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Gogonea V, Gerstenecker GS, Wu Z, Lee X, Topbas C, Wagner MA, Tallant TC, Smith JD, Callow P, Pipich V, Malet H, Schoehn G, DiDonato JA, Hazen SL. The low-resolution structure of nHDL reconstituted with DMPC with and without cholesterol reveals a mechanism for particle expansion. J Lipid Res 2013; 54:966-83. [PMID: 23349207 DOI: 10.1194/jlr.m032763] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Small-angle neutron scattering (SANS) with contrast variation was used to obtain the low-resolution structure of nascent HDL (nHDL) reconstituted with dimyristoyl phosphatidylcholine (DMPC) in the absence and presence of cholesterol, [apoA1:DMPC (1:80, mol:mol) and apoA1:DMPC:cholesterol (1:86:9, mol:mol:mol)]. The overall shape of both particles is discoidal with the low-resolution structure of apoA1 visualized as an open, contorted, and out of plane conformation with three arms in nascent HDL/dimyristoyl phosphatidylcholine without cholesterol (nHDL(DMPC)) and two arms in nascent HDL/dimyristoyl phosphatidylcholine with cholesterol (nHDL(DMPC+Chol)). The low-resolution shape of the lipid phase in both nHDL(DMPC) and nHDL(DMPC+Chol) were oblate ellipsoids, and fit well within their respective protein shapes. Modeling studies indicate that apoA1 is folded onto itself in nHDL(DMPC), making a large hairpin, which was also confirmed independently by both cross-linking mass spectrometry and hydrogen-deuterium exchange (HDX) mass spectrometry analyses. In nHDL(DMPC+Chol), the lipid was expanded and no hairpin was visible. Importantly, despite the overall discoidal shape of the whole particle in both nHDL(DMPC) and nHDL(DMPC+Chol), an open conformation (i.e., not a closed belt) of apoA1 is observed. Collectively, these data show that full length apoA1 retains an open architecture that is dictated by its lipid cargo. The lipid is likely predominantly organized as a bilayer with a micelle domain between the open apoA1 arms. The apoA1 configuration observed suggests a mechanism for accommodating changing lipid cargo by quantized expansion of hairpin structures.
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Affiliation(s)
- Valentin Gogonea
- Department of Cellular and Molecular Medicine, Cleveland Clinic, Cleveland, OH, USA.
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Wu Z, Gogonea V, Lee X, Wagner MA, Li XM, Huang Y, Undurti A, May RP, Haertlein M, Moulin M, Gutsche I, Zaccai G, DiDonato JA, Hazen SL. Double superhelix model of high density lipoprotein. J Biol Chem 2009; 284:36605-36619. [PMID: 19812036 DOI: 10.1074/jbc.m109.039537] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
High density lipoprotein (HDL), the carrier of so-called "good" cholesterol, serves as the major athero-protective lipoprotein and has emerged as a key therapeutic target for cardiovascular disease. We applied small angle neutron scattering (SANS) with contrast variation and selective isotopic deuteration to the study of nascent HDL to obtain the low resolution structure in solution of the overall time-averaged conformation of apolipoprotein AI (apoA-I) versus the lipid (acyl chain) core of the particle. Remarkably, apoA-I is observed to possess an open helical shape that wraps around a central ellipsoidal lipid phase. Using the low resolution SANS shapes of the protein and lipid core as scaffolding, an all-atom computational model for the protein and lipid components of nascent HDL was developed by integrating complementary structural data from hydrogen/deuterium exchange mass spectrometry and previously published constraints from multiple biophysical techniques. Both SANS data and the new computational model, the double superhelix model, suggest an unexpected structural arrangement of protein and lipids of nascent HDL, an anti-parallel double superhelix wrapped around an ellipsoidal lipid phase. The protein and lipid organization in nascent HDL envisages a potential generalized mechanism for lipoprotein biogenesis and remodeling, biological processes critical to sterol and lipid transport, organismal energy metabolism, and innate immunity.
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Affiliation(s)
- Zhiping Wu
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Valentin Gogonea
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Department of Chemistry, Cleveland State University, Cleveland, Ohio 44115
| | - Xavier Lee
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Matthew A Wagner
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Xin-Min Li
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Ying Huang
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Arundhati Undurti
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Roland P May
- Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
| | - Michael Haertlein
- Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
| | - Martine Moulin
- Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
| | - Irina Gutsche
- Unit of Virus-Host Interaction, Unité Mixte de Recherche 5233 Université Joseph Fourier-European Molecular Biology Laboratory-CNRS, 6 Rue Jules Horowitz, BP 181, 38042 Grenoble Cedex 9, France
| | - Giuseppe Zaccai
- Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France; Institut de Biologie Structurale, Commissariat à l'Energie Atomique-CNRS-Université Joseph Fourier, 38027 Grenoble, France
| | - Joseph A DiDonato
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Stanley L Hazen
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195; Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio 44195.
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Abstract
The assignment of specific ribosomal functions to individual ribosomal proteins is difficult due to the enormous cooperativity of the ribosome; however, important roles for distinct ribosomal proteins are becoming evident. Although rRNA has a major role in certain aspects of ribosomal function, such as decoding and peptidyl-transferase activity, ribosomal proteins are nevertheless essential for the assembly and optimal functioning of the ribosome. This is particularly true in the context of interactions at the entrance pore for mRNA, for the translation-factor binding site and at the tunnel exit, where both chaperones and complexes associated with protein transport through membranes bind.
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Stuhrmann HB. Small-angle scattering and its interplay with crystallography, contrast variation in SAXS and SANS. Acta Crystallogr A 2007; 64:181-91. [DOI: 10.1107/s0108767307046569] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2007] [Accepted: 09/21/2007] [Indexed: 11/10/2022] Open
Abstract
Methods of contrast variation are tools that are essential in macromolecular structure research. Anomalous dispersion of X-ray diffraction is widely used in protein crystallography. Recent attempts to extend this method to native resonant labels like sulfur and phosphorus are promising. Substitution of hydrogen isotopes is central to biological applications of neutron scattering. Proton spin polarization considerably enhances an existing contrast prepared by isotopic substitution. Concepts and methods of nuclear magnetic resonance (NMR) become an important ingredient in neutron scattering from dynamically polarized targets.
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