title: Crystal structure of 2-oxoisovalerate and dehydrogenase and the architecture of 2-oxo acid dehydrogenase multienzyme complexes.
abstract: The family of giant multienzyme complexes metabolizing pyruvate, 2-oxoglutarate, branched-chain 2-oxo acids or acetoin contains several of the largest and most sophisticated protein assemblies known, with molecular masses between 4 and 10 million Da. The principal enzyme components, E1, E2 and E3, are present in numerous copies and utilize multiple cofactors to catalyze a directed sequence of reactions via substrate channeling. The crystal structure of a heterotetrameric (alpha2beta2) E1, 2-oxoisovalerate dehydrogenase from Pseudomonas putida, reveals a tightly packed arrangement of the four subunits with the beta2-dimer held between the jaws of a 'vise' formed by the alpha2-dimer. A long hydrophobic channel, suitable to accommodate the E2 lipoyl-lysine arm, leads to the active site, which contains the cofactor thiamin diphosphate (ThDP) and an inhibitor-derived covalent modification of a histidine side chain. The E1 structure, together with previous structural information on E2 and E3, completes the picture of the shared architectural features of these enormous macromolecular assemblies.
authors.affiliation: Departments of Biological Structure and Biochemistry, Biomolecular Structure Center, University of Washington, P.O. Box 357742, Seattle, Washington 98195-7742, USA.
authors.forename: A
authors.initials: A
authors.lastname: Aevarsson
authors.forename: K
authors.initials: K
authors.lastname: Seger
authors.forename: S
authors.initials: S
authors.lastname: Turley
authors.forename: J R
authors.initials: JR
authors.lastname: Sokatch
authors.forename: W G
authors.initials: WG
authors.lastname: Hol
mesh_terms: D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D000215:Acylation; D001665:Binding Sites; D018360:Crystallography, X-Ray; D045782:Hemiterpenes; D007651:Keto Acids / Q000737:chemistry*; D007658:Ketone Oxidoreductases / Q000737:chemistry*; D008958:Models, Molecular; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D008063:Thioctic Acid / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D045782:Hemiterpenes; D007651:Keto Acids; D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D008063:Thioctic Acid; C001505:alpha-ketoisovalerate; C013091:lipoamide; D007658:Ketone Oxidoreductases; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)