1b68

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1b68, resolution 2.00Å ()
Resources: FirstGlance, OCA, RCSB, PDBsum
Coordinates: save as pdb, mmCIF, xml


Contents

APOLIPOPROTEIN E4 (APOE4), 22K FRAGMENT

Publication Abstract from PubMed

Apolipoprotein E (apoE) is an important lipid-transport protein in human plasma and brain. It has three common isoforms (apoE2, apoE3, and apoE4). ApoE is a major genetic risk factor in heart disease and in neurodegenerative disease, including Alzheimer's disease. The interaction of apoE with heparan sulfate proteoglycans plays an important role in lipoprotein remnant uptake and likely in atherogenesis and Alzheimer's disease. Here we report our studies of the interaction of the N-terminal domain of apoE4 (residues 1-191), which contains the major heparin-binding site, with an enzymatically prepared heparin oligosaccharide. Identified by its high affinity for the N-terminal domain of apoE4, this oligosaccharide was determined to be an octasaccharide of the structure DeltaUAp2S(1-->[4)-alpha-D-GlcNpS6S(1-->4)-alpha-L-IdoAp2S(1-->](3)4)-alph a-D-GlcNpS6S by nuclear magnetic resonance spectroscopy, capillary electrophoresis, and polyacrylamide gel electrophoresis. Kinetic analysis of the interaction between the N-terminal apoE4 fragment and immobilized heparin by surface plasmon resonance yielded a K(d) of 150 nM. A similar binding constant (K(d) = 140 nM) was observed for the interaction between immobilized N-terminal apoE4 and the octasaccharide. Isothermal titration calorimetry revealed a K(d) of 75 nM for the interaction of the N-terminal apoE fragment and the octasaccharide with a binding stoichiometry of approximately 1:1. Using previous studies and molecular modeling, we propose a binding site for this octasaccharide in a basic residue-rich region of helix 4 of the N-terminal fragment. From the X-ray crystal structure of the N-terminal apoE4, we predicted that binding of the octasaccharide at this site would result in a change in intrinsic fluorescence. This prediction was confirmed experimentally by an observed increase in fluorescence intensity with octasaccharide binding corresponding to a K(d) of approximately 1 microM.

Interaction of the N-terminal domain of apolipoprotein E4 with heparin., Dong J, Peters-Libeu CA, Weisgraber KH, Segelke BW, Rupp B, Capila I, Hernaiz MJ, LeBrun LA, Linhardt RJ, Biochemistry. 2001 Mar 6;40(9):2826-34. PMID:11258893

