Dewald AH, Hodges JC, Columbus L. Biophysical Journal 100:2131 – 2140.
The spontaneous folding of two Neisseria outer membrane proteins, opacity-associated (Opa)₆₀ and Opa₅₀ into lipid vesicles was investigated by systematically varying bulk and membrane properties. Centrifugal fractionation coupled with sodium dodecyl sulfate polyacrylamide gel electrophoresis mobility assays enabled the discrimination of aggregate, unfolded membrane-associated, and folded membrane-inserted protein states as well as the influence of pH, ionic strength, membrane surface potential, lipid saturation, and urea on each. Protein aggregation was reduced with increasing lipid chain length, basic pH, low salt, the incorporation of negatively charged guest lipids, or by the addition of urea to the folding reaction. Insertion from the membrane-associated form was improved in shorter chain lipids, with more basic pH and low ionic strength; it is hindered by unsaturated or ether-linked lipids. The isolation of the physical determinants of insertion suggests that the membrane surface and dipole potentials are driving forces for outer membrane protein insertion and folding into lipid bilayers.

Kroncke BM, Horanyi PS, and Columbus L. Structural origins of nitroxide side chain dynamics on membrane protein α-helical sites. Biochemistry 49:10045–10060 (2010)

Beuck C, Szymczyna BR, Kerkow DE, Carmel AB, Columbus L, Stanfield RL, Williamson JR. Structure of the GLD-1 homodimerization domain: insights into STAR protein-mediated translational regulation. Structure 18:377-89 (2010).

Columbus L, Lipfert J, Jambunathan K, Fox DA, Sim AYL, Doniach S, and Lesley SA. Mixing and Matching Detergents for Membrane Protein NMR Structure Determination J. Am. Chem. Soc. 131:7320–7326 (2009)

Columbus L, Nakamoto, RK, Cafiso, DS. Chapter in Wiley Encyclopedia of Chemical Biology (2008)

McCleverty C*, Columbus L*, Kreusch A, Lesley SA. Structure and ligand binding of the soluble domain of a Thermotoga maritima membrane protein of unknown function TM1634. Protein Science 17:869-77 (2008).

Lipfert J, Columbus L, Chu V, Doniach S. Analysis of small-angle X-ray scattering data of protein-detergent complexes with singular value decomposition. Journal of Applied Crystallography 40: s235-s239 (2007)

Lipfert J, Columbus L, Chu V, Lesley SA, Doniach S. Size and shape of detergent micelles determined by small-angle X-ray scattering. Journal of Physical Chemistry B 111: 12427-12438 (2007)

Columbus L, Lipfert J, Klock H, Millet I, Doniach S, Lesley SA. Expression, purification, and characterization of Thermotoga maritimamembrane proteins for structure determination. Protein Science 15: 961-975 (2006)

Columbus L, Peti W, Herrmann T, Etezady T, Wüthrich K. NMR structure determination of the conserved hypothetical protein TM1816 from Thermotoga maritima . Proteins: Structure, Function and Bioinformatics 60: 552-557 (2005)

Columbus L, Hubbell WL. Mapping backbone dynamics in solution with site-directed spin labeling: GCN4-58 bZip free and bound to DNA. Biochemistry 43: 7273-7287 (2004)

Liang ZC, Lou Y, Freed JH, Columbus L, Hubbell WL. A multifrequency electron spin resonance study of T4 lysozyme dynamics using the slowly relaxing local structure model Journal of Physical Chemistry B 108: 17649-17659 (2004)

Columbus L, Hubbell WL. A new spin on protein dynamics. Trends in Biochemical Sciences, 27: 288-295 (2002)

Columbus L, Kalai T, Jeko J, Hideg K, Hubbell WL. Molecular motion of spin labeled side chains in α-helices: Analysis by variation of side chain structure. Biochemistry 40: 3828-3846 (2001)

Gaponenko V, Howarth JW, Columbus L, Gasmi-Seabrook G, Yuan J, Hubbell WL, Rosevear PR. Protein global fold determination using site-directed spin and isotope labeling. Protein Science 9: 302-309 (2000)

Gross A, Columbus L, Hideg K, Altenbach C, Hubbell WL. Structure of the KcsA potassium channel from Streptomyces lividans: A site-directed spin labeling study of the second transmembrane segment. Biochemistry 38: 10324-10335 (1999)