β-cyanoalanine synthase is a mitochondrial cysteine synthase-like protein in spinach and Arabidopsis
β-cyanoalanine synthase is a mitochondrial cysteine synthase-like protein in spinach and Arabidopsis
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DOI：
10.1104/pp.123.3.1163
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发表时间：
2000-07-01
期刊：
影响因子：
7.4
通讯作者：
Saito, K
中科院分区：
文献类型：
--
作者：
Hatzfeld, Y;Maruyama, A;Saito, K
β-氰基丙氨酸合酶（GAS; EC www.example.com）在植物的氰化物代谢中起重要作用。虽然已经在多种植物中检测到β-氰基-Ala合酶的酶活性，但迄今为止还没有鉴定出cDNA或基因。我们假设线粒体半胱氨酸合酶（CS; EC www.example.com）同种型Bsas3实际上可能与菠菜（菠菜）和拟南芥中的CAS相同。在拟南芥表达序列标签数据库中搜索推定的Bsas3同源物，并在该过程中鉴定了四种新的CS样亚型ARAth; Bsas1; 1，ARAth; Bsas3; 1，ARAth; Bsas4; 1和ARAth; Bsas4; 2。ARAth; BSAS 3; 1蛋白与菠菜的线粒体SPIol; Bsas 3; 1同种型同源，而ARAth; Bsas 4; 1和ARAth; Bsas 4; 2蛋白定义了CS样蛋白家族中的一类新蛋白。与菠菜SPIol相反; BSAS 1; 1和SPIol; BSAS 2; 1重组蛋白、菠菜SPIol; Bsas3; 1和拟南芥ARAth; Bsas3; 1重组蛋白对CAS反应而不是CS反应表现出优选的底物特异性，这将这些Bsas3同种型鉴定为GAS。免疫印迹研究支持这一结论。这是第一份在活生物体中鉴定编码CAS酶的cDNA的报告。本文还提出了一种新的植物类CS蛋白命名法。
beta-Cyano-alanine synthase (GAS; EC 4.4.1.9) plays an important role in cyanide metabolism in plants. Although the enzymatic activity of beta-cyano-Ala synthase has been detected in a variety of plants, no cDNA or gene has been identified so far. We hypothesized that the mitochondrial cysteine synthase (CS; EC 4.2.99.8) isoform, Bsas3, could actually be identical to CAS in spinach (Spinacia oleracea) and Arabidopsis. An Arabidopsis expressed sequence tag database was searched for putative Bsas3 homologs and four new CS-like isoforms,ARAth;Bsas1;1, ARAth;Bsas3;1, ARAth;Bsas4;1, and ARAth;Bsas4;2, were identified in the process. ARAth;Bsas3;1 protein was homologous to the mitochondrial SPIol;Bsas3;1 isoform from spinach, whereas ARAth;Bsas4;1 and ARAth;Bsas4;2 proteins defined a new class within the CS-like proteins family. In contrast to spinach SPIol;Bsas1;1 and SPIol;Bsas2;1 recombinant proteins, spinach SPIol;Bsas3;1 and Arabidopsis ARAth; Bsas3;1 recombinant proteins exhibited preferred substrate specificities for the CAS reaction rather than for the CS reaction, which identified these Bsas3 isoforms as GAS. Immunoblot studies supported this conclusion. This is the first report of the identification of CAS synthase-encoding cDNAs in a living organism. A new nomenclature for CS-like proteins in plants is also proposed.