THE AMINO-ACID-SEQUENCE SIMILARITY OF PLANT GLUTAMATE-DEHYDROGENASE TO THE EXTREMOPHILIC ARCHAEAL ENZYME CONFORMS TO ITS STRESS-RELATED FUNCTION

A cDNA clone encoding grapevine (Vitis vinifera L. cv Sultanina) NAD(H )-glutamate dehydrogenase (GDH) was isolated from a cDNA expression li brary by immunoscreening with a polyclonal antibody raised against gra pevine GDH. Nucleotide sequence analysis revealed an open reading fram e (ORF) encoding a precursor protein of 411 amino acids (aa) with a ca lculated molecular mass of 44.517 kDa. The deduced aa sequence showed relatively higher homology to GDH from archaebacteria species, than to those from eukaryotes and eubacteria. This resemblance indicated a fu nctional and/or evolutionary relationship in this class of enzymes whi ch might be relevant to the stress-related function of plant GDH, We h ave shown that the bacterially produced plant GDH was thermostable.