title: Structural bases for the specific interactions between the E2 and E3 components of the Thermus thermophilus 2-oxo acid dehydrogenase complexes.
abstract: Pyruvate dehydrogenase (PDH), branched-chain 2-oxo acid dehydrogenase (BCDH) and 2-oxoglutarate dehydrogenase (OGDH) are multienzyme complexes that play crucial roles in several common metabolic pathways. These enzymes belong to a family of 2-oxo acid dehydrogenase complexes that contain multiple copies of three different components (E1, E2 and E3). For the Thermus thermophilus enzymes, depending on its substrate specificity (pyruvate, branched-chain 2-oxo acid or 2-oxoglutarate), each complex has distinctive E1 (E1p, E1b or E1o) and E2 (E2p, E2b or E2o) components and one of the two possible E3 components (E3b and E3o). (The suffixes, p, b and o identify their respective enzymes, PDH, BCDH and OGDH.) Our biochemical characterization demonstrates that only three specific E3*E2 complexes can form (E3b*E2p, E3b*E2b and E3o*E2o). X-ray analyses of complexes formed between the E3 components and the peripheral subunit-binding domains (PSBDs), derived from the corresponding E2-binding partners, reveal that E3b interacts with E2p and E2b in essentially the same manner as observed for Geobacillus stearothermophilus E3*E2p, whereas E3o interacts with E2o in a novel fashion. The buried intermolecular surfaces of the E3b*PSBDp/b and E3o*PSBDo complexes differ in size, shape and charge distribution and thus, these differences presumably confer the binding specificities for the complexes.
authors.affiliation: RIKEN SPring-8 Center, Harima Institute, Sayo, Hyogo 679-5148, Japan. nakaix@u.washington.edu
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nakai
authors.forename: Seiki
authors.initials: S
authors.lastname: Kuramitsu
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kamiya
mesh_terms: D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide) / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism*; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D016963:Thermus thermophilus / Q000201:enzymology*
chemical_list: D009243:NAD; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)