1. Crystal Structures of SgcE6 and SgcC, the Two-Component Monooxygenase That Catalyzes Hydroxylation of a Carrier Protein-Tethered Substrate during the Biosynthesis of the Enediyne Antitumor Antibiotic C-1027 in Streptomyces globisporus
- Author
-
Ragothaman M. Yennamalli, Craig A. Bingman, Ben Shen, Jeremy R. Lohman, Kemin Tan, Hongnan Cao, Lance Bigelow, George N. Phillips, Gyorgy Babnigg, Jeffrey D. Rudolf, Chin-Yuan Chang, Ming Ma, Andrzej Joachimiak, Weijun Xu, and Xiaohui Yan
- Subjects
0301 basic medicine ,Streptomyces globisporus ,Stereochemistry ,Flavin group ,Crystallography, X-Ray ,Hydroxylation ,Biochemistry ,Streptomyces ,Article ,Catalysis ,03 medical and health sciences ,Sarcoglycans ,Enediyne ,Moiety ,Humans ,030102 biochemistry & molecular biology ,biology ,Chemistry ,Active site ,Monooxygenase ,biology.organism_classification ,Anti-Bacterial Agents ,030104 developmental biology ,Aminoglycosides ,FAD binding ,biology.protein ,Enediynes - Abstract
C-1027 is a chromoprotein enediyne antitumor antibiotic produced by Streptomyces globisporus. In the last step of biosynthesis of the (S)-3-chloro-5-hydroxy-β-tyrosine moiety of the C-1027 enediyne chromophore, SgcE6 and SgcC compose a two-component monooxygenase that hydroxylates the C-5 position of (S)-3-chloro-β-tyrosine. This two-component monooxygenase is remarkable for two reasons. (i) SgcE6 specifically reacts with FAD and NADH, and (ii) SgcC is active with only the peptidyl carrier protein (PCP)-tethered substrate. To address the molecular details of substrate specificity, we determined the crystal structures of SgcE6 and SgcC at 1.66 and 2.63 Å resolution, respectively. SgcE6 shares a similar β-barrel fold with the class I HpaC-like flavin reductases. A flexible loop near the active site of SgcE6 plays a role in FAD binding, likely by providing sufficient space to accommodate the AMP moiety of FAD, when compared to that of FMN-utilizing homologues. SgcC shows structural similarity to a few other known FADH2-dependent monooxygenases and sheds light on some biochemically but not structurally characterized homologues. The crystal structures reported here provide insights into substrate specificity, and comparison with homologues provides a catalytic mechanism of the two-component, FADH2-dependent monooxygenase (SgcE6 and SgcC) that catalyzes the hydroxylation of a PCP-tethered substrate.
- Published
- 2016