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首页> 外文期刊>Biochemistry >Deamination of 6-aminodeoxyfutalosine in menaquinone biosynthesis by distantly related enzymes
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Deamination of 6-aminodeoxyfutalosine in menaquinone biosynthesis by distantly related enzymes

机译：远缘相关酶在甲萘醌生物合成中的6-氨基脱氧富他洛糖胺的脱氨反应

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摘要

Proteins of unknown function belonging to cog1816 and cog0402 were characterized. Sav2595 from Steptomyces avermitilis MA-4680, Acel0264 from Acidothermus cellulolyticus 11B, Nis0429 from Nitratiruptor sp. SB155-2 and Dr0824 from Deinococcus radiodurans R1 were cloned, purified, and their substrate profiles determined. These enzymes were previously incorrectly annotated as adenosine deaminases or chlorohydrolases. It was shown here that these enzymes actually deaminate 6-aminodeoxyfutalosine. The deamination of 6-aminodeoxyfutalosine is part of an alternative menaquinone biosynthetic pathway that involves the formation of futalosine. 6-Aminodeoxyfutalosine is deaminated by these enzymes with catalytic efficiencies greater than 10 ~5 M~(-1) s~(-1), K_m values of 0.9-6.0 μM, and k_(cat) values of 1.2-8.6 s~(-1). Adenosine, 2′-deoxyadenosine, thiomethyladenosine, and S-adenosylhomocysteine are deaminated at least an order of magnitude slower than 6-aminodeoxyfutalosine. The crystal structure of Nis0429 was determined and the substrate, 6-aminodeoxyfutalosine, was positioned in the active site on the basis of the presence of adventitiously bound benzoic acid. In this model, Ser-145 interacts with the carboxylate moiety of the substrate. The structure of Dr0824 was also determined, but a collapsed active site pocket prevented docking of substrates. A computational model of Sav2595 was built on the basis of the crystal structure of adenosine deaminase and substrates were docked. The model predicted a conserved arginine after β-strand 1 to be partially responsible for the substrate specificity of Sav2595.
机译：对属于cog1816和cog0402的功能未知的蛋白质进行了表征。来自阿维链霉菌MA-4680的Sav2595，来自嗜酸解热菌11B的Acel0264，来自Nitratiruptor sp。的Nis0429。克隆，纯化了来自Deinococcus radiodurans R1的SB155-2和Dr0824，并确定了它们的底物谱。这些酶以前被错误地标注为腺苷脱氨酶或氯水解酶。在此表明，这些酶实际上使6-氨基脱氧富他洛因脱氨基。 6-氨基脱氧富他洛糖胺的脱氨反应是替代甲萘醌生物合成途径的一部分，该途径涉及氟他洛辛的形成。这些酶可将6-氨基脱氧富他肌苷脱氨，催化效率大于10〜5 M〜（-1）s〜（-1），K_m值为0.9-6.0μM，k_（cat）值为1.2-8.6 s〜（ -1）。腺苷，2'-脱氧腺苷，硫代甲基腺苷和S-腺苷同型半胱氨酸的脱氨基速度比6-氨基脱氧富他洛糖碱至少慢一个数量级。确定了Nis0429的晶体结构，并基于不规则结合的苯甲酸的存在，将6-氨基脱氧富他洛糖碱置于活性位点。在该模型中，Ser-145与底物的羧酸根部分相互作用。还确定了Dr0824的结构，但塌陷的活性位点袋阻止了基质的对接。基于腺苷脱氨酶的晶体结构建立了Sav2595的计算模型，并将底物对接。该模型预测β链1后的精氨酸保守，部分负责Sav2595的底物特异性。

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