Functional analysis of all aminotransferase proteins inferred from the genome sequence of Corynebacterium glutamicum
Functional analysis of all aminotransferase proteins inferred from the genome sequence of Corynebacterium glutamicum
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DOI：
10.1128/jb.187.22.7639-7646.2005
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发表时间：
2005-11-01
影响因子：
3.2
通讯作者：
Eggeling, L
中科院分区：
文献类型：
--
作者：
Marienhagen, J;Kennerknecht, N;Eggeling, L
以E-谷氨酸、L-天冬氨酸和L-丙氨酸为氨基供体，以一些2-氧代酸为氨基受体，分离和分析了谷氨酸棒杆菌的20个可能的转氨酶(AT)蛋白，或更确切地说，是依赖于吡哆醛-5‘-磷酸(PLP)的酶。其中一个突出的AT是丙氨酸，它具有广泛的氨基供体特异性，利用(按偏好顺序)L-谷氨酸>；2-氨基丁酸>；L-天冬氨酸作为受体。另一个AT是AVTA，它利用L-丙氨酸对L-缬氨酸前体2-氧代异戊酸酯和2-氧代丁酸酯进行胺化。第二个AT与L-缬氨酸前体和另外两个支链氨基酸的活性相同，缺失突变分析表明，这两种酶的活性在体内都有部分重叠。还鉴定了芳香族AT芳香族AT，并且This和ILVE具有与苯丙酮酸类似的活性，从而证明了这两种AT对L-苯丙氨酸合成的相关性。我们还评估了两个含有PLP的半胱氨酸脱硫酶的活性，提供了一个过硫化物中间体。其中之一是SuFS，它帮助Fe-S簇组装的硫转移途径。与进一步的ATS的鉴定和对缺失突变体的额外分析一起，这导致了对生物体内的ATS的概述，这可能到目前为止还没有实现。
Twenty putative aminotransferase (AT) proteins of Corynebacterium glutamicum, or rather pyridoxal-5'-phosphate (PLP)-dependent enzymes, were isolated and assayed among others with E-glutamate, L-aspartate, and L-alanine as amino donors and a number of 2-oxo-acids as amino acceptors. One outstanding AT identified is AlaT, which has a broad amino donor specificity utilizing (in the order of preference) L-glutamate > 2-aminobutyrate > L-aspartate with pyruvate as acceptor. Another AT is AvtA, which utilizes L-alanine to aminate 2-oxo-isovalerate, the L-valine precursor, and 2-oxo-butyrate. A second AT active with the L-valine precursor and that of the other two branched-chain amino acids, too, is IlvE, and both enzyme activities overlap partially in vivo, as demonstrated by the analysis of deletion mutants. Also identified was AroT, the aromatic AT, and this and IlvE were shown to have comparable activities with phenylpyruvate, thus demonstrating the relevance of both ATs for L-phenylalanine synthesis. We also assessed the activity of two PLP-containing cysteine desulfurases, supplying a persulfide intermediate. One of them is SufS, which assists in the sulfur transfer pathway for the Fe-S cluster assembly. Together with the identification of further ATs and the additional analysis of deletion Mutants, this results in an overview of the ATs within an organism that may not have been achieved thus far.