An alternative route for UDP-diacylglucosamine hydrolysis in bacterial lipid A biosynthesis.
An alternative route for UDP-diacylglucosamine hydrolysis in bacterial lipid A biosynthesis.
复制标题
DOI：
10.1021/bi1008744
复制
发表时间：
2010-08-10
期刊：
影响因子：
2.9
通讯作者：
Raetz, Christian R. H.
中科院分区：
文献类型：
--
作者：
Metzger, Louis E.;Raetz, Christian R. H.
革兰氏阴性菌外膜的外小叶主要由脂A（脂多糖的疏水性锚）组成。像大肠杆菌一样，大多数革兰氏阴性细菌编码脂质A生物合成所需的九个基因中的每一个的一个拷贝。一个重要的例外存在于第四种酶LpxH的情况中，LpxH是一种外周膜蛋白，其通过催化水攻击α-P原子水解UDP-2，3-二酰基葡糖胺以形成2，3-二酰基葡糖胺1-磷酸和UMP。许多革兰氏阴性菌，包括所有α-变形菌和各种环境分离株，缺乏LpxH。在这里，我们报告了一个独特的UDP-2，3-二酰基葡糖胺焦磷酸酶，命名为LpxI，它没有序列相似性LpxH，但产生相同的产品通过不同的路线。LpxI的结构基因位于新月柄杆菌的lpxA和lpxB之间。lpxI基因挽救了lpxH缺陷型大肠杆菌的条件致死性。杆菌E. coli中，C. crescentus LpxI（CcLpxI）过度表达，显示高水平的UDP-2，3-二酰基葡糖胺焦磷酸酶活性。将CcLpxI纯化至> 90%的均一性。CcLpxI被二价阳离子刺激，被EDTA抑制。与E. coliLpxH，CcLpxI的活性不受去污剂浓度的影响，且pH依赖性不同。当CcLpxI反应在H218 O存在下进行时，通过质谱判断，18 O仅掺入2，3-二酰基葡糖胺1-磷酸产物中，表明CcLpxI催化水对UDP-2，3-二酰基葡糖胺的β-P原子的攻击。
The outer leaflet of the outer membranes of Gram-negative bacteria is composed primarily of lipid A, the hydrophobic anchor of lipopolysaccharide. Like Escherichia coli, most Gram-negative bacteria encode one copy of each of the nine genes required for lipid A biosynthesis. An important exception exists in the case of the fourth enzyme, LpxH, a peripheral-membrane protein that hydrolyzes UDP-2,3-diacylglucosamine to form 2,3-diacylglucosamine 1-phosphate and UMP by catalyzing the attack of water at the α-P atom. Many Gram-negative organisms, including all α-proteobacteria and diverse environmental isolates, lack LpxH. Here, we report a distinct UDP-2,3-diacylglucosamine pyrophosphatase, designated LpxI, which has no sequence similarity to LpxH, but generates the same products by a different route. LpxI was identified because its structural gene is located between lpxA and lpxB in Caulobacter crescentus. The lpxI gene rescues the conditional lethality of lpxH-deficient E. coli. Lysates of E. coli in which C. crescentus LpxI (CcLpxI) is over-expressed display high levels of UDP-2,3-diacylglucosamine pyrophosphatase activity. CcLpxI was purified to >90% homogeneity. CcLpxI is stimulated by divalent cations and is inhibited by EDTA. Unlike E. coli LpxH, CcLpxI is not inhibited by increasing the concentration of detergent, and its pH-dependency is different. When the CcLpxI reaction is carried out in the presence of H218O, the 18O is incorporated exclusively into the 2,3-diacylglucosamine 1-phosphate product, as judged by mass spectrometry, demonstrating that CcLpxI catalyzes the attack of water on the β-P atom of UDP-2,3-diacylglucosamine.
登录
查看更多内容
影响因子：
2.9
作者：
McClerren, AL;Endsley, S;Raetz, CRH
通讯作者：
Raetz, CRH
影响因子：
2.9
作者：
LARSON, TJ;DOWHAN, W
通讯作者：
DOWHAN, W
影响因子：
2.9
作者：
Metzger, Louis E.;Raetz, Christian R. H.
通讯作者：
Raetz, Christian R. H.
影响因子：
4.1
作者：
Kaneko, T;Nakamura, Y;Tabata, S
通讯作者：
Tabata, S
DOI：
10.1073/pnas.0807028105
发表时间：
2008-09-16
影响因子：
11.1
作者：
Ma, Bing;Reynolds, C. Michael;Raetz, Christian R. H.
通讯作者：
Raetz, Christian R. H.