Glutamate dehydrogenase from hyperthermophilic Bacteria and Archaea: determinants of thermostability and catalysis at extremely high temperatures

摘要

Insight in the molecular mechanisms determining the extreme intrinsic thermostability of enzymes isolated from hyperthermophilic Archaea and Bacteria, is increasing rapidly as more comparative studies on their amino acid sequences, biochemical characteristics and three-dimensional structures are reported. In order to test the hypotheses arising from these data, protein engineering strategies have been applied to mesophilic and thermostable glutamate dehydrogenases (GDH) from different prokaryotic sources, followed by biochemical and structural characterization of the engineered enzymes. This revie aims to provide an overview of (i) the state of the art on biochemical and structural characterization of thermostable GDHs, (ii) the construction and properties of hybrid GDHs obtained by domain swapping between GDHs from the mesophilic bacterium Clostridium difficile and the hyperthermophilic archaeon Pyrococcus furiosus, and (iii) the elucidation of the role of large ion-pair networks in conferring stability to GDHs from hyperthermophiles by the introduction of ion-pain networks into GDH from Thermotoga maritima.