Thermal stabilization of the protozoan Entamoeba histolytica alcohol dehydrogenase by a single proline substitution

Analysis of the three-dimensional structures of two closely related thermophilic and hyperthermophilic alcohol dehydrogenases (ADHs) from the respective microorganisms Entamoeba histolytica (EhADH1) and Thermoanaerobacter brockii (TbADH) suggested that a unique, strategically located proline residue (Pro275) at the center of the dimerization interface might be crucial for maintaining the thermal stability of TbADH. To assess the contribution of Pro275 to the thermal stability of the ADHs, we applied site-directed mutagenesis to replace Asp275 of EhADH1 with Pro (D275P-EhADH1) and conversely Pro275 of TbADH with Asp (P275D-TbADH). The results indicate that replacing Asp275 with Pro significantly enhances the thermal stability of EhADH1 (DeltaT(1/2)