硫胺素单磷酸激酶与底物和产物复合物的结构研究。
Structural studies of thiamin monophosphate kinase in complex with substrates and products.
作者信息
McCulloch Kathryn M, Kinsland Cynthia, Begley Tadhg P, Ealick Steven E
机构信息
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.
出版信息
Biochemistry. 2008 Mar 25;47(12):3810-21. doi: 10.1021/bi800041h. Epub 2008 Mar 1.
Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent phosphorylation of thiamin monophosphate (TMP) to form thiamin pyrophosphate (TPP), the active form of vitamin B 1. ThiL is a member of a small ATP binding superfamily that also includes the purine biosynthetic enzymes, PurM and PurL, NiFe hydrogenase maturation protein, HypE, and selenophosphate synthase, SelD. The latter four enzymes are believed to utilize phosphorylated intermediates during catalysis. To understand the mechanism of ThiL and its relationship to the other superfamily members, we determined the structure of Aquifex aeolicus ThiL (AaThiL) with nonhydrolyzable AMP-PCP and TMP, and also with the products of the reaction, ADP and TPP. The results suggest that AaThiL utilizes a direct, inline transfer of the gamma-phosphate of ATP to TMP rather than a phosphorylated enzyme intermediate. The structure of ThiL is compared to those of PurM, PurL, and HypE, and the ATP binding site is compared to that of PurL, for which nucleotide complexes are available.
硫胺素单磷酸激酶（ThiL）催化硫胺素单磷酸（TMP）的ATP依赖性磷酸化反应，形成硫胺素焦磷酸（TPP），即维生素B1的活性形式。ThiL是一个小型ATP结合超家族的成员，该超家族还包括嘌呤生物合成酶PurM和PurL、NiFe氢化酶成熟蛋白HypE以及硒代磷酸合成酶SelD。据信，后四种酶在催化过程中利用磷酸化中间体。为了了解ThiL的作用机制及其与其他超家族成员的关系，我们测定了嗜热栖热菌ThiL（AaThiL）与不可水解的AMP-PCP和TMP以及反应产物ADP和TPP结合时的结构。结果表明，AaThiL利用ATP的γ-磷酸基团直接、线性地转移至TMP，而非通过磷酸化的酶中间体。将ThiL的结构与PurM、PurL和HypE的结构进行了比较，并将ATP结合位点与有核苷酸复合物的PurL的ATP结合位点进行了比较。
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