Characterization and a role of Pseudomonas aeruginosa spermidine dehydrogenase in polyamine catabolism
Characterization and a role of Pseudomonas aeruginosa spermidine dehydrogenase in polyamine catabolism
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DOI：
10.1099/mic.0.28920-0
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发表时间：
2006-08-01
期刊：
影响因子：
2.8
通讯作者：
Itoh, Yoshifumi
中科院分区：
文献类型：
--
作者：
Dasu, Veeranki Venkata;Nakada, Yuji;Itoh, Yoshifumi
铜绿假单胞菌PAO1有亚精胺和精胺两种可能的分解代谢途径；一种包括功能未知的 spuA 和 spuB 产物，另一种涉及由未知基因编码的亚精胺脱氢酶（SpdH；EC 1.5.99.6）。对铜绿假单胞菌 PAO1 中 SpdH 的特性进行了表征，并鉴定了该菌株中相应的 spdH 基因。推导的 SpdH（620 个残基，计算出的 Mr 为 68 861）在氨基末端具有 28 个氨基酸的信号序列，根据酶的膜位置，在残基 76 和 92 之间有一个潜在的跨膜片段。纯化的 SpdH 将亚精胺氧化裂解为 1,3-二氨基丙烷和 4-氨基丁醛，比活为 37 单位（mg 蛋白质）(-1)，K 值为 36 mu M。该酶还将精胺水解为亚精胺和 3-氨基丙醛，比活为 25 单位（mg 蛋白质）(-1)，K-m 为 18 mu M。spdH 的敲除没有明显的结果。对两种多胺利用的影响，表明该基因很少参与多胺分解代谢。然而，当spdH与spuA的多胺诱导型启动子融合时，它完全恢复了spuA突变体利用亚精胺的能力。结论是 SpdH 在体内可以发挥分解代谢作用，但铜绿假单胞菌 PAO1 不能产生足够量的酶来执行此功能。
Pseudomonas aeruginosa PAO1 has two possible catabolic pathways of spermidine and spermine; one includes the spuA and spuB products with unknown functions and the other involves spermidine dehydrogenase (SpdH; EC 1.5.99.6) encoded by an unknown gene. The properties of SpdH in P. aeruginosa PAO1 were characterized and the corresponding spdH gene in this strain identified. The deduced SpdH (620 residues, calculated Mr of 68 861) had a signal sequence of 28 amino acids at the amino terminal and a potential transmembrane segment between residues 76 and 92, in accordance with membrane location of the enzyme. Purified SpdH oxidatively cleaved spermidine into 1,3-diaminopropane and 4-aminobutyraldehyde with a specific activity of 37 units (mg protein)(-1) and a K. value of 36 mu M The enzyme also hydrolysed spermine into spermidine and 3-aminopropanaldehyde with a specific activity of 25 units (mg protein)(-1) and a K-m of 18 mu M. Knockout of spdH had no apparent effect on the utilization of both polyamines, suggesting that this gene is minimally involved in polyamine catabolism. However, when spdH was fused to the polyamine-inducible promoter of spuA, it fully restored the ability of a spuA mutant to utilize spermidine. It is concluded that SpdH can perform a catabolic role in vivo, but P. aeruginosa PAO1 does not produce sufficient amounts of the enzyme to execute this function.