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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Dioxygenases in Burkholderia ambifaria and Yersinia pestis that hydroxylate the outer Kdo unit of lipopolysaccharide
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Dioxygenases in Burkholderia ambifaria and Yersinia pestis that hydroxylate the outer Kdo unit of lipopolysaccharide

机译：伯克霍尔德氏菌和鼠疫耶尔森氏菌中的双加氧酶可羟化脂多糖的外部Kdo单元

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摘要

Several Gram-negative pathogens, including Yersinia pestis. Burkholderia cepacia, and Acinetobacter haemolyticus, synthesize an isosteric analog of 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo), known as D-glycero-D-talo-oct-2-ulosonic acid (Ko), in which the axial hydrogen atom at the Kdo 3-position is replaced with OH. Here we report a unique Kdo 3-hydroxylase (KdoO) from Burkholderia ambifaria and Yersinia pestis, encoded by the bamb_0774 (BakdoO) and the y1812 (YpkdoO) genes, respectively. When expressed in heptosyl transferase-deficient Escherichia coli, these genes result in conversion of the outer Kdo unit of Kdo_2-lipid A to Ko in an O_2-dependent manner. KdoO contains the putative iron-binding motif, HXDX_(n>40)H. Reconstitution of KdoO activity in vitro with Kdo_2-lipid A as the substrate required addition of Fe~(2+), α-ketoglutarate, and ascorbic acid, confirming that KdoO is a Fe~(2+)/α-ketoglutarate/O_2-dependent dioxygenase. Conversion of Kdo to Ko in Kdo_2-lipid A conferred reduced susceptibility to mild acid hydrolysis. Although two enzymes that catalyze Fe~(2+)Ax-ketoglutarate/O_2-dependent hydroxylation of deoxyuri-dine in fungal extracts have been reported previously, kdoO is the first example of a gene encoding a deoxy-sugar hydroxylase. Homologues of KdoO are found exclusively in Gram-negative bacteria, including the human pathogens Burkholderia mallei. Yersinia pestis, Klebsiella pneumoniae, Legionella longbeachae, and Coxiel-la burnetii, as well as the plant pathogen Ralstonia solanacearum.
机译：几种革兰氏阴性病原体，包括鼠疫耶尔森菌。洋葱伯克霍尔德氏菌和溶血不动杆菌合成了3个脱氧-D-甘露聚糖-八-2-核糖酸（Kdo）的等排类似物，称为D-甘油-D-talo-oct-2-乌糖酸（Ko），其中Kdo 3位的轴向氢原子被OH取代。在这里，我们报告了一个独特的Kdo 3-羟化酶（KdoO），它来自伯克霍尔德菌和鼠疫耶尔森氏菌，分别由bamb_0774（BakdoO）和y1812（YpkdoO）基因编码。当在庚糖基转移酶缺陷的大肠杆菌中表达时，这些基因导致Kdo_2-脂质A的外部Kdo单元以O_2依赖性的方式转化为Ko。 KdoO包含推定的铁结合基序HXDX_（n> 40）H。以Kdo_2-脂质A为底物体外重建KdoO活性需要添加Fe〜（2 +），α-酮戊二酸和抗坏血酸，证实KdoO是Fe〜（2 +）/α-酮戊二酸/ O_2-依赖性双加氧酶。在Kdo_2-脂质A中将Kdo转化为Ko可降低对轻度酸水解的敏感性。尽管以前已经报道了两种酶催化真菌提取物中脱氧尿嘧啶的Fe〜（2+）Ax-酮戊二酸/ O_2依赖性羟基化反应，但kdoO是编码脱氧糖羟化酶的基因的第一个例子。 KdoO的同源物仅存在于革兰氏阴性细菌中，包括人类病原体Burkholderia mallei。鼠疫耶尔森氏菌，肺炎克雷伯氏菌，长军团菌和伯克氏菌，以及植物病原体青枯菌。

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