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Crystal structure of the glyceraldehyde-3-phosphate dehydrogenase from the hyperthermophilic archaeon Sulfolobus
M N Isupov1, T M Fleming, A R Dalby
1Schools of Chemistry and Biological Sciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
Abstract:
The enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from the archaea shows low sequence identity (16-20%) with its eubacterial and eukaryotic counterparts. The crystal structure of the apo GAPDH from Sulfolobus solfataricus has been determined by multiple isomorphous replacement at 2.05 A resolution. The enzyme has several differences in secondary structure when compared with eubacterial GAPDHs, with an overall increase in the number of alpha-helices. There is a relocation of the active-site residues within the catalytic domain of the enzyme. The thermostability of the S. solfataricus enzyme can be attributed to a combination of an ion pair cluster and an intrasubunit disulphide bond.