The NAD-dependent glutamate dehydrogenase from the hyperthermophilic archaeon Pyrobaculum islandicum: cloning, sequencing, and expression of the enzyme gene

The NAD-dependent glutamate dehydrogenase (GluDH) gene from the hyperthermo philic archaeon Pyrobaculum islandicum was cloned and expressed in Escheric hia coli. Analysis of the nucleotide sequence revealed an open reading fram e of 1266 bp encoding a protein of 421 amino acids with a molecular weight of 46 905. In the alignment of the amino acid sequence with those of mesoph ilic Clostridium symbiosum NAD-dependent GluDH and hyperthermophilic NADP-d ependent enzymes from Thermococcus profundus and Pyrococcus furiosus, subst itutions in the residues involved in dinucleotide binding were observed. On the other hand, the residues involved in glutamate binding were well conse rved. This is the first description of the primary structure of NAD-depende nt GluDH in hyperthermophilic archaea. (C) 1999 Elsevier Science B.V. All r ights reserved.