title: Flexible metal binding of the metallo-beta-lactamase domain: glyoxalase II incorporates iron, manganese, and zinc in vivo.
abstract: Glyoxalase II belongs to the metallo-beta-lactamase superfamily of proteins, possessing the characteristic dinuclear active site. Within this protein family, glyoxalase II from Arabidopsis thaliana is the first member to be isolated with significant amounts of iron, manganese, and zinc when being recombinantly produced in Escherichia coli. Enzyme preparations with different ratios of these three metals all yield k(cat)/K(M) values in the range of 1.5-1.9 s(-1) microM(-1) with the substrate S-d-lactoylglutathione. X-ray absorption spectroscopy reveals binding of all three metals to the dinuclear active site with 5-6-fold coordination consisting of 2.5 +/- 0.5 histidine and 2.5 +/- 0.5 oxygen ligands. This model does not distinguish site-specific or distributed binding. The metal-metal distance is determined to be 3.18 +/- 0.06 A. Electron paramagnetic resonance spectroscopy gives evidence for several different types of dimetal sites, including spin-coupled Fe(III)Fe(II), Fe(III)Zn(II), and Mn(II)Mn(II) centers. The metal-ligand distances measured by X-ray absorption spectroscopy vary depending on the metal type and comply with their element-specific, characteristic values. This reflects a high degree of structural flexibility within the glyoxalase II dinuclear active site, which is considered as the structural basis for its broad metal selectivity.
authors.affiliation: EMBL Outstation Hamburg, Notkestrasse 85, 22603 Hamburg, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Schilling
authors.forename: Nathan
authors.initials: N
authors.lastname: Wenzel
authors.forename: Melissa
authors.initials: M
authors.lastname: Naylor
authors.forename: Andreas
authors.initials: A
authors.lastname: Vogel
authors.forename: Michael
authors.initials: M
authors.lastname: Crowder
authors.forename: Christopher
authors.initials: C
authors.lastname: Makaroff
authors.forename: Wolfram
authors.initials: W
authors.lastname: Meyer-Klaucke
mesh_terms: D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000302:isolation & purification; D001665:Binding Sites; D002384:Catalysis; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D007501:Iron / Q000737:chemistry; D008345:Manganese / Q000737:chemistry; D019216:Metals, Heavy / Q000737:chemistry*; D008969:Molecular Sequence Data; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D013057:Spectrum Analysis; D013329:Structure-Activity Relationship; D013869:Thiolester Hydrolases / Q000737:chemistry* / Q000302:isolation & purification; D014965:X-Rays; D015032:Zinc / Q000737:chemistry; D001618:beta-Lactamases / Q000737:chemistry*; D000099301:Hydroxyacylglutathione Hydrolase
chemical_list: D029681:Arabidopsis Proteins; D007501:Iron; D008345:Manganese; D019216:Metals, Heavy; D011994:Recombinant Proteins; D013869:Thiolester Hydrolases; D015032:Zinc; D001618:beta-Lactamases; D000099301:Hydroxyacylglutathione Hydrolase