Functional analysis of ROXY-type glutaredoxin ROXY19 in Arabidopsis thaliana

点击翻译按钮获取中文摘要

In Arabidopsis thaliana, ROXY-type glutarexdoxins (GRXs) form a group of 21 genes. ROXYs, which occur only in higher land plants, are distinguished from GRXs found in all organisms including plants by a CC(M/L)(CS) rather than a CPYC or CGFS motif. Two functions are known for ROXYs: regulation of petal number (ROXY1) and repression of the ethylene defense pathway (ROXY19). Repression of the ethylene pathway occurs at the promoter of the key transcriptional activator ORA59. Fourteen of the 21 ROXYs can functionally replace each other if their expression pattern is altered accordingly. The ability to interact with bZIP TGA transcription factors and a C-terminal ALWL motif is important for the two known ROXY functions. In contrast, the CCMC motif can be replaced by a CPYC or even a SSMS motif. This unexpected finding raises the question why the CC(M/L)(CS) motif is so conserved. We aim to identify conditions under which only ROXY19 but not ROXY19(SSMS) is functional. Moreover, we will elucidate the composition of the ROXY19-containing repressive complex at the ORA59 promoter since this might contain a redox-modulated compound allowing release of repression.