates BZS1 protein level, forming a feedback loop that potentially contributes to signaling dynamics. In contrast to BR, strigolactone (SL) increases BZS1 level, whereas the SL responses of hypocotyl elongation, chlorophyll and HY5 accumulation are diminished in the BZS1-SRDX seedlings, indicating that BZS1 is involved in these SL responses. These results demonstrate that BZS1 interacts with HY5 and plays a central role in integrating light and multiple hormone signals for photomorphogenesis in Arabidopsis.