Pyruvate dehydrogenase kinase isoform 3 in complex with antitumor drug radicicol
[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.
Publication Abstract from PubMed
Pyruvate dehydrogenase kinase (PDK) isoforms are molecular switches that downregulate the pyruvate dehydrogenase complex (PDC) by reversible phosphorylation in mitochondria. We have determined structures of human PDK1 or PDK3 bound to the inhibitors AZD7545, dichloroacetate (DCA), and radicicol. We show that the trifluoromethylpropanamide end of AZD7545 projects into the lipoyl-binding pocket of PDK1. This interaction results in inhibition of PDK1 and PDK3 activities by aborting kinase binding to the PDC scaffold. Paradoxically, AZD7545 at saturating concentrations robustly increases scaffold-free PDK3 activity, similar to the inner lipoyl domain. Good DCA density is present in the helix bundle in the N-terminal domain of PDK1. Bound DCA promotes local conformational changes that are communicated to both nucleotide-binding and lipoyl-binding pockets of PDK1, leading to the inactivation of kinase activity. Finally, radicicol inhibits kinase activity by binding directly to the ATP-binding pocket of PDK3, similar to Hsp90 and Topo VI from the same ATPase/kinase superfamily.
Distinct structural mechanisms for inhibition of pyruvate dehydrogenase kinase isoforms by AZD7545, dichloroacetate, and radicicol.,Kato M, Li J, Chuang JL, Chuang DT Structure. 2007 Aug;15(8):992-1004. Epub 2007 Aug 2. PMID:17683942
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.