title: Structural Basis for Cyclopropanation by a Unique Enoyl-Acyl Carrier Protein Reductase.
abstract: The natural product curacin A, a potent anticancer agent, contains a rare cyclopropane group. The five enzymes for cyclopropane biosynthesis are highly similar to enzymes that generate a vinyl chloride moiety in the jamaicamide natural product. The structural biology of this remarkable catalytic adaptability is probed with high-resolution crystal structures of the curacin cyclopropanase (CurF ER), an in vitro enoyl reductase (JamJ ER), and a canonical curacin enoyl reductase (CurK ER). The JamJ and CurK ERs catalyze NADPH-dependent double bond reductions typical of enoyl reductases (ERs) of the medium-chain dehydrogenase reductase (MDR) superfamily. Cyclopropane formation by CurF ER is specified by a short loop which, when transplanted to JamJ ER, confers cyclopropanase activity on the chimeric enzyme. Detection of an adduct of NADPH with the model substrate crotonyl-CoA provides indirect support for a recent proposal of a C2-ene intermediate on the reaction pathway of MDR enoyl-thioester reductases.
authors.affiliation: Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
authors.forename: Dheeraj
authors.initials: D
authors.lastname: Khare
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
authors.forename: Wendi A
authors.initials: WA
authors.lastname: Hale
authors.affiliation: Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
authors.forename: Ashootosh
authors.initials: A
authors.lastname: Tripathi
authors.affiliation: Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA; Department Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109-1065, USA.
authors.forename: Liangcai
authors.initials: L
authors.lastname: Gu
authors.affiliation: Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA; Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA; Department Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109-1065, USA; Department Microbiology & Immunology, University of Michigan, Ann Arbor, MI 48109-5620, USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Sherman
authors.affiliation: Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, San Diego, CA 92093, USA.
authors.forename: William H
authors.initials: WH
authors.lastname: Gerwick
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
authors.forename: Kristina
authors.initials: K
authors.lastname: Håkansson
authors.affiliation: Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA; Department Biological Chemistry, University of Michigan, Ann Arbor, MI 48109-0600, USA. Electronic address: janetsmith@umich.edu.
authors.forename: Janet L
authors.initials: JL
authors.lastname: Smith
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D003521:Cyclopropanes / Q000378:metabolism*; D050753:Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D013844:Thiazoles / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003521:Cyclopropanes; D013844:Thiazoles; C095843:curacin A; D050753:Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)