Transcriptome analysis of agmatine and putrescine catabolism in Pseudomonas aeruginosa PAO1
Transcriptome analysis of agmatine and putrescine catabolism in Pseudomonas aeruginosa PAO1
复制标题
DOI：
10.1128/jb.01804-07
复制
发表时间：
2008-03-01
影响因子：
3.2
通讯作者：
Lu, Chung-Dar
中科院分区：
文献类型：
--
作者：
Chou, Han Ting;Kwon, Dong-Hyeon;Lu, Chung-Dar
多胺（腐胺，亚精胺和精胺）是重要的有机聚阳离子所必需的广泛的细胞过程。细胞需要机制来维持细胞内多胺的稳态，以防止严重的不良反应。我们对铜绿假单胞菌对胍丁胺和腐胺的反应进行了详细的转录组分析，重点是多胺催化剂。胍丁胺作为腐胺（以及亚精胺和精胺）的前体化合物，其被提议在进入三羧酸循环以支持细胞生长之前转化为4-氨基丁酸（GABA）和琥珀酸，作为碳和氮的唯一来源。两个乙酰多胺酰胺水解酶，AphA和AphB，被发现参与胍丁胺转化为腐胺。通过质谱分析确认AphA的酶促产物。有趣的是，丙氨酸-丙酮酸循环被证明是必不可少的多胺利用。新鉴定的dadRAX基因座编码调节丙氨酸转氨酶和消旋酶，与主要的腐殖酸-丙酮酸转氨酶SpuC偶联，是维持丙氨酸稳态的关键组分。相应的突变株在多胺利用方面受到严重阻碍。另一方面，在某些生物体中存在将腐胺转化为GABA的替代γ-谷氨酰化途径。随后，GabD，GabT和PA 5313被鉴定为GABA利用。GABA的PA 5313 gabT双突变体的生长缺陷表明这两种转氨酶的重要性。在体外实验中，还证实了GabD的琥珀酸半醛脱氢酶活性及其被GABA诱导。多胺的利用一般被证明是独立的PhoPQ双组分系统，即使适度诱导该操纵子诱导的多胺。如本研究所述，多种有效的分解代谢途径在细胞内多胺水平的控制中起着关键作用。
Polyamines (putrescine, spermidine, and spermine) are major organic polycations essential for a wide spectrum of cellular processes. The cells require mechanisms to maintain homeostasis of intracellular polyamines to prevent otherwise severe adverse effects. We performed a detailed transcriptome profile analysis of Pseudomonas aeruginosa in response to agmatine and putrescine with an emphasis in polyamine catabolism. Agmatine serves as the precursor compound for putrescine (and hence spermidine and spermine), which was proposed to convert into 4-aminobutyrate (GABA) and succinate before entering the tricarboxylic acid cycle in support of cell growth, as the sole source of carbon and nitrogen. Two acetylpolyamine amidohydrolases, AphA and AphB, were found to be involved in the conversion of agmatine into putrescine. Enzymatic products of AphA were confirmed by mass spectrometry analysis. Interestingly, the alanine-pyruvate cycle was shown to be indispensable for polyamine utilization. The newly identified dadRAX locus encoding the regulator alanine transaminase and racemase coupled with SpuC, the major putrescine-pyruvate transaminase, were key components to maintaining alanine homeostasis. Corresponding mutant strains were severely hampered in polyamine utilization. On the other hand, an alternative gamma-glutamylation pathway for the conversion of putrescine into GABA is present in some organisms. Subsequently, GabD, GabT, and PA5313 were identified for GABA utilization. The growth defect of the PA5313 gabT double mutant in GABA suggested the importance of these two transaminases. The succinic-semialdehyde dehydrogenase activity of GabD and its induction by GABA were also demonstrated in vitro. Polyamine utilization in general was proven to be independent of the PhoPQ two-component system, even though a modest induction of this operon was induced by polyamines. Multiple potent catabolic pathways, as depicted in this study, could serve pivotal roles in the control of intracellular polyamine levels.