title: Visualizing Specific Cross-Protomer Interactions in the Homo-Oligomeric Membrane Protein Proteorhodopsin by Dynamic-Nuclear-Polarization-Enhanced Solid-State NMR.
abstract: Membrane proteins often form oligomeric complexes within the lipid bilayer, but factors controlling their assembly are hard to predict and experimentally difficult to determine. An understanding of protein-protein interactions within the lipid bilayer is however required in order to elucidate the role of oligomerization for their functional mechanism and stabilization. Here, we demonstrate for the pentameric, heptahelical membrane protein green proteorhodopsin that solid-state NMR could identify specific interactions at the protomer interfaces, if the sensitivity is enhanced by dynamic nuclear polarization. For this purpose, differently labeled protomers have been assembled into the full pentamer complex embedded within the lipid bilayer. We show for this proof of concept that one specific salt bridge determines the formation of pentamers or hexamers. Data are supported by laser-induced liquid bead ion desorption mass spectrometry and by blue native polyacrylamide gel electrophoresis analysis. The presented approach is universally applicable and opens the door toward analyzing membrane protein interactions within homo-oligomers directly in the membrane.
authors.forename: Jakob
authors.initials: J
authors.lastname: Maciejko
authors.forename: Michaela
authors.initials: M
authors.lastname: Mehler
authors.forename: Jagdeep
authors.initials: J
authors.lastname: Kaur
authors.forename: Tobias
authors.initials: T
authors.lastname: Lieblein
authors.forename: Nina
authors.initials: N
authors.lastname: Morgner
authors.affiliation: §Aix-Marseille Université, CNRS, ICR, UMR 7273, 13013 Marseille, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Ouari
authors.affiliation: §Aix-Marseille Université, CNRS, ICR, UMR 7273, 13013 Marseille, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Tordo
authors.forename: Johanna
authors.initials: J
authors.lastname: Becker-Baldus
authors.forename: Clemens
authors.initials: C
authors.lastname: Glaubitz
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D055503:Protein Multimerization; D020560:Proteobacteria / Q000737:chemistry*; D025604:Rhodopsins, Microbial / Q000737:chemistry*; D012492:Salts / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D008051:Lipid Bilayers; D025604:Rhodopsins, Microbial; D012492:Salts; C413548:proteorhodopsin