Crystal structure of 3,4-dihydroxy-2-butanone 4-phosphate synthase of riboflavin biosynthesis
Crystal structure of 3,4-dihydroxy-2-butanone 4-phosphate synthase of riboflavin biosynthesis
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DOI：
10.1016/s0969-2126(00)00550-5
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发表时间：
2001-01-10
期刊：
影响因子：
5.7
通讯作者：
Jordan, DB
中科院分区：
文献类型：
--
作者：
Liao, DI;Calabrese, JC;Jordan, DB
背景：3，4-二羟基-2-丁酮-4-磷酸合酶催化核黄素生物合成中的一个关键步骤。在酶上，5-磷酸核酮糖在涉及烯醇化、酮化、脱水、骨架重排和甲酸消除的步骤中转化为3，4-二羟基-2-丁酮4-磷酸和甲酸。这种酶在人类中是不存在的，并且是发现针对不能从其宿主获得足够核黄素的病原体的抗菌剂的有吸引力的靶标。23 kDa亚基的同源二聚体需要Mg 2+才能发挥活性。结果：利用多波长反常衍射（MAD）方法在含金的大肠杆菌蛋白晶体上以1. 4A-埃的分辨率测定了该酶的第一个三维结构。该蛋白质由具有β链的复杂连接的α + β折叠组成。亚基间的相互作用是由大量的疏水相互作用和三个氢键网络介导的。结论：根据19种酶中保守的氨基酸残基，确定了一个可能的活性位点。每个二聚体有两个分离良好的活性位点，每个活性位点包含来自两个亚基的残基。除了可用于识别底物的磷酸基团的三个丝氨酸和两个苏氨酸之外，活性位点由三个谷氨酸、两个谷氨酸、两个组氨酸和一个半胱氨酸组成，其可提供用于一般酸和碱催化以及用于在活性位点内配位Mg 2+辅因子的手段。
Background: 3,4-Dihydroxy-2-butanone-4-phosphate synthase catalyzes a commitment step in the biosynthesis of riboflavin. On the enzyme, ribulose 5-phosphate is converted to 3,4-dihydroxy-2-butanone 4-phosphate and formate in steps involving enolization, ketonization, dehydration, skeleton rearrangement, and formate elimination. The enzyme is absent in humans and an attractive target for the discovery of antimicrobials for pathogens incapable of acquiring sufficient riboflavin from their hosts. The homodimer of 23 kDa subunits requires Mg2+ for activity.Results: The first three-dimensional structure of the enzyme was determined at 1.4A-angstrom resolution using the multiwavelength anomalous diffraction (MAD) method on Escherichia coli protein crystals containing gold. The protein consists of an alpha + Beta fold having a complex linkage of beta strands. Intersubunit contacts are mediated by numerous hydrophobic interactions and three hydrogen bond networks.Counclusions: A proposed active site was identified on the basis of amino acid residues that are conserved among the enzyme from 19 species. There are two well-separated active sites per dimer, each of which comprise residues from both subunits. In addition to three arginines and two threonines, which may be used for recognizing the phosphate group of the substrate, the active site consists of three glutamates, two aspartates, two histidines, and a cysteine which may provide the means for general acid and base catalysis and for coordinating the Mg2+ cofactor within the active site.