title: Atrazine chlorohydrolase from Pseudomonas sp. strain ADP is a metalloenzyme.
abstract: Atrazine chlorohydrolase (AtzA) from Pseudomonas sp. ADP initiates the metabolism of the herbicide atrazine by catalyzing a hydrolytic dechlorination reaction to produce hydroxyatrazine. Sequence analysis revealed AtzA to be homologous to metalloenzymes within the amidohydrolase protein superfamily. AtzA activity was experimentally shown to depend on an enzyme-bound, divalent transition-metal ion. Loss of activity obtained by incubating AtzA with the chelator 1,10-phenanthroline or oxalic acid was reversible upon addition of Fe(II), Mn(II), or Co(II) salts. Experimental evidence suggests a 1:1 metal to subunit stoichiometry, with the native metal being Fe(II). Our data show that the inhibitory effects of metals such as Zn(II) and Cu(II) are not the result of displacing the active site metal. Taken together, these data indicate that AtzA is a functional metalloenzyme, making this the first report, to our knowledge, of a metal-dependent dechlorinating enzyme that proceeds via a hydrolytic mechanism.
authors.affiliation: Department of Biochemistry, Molecular Biology, and Biophysics, Center for Microbial and Plant Genomics, University of Minnesota, St. Paul, Minnesota 55108, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Seffernick
authors.forename: Hugh
authors.initials: H
authors.lastname: McTavish
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Osborne
authors.forename: Mervyn L
authors.initials: ML
authors.lastname: de Souza
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sadowsky
authors.forename: Lawrence P
authors.initials: LP
authors.lastname: Wackett
mesh_terms: D000595:Amino Acid Sequence; D001051:Apoenzymes / Q000737:chemistry; D001280:Atrazine / Q000378:metabolism*; D002413:Cations, Divalent / Q000737:chemistry; D002614:Chelating Agents / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D004791:Enzyme Inhibitors / Q000737:chemistry; D006867:Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D008667:Metalloproteins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D008969:Molecular Sequence Data; D011549:Pseudomonas / Q000201:enzymology*; D013053:Spectrophotometry; D015032:Zinc / Q000737:chemistry
chemical_list: D001051:Apoenzymes; D002413:Cations, Divalent; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D008667:Metalloproteins; D019216:Metals, Heavy; D003035:Cobalt; D003300:Copper; D006867:Hydrolases; C100894:atrazine chlorohydrolase; D015032:Zinc; D001280:Atrazine