title: The structure, dynamics, and binding of the LA45 module pair of the low-density lipoprotein receptor suggest an important role for LA4 in ligand release.
abstract: The low-density lipoprotein receptor (LDLR), the primary receptor for cholesterol uptake, binds ligands through its seven LDL-A modules (LAs). We present nuclear magnetic resonance (NMR) and ligand binding measurements on the fourth and fifth modules of the LDLR (LA45), the modules critical for ApoE binding, at physiological pH. Unlike LA5 and all other modules in LDLR, LA4 has a very weak calcium affinity, which probably plays a critical role in endosomal ligand release. The NMR solution structure of each module in the LA45 pair only showed minor differences compared to the analogous domains in previously determined crystal structures. The 12-residue linker connecting the modules, though slightly structured through an interaction with LA4, is highly flexible. Although no intermodule nuclear Overhauser effects were detected, chemical shift perturbations and backbone dynamics suggest cross talk between the two modules. The ligand affinity of both modules is enhanced when the two are linked. LA4 is more flexible than LA5 and remains so even in the module pair, which likely is related to its weaker calcium binding affinity.
authors.affiliation: Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0378, United States.
authors.forename: Miklos
authors.initials: M
authors.lastname: Guttman
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Komives
mesh_terms: D001057:Apolipoproteins E / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002151:Calorimetry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D058849:Protein Refolding; D011973:Receptors, LDL / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013816:Thermodynamics; D017186:Titrimetry
chemical_list: D001057:Apolipoproteins E; D008024:Ligands; D010446:Peptide Fragments; D011973:Receptors, LDL; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D002118:Calcium
references.citation: Science. 2002 Dec 20;298(5602):2353-8
references.pmid: 12459547
references.citation: J Magn Reson. 2001 Apr;149(2):271-5
references.pmid: 11318629
references.citation: Biochemistry. 2001 Dec 18;40(50):15127-34
references.pmid: 11735395
references.citation: Curr Opin Struct Biol. 2007 Aug;17(4):419-26
references.pmid: 17870468
references.citation: Mol Cell. 2006 Apr 21;22(2):277-83
references.pmid: 16630895
references.citation: J Biol Chem. 1989 Dec 25;264(36):21682-8
references.pmid: 2600087
references.citation: BMC Biochem. 2003 Aug 18;4:7
references.pmid: 12921543
references.citation: J Biomol NMR. 1999 Feb;13(2):175-80
references.pmid: 10070758
references.citation: Nat Protoc. 2008;3(4):679-90
references.pmid: 18388951
references.citation: J Biol Chem. 2004 Apr 16;279(16):16629-37
references.pmid: 14749324
references.citation: J Magn Reson. 2000 Nov;147(1):138-46
references.pmid: 11042057
references.citation: Biochemistry. 1995 Nov 7;34(44):14474-81
references.pmid: 7578052
references.citation: Proc Natl Acad Sci U S A. 1995 Jul 3;92(14):6334-8
references.pmid: 7603991
references.citation: Biochemistry. 2010 Feb 16;49(6):1207-16
references.pmid: 20030366
references.citation: Biochemistry. 2001 Mar 6;40(9):2808-15
references.pmid: 11258891
references.citation: Nat Protoc. 2007;2(11):2728-33
references.pmid: 18007608
references.citation: Biochemistry. 2000 Mar 14;39(10):2564-71
references.pmid: 10704205
references.citation: J Biol Chem. 2008 Aug 15;283(33):22670-9
references.pmid: 18574243
references.citation: Nature. 1997 Aug 14;388(6643):691-3
references.pmid: 9262405
references.citation: Protein Sci. 2000 Jul;9(7):1282-93
references.pmid: 10933493
references.citation: J Biomol NMR. 1999 Mar;13(3):289-302
references.pmid: 10212987
references.citation: J Biomol NMR. 1991 Sep;1(3):299-304
references.pmid: 1841700
references.citation: Biochemistry. 2005 Apr 5;44(13):5075-85
references.pmid: 15794645
references.citation: Curr Biol. 1998 Dec 3;8(24):1335-8
references.pmid: 9843688
references.citation: J Mol Biol. 1998 Aug 14;281(2):341-61
references.pmid: 9698552
references.citation: J Magn Reson B. 1996 Aug;112(2):200-5
references.pmid: 8812906
references.citation: Curr Opin Struct Biol. 2003 Dec;13(6):683-9
references.pmid: 14675545
references.citation: J Mol Biol. 2009 Oct 23;393(2):409-24
references.pmid: 19715701
references.citation: Biochemistry. 2005 Dec 6;44(48):15750-9
references.pmid: 16313178
references.citation: J Biomol NMR. 1995 Nov;6(3):277-93
references.pmid: 8520220
references.citation: J Biol Chem. 2000 Sep 29;275(39):30458-64
references.pmid: 10889196
references.citation: J Biol Chem. 1988 Sep 15;263(26):13282-90
references.pmid: 3417658
references.citation: Biochemistry. 2009 Aug 4;48(30):7313-24
references.pmid: 19583244
references.citation: J Biol Chem. 2009 May 15;284(20):13396-13400
references.pmid: 19329437
references.citation: J Mol Biol. 2006 Sep 29;362(4):700-16
references.pmid: 16938309
references.citation: J Lipid Res. 2005 Aug;46(8):1721-31
references.pmid: 15863833
references.citation: Proc Natl Acad Sci U S A. 2010 Jan 19;107(3):1059-64
references.pmid: 20080547
references.citation: Biochemistry. 2001 Dec 18;40(50):15408-17
references.pmid: 11735425
references.citation: Biochemistry. 2004 Feb 3;43(4):1037-44
references.pmid: 14744149
references.citation: Nat Struct Biol. 1996 Sep;3(9):758-62
references.pmid: 8784348
references.citation: Biochemistry. 1999 Mar 30;38(13):3926-35
references.pmid: 10194304
references.citation: Nucleic Acids Res. 2004 Jul 1;32(Web Server issue):W590-4
references.pmid: 15215457
references.citation: Biochemistry. 1998 Aug 4;37(31):10994-1002
references.pmid: 9692993
references.citation: Biochemistry. 2000 Feb 8;39(5):890-902
references.pmid: 10653632
references.citation: J Magn Reson. 2011 Dec;213(2):423-41
references.pmid: 22152361
references.citation: Bioinformatics. 2007 Feb 1;23(3):381-2
references.pmid: 17121777
references.citation: J Mol Biol. 1997 Feb 7;265(5):565-79
references.pmid: 9048949