Structure of a cephalosporin synthase
Structure of a cephalosporin synthase
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DOI：
10.1038/29575
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发表时间：
1998-08-20
期刊：
影响因子：
64.8
通讯作者：
Andersson, I
中科院分区：
文献类型：
--
作者：
Valegård, K;van Scheltinga, ACT;Andersson, I
青霉素类和头孢菌素类是最广泛使用的治疗剂。这些抗生素是由发酵衍生的材料生产的，因为它们的化学合成在商业上不可行。其生物合成中的非常规步骤由Fe（II）依赖性氧化酶/加氧酶催化;异青霉素N合酶（IPNS）（1，2）在一个步骤中产生青霉素的双环核，并且脱乙酰氧基头孢菌素C合酶（DAOCS）催化青霉素核扩展成头孢菌素核。这两种酶在催化中使用双氧衍生的铁基中间体，但与IPNS相反，DAOCS的铁基形式是通过共底物2-酮戊二酸（α-酮戊二酸）的氧化裂解产生的。这种受控的铁基形成和反应的途径对于许多单核亚铁酶是常见的（3），其参与比其充分表征的对应物血红素酶更广泛的反应。在这里，我们报告了2-含氧酸依赖性加氧酶的第一个晶体结构，apo-DAOCS的高分辨率结构，该酶与Fe（II）络合，并与Fe（II）和2-酮戊二酸络合，从半面体孪晶中获得。使用基于这些结构的模型，我们提出了一个铁基形成的机制。
Penicillins and cephalosporins are among the most widely used therapeutic agents. These antibiotics are produced from fermentation-derived materials as their chemical synthesis is not commercially viable. Unconventional steps in their biosynthesis are catalysed by Fe(II)-dependent oxidases/oxygenases; isopenicillin N synthase (IPNS)(1,2) creates in one step the bicyclic nucleus of penicillins, and deacetoxycephalosporin C synthase (DAOCS) catalyses the expansion of the penicillin nucleus into the nucleus of cephalosporins. Both enzymes use dioxygen-derived ferryl intermediates in catalysis but, in contrast to IPNS, the ferryl form of DAOCS is produced by the oxidative splitting of a cosubstrate, 2-oxoglutarate (alpha-ketoglutarate). This route of controlled ferryl formation and reaction is common to many mononuclear ferrous enzymes(3), which participate in a broader range of reactions than their well-characterized counterparts, the haem enzymes, Here we report the first crystal structure of a 2-oxoacid-dependent oxygenase, High-resolution structures for apo-DAOCS, the enzyme complexed with Fe(II), and with Fe(II) and 2-oxoglutarate, were obtained from merohedrally twinned crystals. Using a model based on these structures, we propose a mechanism for ferryl formation.