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|2pnr, resolution 2.50Å ()|
|Gene:||PDK3 (Homo sapiens), DLAT, DLTA (Homo sapiens)|
Crystal Structure of the asymmetric Pdk3-l2 Complex
A homodimer of pyruvate dehydrogenase kinase (PDHK) is an integral part of pyruvate dehydrogenase complex (PDC) to which it is anchored primarily through the inner lipoyl-bearing domains (L2) of transacetylase component. The catalytic cycle of PDHK and its translocation over the PDC surface is thought to be mediated by the "symmetric" and "asymmetric" modes, in which the PDHK dimer binds to two and one L2-domain(s), respectively. Whereas the structure of the symmetric PDHK/L2 complex was reported, the structural organization and functional role of the asymmetric complex remain obscure. Here, we report the crystal structure of the asymmetric PDHK3/L2 complex that reveals several functionally important features absent from the previous structures. First, the PDHK3 subunits have distinct conformations: one subunit exhibits "open" and the other "closed" configuration of the putative substrate-binding cleft. Second, access to the closed cleft is additionally restricted by local unwinding of the adjacent alpha-helix. Modeling indicates that the target peptide might gain access to the PDHK active center through the open but not through the closed cleft. Third, the ATP-binding loop in one PDHK3 subunit adopts an open conformation, implying that the nucleotide loading into the active site is mediated by the inactive "pre-insertion" binding mode. Altogether our data suggest that the asymmetric complex represents a physiological state in which binding of a single L2-domain activates one of the PDHK protomers while inactivating another. Thus, the L2-domains likely act not only as the structural anchors but also modulate the catalytic cycle of PDHK.
Crystal structure of an asymmetric complex of pyruvate dehydrogenase kinase 3 with lipoyl domain 2 and its biological implications., Devedjiev Y, Steussy CN, Vassylyev DG, J Mol Biol. 2007 Jul 13;370(3):407-16. Epub 2007 May 10. PMID:17532006
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
[ODP2_HUMAN] Note=Primary biliary cirrhosis is a chronic, progressive cholestatic liver disease characterized by the presence of antimitochondrial autoantibodies in patients' serum. It manifests with inflammatory obliteration of intra-hepatic bile duct, leading to liver cell damage and cirrhosis. Patients with primary biliary cirrhosis show autoantibodies against the E2 component of pyruvate dehydrogenase complex. Defects in DLAT are the cause of pyruvate dehydrogenase E2 deficiency (PDHE2 deficiency) [MIM:245348]; also known as lactic acidemia due to defect of E2 lipoyl transacetylase of the pyruvate dehydrogenase complex. Pyruvate dehydrogenase (PDH) deficiency is a major cause of primary lactic acidosis and neurological dysfunction in infancy and early childhood. In this form of PDH deficiency episodic dystonia is the major neurological manifestation, with other more common features of pyruvate dehydrogenase deficiency, such as hypotonia and ataxia, being less prominent.
[PDK3_HUMAN] Inhibits pyruvate dehydrogenase activity by phosphorylation of the E1 subunit PDHA1, and thereby regulates glucose metabolism and aerobic respiration. Can also phosphorylate PDHA2. Decreases glucose utilization and increases fat metabolism in response to prolonged fasting, and as adaptation to a high-fat diet. Plays a role in glucose homeostasis and in maintaining normal blood glucose levels in function of nutrient levels and under starvation. Plays a role in the generation of reactive oxygen species. [ODP2_HUMAN] The pyruvate dehydrogenase complex catalyzes the overall conversion of pyruvate to acetyl-CoA and CO(2), and thereby links the glycolytic pathway to the tricarboxylic cycle.
About this Structure
- Devedjiev Y, Steussy CN, Vassylyev DG. Crystal structure of an asymmetric complex of pyruvate dehydrogenase kinase 3 with lipoyl domain 2 and its biological implications. J Mol Biol. 2007 Jul 13;370(3):407-16. Epub 2007 May 10. PMID:17532006 doi:10.1016/j.jmb.2007.04.083
- ↑ Baker JC, Yan X, Peng T, Kasten S, Roche TE. Marked differences between two isoforms of human pyruvate dehydrogenase kinase. J Biol Chem. 2000 May 26;275(21):15773-81. PMID:10748134 doi:10.1074/jbc.M909488199
- ↑ Korotchkina LG, Patel MS. Site specificity of four pyruvate dehydrogenase kinase isoenzymes toward the three phosphorylation sites of human pyruvate dehydrogenase. J Biol Chem. 2001 Oct 5;276(40):37223-9. Epub 2001 Aug 2. PMID:11486000 doi:10.1074/jbc.M103069200
- ↑ Korotchkina LG, Sidhu S, Patel MS. Characterization of testis-specific isoenzyme of human pyruvate dehydrogenase. J Biol Chem. 2006 Apr 7;281(14):9688-96. Epub 2006 Jan 25. PMID:16436377 doi:10.1074/jbc.M511481200
- ↑ Lu CW, Lin SC, Chen KF, Lai YY, Tsai SJ. Induction of pyruvate dehydrogenase kinase-3 by hypoxia-inducible factor-1 promotes metabolic switch and drug resistance. J Biol Chem. 2008 Oct 17;283(42):28106-14. doi: 10.1074/jbc.M803508200. Epub 2008, Aug 21. PMID:18718909 doi:10.1074/jbc.M803508200
- ↑ Kluza J, Corazao-Rozas P, Touil Y, Jendoubi M, Maire C, Guerreschi P, Jonneaux A, Ballot C, Balayssac S, Valable S, Corroyer-Dulmont A, Bernaudin M, Malet-Martino M, de Lassalle EM, Maboudou P, Formstecher P, Polakowska R, Mortier L, Marchetti P. Inactivation of the HIF-1alpha/PDK3 signaling axis drives melanoma toward mitochondrial oxidative metabolism and potentiates the therapeutic activity of pro-oxidants. Cancer Res. 2012 Oct 1;72(19):5035-47. doi: 10.1158/0008-5472.CAN-12-0979. Epub, 2012 Aug 3. PMID:22865452 doi:10.1158/0008-5472.CAN-12-0979
- ↑ Kato M, Chuang JL, Tso SC, Wynn RM, Chuang DT. Crystal structure of pyruvate dehydrogenase kinase 3 bound to lipoyl domain 2 of human pyruvate dehydrogenase complex. EMBO J. 2005 May 18;24(10):1763-74. Epub 2005 Apr 28. PMID:15861126
- ↑ Kato M, Li J, Chuang JL, Chuang DT. Distinct structural mechanisms for inhibition of pyruvate dehydrogenase kinase isoforms by AZD7545, dichloroacetate, and radicicol. Structure. 2007 Aug;15(8):992-1004. Epub 2007 Aug 2. PMID:17683942 doi:10.1016/j.str.2007.07.001