Heider Johann, Szaleniec Maciej, Martins Berta M, Seyhan Deniz, Buckel Wolfgang, Golding Bernard T
Laboratory of Microbial Biochemistry, LOEWE Center for Synthetic Microbiology, Philipps University Marburg, Marburg, Germany.
J Mol Microbiol Biotechnol. 2016;26(1-3):29-44. doi: 10.1159/000441656. Epub 2016 Mar 10.
The pathway of anaerobic toluene degradation is initiated by a remarkable radical-type enantiospecific addition of the chemically inert methyl group to the double bond of a fumarate cosubstrate to yield (R)-benzylsuccinate as the first intermediate, as catalyzed by the glycyl radical enzyme benzylsuccinate synthase. In recent years, it has become clear that benzylsuccinate synthase is the prototype enzyme of a much larger family of fumarate-adding enzymes, which play important roles in the anaerobic metabolism of further aromatic and even aliphatic hydrocarbons. We present an overview on the biochemical properties of benzylsuccinate synthase, as well as its recently solved structure, and present the results of an initial structure-based modeling study on the reaction mechanism. Moreover, we compare the structure of benzylsuccinate synthase with those predicted for different clades of fumarate-adding enzymes, in particular the paralogous enzymes converting p-cresol, 2-methylnaphthalene or n-alkanes.
厌氧甲苯降解途径由一种显著的自由基型对映体特异性加成反应起始，即化学性质惰性的甲基加成到富马酸酯共底物的双键上，生成（R）-苄基琥珀酸作为首个中间体，此反应由甘氨酰自由基酶苄基琥珀酸合酶催化。近年来，已明确苄基琥珀酸合酶是一个更大的富马酸加成酶家族的原型酶，这些酶在进一步的芳香烃甚至脂肪烃的厌氧代谢中发挥重要作用。我们概述了苄基琥珀酸合酶的生化特性及其最近解析的结构，并展示了基于结构的反应机制初步建模研究结果。此外，我们将苄基琥珀酸合酶的结构与针对富马酸加成酶不同进化枝预测的结构进行了比较，特别是转化对甲酚、2-甲基萘或正构烷烃的旁系同源酶。
