Structural characterization of enterobactin hydrolase IroE
Structural characterization of enterobactin hydrolase IroE
复制标题
肠杆菌素水解酶 IroE 的结构特征
DOI：
10.1021/bi060950i
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发表时间：
2006-08-29
期刊：
影响因子：
2.9
通讯作者：
Walsh, C. T.
中科院分区：
文献类型：
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作者：
Larsen, N. A.;Lin, H.;Walsh, C. T.
许多致病菌的增殖受到其环境中可溶性铁缺乏的限制。这些细菌中的许多通过合成和输出螯合铁的小分子铁载体来吸收铁。铁结合的铁载体随后被输入用于代谢处理。三个相关的丝氨酸水解酶已在该途径中进行了生化表征：Fes，IroD和IroE。在这里，我们报告的晶体结构的IroE从尿路致病性大肠杆菌CFT 073。天然结构和复合物与二异丙基氟膦酸酯（DFP，一种有效的丝氨酸水解酶抑制剂），分别在2.3和1.4埃的分辨率。IroE具有典型的α/β-水解酶折叠，具有由Ser 189和His 287组成的非典型催化二联体。任何一个残基的突变对催化都是有害的。此外，而不是典型的含氧阴离子孔骨架酰胺组成，IroE采用非典型胍部分的精氨酸130。Asp 90锚定Arg 130的活性位点，和任何残基的突变同样是有害的催化。我们还比较了IroE的结构与来自福氏志贺菌的Fes的结构（PDB条目2B 20）。这两种酶具有相似的活性位点，但Fes具有额外的氨基末端盖结构域。这些盖结构域被认为赋予这些相关水解酶的特异性。
The proliferation of many pathogenic bacteria is limited by the scarcity of soluble iron in their environment. Many of these bacteria scavenge iron by synthesizing and exporting small molecule siderophores that chelate iron. Iron-bound siderophores are subsequently imported for metabolic processing. Three related serine hydrolases have been characterized biochemically in this pathway: Fes, IroD, and IroE. Here, we report the crystal structure of IroE from uropathogenic Escherichia coli CFT073. The native structure and a complex with diisopropyl fluorophosphonate (DFP, a potent serine hydrolase inhibitor) were determined at 2.3 and 1.4 angstrom resolution, respectively. IroE has the typical alpha/beta-hydrolase fold with an atypical catalytic dyad composed of Ser 189 and His 287. Mutation of either residue was detrimental to catalysis. In addition, rather than the typical oxyanion hole composed of backbone amides, IroE employs the atypical guanidinium moiety of Arg 130. Asp 90 anchors Arg 130 in the active site, and mutation of either residue was likewise detrimental to catalysis. We also compare the structure of IroE to the structure of Fes from Shigella flexneri (PDB entry 2B20). Both enzymes have similar active sites, but Fes has an additional amino-terminal lid domain. These lid domains are proposed to confer specificity to these related hydrolases.