Analysis of the target sequence of ETO1.

Abstract

The ETO1 family is thought to be a conserved negative regulator of ethylene biosynthesis in higher plants, that interacts with a class of ACC synthases (type 2 ACS) and decreases their stability through the proteasome-dependent pathway. By Y2H analysis, we identified a C-terminal amino acid sequence of the type 2 ACS required for the interaction with ETO1, and named TOE (target of ETO1). When the TOE from LE-ACS3 was fused to the C-terminus of GFP and introduced into rice callus, fluorescence of GFP-TOE^LE-ACS3 was significantly reduced compared to the native GFP. Furthermore, Western blot analysis showed significant reduction of the fusion protein in rice callus. These results indicate TOE is sufficient to decrease the protein stability.