title: Modeling and experiment yields the structure of acireductone dioxygenase from Klebsiella pneumoniae.
abstract: Here we report the structure of acireductone dioxygenase (ARD), the first determined for a new family of metalloenzymes. ARD represents a branch point in the methionine salvage pathway leading from methylthioadenosine to methionine and has been shown to catalyze different reactions depending on the type of metal ion bound in the active site. The solution structure of nickel-containing ARD (Ni-ARD) was determined using NMR methods. X-ray absorption spectroscopy, assignment of hyperfine shifted NMR resonances and conserved domain homology were used to model the metal-binding site because of the paramagnetism of the bound Ni2+. Although there is no structure in the Protein Data Bank within 3 A r.m.s deviation of that of Ni-ARD, the enzyme active site is located in a conserved double-stranded b-helix domain. Furthermore, the proposed Ni-ARD active site shows significant post-facto structural homology to the active sites of several metalloenzymes in the cupin superfamily.
authors.affiliation: Department of Chemistry, Brandeis University, MS 015, 415 South Street, Waltham, Massachusetts 02454-9110, USA. pochapsk@brandeis.edu
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Pochapsky
authors.forename: Susan Sondej
authors.initials: SS
authors.lastname: Pochapsky
authors.forename: Tingting
authors.initials: T
authors.lastname: Ju
authors.forename: Huaping
authors.initials: H
authors.lastname: Mo
authors.forename: Faizah
authors.initials: F
authors.lastname: Al-Mjeni
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Maroney
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D049308:Dioxygenases; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D010105:Oxygenases / Q000737:chemistry* / Q000378:metabolism; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D009532:Nickel; D008715:Methionine; D010105:Oxygenases; D049308:Dioxygenases; C083734:aci-reductone oxidase (CO-forming)