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首页> 外文期刊>Acta crystallographica.Section D. Biological crystallography >Structure of the phenazine biosynthesis enzyme PhzG.
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Structure of the phenazine biosynthesis enzyme PhzG.

机译：结构的吩嗪合成的酶PhzG。

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PhzG is a flavin-dependent oxidase that is believed to play a role in phenazine antibiotic synthesis in various bacteria, including Pseudomonas. Phenazines are chorismic acid derivatives that provide the producing organisms, including the opportunistic pathogen P. aeruginosa, with a competitive growth advantage. Here, the crystal structures of PhzG from both P. aeruginosa and P. fluorescens solved in an unliganded state at 1.9 and 1.8 A resolution, respectively, are described. Although the specific reaction in phenazine biosynthesis catalyzed by PhzG is unknown, the structural data indicates that PhzG is closely related to pyridoxine-5'-phosphate oxidase, the Escherichia coli pdxH gene product, which catalyzes the final step in pyridoxal-5'-phosphate (PLP) biosynthesis. A previous proposal suggested that the physiological substrate of PhzG to be 2,3-dihydro-3-hydroxyanthranilic acid (DHHA), a phenazine precursor produced by the sequential actions of the PhzE and PhzD enzymes on chorismate, and that twoDHHA molecules dimerized in another enzyme-catalyzed reaction to yield phenazine-1-carboxylate. However, it was not possible to demonstrate any in vitro activity upon incubation of PhzG and DHHA. Interestingly, analysis of the in vitro activities of PhzG in combination with PhzF suggests that PhzF acts on DHHA and that PhzG then reacts with a non-aromatic tricyclic phenazine precusor to catalyze an oxidation/aromatization reaction that yields phenazine-1-carboxylate. It is proposed that phzG arose by duplication of pdxH and that the subtle differences seen between the structures of PhzG and PdxH correlate with the loss of the ability of PhzG to catalyze PLP formation. Sequence alignments and superimpositions of the active sites of PhzG and PdxH reveal that the residues that form a positively charged pocket around the phosphate of PLP in the PdxH-PLP complex are not conserved in PhzG, consistent with the inability of phosphorylated compounds to serve as substrates for PhzG.
机译：PhzG是flavin-dependent氧化酶相信在吩嗪抗生素发挥作用合成的各种细菌,包括假单胞菌。衍生品提供生产的生物,包括机会病原体P。绿脓杆菌,竞争生长优势。在这里,晶体结构的PhzG P。荧光绿脓杆菌和p在一次解决unliganded状态在1.9和1.8的决议,分别描述。具体反应吩嗪合成催化PhzG是未知的,结构性的数据表明PhzG密切相关pyridoxine-5磷酸氧化酶,大肠杆菌pdxH基因产物的催化决赛一步pyridoxal-5磷酸(PLP)生物合成。的生理基质PhzG2, 3-dihydro-3-hydroxyanthranilic酸(DHHA)吩嗪前体产生的顺序的行为PhzE PhzD酶chorismate, twoDHHA分子化学活性在另一个酶催化反应产生phenazine-1-carboxylate。可以展示任何体外活动在孵化PhzG DHHA。分析体外PhzG的活动结合PhzF表明PhzF行为DHHA PhzG然后与一个反应non-aromatic三环吩嗪前身催化氧化/芳构化反应收益率phenazine-1-carboxylate。重复pdxH phzG兴起的之间的细微差别PhzG和PdxH关联结构PhzG催化PLP的能力的丧失形成。叠加PhzG和活跃的网站PdxH表明形成的残留物带正电的口袋的磷酸的在PdxH-PLP复杂不保守PhzG,符合的无能磷酸化化合物作为底物美国小妞PhzG。

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