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).
Posttranscriptional regulation of gene expression is an important mechanism for modulating protein levels in eukaryotes, especially in developmental pathways. The highly conserved homodimeric STAR/GSG proteins play a key role in regulating translation by binding bipartite consensus sequences in the untranslated regions of target mRNAs, but the exact mechanism remains unknown. Structures of STAR protein RNA binding subdomains have been determined, but structural information is lacking for the homodimerization subdomain. Here, we present the structure of the C. elegans GLD-1 homodimerization domain dimer, determined by a combination of X-ray crystallography and NMR spectroscopy, revealing a helix-turn-helix monomeric fold with the two protomers stacked perpendicularly. Structure-based mutagenesis demonstrates that the dimer interface is not easily disrupted, but the structural integrity of the monomer is crucial for GLD-1 dimerization. Finally, an improved model for STAR-mediated translational regulation of mRNA, based on the GLD-1 homodimerization domain structure, is presented.

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., 2009, 131 (21), pp 7320–7326

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, 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)

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)

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)

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