title: C3'-Deoxygenation of Paromamine Catalyzed by a Radical S-Adenosylmethionine Enzyme: Characterization of the Enzyme AprD4 and Its Reductase Partner AprD3.
abstract: C3'-deoxygenation of aminoglycosides results in their decreased susceptibility to phosphorylation thereby increasing their efficacy as antibiotics. However, the biosynthetic mechanism of C3'-deoxygenation is unknown. To address this issue, aprD4 and aprD3 genes from the apramycin gene cluster in Streptomyces tenebrarius were expressed in E. coli and the resulting gene products were characterized in vitro. AprD4 is shown to be a radical S-adenosylmethionine (SAM) enzyme, catalyzing homolysis of SAM to 5'-deoxyadenosine (5'-dAdo) in the presence of paromamine. [4'-(2) H]-Paromamine was prepared and used to show that its C4'-H is transferred to 5'-dAdo by AprD4, during which the substrate is dehydrated to a product consistent with 4'-oxolividamine. In contrast, paromamine is reduced to a deoxy product when incubated with AprD4/AprD3/NADPH. These results show that AprD4 is the first radical SAM diol-dehydratase and, along with AprD3, is responsible for 3'-deoxygenation in aminoglycoside biosynthesis.
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy and Department of Chemistry, University of Texas at Austin, Austin, TX, 78712, USA.
authors.forename: Hak Joong
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy and Department of Chemistry, University of Texas at Austin, Austin, TX, 78712, USA.
authors.forename: Jake
authors.initials: J
authors.lastname: LeVieux
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy and Department of Chemistry, University of Texas at Austin, Austin, TX, 78712, USA.
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Yeh
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy and Department of Chemistry, University of Texas at Austin, Austin, TX, 78712, USA. h.w.liu@mail.utexas.edu.
authors.forename: Hung-Wen
authors.identifier: http://orcid.org/0000-0001-8953-4794
authors.initials: HW
authors.lastname: Liu
mesh_terms: D000617:Aminoglycosides / Q000737:chemistry*; D002384:Catalysis; D004798:Enzymes / Q000378:metabolism*; D010100:Oxygen / Q000737:chemistry*; D012436:S-Adenosylmethionine / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000617:Aminoglycosides; D004798:Enzymes; C005936:paromamine; D012436:S-Adenosylmethionine; D010100:Oxygen
keywords: aminoglycosides; biosynthesis; enzyme catalysis; radical enzymes; reaction mechanisms