A new view of the mechanisms of UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) and 5-enolpyruvylshikimate-3-phosphate synthase (AroA) derived from X-ray structures of their tetrahedral reaction intermediate states
A new view of the mechanisms of UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) and 5-enolpyruvylshikimate-3-phosphate synthase (AroA) derived from X-ray structures of their tetrahedral reaction intermediate states
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DOI：
10.1074/jbc.m309741200
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发表时间：
2003-12-05
影响因子：
4.8
通讯作者：
Schönbrunn, E
中科院分区：
文献类型：
--
作者：
Eschenburg, S;Kabsch, W;Schönbrunn, E
UDP-N-乙酰葡糖胺烯醇丙酮酰转移酶 (MurA) 和 5-烯醇丙酮酰莽草酸-3-磷酸合酶 (AroA) 构成烯醇丙酮酰转移酶的小酶家族，可催化烯醇丙酮酰转移的化学异常反应。 MurA 催化细菌细胞壁生物合成的第一步； AroA 是莽草酸途径中的第六种酶，导致许多微生物和植物中芳香化合物的合成。由于这两种代谢途径在哺乳动物中不存在，但对于微生物的生长至关重要，因此 MurA 和 AroA 是开发新型抗菌药物的有吸引力的靶标。我们确定了阴沟肠杆菌 MurA 的 D305A 突变体和大肠杆菌 AroA 的 D313A 突变体的 X 射线结构，这两种突变体都在其底物存在下结晶。该结构描绘了酶的四面体反应中间状态，并证明，如果没有天冬氨酸侧链，两种酶中的整体加成-消除反应在添加步骤后停止。所提出的结构带来了催化机制的新观点，而且为合理设计 MurA 和 AroA 的有效抑制剂提供了理想的起点。
UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) and 5-enolpyruvylshikimate-3-phosphate synthase (AroA) constitute the small enzyme family of enolpyruvyl transferases, which catalyze the chemically unusual reaction of enolpyruvyl transfer. MurA catalyzes the first step in the biosynthesis of the bacterial cell wall; AroA is the sixth enzyme of the shikimate pathway leading to the synthesis of aromatic compounds in numerous microorganisms and plants. Because both metabolic pathways are absent from mammals but essential for the growth of microorganisms, MurA and AroA are attractive targets for the development of novel antimicrobial drugs. We have determined the x-ray structures of the D305A mutant of Enterobacter cloacae MurA and the D313A mutant of Escherichia coli AroA, both of which crystallized in the presence of their substrates. The structures depict the tetrahedral reaction intermediate states of the enzymes and prove that, without the aspartate side chain, the overall addition-elimination reaction in both enzymes is halted after the addition step. The presented structures lead to a new view of the catalytic mechanism and, moreover, provide an ideal starting point for the rational design of potent inhibitors of MurA and AroA.