title: Glutamate dehydrogenase isoenzyme 3 (GDH3) of Arabidopsis thaliana is less thermostable than GDH1 and GDH2 isoenzymes.
abstract: NAD(H)-glutamate dehydrogenase (GDH; EC 1.4.1.2) is an abundant and ubiquitous enzyme that may exist in different isoenzymic forms. Variation in the composition of the GDH isoenzyme pattern is observed during plant development and specific cell, tissue and organ localization of the different isoforms have been reported. However, the mechanisms involved in the regulation of the isoenzymatic pattern are still obscure. Regulation may be exerted at several levels, i.e. at the level of transcription and translation of the relevant genes, but also when the enzyme is assembled to originate the catalytically active form of the protein. In Arabidopsis thaliana, three genes (GDH1, GDH2 and GDH3) encode three different GDH subunits (β, α and γ) that randomly associate to form a complex array of homo- and hetero-hexamers. In order to asses if the different Arabidopsis GDH isoforms may display different structural properties we have investigated their thermal stability. In particular the stability of GDH1 and GDH3 isoenzymes was studied using site-directed mutagenesis in a heterologous yeast expression system. It was established that the carboxyl terminus of the GDH subunit is involved in the stabilization of the oligomeric structure of the enzyme.
authors.affiliation: Dipartimento di Bioscienze, Università di Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Marchi
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università di Parma, Parco Area delle Scienze 7/A, 43124 Parma, Italy.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Polverini
authors.affiliation: Dipartimento di Bioscienze, Università di Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Degola
authors.affiliation: Dipartimento di Bioscienze, Università di Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Baruffini
authors.affiliation: Dipartimento di Bioscienze, Università di Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy. Electronic address: francescomaria.restivo@unipr.it.
authors.forename: Francesco Maria
authors.initials: FM
authors.lastname: Restivo
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D018086:Glutamate Dehydrogenase (NADP+) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D007527:Isoenzymes; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D007527:Isoenzymes; D021122:Protein Subunits; D018086:Glutamate Dehydrogenase (NADP+)
keywords: Glutamate dehydrogenase; Isoenzymes; Subunits; Thermal stability