The Glycyl Radical Enzyme Arylacetate Decarboxylase from <i>Olsenella scatoligenes</i>
Qiang Lu, Yifeng Wei, Lianyun Lin, Jiayi Liu, Yongxu Duan, Yaxin Li, Weixiang Zhai, Yangping Liu, Ee Lui Ang, Huimin Zhao, Zhiguang Yuchi, Yan Zhang
Abstract
The glycyl radical enzymes (GREs) p-hydroxyphenylacetate (HPA) decarboxylase (HPAD), indoleacetate decarboxylase, and phenylacetate decarboxylase catalyze the radical-mediated decarboxylation of arylacetates, which are products of bacterial aromatic amino acid fermentation. Here, we report the discovery and structural and biochemical investigation of a fourth GRE arylacetate decarboxylase (AAD) from Olsenella scatoligenes that catalyzes HPA decarboxylation. AAD also catalyzes the decarboxylation of p-aminophenylacetate, which is not a substrate of HPAD, and lacks the Fe–S cluster containing small subunit. The structure of AAD in complex with p-hydroxyphenylacetate was determined by X-ray crystallography. The differing substrate ranges and active site structures of AAD and HPAD suggest distinct catalytic mechanisms, underscoring the diversity of radical-mediated decarboxylation reactions.