Researchers using the SER-CAT 22-BM-D and 22-ID-D beamlines at the APS are investigating coumarins, a major group of plant secondary metabolites. Coumarins play an important role in the environmental adaptation of plants and contribute to the defense against phytopathogens. Coumarin derivatives have demonstrated multiple pharmaceutical activities such as anticoagulative, antibacterial and anti-inflammatory utilities.
Coumarins belong to an important class of plant secondary metabolites. Feruloyl-CoA 6’-hydroxylase (F6’H), a 2-oxoglutarate dependent dioxygenase (2OGD), catalyzes a pivotal step in the biosynthesis of a simple coumarin scopoletin. In this study, we determined the 3-dimensional structure of the F6’H1 apo enzyme by X-ray crystallography. It is the first reported structure of a 2OGD enzyme involved in coumarin biosynthesis and closely resembles the structure of Arabidopsis thaliana anthocyanidin synthase.
To better understand the mechanism of enzyme catalysis and substrate specificity, we also generated a homology model of a related ortho-hydroxylase (C2’H) from sweet potato. By comparing these two structures, we targeted two amino acid residues and verified their roles in substrate binding and specificity by site-directed mutagenesis.
Xinxiao Sun, Dayong Zhou, Palani Kandavelu, Hua Zhang, Qipeng Yuan, Bi-Cheng Wang, John Rose and Yajun Yan, “Structural Insights into Substrate Specificity of Feruloyl-CoA 6’-Hydroxylase from Arabidopsis thaliana,” Nature Scientific Reports 5, Article Number: 10355. DOI: 10.1038/srep10355, Published May 20, 2015.