A genome-wide screen for mutants showing altered brassinosteroid （BR） sensitivity or bril-like phenotypes resulted in the identification of two new mutant alleles of TWISTED DWARF 1 （TWD1）, twd1-4, and twdl-5. Pre...A genome-wide screen for mutants showing altered brassinosteroid （BR） sensitivity or bril-like phenotypes resulted in the identification of two new mutant alleles of TWISTED DWARF 1 （TWD1）, twd1-4, and twdl-5. Pre- vious studies indicated that TWD1, also named as ULTRACURVATA 2 or FKBP42, associates with auxin efflux transporters and is essential for their biological functions. Although earlier reports showed that BR signaling is downregulated in twdl, how TWD1 is integrated in BR signaling has not been elucidated. Here, we provide ge- netic and biochemical evidence demonstrating that TWD1 interacts with the BR receptor BRI1 in vivo in a BR- independent manner. Further analyses indicated that TWD1 modulates the BR signal transduction not by altering ER quality control or protein abundance of BRI1; instead, TWD1 appears to be critical in BR- induced interaction of BRI1 and its co-receptor BAK1, as well as BR-induced phosphorylation of these two proteins. These results provide better understanding of the early events of the BR signaling pathway.展开更多
文摘A genome-wide screen for mutants showing altered brassinosteroid （BR） sensitivity or bril-like phenotypes resulted in the identification of two new mutant alleles of TWISTED DWARF 1 （TWD1）, twd1-4, and twdl-5. Pre- vious studies indicated that TWD1, also named as ULTRACURVATA 2 or FKBP42, associates with auxin efflux transporters and is essential for their biological functions. Although earlier reports showed that BR signaling is downregulated in twdl, how TWD1 is integrated in BR signaling has not been elucidated. Here, we provide ge- netic and biochemical evidence demonstrating that TWD1 interacts with the BR receptor BRI1 in vivo in a BR- independent manner. Further analyses indicated that TWD1 modulates the BR signal transduction not by altering ER quality control or protein abundance of BRI1; instead, TWD1 appears to be critical in BR- induced interaction of BRI1 and its co-receptor BAK1, as well as BR-induced phosphorylation of these two proteins. These results provide better understanding of the early events of the BR signaling pathway.
