Antonyuk Svetlana V, Eady Robert R, Strange Richard W, Hasnain S Samar
Molecular Biophysics Group, CCLRC Daresbury Laboratory, Warrington, Cheshire WA4 4AD, England.
Acta Crystallogr D Biol Crystallogr. 2003 May;59(Pt 5):835-42. doi: 10.1107/s0907444903041441. Epub 2003 Apr 25.
The enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from the Gram-negative denitrifying bacterial species Alcaligenes xylosoxidans was purified and crystallized as a contaminant protein during purification of nitrous oxide reductase. This is the first structure of a GAPDH from a denitrifying species. The crystal structure was solved at 1.7 A resolution by molecular replacement using the structure of GAPDH from Bacillus stearothermophilus as a starting model. The quality of the structure enabled the amino-acid sequence of the A. xylosoxidans GAPDH to be assigned. The structure is that of the apo-enzyme, lacking the NAD+ cofactor and with the active-site residue Cys154 oxidized. The global structure of the enzyme has a homotetrameric quaternary structure similar to that observed for its bacterial and eukaryotic counterparts. The essential role of Cys154 in the enzyme activity has been confirmed. In monomer O two half-occupancy sulfate ions were found at the active site, which are analogous to the substrate and the "attacking" phosphate seen in B. stearothermophilus. One half-occupancy sulfate ion is also located in the substrate-binding site of monomer P.
