The non-catalytic N-terminal domain of ACS7 is involved in the post-translational regulation of this gene in Arabidopsis.
The non-catalytic N-terminal domain of ACS7 is involved in the post-translational regulation of this gene in Arabidopsis.
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DOI：
10.1093/jxb/eru211
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发表时间：
2014-08
影响因子：
6.9
通讯作者：
Li Xiong;D. Xiao;Xinxin Xu;Zhaoxia Guo;N. Wang
中科院分区：
文献类型：
--
作者：
Li Xiong;D. Xiao;Xinxin Xu;Zhaoxia Guo;N. Wang
1-氨基环丙烷-1-羧酸合酶（ACS）基因家族的表达的转录后控制对于维持适当水平的乙烯产生是重要的。然而，3型ACS蛋白的转录后调控的分子机制仍不清楚。多序列比对结果显示，3型ACS的N-末端比其他ACS的N-末端长。将拟南芥中唯一的3型ACS--ACS 7的N-末端54个残基与GUS报告基因融合，显著降低了N（7（1-54））-GUS融合蛋白的稳定性。在这54个残基中，残基1-14赋予GUS融合基因这种负面影响。一致的是，缺失残基1-14的ACS 7的截短形式在拟南芥中转基因表达时比全长ACS 7更稳定，并且在光生长的转基因幼苗中导致更严重的乙烯反应表型。有趣的是，ACS 7 N-末端对N（7）-GUS和ACS 7蛋白在黄化幼苗阶段的稳定性没有影响。外源1-氨基环丙烷-1-羧酸（ACC）处理和盐胁迫均能提高光生幼苗中N（7）-GUS融合蛋白的积累水平。这些结果表明，非催化N-末端的ACS 7参与其自身的翻译后调节。蛋白酶体抑制剂MG 132抑制了体内全长ACS 7的降解，但对N-末端截短形式的ACS 7几乎没有影响，表明N-末端通过泛素-26 S蛋白酶体途径介导ACS 7稳定性的调节。
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.