γ-glutamylputrescine synthetase in the putrescine utilization pathway of Escherichia coli K-12
γ-glutamylputrescine synthetase in the putrescine utilization pathway of Escherichia coli K-12
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DOI：
10.1074/jbc.m800133200
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发表时间：
2008-07-18
影响因子：
4.8
通讯作者：
Suzuki, Hideyuki
中科院分区：
文献类型：
--
作者：
Kurihara, Shin;Oda, Shinpei;Suzuki, Hideyuki
谷氨酸-腐胺连接酶（γ-谷氨酰腐胺合成酶，PuuA，EC 6.3.1.11）催化腐胺的γ-谷氨酰化，这是大肠杆菌中涉及γ-谷氨酰化中间体的新型腐胺利用途径（Puu途径）的第一步。在这份报告中，PuuA的性质和生理意义进行了描述。纯化的非标记PuuA催化腐胺的ATP依赖性γ-谷氨酰化。谷氨酸、ATP和腐胺的Km值分别为2.07、2.35和44.6 mM。E.大肠杆菌：Puu途径和无γ-谷氨酰化的途径。然而，puuA基因缺失实验表明，Puu途径在利用腐胺作为唯一碳源或氮源方面更为关键。腐胺诱导puuA的转录，并在puuR缺失的菌株。PuuA的氨基酸序列与谷氨酰胺合成酶（GS）的氨基酸序列高度相似。两种酶的单体的分子量非常相似，PuuA和GS一样以十二聚体存在。此外，E.大肠杆菌GS中的金属催化氧化的酶分子参与蛋白质周转的重要是保守的PuuA，它是实验表明，PuuA中的相应的氨基酸残基参与金属催化氧化类似GS。这表明，腐胺的细胞内浓度的优化PuuA的转录和postperformationally和多余的腐胺转化为营养源的Puu途径。
Glutamate-putrescine ligase (gamma-glutamylputrescine synthetase, PuuA, EC 6.3.1.11) catalyzes the gamma-glutamylation of putrescine, the first step in a novel putrescine utilization pathway involving gamma-glutamylated intermediates, the Puu pathway, in Escherichia coli. In this report, the character and physiological importance of PuuA are described. Purified non-tagged PuuA catalyzed the ATP-dependent gamma-glutamylation of putrescine. The K-m values for glutamate, ATP, and putrescine are 2.07, 2.35, and 44.6 mM, respectively. There are two putrescine utilization pathways in E. coli: the Puu pathway and the pathway without gamma-glutamylation. Gene deletion experiments of puuA, however, indicated that the Puu pathway was more critical in utilizing putrescine as a sole carbon or nitrogen source. The transcription of puuA was induced by putrescine and in a puuR-deleted strain. The amino acid sequences of PuuA and glutamine synthetase (GS) show high similarity. The molecular weights of the monomers of the two enzymes are quite similar, and PuuA exists as a dodecamer as does GS. Moreover the two amino acid residues of E. coli GS that are important for the metal-catalyzed oxidation of the enzyme molecule involved in protein turnover are conserved in PuuA, and it was experimentally shown that the corresponding amino acid residues in PuuA were involved in the metal-catalyzed oxidation similarly to GS. It is suggested that the intracellular concentration of putrescine is optimized by PuuA transcriptionally and posttranslationally and that excess putrescine is converted to a nutrient source by the Puu pathway.