Ubiquitination and stress signaling
作者单位：Institute of Genetics and Developmental Biology Chinese Academy of ScienceBeijing China
会议名称：《2006中国植物细胞发育与分子生物学学术研讨会》
会议日期：2006年
学科分类：0710[理学-生物学] 071001[理学-植物学] 07[理学]
关 键 词：ABA Ubiquitination E3 ligase drought stress cold signal Stomata
摘 要：正Ubiquitination has been demonstrated to play very important roles in plant hormone signal transduction. Recently, AFP and AIP2 promote ABI5 and ABI3 degradation, respectively have been found to be crucial in ABA signaling pathway. While AtCHIP1 was demonstrated to be an U-bos protein to mono-ubiquitinate PP2A to stabilize it in ABA signaling pathway. Here we show two different RING-finger E3 ligases, AtHOS1 and AtSIR1are involved in different stress signal transduction. HOS1 a RING-variant E3 ligase was demonstrated to be a functional E3 ligase both in vitro and in vivo assays. It negatively regulates a key transcriptional factor ICE1 and play important role in cold stress signaling. While microarray analysis has demonstrated that AtRINGF1 is a salt inducible gene. The expression of AtRINGF1 was detected in all tissues of Arabidopsis by RT-PCR. AtRINGF1 expression is up-regulated by drought and NaCl, but not by cold and ABA. Transgenic Arabidopsis plants carrying AtRINGF1 promoter fused to GUS gene confirmed results above, in particular, the strong induction of GUS expression was found in stomatal guard cells and leaf mesophyll cells under drought stress. AtRINGF1 was tested in an in vitro ubiquitination experiment and the result demonstrated that AtRINGF1 is an E3 ubiquitin ligase. Overexpression of AtRINGF1, conferred ABA-associated phenotypes, such as ABA hypersensitivity, salt hypersensitivity in germination, reduced water loss, partial stomatal closure, enhanced ABA-induced stomata closing and enhanced drought tolerance. The results suggest that AtRINGF1 is involved in drought response by regulating ABA signaling.