Modulating glyoxalase I metal selectivity by deletional mutagenesis: underlying structural factors contributing to nickel activation profilesThis article is dedicated to Professor Iwao Ojima, in honor of his 70th birthday.Electronic supplementary information (ESI) available: Table of amino acid sequence identities of pertinent glyoxalase I enzymes, table of recovery yields and theoretical pIs of overproduced enzymes, two tables of kinetic data, predicted subunit structure of GloA3, electrospray

• Main Authors: Suttisansanee, Uthaiwan, Ran, Yanhong, Mullings, Kadia Y, Sukdeo, Nicole, Honek, John F
• Format: Article
• Language: English
• ISSN: 1756-5901; 1756-591X
• DOI: 10.1039/c4mt00299g

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. Switching between the two metal activation classes of glyoxalase I by protein engineering using deletional mutagenesis.