Fosfomycin resistance protein (FosA) is a manganese metalloglutathione transferase related to glyoxalase I and the extradiol dioxygenases.
The enzyme conferring resistance to the antibiotic fosfomycin [(1R,2S)-1,2-epoxypropylphosphonic acid] originally reported by Suarez and co-workers [Area, P., Hardisson, C., & Suarez, J. E. (1990) Antimicrob. Agents Chemother. 34, 844-848] is demonstrated in this study to be a metalloglutathione transferase. The apoenzyme is a dimer of 16 kDa subunits. Electron paramagnetic resonance spectroscopy and water proton nuclear magnetic resonance longitudinal relaxation rates suggest that each subunit contains a mononuclear Mn2+ center that interacts strongly with the substrate fosfomycin (Kd = 17 microM) more weakly with the product (Kd = 1.1 mM) and very weakly or not at all with GSH. Inhomogeneous broadening of the EPR signals of enzyme-bound Mn2+ in the presence of H2(17)O indicates that three of the coordination sites on the metal are occupied by water. Sequence alignments, three-dimensional structures, and mechanistic considerations suggest that FosA is related to at least two other metalloenzymes, glyoxalase I and the Mn2+- or Fe2+-containing extradiol dioxygenases. The mechanistic imperative driving the evolution of this previously unidentified superfamily of metalloenzymes is proposed to be bidentate coordination of a substrate or intermediate to the metal center in the enzyme-catalyzed reactions.
Bernat
B A
BA
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA.
Laughlin
L T
LT
Armstrong
R N
RN
D000595:Amino Acid Sequence; D001051:Apoenzymes / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D001426:Bacterial Proteins; D004352:Drug Resistance, Microbial; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli / Q000201:enzymology; D005578:Fosfomycin / Q000494:pharmacology; D005982:Glutathione Transferase / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D007791:Lactoylglutathione Lyase / Q000737:chemistry*; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010105:Oxygenases / Q000737:chemistry*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid
D001051:Apoenzymes; D001426:Bacterial Proteins; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D005578:Fosfomycin; D010105:Oxygenases; D005982:Glutathione Transferase; D007791:Lactoylglutathione Lyase