The Crystal Structure of a Homodimeric Pseudomonas Glyoxalase I Enzyme Reveals Asymmetric Metallation Commensurate with Half‐of‐Sites Activity |
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| Authors: | Dr. Rohan Bythell‐Douglas Dr. Uthaiwan Suttisansanee Dr. Gavin R. Flematti Michael Challenor Dr. Mihwa Lee Dr. Santosh Panjikar Prof. John F. Honek Prof. Charles S. Bond |
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| Affiliation: | 1. School of Chemistry and Biochemistry, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia (Australia);2. Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2?L 3G1 (Canada);3. Department of Biochemistry and Molecular Biology, Monash University, Clayton Campus, Melbourne 3800, Victoria (Australia);4. Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168 (Australia) |
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| Abstract: | The Zn inactive class of glyoxalase I (Glo1) metalloenzymes are typically homodimeric with two metal‐dependent active sites. While the two active sites share identical amino acid composition, this class of enzyme is optimally active with only one metal per homodimer. We have determined the X‐ray crystal structure of GloA2, a Zn inactive Glo1 enzyme from Pseudomonas aeruginosa. The presented structures exhibit an unprecedented metal‐binding arrangement consistent with half‐of‐sites activity: one active site contains a single activating Ni2+ ion, whereas the other contains two inactivating Zn2+ ions. Enzymological experiments prompted by the binuclear Zn2+ site identified a novel catalytic property of GloA2. The enzyme can function as a Zn2+/Co2+‐dependent hydrolase, in addition to its previously determined glyoxalase I activity. The presented findings demonstrate that GloA2 can accommodate two distinct metal‐binding arrangements simultaneously, each of which catalyzes a different reaction. |
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| Keywords: | crystal‐structure determination enzymes metalloenzymes proteins zinc |
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