title: Structural variation in bacterial glyoxalase I enzymes: investigation of the metalloenzyme glyoxalase I from Clostridium acetobutylicum.
abstract: The glyoxalase system catalyzes the conversion of toxic, metabolically produced α-ketoaldehydes, such as methylglyoxal, into their corresponding nontoxic 2-hydroxycarboxylic acids, leading to detoxification of these cellular metabolites. Previous studies on the first enzyme in the glyoxalase system, glyoxalase I (GlxI), from yeast, protozoa, animals, humans, plants, and Gram-negative bacteria, have suggested two metal activation classes, Zn(2+) and non-Zn(2+) activation. Here, we report a biochemical and structural investigation of the GlxI from Clostridium acetobutylicum, which is the first GlxI enzyme from Gram-positive bacteria that has been fully characterized as to its three-dimensional structure and its detailed metal specificity. It is a Ni(2+)/Co(2+)-activated enzyme, in which the active site geometry forms an octahedral coordination with one metal atom, two water molecules, and four metal-binding ligands, although its inactive Zn(2+)-bound form possesses a trigonal bipyramidal geometry with only one water molecule liganded to the metal center. This enzyme also possesses a unique dimeric molecular structure. Unlike other small homodimeric GlxI where two active sites are located at the dimeric interface, the C. acetobutylicum dimeric GlxI enzyme also forms two active sites but each within single subunits. Interestingly, even though this enzyme possesses a different dimeric structure from previously studied GlxI, its metal activation characteristics are consistent with properties of other GlxI. These findings indicate that metal activation profiles in this class of enzyme hold true across diverse quaternary structure arrangements.
authors.affiliation: Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Uthaiwan
authors.initials: U
authors.lastname: Suttisansanee
authors.affiliation: Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Kelvin
authors.initials: K
authors.lastname: Lau
authors.affiliation: Biology Department, Brookhaven National Laboratory, Upton, New York 11973.
authors.forename: Satyanarayana
authors.initials: S
authors.lastname: Lagishetty
authors.affiliation: Biology Department, Brookhaven National Laboratory, Upton, New York 11973.
authors.forename: Krishnamurthy N
authors.initials: KN
authors.lastname: Rao
authors.affiliation: Biology Department, Brookhaven National Laboratory, Upton, New York 11973.
authors.forename: Subramanyam
authors.initials: S
authors.lastname: Swaminathan
authors.affiliation: Eli Lilly and Co., San Diego, California 92121.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Sauder
authors.affiliation: Eli Lilly and Co., San Diego, California 92121. Electronic address: sburley@sgxpharma.com.
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Burley
authors.affiliation: Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Electronic address: jhonek@uwaterloo.ca.
authors.forename: John F
authors.initials: JF
authors.lastname: Honek
mesh_terms: D046969:Clostridium acetobutylicum / Q000201:enzymology*; D018360:Crystallography, X-Ray / Q000379:methods; D019281:Dimerization; D004789:Enzyme Activation; D007700:Kinetics; D007791:Lactoylglutathione Lyase / Q000737:chemistry*; D008024:Ligands; D008670:Metals / Q000737:chemistry; D008956:Models, Chemical; D008968:Molecular Conformation; D009532:Nickel / Q000737:chemistry; D011487:Protein Conformation; D019998:Racemases and Epimerases / Q000737:chemistry; D015032:Zinc / Q000737:chemistry*
chemical_list: D008024:Ligands; D008670:Metals; D009532:Nickel; D007791:Lactoylglutathione Lyase; D019998:Racemases and Epimerases; C021581:methylmalonyl-coenzyme A racemase; D015032:Zinc