title: In situ structural studies of Anabaena sensory rhodopsin in the E. coli membrane.
abstract: Magic-angle spinning nuclear magnetic resonance is well suited for the study of membrane proteins in the nativelike lipid environment. However, the natural cellular membrane is invariably more complex than the proteoliposomes most often used for solid-state NMR (SSNMR) studies, and differences may affect the structure and dynamics of the proteins under examination. In this work we use SSNMR and other biochemical and biophysical methods to probe the structure of a seven-transmembrane helical photoreceptor, Anabaena sensory rhodopsin (ASR), prepared in the Escherichia coli inner membrane, and compare it to that in a bilayer formed by DMPC/DMPA lipids. We find that ASR is organized into trimers in both environments but forms two-dimensional crystal lattices of different symmetries. It favors hexagonal packing in liposomes, but may form a square lattice in the E. coli membrane. To examine possible changes in structure site-specifically, we perform two- and three-dimensional SSNMR experiments and analyze the differences in chemical shifts and peak intensities. Overall, this analysis reveals that the structure of ASR is largely conserved in the inner membrane of E. coli, with many of the important structural features of rhodopsins previously observed in ASR in proteoliposomes being preserved. Small, site-specific perturbations in protein structure that occur as a result of the membrane changes indicate that the protein can subtly adapt to its environment without large structural rearrangement.
authors: Department of Physics, University of Guelph, Guelph, Ontario, Canada; Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada.
authors: Meaghan E
authors: ME
authors: Ward
authors: Department of Physics, University of Guelph, Guelph, Ontario, Canada; Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada.
authors: Shenlin
authors: S
authors: Wang
authors: Department of Physics, University of Guelph, Guelph, Ontario, Canada; Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada.
authors: Rachel
authors: R
authors: Munro
authors: Department of Physics, University of Guelph, Guelph, Ontario, Canada.
authors: Emily
authors: E
authors: Ritz
authors: National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida.
authors: Ivan
authors: I
authors: Hung
authors: National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida.
authors: Peter L
authors: PL
authors: Gor'kov
authors: Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado.
authors: Yunjiang
authors: Y
authors: Jiang
authors: Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado.
authors: Hongjun
authors: H
authors: Liang
authors: Department of Physics, University of Guelph, Guelph, Ontario, Canada; Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada. Electronic address: lebrown@uoguelph.ca.
authors: Leonid S
authors: LS
authors: Brown
authors: Department of Physics, University of Guelph, Guelph, Ontario, Canada; Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada. Electronic address: vladizha@uoguelph.ca.
authors: Vladimir
authors: V
authors: Ladizhansky
mesh_terms: D000595:Amino Acid Sequence; D017033:Anabaena / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D025603:Sensory Rhodopsins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D008051:Lipid Bilayers; D025603:Sensory Rhodopsins