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

Disease

[APOE_HUMAN] Defects in APOE are a cause of hyperlipoproteinemia type 3 (HLPP3) [MIM:107741]; also known as familial dysbetalipoproteinemia. Individuals with HLPP3 are clinically characterized by xanthomas, yellowish lipid deposits in the palmar crease, or less specific on tendons and on elbows. The disorder rarely manifests before the third decade in men. In women, it is usually expressed only after the menopause. The vast majority of the patients are homozygous for APOE*2 alleles. More severe cases of HLPP3 have also been observed in individuals heterozygous for rare APOE variants. The influence of APOE on lipid levels is often suggested to have major implications for the risk of coronary artery disease (CAD). Individuals carrying the common APOE*4 variant are at higher risk of CAD.[1][2][3][4][5] Genetic variations in APOE are associated with Alzheimer disease type 2 (AD2) [MIM:104310]. It is a late-onset neurodegenerative disorder characterized by progressive dementia, loss of cognitive abilities, and deposition of fibrillar amyloid proteins as intraneuronal neurofibrillary tangles, extracellular amyloid plaques and vascular amyloid deposits. The major constituent of these plaques is the neurotoxic amyloid-beta-APP 40-42 peptide (s), derived proteolytically from the transmembrane precursor protein APP by sequential secretase processing. The cytotoxic C-terminal fragments (CTFs) and the caspase-cleaved products such as C31 derived from APP, are also implicated in neuronal death. Note=The APOE*4 allele is genetically associated with the common late onset familial and sporadic forms of Alzheimer disease. Risk for AD increased from 20% to 90% and mean age at onset decreased from 84 to 68 years with increasing number of APOE*4 alleles in 42 families with late onset AD. Thus APOE*4 gene dose is a major risk factor for late onset AD and, in these families, homozygosity for APOE*4 was virtually sufficient to cause AD by age 80. The mechanism by which APOE*4 participates in pathogenesis is not known.[6] Defects in APOE are a cause of sea-blue histiocyte disease (SBHD) [MIM:269600]; also known as sea-blue histiocytosis. This disorder is characterized by splenomegaly, mild thrombocytopenia and, in the bone marrow, numerous histiocytes containing cytoplasmic granules which stain bright blue with the usual hematologic stains. The syndrome is the consequence of an inherited metabolic defect analogous to Gaucher disease and other sphingolipidoses.[7][8][9] Defects in APOE are a cause of lipoprotein glomerulopathy (LPG) [MIM:611771]. LPG is an uncommon kidney disease characterized by proteinuria, progressive kidney failure, and distinctive lipoprotein thrombi in glomerular capillaries. It mainly affects people of Japanese and Chinese origin. The disorder has rarely been described in Caucasians.[10][11][12][13] Defects in APOE are a cause of familial hypercholesterolemia (FH) [MIM:143890]. FH is a condition characterized by elevated circulating cholesterol contained in either low-density lipoproteins alone or also in very-low-density lipoproteins.[14][15]

Function

[APOE_HUMAN] Mediates the binding, internalization, and catabolism of lipoprotein particles. It can serve as a ligand for the LDL (apo B/E) receptor and for the specific apo-E receptor (chylomicron remnant) of hepatic tissues.

About this Structure

1b68 is a 1 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA.

