title: 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.
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.
authors: Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors: Chin-Yuan
authors: CY
authors: Chang
authors: Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors: Jeremy R
authors: JR
authors: Lohman
authors: BioScience at Rice and Department of Chemistry, Rice University , Houston, Texas 77251, United States.
authors: Hongnan
authors: H
authors: Cao
authors: Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors: Kemin
authors: K
authors: Tan
authors: Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors: Jeffrey D
authors: JD
authors: Rudolf
authors: Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors: Ming
authors: M
authors: Ma
authors: BioScience at Rice and Department of Chemistry, Rice University , Houston, Texas 77251, United States.
authors: Weijun
authors: W
authors: Xu
authors: Department of Biochemistry, University of Wisconsin-Madison , Madison, Wisconsin 53705, United States.
authors: Craig A
authors: CA
authors: Bingman
authors: BioScience at Rice and Department of Chemistry, Rice University , Houston, Texas 77251, United States.|Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology , Waknaghat, Himachal Pradesh, India 173234.
authors: Ragothaman M
authors: RM
authors: Yennamalli
authors: Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors: Lance
authors: L
authors: Bigelow
authors: Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors: Gyorgy
authors: G
authors: Babnigg
authors: Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors: Xiaohui
authors: X
authors: Yan
authors: Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors: Andrzej
authors: A
authors: Joachimiak
authors: BioScience at Rice and Department of Chemistry, Rice University , Houston, Texas 77251, United States.
authors: George N
authors: GN
authors: Phillips
authors: Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States.
authors: Ben
authors: B
authors: Shen
mesh_terms: D000617:Aminoglycosides / Q000096:biosynthesis*; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D002384:Catalysis; D018360:Crystallography, X-Ray; D053281:Enediynes; D006801:Humans; D006900:Hydroxylation; D049031:Sarcoglycans / Q000737:chemistry*; D013302:Streptomyces / Q000378:metabolism*
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D053281:Enediynes; C526573:SGCG protein, human; D049031:Sarcoglycans; C058024:C 1027