Essential Roles of the Linker Sequence Between Tetratricopeptide Repeat Motifs of Ethylene Overproduction 1 in Ethylene Biosynthesis.

Chuanjing An,Yuefang Gao

doi:10.3389/fpls.2021.657300

Abstract

Ethylene Overproduction 1 (ETO1) is a negative regulator of ethylene biosynthesis. However, the regulation mechanism of ETO1 remains largely unclear. Here, a novel eto1 allele (eto1-16) was isolated with typical triple phenotypes due to an amino acid substitution of G480C in the uncharacterized linker sequence between the TPR1 and TPR2 motifs. Further genetic and biochemical experiments confirmed the eto1-16 mutation site. Sequence analysis revealed that G480 is conserved not only in two paralogs, EOL1 and EOL2, in Arabidopsis, but also in the homologous protein in other species. The glycine mutations (eto1-11, eto1-12, and eto1-16) do not influence the mRNA abundance of ETO1, which is reflected by the mRNA secondary structure similar to that of WT. According to the protein-protein interaction analysis, the abnormal root phenotype of eto1-16 might be caused by the disruption of the interaction with type 2 1-aminocyclopropane-1-carboxylic acid (ACC) synthases (ACSs) proteins. Overall, these data suggest that the linker sequence between tetratricopeptide repeat (TPR) motifs and the glycine in TPR motifs or the linker region are essential for ETO1 to bind with downstream mediators, which strengthens our knowledge of ETO1 regulation in balancing ACSs.

Highlights

Ethylene, a simple gaseous plant hormone, is involved in numerous aspects of plant growth and development processes, including seed germination and shoot and root growth and development (Lin et al, 2009; Ahammed et al, 2020; Binder, 2020)
The results indicated that Gly480 is crucial in the Ethylene Overproduction 1 (ETO1) and ACC synthase (ACS) interaction it is not required for the interaction with CUL3A
We isolated a novel eto1 allele with typical triple response phenotypes of shortened and swollen hypocotyls, exaggerated apical hooks, and short roots with excessive root hairs that is observed in ethylene biosynthesis and signaling defective mutants, such as eto1, eto2, eto3, and ctr1 (Guzman and Ecker, 1990; Kieber et al, 1993; Chae et al, 2003)

Summary

Introduction

A simple gaseous plant hormone, is involved in numerous aspects of plant growth and development processes, including seed germination and shoot and root growth and development (Lin et al, 2009; Ahammed et al, 2020; Binder, 2020). Bakshi et al, 2015; Binder, 2020). SAM is converted into 1-aminocyclopropane1-carboxylic acid (ACC) by ACC synthase (ACS). ACC is transformed into ethylene by ACC oxidase (ACO; Rodrigues et al, 2014; Bakshi et al, 2015; Binder, 2020)

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Results

Conclusion