title: The non-catalytic N-terminal domain of ACS7 is involved in the post-translational regulation of this gene in Arabidopsis.
abstract: Post-transcriptional control of the expression of the 1-aminocyclopropane-1-carboxylate synthase (ACS) gene family is important for maintaining appropriate levels of ethylene production. However, the molecular mechanism underlying the post-transcriptional regulation of type 3 ACS proteins remains unclear. Multiple sequence alignment revealed that the N-terminus of type 3 ACSs was longer than that of other ACSs. Fusing the N-terminal 54 residues of ACS7, the sole type 3 ACS in Arabidopsis, to the β-glucuronidase (GUS) reporter significantly decreased the stability of N(7(1-54))-GUS fusion protein. Among these 54 residues, residues 1-14 conferred this negative effect on the GUS fusion gene. Consistently, a truncated form of ACS7 lacking residues 1-14 was more stable than full-length ACS7 when transgenically expressed in Arabidopsis and led to a more severe ethylene response phenotype in the light-grown transgenic seedlings. Interestingly, the ACS7 N-terminus had no effect on the stability of N(7)-GUS and ACS7 proteins at the etiolated seedling stage. Both exogenous 1-aminocyclopropane-1-carboxylic acid (ACC) treatment and salt stress could rescue the levels of accumulation of N(7)-GUS fusion protein in light-grown seedlings. These results suggest that the non-catalytic N-terminus of ACS7 is involved in its own post-translational regulation. The proteasome inhibitor MG132 suppressed degradation of full-length ACS7 in vivo, but had little effect on the N-terminal truncated form of ACS7, indicating that the N-terminus mediates the regulation of ACS7 stability through the ubiquitin-26S proteasome pathway.
authors.affiliation: Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, and Tianjin Key Laboratory of Protein Sciences, Tianjin 300071, China.
authors.forename: Li
authors.initials: L
authors.lastname: Xiong
authors.affiliation: Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, and Tianjin Key Laboratory of Protein Sciences, Tianjin 300071, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Xiao
authors.affiliation: Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, and Tianjin Key Laboratory of Protein Sciences, Tianjin 300071, China.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, and Tianjin Key Laboratory of Protein Sciences, Tianjin 300071, China.
authors.forename: Zhaoxia
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, and Tianjin Key Laboratory of Protein Sciences, Tianjin 300071, China wangnn@nankai.edu.cn.
authors.forename: Ning Ning
authors.initials: NN
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008190:Lyases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary
chemical_list: D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase
keywords: 1-Aminocyclopropane-1-carboxylate synthase 7; Arabidopsis; N-terminus; ethylene; post-translational regulation; protein stability.