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Title: Oxidative cyclizations in orthosomycin biosynthesis expand the known chemistry of an oxygenase superfamily

Orthosomycins are oligosaccharide antibiotics that include avilamycin, everninomicin, and hygromycin B and are hallmarked by a rigidifying interglycosidic spirocyclic ortho-δ-lactone (orthoester) linkage between at least one pair of carbohydrates. A subset of orthosomycins additionally contain a carbohydrate capped by a methylenedioxy bridge. The orthoester linkage is necessary for antibiotic activity but rarely observed in natural products. Orthoester linkage and methylenedioxy bridge biosynthesis require similar oxidative cyclizations adjacent to a sugar ring. In this paper, we have identified a conserved group of nonheme iron, α-ketoglutarate–dependent oxygenases likely responsible for this chemistry. High-resolution crystal structures of the EvdO1 and EvdO2 oxygenases of everninomicin biosynthesis, the AviO1 oxygenase of avilamycin biosynthesis, and HygX of hygromycin B biosynthesis show how these enzymes accommodate large substrates, a challenge that requires a variation in metal coordination in HygX. Excitingly, the ternary complex of HygX with cosubstrate α-ketoglutarate and putative product hygromycin B identified an orientation of one glycosidic linkage of hygromycin B consistent with metal-catalyzed hydrogen atom abstraction from substrate. These structural results are complemented by gene disruption of the oxygenases evdO1 and evdMO1 from the everninomicin biosynthetic cluster, which demonstrate that functional oxygenase activity is critical for antibiotic production. Finally, our data therefore support amore » role for these enzymes in the production of key features of the orthosomycin antibiotics.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [1] ;  [1] ;  [2] ;  [4] ;  [5]
  1. Vanderbilt Univ., Nashville, TN (United States). Dept. of Pharmacology
  2. Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemistry
  3. Vanderbilt Univ., Nashville, TN (United States). Dept. of Biochemistry
  4. Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemistry. Dept. of Biochemistry
  5. Vanderbilt Univ., Nashville, TN (United States). Dept. of Pharmacology. Dept. of Biochemistry
Publication Date:
OSTI Identifier:
1239412
Grant/Contract Number:
AC02-06CH11357; T32 HL007751; N00014-09-1-012; 12GRNT11920011; S10 RR026915; 085P1000817
Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 37; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Vanderbilt Univ., Nashville, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC); National Inst. of Health (NIH) (United States); Vanderbilt Summer Science Academy (United States); Vanderbilt Inst. of Chemical Biology (United States); Office of Naval Research (ONR) (United States); American Heart Association (United States); Michigan Economic Development Corporation (United States); Michigan Technology Tri-Corridor (United States)
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 60 APPLIED LIFE SCIENCES; antibiotic biosynthesis; oxidative cyclization; crystal structure; nonheme iron α-ketoglutarate–dependent oxygenases