title: Structure of rat BCKD kinase: nucleotide-induced domain communication in a mitochondrial protein kinase.
abstract: Mitochondrial protein kinases (mPKs) are molecular switches that down-regulate the oxidation of branched-chain alpha-ketoacids and pyruvate. Elevated levels of these metabolites are implicated in disease states such as insulin-resistant Type II diabetes, branched-chain ketoaciduria, and primary lactic acidosis. We report a three-dimensional structure of a member of the mPK family, rat branched-chain alpha-ketoacid dehydrogenase kinase (BCK). BCK features a characteristic nucleotide-binding domain and a four-helix bundle domain. These two domains are reminiscent of modules found in protein histidine kinases (PHKs), which are involved in two-component signal transduction systems. Unlike PHKs, BCK dimerizes through direct interaction of two opposing nucleotide-binding domains. Nucleotide binding to BCK is uniquely mediated by both potassium and magnesium. Binding of ATP induces disorder-order transitions in a loop region at the nucleotide-binding site. These structural changes lead to the formation of a quadruple aromatic stack in the interface between the nucleotide-binding domain and the four-helix bundle domain, where they induce a movement of the top portion of two helices. Phosphotransfer induces further ordering of the loop region, effectively trapping the reaction product ADP, which explains product inhibition in mPKs. The BCK structure is a prototype for all mPKs and will provide a framework for structure-assisted inhibitor design for this family of kinases.
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA. Mischa.Machius@UTSouthwestern.edu
authors.forename: M
authors.initials: M
authors.lastname: Machius
authors.forename: J L
authors.initials: JL
authors.lastname: Chuang
authors.forename: R M
authors.initials: RM
authors.lastname: Wynn
authors.forename: D R
authors.initials: DR
authors.lastname: Tomchick
authors.forename: D T
authors.initials: DT
authors.lastname: Chuang
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology; D004926:Escherichia coli; D000071677:Histidine Kinase; D006801:Humans; D008928:Mitochondria / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011494:Protein Kinases / Q000737:chemistry* / Q000378:metabolism*; D017433:Protein Structure, Secondary; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D011994:Recombinant Proteins; C022571:adenosine 5'-O-(3-thiotriphosphate); D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011494:Protein Kinases; C035627:(3-methyl-2-oxobutanoate dehydrogenase (lipoamide)) kinase; D000071677:Histidine Kinase