title: Methanoarchaeal sulfolactate dehydrogenase: prototype of a new family of NADH-dependent enzymes.
abstract: The crystal structure of the sulfolactate dehydrogenase from the hyperthermophilic and methanogenic archaeon Methanocaldococcus jannaschii was solved at 2.5 A resolution (PDB id. 1RFM). The asymmetric unit contains a tetramer of tight dimers. This structure, complexed with NADH, does not contain a cofactor-binding domain with 'Rossmann-fold' topology. Instead, the tertiary and quaternary structures indicate a novel fold. The NADH is bound in an extended conformation in each active site, in a manner that explains the pro-S specificity. Cofactor binding involves residues belonging to both subunits within the tight dimers, which are therefore the smallest enzymatically active units. The protein was found to be a homodimer in solution by size-exclusion chromatography, analytical ultracentrifugation and small-angle neutron scattering. Various compounds were tested as putative substrates. The results indicate the existence of a substrate discrimination mechanism, which involves electrostatic interactions. Based on sequence homology and phylogenetic analyses, several other enzymes were classified as belonging to this novel family of homologous (S)-2-hydroxyacid dehydrogenases.
authors.affiliation: Laboratoire de Biophysique Moléculaire, Institut de Biologie Structurale J-P Ebel CEA CNRS UJF, Grenoble, France.
authors.forename: Adriana
authors.initials: A
authors.lastname: Irimia
authors.forename: Dominique
authors.initials: D
authors.lastname: Madern
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zaccaï
authors.forename: Frédéric M D
authors.initials: FM
authors.lastname: Vellieux
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology; D019143:Evolution, Molecular; D007785:Lactose / Q000737:chemistry / Q000378:metabolism*; D017015:Methanococcales / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D009243:NAD / Q000378:metabolism*; D010088:Oxidoreductases / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D012996:Solutions; D040681:Structural Homology, Protein; D013379:Substrate Specificity; D013401:Sugar Alcohol Dehydrogenases / Q000737:chemistry / Q000378:metabolism; D013455:Sulfur / Q000737:chemistry*
chemical_list: D012996:Solutions; D009243:NAD; D013455:Sulfur; D010088:Oxidoreductases; D013401:Sugar Alcohol Dehydrogenases; C484696:2,3-diketo-L-gulonate reductase; D007785:Lactose