title: Differences in the oligomeric states of the LDH-like L-MalDH from the hyperthermophilic archaea Methanococcus jannaschii and Archaeoglobus fulgidus.
abstract: L-Malate (MalDH) and L-lactate (LDH) dehydrogenases belong to the same family of NAD-dependent enzymes. To gain insight into molecular relationships within this family, we studied two hyperthermophilic (LDH-like) L-MalDH (proteins with LDH-like structure and MalDH enzymatic activity) from the archaea Archaeoglobus fulgidus (Af) and Methanococcus jannaschii (Mj). The structural parameters of these enzymes determined by neutron scattering and analytical centrifugation showed that the Af (LDH-like) L-MalDH is a dimer whereas the Mj (LDH-like) L-MalDH is a tetramer. The effects of high temperature, cofactor binding, and high phosphate concentration were studied. They did not modify the oligomeric state of either enzyme. The enzymatic activity of the dimeric Af (LDH-like) L-MalDH is controlled by a pH-dependent transition at pH 7 without dissociation of the subunits. The data were analyzed in the light of the crystallographic structure of the LDH-like L-MalDH from Haloarcula marismortui. This showed that a specific loop at the dimer-dimer contact regions in these enzymes controls the tetramer formation.
authors.affiliation: Laboratoire de Biophysique Moléculaire, Institut de Biologie Structurale, UMR 5075, CEA-CNRS-UJF, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1, France. madern@ibs.fr
authors.forename: D
authors.initials: D
authors.lastname: Madern
authors.forename: C
authors.initials: C
authors.lastname: Ebel
authors.forename: H A
authors.initials: HA
authors.lastname: Dale
authors.forename: T
authors.initials: T
authors.lastname: Lien
authors.forename: I H
authors.initials: IH
authors.lastname: Steen
authors.forename: N K
authors.initials: NK
authors.lastname: Birkeland
authors.forename: G
authors.initials: G
authors.lastname: Zaccai
mesh_terms: D000595:Amino Acid Sequence; D019611:Archaeoglobus fulgidus / Q000201:enzymology*; D003001:Cloning, Molecular; D017931:DNA Primers; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000737:chemistry*; D046911:Macromolecular Substances; D008291:Malate Dehydrogenase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017017:Methanococcus / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009502:Neutrons; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012542:Scattering, Radiation; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014461:Ultracentrifugation
chemical_list: D017931:DNA Primers; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase