title: Crystal Structure of the Glycophorin A Transmembrane Dimer in Lipidic Cubic Phase.
abstract: The mechanisms of assembly and function for many important type I/II (single-pass) transmembrane (TM) receptors are proposed to involve the formation and/or alteration of specific interfaces among their membrane-embedded α-helical TM domains. The application of lipidic cubic phase (LCP) bilayer media for crystallization of single-α-helical TM complexes has the potential to provide valuable structural and mechanistic insights into many such systems. However, the fidelity of the interfaces observed in crowded crystalline arrays has been difficult to establish from the very limited number of such structures determined using X-ray diffraction data. Here we examine this issue using the glycophorin A (GpA) model system, whose homodimeric TM helix interface has been characterized by solution and solid-state NMR and biochemical techniques but never crystallographically. We report that a GpA-TM peptide readily crystallized in a monoolein cubic phase bilayer, yielding a dimeric α-helical structure that is in excellent agreement with previously reported NMR measurements made in several different types of host media. These results provide compelling support for the wider application of LCP techniques to enable X-ray crystallographic analysis of single-pass TM interactions.
authors.affiliation: Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research , Parkville, Victoria 3052, Australia.|Department of Medical Biology, The University of Melbourne , Parkville, Victoria 3052, Australia.
authors.forename: Raphael
authors.initials: R
authors.lastname: Trenker
authors.affiliation: Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research , Parkville, Victoria 3052, Australia.|Department of Medical Biology, The University of Melbourne , Parkville, Victoria 3052, Australia.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Call
authors.affiliation: Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research , Parkville, Victoria 3052, Australia.|Department of Medical Biology, The University of Melbourne , Parkville, Victoria 3052, Australia.
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Call
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D006021:Glycophorins / Q000737:chemistry*; D008051:Lipid Bilayers; D008969:Molecular Sequence Data; D011487:Protein Conformation
chemical_list: D006021:Glycophorins; D008051:Lipid Bilayers