Reference

  • Dong J, Peters-Libeu CA, Weisgraber KH, Segelke BW, Rupp B, Capila I, Hernaiz MJ, LeBrun LA, Linhardt RJ. Interaction of the N-terminal domain of apolipoprotein E4 with heparin. Biochemistry. 2001 Mar 6;40(9):2826-34. PMID:11258893
  1. Corder EH, Saunders AM, Strittmatter WJ, Schmechel DE, Gaskell PC, Small GW, Roses AD, Haines JL, Pericak-Vance MA. Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer's disease in late onset families. Science. 1993 Aug 13;261(5123):921-3. PMID:8346443
  2. Wardell MR, Weisgraber KH, Havekes LM, Rall SC Jr. Apolipoprotein E3-Leiden contains a seven-amino acid insertion that is a tandem repeat of residues 121-127. J Biol Chem. 1989 Dec 15;264(35):21205-10. PMID:2556398
  3. Lohse P, Mann WA, Stein EA, Brewer HB Jr. Apolipoprotein E-4Philadelphia (Glu13----Lys,Arg145----Cys). Homozygosity for two rare point mutations in the apolipoprotein E gene combined with severe type III hyperlipoproteinemia. J Biol Chem. 1991 Jun 5;266(16):10479-84. PMID:1674745
  4. Richard P, Thomas G, de Zulueta MP, De Gennes JL, Thomas M, Cassaigne A, Bereziat G, Iron A. Common and rare genotypes of human apolipoprotein E determined by specific restriction profiles of polymerase chain reaction-amplified DNA. Clin Chem. 1994 Jan;40(1):24-9. PMID:8287539
  5. Solanas-Barca M, de Castro-Oros I, Mateo-Gallego R, Cofan M, Plana N, Puzo J, Burillo E, Martin-Fuentes P, Ros E, Masana L, Pocovi M, Civeira F, Cenarro A. Apolipoprotein E gene mutations in subjects with mixed hyperlipidemia and a clinical diagnosis of familial combined hyperlipidemia. Atherosclerosis. 2012 Jun;222(2):449-55. doi:, 10.1016/j.atherosclerosis.2012.03.011. Epub 2012 Mar 16. PMID:22481068 doi:10.1016/j.atherosclerosis.2012.03.011
  6. Corder EH, Saunders AM, Strittmatter WJ, Schmechel DE, Gaskell PC, Small GW, Roses AD, Haines JL, Pericak-Vance MA. Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer's disease in late onset families. Science. 1993 Aug 13;261(5123):921-3. PMID:8346443
  7. Corder EH, Saunders AM, Strittmatter WJ, Schmechel DE, Gaskell PC, Small GW, Roses AD, Haines JL, Pericak-Vance MA. Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer's disease in late onset families. Science. 1993 Aug 13;261(5123):921-3. PMID:8346443
  8. Nguyen TT, Kruckeberg KE, O'Brien JF, Ji ZS, Karnes PS, Crotty TB, Hay ID, Mahley RW, O'Brien T. Familial splenomegaly: macrophage hypercatabolism of lipoproteins associated with apolipoprotein E mutation [apolipoprotein E (delta149 Leu)]. J Clin Endocrinol Metab. 2000 Nov;85(11):4354-8. PMID:11095479
  9. Faivre L, Saugier-Veber P, Pais de Barros JP, Verges B, Couret B, Lorcerie B, Thauvin C, Charbonnier F, Huet F, Gambert P, Frebourg T, Duvillard L. Variable expressivity of the clinical and biochemical phenotype associated with the apolipoprotein E p.Leu149del mutation. Eur J Hum Genet. 2005 Nov;13(11):1186-91. PMID:16094309 doi:5201480
  10. Corder EH, Saunders AM, Strittmatter WJ, Schmechel DE, Gaskell PC, Small GW, Roses AD, Haines JL, Pericak-Vance MA. Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer's disease in late onset families. Science. 1993 Aug 13;261(5123):921-3. PMID:8346443
  11. Oikawa S, Matsunaga A, Saito T, Sato H, Seki T, Hoshi K, Hayasaka K, Kotake H, Midorikawa H, Sekikawa A, Hara S, Abe K, Toyota T, Jingami H, Nakamura H, Sasaki J. Apolipoprotein E Sendai (arginine 145-->proline): a new variant associated with lipoprotein glomerulopathy. J Am Soc Nephrol. 1997 May;8(5):820-3. PMID:9176854
  12. Matsunaga A, Sasaki J, Komatsu T, Kanatsu K, Tsuji E, Moriyama K, Koga T, Arakawa K, Oikawa S, Saito T, Kita T, Doi T. A novel apolipoprotein E mutation, E2 (Arg25Cys), in lipoprotein glomerulopathy. Kidney Int. 1999 Aug;56(2):421-7. PMID:10432380 doi:kid572
  13. Rovin BH, Roncone D, McKinley A, Nadasdy T, Korbet SM, Schwartz MM. APOE Kyoto mutation in European Americans with lipoprotein glomerulopathy. N Engl J Med. 2007 Dec 13;357(24):2522-4. PMID:18077821 doi:10.1056/NEJMc072088
  14. Corder EH, Saunders AM, Strittmatter WJ, Schmechel DE, Gaskell PC, Small GW, Roses AD, Haines JL, Pericak-Vance MA. Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer's disease in late onset families. Science. 1993 Aug 13;261(5123):921-3. PMID:8346443
  15. Marduel M, Ouguerram K, Serre V, Bonnefont-Rousselot D, Marques-Pinheiro A, Erik Berge K, Devillers M, Luc G, Lecerf JM, Tosolini L, Erlich D, Peloso GM, Stitziel N, Nitchke P, Jais JP, Abifadel M, Kathiresan S, Leren TP, Rabes JP, Boileau C, Varret M. Description of a large family with autosomal dominant hypercholesterolemia associated with the APOE p.Leu167del mutation. Hum Mutat. 2013 Jan;34(1):83-7. doi: 10.1002/humu.22215. Epub 2012 Oct 11. PMID:22949395 doi:10.1002/humu.22215

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