THE CRYSTAL-STRUCTURE OF HOLO-GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE FROM THE HYPERTHERMOPHILIC BACTERIUM THERMOTOGA-MAUITIMA AT 2.5-ANGSTROM RESOLUTION

The crystal structure of holo-glyceraldehyde-3-phosphate dehydrogenase from the hyperthermophile Thermotoga maritima was determined by Patterson search methods using the known structure of the Bacillus stearothermophilus enzyme. The structure was refined at a resolution of 2.5 Angstrom to an R-factor of 16.63% for 26289 reflections between 8.0 Angstrom an 2.5 Angstrom with F > 2 sigma(F). The crystallographic asymmetric unit contains two monomers related by approximate 2-fold symmetry and a tetramer is built up by crystallographic symmetry. The root-mean-square deviation of C-alpha positions of glyceraldehyde-3-phosphate dehydrogenase from T. maritima and B. stearothermophilus is 0.83 Angstrom in the NAD(+) binding domains and smaller close to the cofactor. In contrast, the largest deviations in the catalytic domains are found at residues involved in coordination of sulphate ion SO4 339, which most likely marks the site of the attacking inorganic phosphate ion in catalysis. A large number of extra salt-bridges may be an important factor contributing to the high thermostability of this protein.