PDK3

Pyruvate dehydrogenase kinase, isozyme 3

PDB rendering based on 1y8n.
Available structures
PDB Ortholog search: PDBe, RCSB
Identifiers
Symbols PDK3 ; CMTX6; GS1-358P8.4
External IDs OMIM: 300906 MGI: 2384308 HomoloGene: 55897 ChEMBL: 3893 GeneCards: PDK3 Gene
EC number 2.7.11.2
RNA expression pattern
More reference expression data
Orthologs
Species Human Mouse
Entrez 5165 236900
Ensembl ENSG00000067992 ENSMUSG00000035232
UniProt Q15120 Q922H2
RefSeq (mRNA) NM_001142386 NM_145630
RefSeq (protein) NP_001135858 NP_663605
Location (UCSC) Chr X:
24.47 – 24.54 Mb		 Chr X:
93.76 – 93.83 Mb
PubMed search

Pyruvate dehydrogenase lipoamide kinase isozyme 3, mitochondrial is an enzyme that in humans is encoded by the PDK3 gene.[1] [2] It codes for an isozyme of pyruvate dehydrogenase kinase.The pyruvate dehydrogenase (PDH) complex is a nuclear-encoded mitochondrial multienzyme complex that catalyzes the overall conversion of pyruvate to acetyl-CoA and CO(2). It provides the primary link between glycolysis and the tricarboxylic acid (TCA) cycle, and thus is one of the major enzymes responsible for the regulation of glucose metabolism. The enzymatic activity of PDH is regulated by a phosphorylation/dephosphorylation cycle, and phosphorylation results in inactivation of PDH. The protein encoded by this gene is one of the four pyruvate dehydrogenase kinases that inhibits the PDH complex by phosphorylation of the E1 alpha subunit. This gene is predominantly expressed in the heart and skeletal muscles. Alternatively spliced transcript variants encoding different isoforms have been found for this gene.[2]

Structure

The structure of the PDK3/L2 complex has been elucidated, and there are several key features. When the L2 domain binds to PDK3, it induces a “cross-tail” conformation in PDK3, thereby stimulating activity. There are three crucial residues, Leu-140, Glu-170, and Glu-179, in the C-terminal domain that are crucial for this interaction.[3] Structural studies have indicated that L2 binding stimulates activity by disrupting the closed conformation, or ATP lid, to remove product inhibition.[4] The PDK3 subunits are in one of two conformations; one subunit exists as an “open” subunit, while the other subunit is “closed”. The open subunit is the configuration most crucial to the putative substrate-binding cleft, as it is where the target peptide can access the active center. The closed subunit blocks this target peptide because of a neighboring unwound alpha helix. Additionally, the ATP-binding loop in one PDK3 subunit adopts an open conformation, implying that the nucleotide loading into the active site is mediated by the inactive "pre-insertion" binding mode. This asymmetric complex represents a physiological state in which binding of a single L2-domain activates one of the PDHK subunits while inactivating another.[5] Thus, the L2-domains likely act not only as the structural anchors but also modulate the catalytic cycle of PDK3.

Function

The Pyruvate Dehydrogenase (PDH) complex must be tightly regulated due to its central role in general metabolism. Within the complex, there are three serine residues on the E1 component that are sites for phosphorylation; this phosphorylation inactivates the complex. In humans, there have been four isozymes of Pyruvate Dehydrogenase Kinase that have been shown to phosphorylate these three sites: PDK1, PDK2, PDK3, and PDK4.[6] The PDK3 protein is primarily found in the kidney, brain, and testis.[7]

Regulation

As the primary regulators of a crucial step in the central metabolic pathway, the pyruvate dehydrogenase family is tightly regulated itself by a myriad of factors. PDK3, in conjunction with PDK2 and PDK4, are primary targets of Peroxisome proliferator-activated receptor delta or beta, with PDK3 having five elements that respond to these receptors.[8]

Model organisms

Model organisms have been used in the study of PDK3 function. A conditional knockout mouse line called Pdk3tm2a(KOMP)Wtsi was generated at the Wellcome Trust Sanger Institute.[9] Male and female animals underwent a standardized phenotypic screen[10] to determine the effects of deletion.[11][12][13][14] Additional screens performed: - In-depth immunological phenotyping[15]

