Biochemical and Structural Characterization of OvoA<sub><i>Th2</i></sub>: A Mononuclear Nonheme Iron Enzyme from <i>Hydrogenimonas thermophila</i> for Ovothiol Biosynthesis
Xinye Wang, Sha Hu, Jun Wang, Tao Zhang, Ke Ye, Aiwen Wen, Guoliang Zhu, Arturo J. Vegas, Lixin Zhang, Wupeng Yan, Xueting Liu, Pinghua Liu
Abstract
High Resolution Image Download MS PowerPoint Slide Ovothiol A and ergothioneine are thiol-histidine derivatives with sulfur substitutions at the δ-carbon or ε-carbon of the l -histidine imidazole ring, respectively. Both ovothiol A and ergothioneine have protective effects on many aging-related diseases, and the sulfur substitution plays a key role in determining their chemical and biological properties, while factors governing sulfur incorporation regioselectivities in ovothiol and ergothioneine biosynthesis in the corresponding enzymes (OvoA, Egt1, or EgtB) are not yet known. In this study, we have successfully obtained the first OvoA crystal structure, which provides critical information to explain their C–S bond formation regioselectivity. Furthermore, OvoA Th2 exhibits several additional activities: (1) ergothioneine sulfoxide synthase activity akin to Egt1 in ergothioneine biosynthesis; (2) cysteine dioxygenase activity using l -cysteine and l -histidine analogues as substrates; (3) cysteine dioxygenase activity upon mutation of an active site tyrosine residue (Y406). The structural insights and diverse chemistries demonstrated by OvoA Th2 pave the way for future comprehensive structure–function correlation studies.