Biosynthesis of the thiamin pyrimidine: the reconstitution of a remarkable rearrangement reaction
作者:Brian G. Lawhorn、Ryan A. Mehl、Tadhg P. Begley
DOI:10.1039/b405429f
日期:——
The conversion of 5-aminoimidazole ribonucleotide (AIR) into 4-amino-2-methyl-5-hydroxymethylpyrimidine (HMP) is a fascinating reaction on the thiamin biosynthetic pathway in bacteria and is probably the most complex unresolved rearrangement in primary metabolism. We have successfully reconstituted this reaction in a cell-free system. The E. coli thiC gene product and an additional unidentified E. coli protein are required for the reaction. In addition, SAM and nicotinamide cofactors are required for full activity. Labeling studies to determine the origin of most of the atoms in the pyrimidine are described. Based on these studies, a new mechanism for HMP formation is proposed.
5-氨基咪唑核苷酸(AIR)转化为4-氨基-2-甲基-5-羟甲基嘧啶(HMP)的反应是细菌硫胺素生物合成途径中的一个迷人反应,可能是初级代谢中最复杂的未解决重排反应。我们已经成功地在无细胞系统中重构了这个反应。E. coli 的 thiC 基因产物以及一个额外的未鉴定的 E. coli 蛋白质是反应所必需的。此外,SAM 和烟酰胺辅因子也是完全活性所需的。我们描述了标记研究,以确定嘧啶中大多数原子的来源。基于这些研究,提出了一种 HMP 形成的新机制。