References

  1. ↑ Gudi R, Bowker-Kinley MM, Kedishvili NY, Zhao Y, Popov KM (Dec 1995). "Diversity of the pyruvate dehydrogenase kinase gene family in humans". The Journal of Biological Chemistry 270 (48): 28989–94. doi:10.1074/jbc.270.48.28989. PMID 7499431.
  2. 1 2 "Entrez Gene: PDK3 pyruvate dehydrogenase kinase, isozyme 3".
  3. ↑ Tso SC, Kato M, Chuang JL, Chuang DT (Sep 2006). "Structural determinants for cross-talk between pyruvate dehydrogenase kinase 3 and lipoyl domain 2 of the human pyruvate dehydrogenase complex". The Journal of Biological Chemistry 281 (37): 27197–204. doi:10.1074/jbc.M604339200. PMID 16849321.
  4. ↑ Kato M, Chuang JL, Tso SC, Wynn RM, Chuang DT (May 2005). "Crystal structure of pyruvate dehydrogenase kinase 3 bound to lipoyl domain 2 of human pyruvate dehydrogenase complex". The EMBO Journal 24 (10): 1763–74. doi:10.1038/sj.emboj.7600663. PMC 1142596. PMID 15861126.
  5. ↑ Devedjiev Y, Steussy CN, Vassylyev DG (Jul 2007). "Crystal structure of an asymmetric complex of pyruvate dehydrogenase kinase 3 with lipoyl domain 2 and its biological implications". Journal of Molecular Biology 370 (3): 407–16. doi:10.1016/j.jmb.2007.04.083. PMC 1994203. PMID 17532006.
  6. ↑ Kolobova E, Tuganova A, Boulatnikov I, Popov KM (Aug 2001). "Regulation of pyruvate dehydrogenase activity through phosphorylation at multiple sites". The Biochemical Journal 358 (Pt 1): 69–77. doi:10.1042/0264-6021:3580069. PMC 1222033. PMID 11485553.
  7. ↑ Sugden MC, Holness MJ (Jul 2002). "Therapeutic potential of the mammalian pyruvate dehydrogenase kinases in the prevention of hyperglycaemia". Current Drug Targets. Immune, Endocrine and Metabolic Disorders 2 (2): 151–65. doi:10.2174/1568005310202020151. PMID 12476789.
  8. ↑ Degenhardt T, Saramäki A, Malinen M, Rieck M, Väisänen S, Huotari A, Herzig KH, Müller R, Carlberg C (Sep 2007). "Three members of the human pyruvate dehydrogenase kinase gene family are direct targets of the peroxisome proliferator-activated receptor beta/delta". Journal of Molecular Biology 372 (2): 341–55. doi:10.1016/j.jmb.2007.06.091. PMID 17669420.
  9. ↑ Gerdin AK (2010). "The Sanger Mouse Genetics Programme: high throughput characterisation of knockout mice". Acta Ophthalmologica 88: 925–7. doi:10.1111/j.1755-3768.2010.4142.x.
  10. 1 2 "International Mouse Phenotyping Consortium".
  11. ↑ Skarnes WC, Rosen B, West AP, Koutsourakis M, Bushell W, Iyer V, Mujica AO, Thomas M, Harrow J, Cox T, Jackson D, Severin J, Biggs P, Fu J, Nefedov M, de Jong PJ, Stewart AF, Bradley A (Jun 2011). "A conditional knockout resource for the genome-wide study of mouse gene function". Nature 474 (7351): 337–42. doi:10.1038/nature10163. PMC 3572410. PMID 21677750.
  12. ↑ Dolgin E (Jun 2011). "Mouse library set to be knockout". Nature 474 (7351): 262–3. doi:10.1038/474262a. PMID 21677718.
  13. ↑ Collins FS, Rossant J, Wurst W (Jan 2007). "A mouse for all reasons". Cell 128 (1): 9–13. doi:10.1016/j.cell.2006.12.018. PMID 17218247.
  14. ↑ White JK, Gerdin AK, Karp NA, Ryder E, Buljan M, Bussell JN, Salisbury J, Clare S, Ingham NJ, Podrini C, Houghton R, Estabel J, Bottomley JR, Melvin DG, Sunter D, Adams NC, Tannahill D, Logan DW, Macarthur DG, Flint J, Mahajan VB, Tsang SH, Smyth I, Watt FM, Skarnes WC, Dougan G, Adams DJ, Ramirez-Solis R, Bradley A, Steel KP (Jul 2013). "Genome-wide generation and systematic phenotyping of knockout mice reveals new roles for many genes". Cell 154 (2): 452–64. doi:10.1016/j.cell.2013.06.022. PMC 3717207. PMID 23870131.
  15. 1 2 "Infection and Immunity Immunophenotyping (3i) Consortium".

Further reading

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