title: Modulating glyoxalase I metal selectivity by deletional mutagenesis: underlying structural factors contributing to nickel activation profiles.
abstract: Metabolically produced methylglyoxal is a cytotoxic compound that can lead to covalent modification of cellular DNA, RNA and protein. One pathway to detoxify this compound is via the glyoxalase enzyme system. The first enzyme of this detoxification system, glyoxalase I (GlxI), can be divided into two classes according to its metal activation profile, a Zn(2+)-activated class and a Ni(2+)-activated class. In order to elucidate some of the key structural features required for selective metal activation by these two classes of GlxI, deletional mutagenesis was utilized to remove, in a step-wise fashion, a key α-helix (residues 73-87) and two small loop regions (residues 99-103 and 111-114) from the Zn(2+)-activated Pseudomonas aeruginosa GlxI (GloA3) in order to mimic the smaller Ni(2+)-activated GlxI (GloA2) from the same organism. This approach was observed to clearly shift the metal activation profile of a Zn(2+)-activated class GlxI into a Ni(2+)-activated class GlxI enzyme. The α-helix structural component was found to contribute significantly toward GlxI metal specificity, while the two small loop regions were observed to play a more crucial role in the magnitude of the enzymatic activity. The current study should provide additional information on the fundamental relationship of protein structure to metal selectivity in these metalloenzymes.
authors.affiliation: Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada. jhonek@uwaterloo.ca.
authors.forename: Uthaiwan
authors.initials: U
authors.lastname: Suttisansanee
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Ran
authors.forename: Kadia Y
authors.initials: KY
authors.lastname: Mullings
authors.forename: Nicole
authors.initials: N
authors.lastname: Sukdeo
authors.forename: John F
authors.initials: JF
authors.lastname: Honek
mesh_terms: D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D007791:Lactoylglutathione Lyase / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009532:Nickel / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D016958:Pseudomonas putida / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015032:Zinc / Q000737:chemistry
chemical_list: D008670:Metals; D009532:Nickel; D007791:Lactoylglutathione Lyase; D015032:Zinc