The human cDNA for a homologue of the plant enzyme 1-aminocyclopropane-1-carboxylate synthase encodes a protein lacking that activity
The human cDNA for a homologue of the plant enzyme 1-aminocyclopropane-1-carboxylate synthase encodes a protein lacking that activity
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DOI：
10.1016/s0378-1119(01)00533-9
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发表时间：
2001-07-11
期刊：
影响因子：
3.5
通讯作者：
Kirsch, JF
中科院分区：
文献类型：
--
作者：
Koch, KA;Capitani, G;Kirsch, JF
编码1-氨基环丙烷-1-羧酸（ACC）合酶（重要植物激素乙烯的两步生物合成途径中的第一个酶）的同源物的基因序列最近已在红鳍东方（Fugu rubripes）和智人（Homo sapiens）中发现（Peixoto等人，Gene 246（2000）275）。ACC合酶（ACS）催化S-腺苷-L-甲硫氨酸形成ACC。ACC在乙烯生物合成的第二步和最后一步被氧化成乙烯。如果能够证明ACC是在动物体内形成的，那么将提出深刻的生理学问题，因为乙烯在这些生物体中没有已知的功能。我们描述了克隆的推定的人类ACS（PHACS）的cDNA编码的501个氨基酸的蛋白质，表现出58%的序列同一性推定的河豚ACS和类似的30%的序列同一性植物ACS。在毕赤酵母中表达的纯化的重组PHACS含有结合的吡哆醛-5 ' -磷酸（PLP），但不催化ACC的合成。然而，PHACS确实催化L-乙烯基甘氨酸的脱氨基，这是苹果ACS的已知副反应。生物信息学分析表明，PHACS是PLP依赖性酶的Ct家族的成员。分子模拟数据表明，PHACS和植物ACS之间的残基的保守性分散在其整个结构中，并且对于植物中ACS活性重要的两个活性位点残基在PHACS中不保守。(C)2001 Elsevier Science B. V.保留所有权利。
The sequences of genes encoding homologues of 1-aminocyclopropane-1-carboxylate (ACC) synthase, the first enzyme in the two-step biosynthetic pathway of the important plant hormone ethylene, have recently been found in Fugu rubripes and Homo sapiens (Peixoto et al., Gene 246 (2000) 275). ACC synthase (ACS) catalyzes the formation of ACC from S-adenosyl-L-methionine. ACC is oxidized to ethylene in the second and final step of ethylene biosynthesis. Profound physiological questions would be raised if it could be demonstrated that ACC is formed in animals, because there is no known function for ethylene in these organisms. We describe the cloning of the putative human ACS (PHACS) cDNA that encodes a 501 amino acid protein that exhibits 58% sequence identity to the putative Fugu ACS and similar to 30% sequence identity to plant ACSs. Purified recombinant PHACS, expressed in Pichia pastoris, contains bound pyridoxal-5 ' -phosphate (PLP), but does not catalyze the synthesis of ACC. PHACS does, however, catalyze the deamination of L-vinylglycine, a known side-reaction of apple ACS. Bioinformatic analysis indicates that PHACS is a member of the ct-family of PLP-dependent enzymes. Molecular modeling data illustrate that the conservation of residues between PHACS and the plant ACSs is dispersed throughout its structure and that two active site residues that are important for ACS activity in plants are not conserved in PHACS. (C) 2001 Elsevier Science B.V. All rights reserved.