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Cleveland IV T, Blick E, Krueger S, Leung A, Darwish T, Butler P. Direct localization of detergents and bacteriorhodopsin in the lipidic cubic phase by small-angle neutron scattering. IUCRJ 2021; 8:22-32. [PMID: 33520240 PMCID: PMC7792994 DOI: 10.1107/s2052252520013974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 10/19/2020] [Indexed: 06/12/2023]
Abstract
Lipidic cubic phase (LCP) crystallization methods have been essential in obtaining crystals of certain membrane proteins, particularly G-protein-coupled receptors. LCP crystallization is generally optimized across a large number of potential variables, one of which may be the choice of the solubilizing detergent. A better fundamental understanding of the behavior of detergents in the LCP may guide and simplify the detergent selection process. This work investigates the distribution of protein and detergent in LCP using the membrane protein bacteriorhodopsin (bR), with the LCP prepared from highly deuterated monoolein to allow contrast-matched small-angle neutron scattering. Contrast-matching allows the scattering from the LCP bilayer itself to be suppressed, so that the distribution and behavior of the protein and detergent can be directly studied. The results showed that, for several common detergents, the detergent micelle dissociates and incorporates into the LCP bilayer essentially as free detergent monomers. In addition, the detergent octyl glucoside dissociates from bR, and neither the protein nor detergent forms clusters in the LCP. The lack of detergent assemblies in the LCP implies that, upon incorporation, micelle sizes and protein/detergent interactions become less important than they would be in solution crystallization. Crystallization screening confirmed this idea, with crystals obtained from bR in the presence of most detergents tested. Thus, in LCP crystallization, detergents can be selected primarily on the basis of protein stabilization in solution, with crystallization suitability a lesser consideration.
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Affiliation(s)
- Thomas Cleveland IV
- National Institute of Standards and Technology and Institute for Bioscience and Biotechnology Research, 9600 Gudelsky Drive, Rockville, MD 20850, USA
- National Institute of Standards and Technology Center for Neutron Research, 100 Bureau Drive, Gaithersburg, MD 20899, USA
| | - Emily Blick
- National Institute of Standards and Technology Center for Neutron Research, 100 Bureau Drive, Gaithersburg, MD 20899, USA
| | - Susan Krueger
- National Institute of Standards and Technology Center for Neutron Research, 100 Bureau Drive, Gaithersburg, MD 20899, USA
| | - Anna Leung
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
- Scientific Activities Division, European Spallation Source ERIC, Lund 224 84, Sweden
| | - Tamim Darwish
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Paul Butler
- National Institute of Standards and Technology Center for Neutron Research, 100 Bureau Drive, Gaithersburg, MD 20899, USA
- Department of Chemistry, University of Tennessee, 552 Buehler Hall, 1420 Circle Dr., Knoxville, TN 37996-1600, USA
- Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy Street, Colburn Laboratory, Newark, DE 19716, USA
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Mahieu E, Gabel F. Biological small-angle neutron scattering: recent results and development. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2018; 74:715-726. [DOI: 10.1107/s2059798318005016] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 03/27/2018] [Indexed: 02/06/2023]
Abstract
Small-angle neutron scattering (SANS) has increasingly been used by the structural biology community in recent years to obtain low-resolution information on solubilized biomacromolecular complexes in solution. In combination with deuterium labelling and solvent-contrast variation (H2O/D2O exchange), SANS provides unique information on individual components in large heterogeneous complexes that is perfectly complementary to the structural restraints provided by crystallography, nuclear magnetic resonance and electron microscopy. Typical systems studied include multi-protein or protein–DNA/RNA complexes and solubilized membrane proteins. The internal features of these systems are less accessible to the more broadly used small-angle X-ray scattering (SAXS) technique owing to a limited range of intra-complex and solvent electron-density variation. Here, the progress and developments of biological applications of SANS in the past decade are reviewed. The review covers scientific results from selected biological systems, including protein–protein complexes, protein–RNA/DNA complexes and membrane proteins. Moreover, an overview of recent developments in instruments, sample environment, deuterium labelling and software is presented. Finally, the perspectives for biological SANS in the context of integrated structural biology approaches are discussed.
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