Tang Xianglin, Liu Ran, Mei Yuanyuan, Wang Dan, He Kaixuan, Wang Ning Ning
Tianjin Key Laboratory of Protein Sciences, Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tianjin 300071, China.
Int J Mol Sci. 2024 Mar 2;25(5):2931. doi: 10.3390/ijms25052931.
The gaseous hormone ethylene plays pivotal roles in plant growth and development. The rate-limiting enzyme of ethylene biosynthesis in seed plants is 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS). ACS proteins are encoded by a multigene family and the expression of genes is highly regulated, especially at a post-translational level. AtACS7, the only type III ACS in , is degraded in a 26S proteasome-dependent pathway. Here, by using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analysis, two lysine residues of AtACS7, lys285 (K285) and lys366 (K366), were revealed to be ubiquitin-modified in young, light-grown seedlings but not in etiolated seedlings. Deubiquitylation-mimicking mutations of these residues significantly increased the stability of the AtACS7 mutant protein in cell-free degradation assays. All results suggest that K285 and K366 are the major ubiquitination sites on AtACS7, providing deeper insights into the post-translational regulation of AtACS7 in .
气态激素乙烯在植物生长发育中起关键作用。种子植物中乙烯生物合成的限速酶是1-氨基环丙烷-1-羧酸（ACC）合酶（ACS）。ACS蛋白由一个多基因家族编码，基因表达受到高度调控，尤其是在翻译后水平。拟南芥AtACS7是拟南芥中唯一的III型ACS，通过26S蛋白酶体依赖性途径降解。在这里，通过液相色谱-质谱联用/质谱（LC-MS/MS）分析发现，AtACS7的两个赖氨酸残基，即赖氨酸285（K285）和赖氨酸366（K366），在幼嫩的、光照生长的拟南芥幼苗中被泛素化修饰，而在黄化幼苗中未被修饰。在无细胞降解试验中，这些残基的去泛素化模拟突变显著提高了AtACS7突变蛋白的稳定性。所有结果表明，K285和K366是AtACS7上主要的泛素化位点，为深入了解拟南芥中AtACS7的翻译后调控提供了依据。
