Structure of outer membrane protein G in lipid bilayers.
Retel, J.S., Nieuwkoop, A.J., Hiller, M., Higman, V.A., Barbet-Massin, E., Stanek, J., Andreas, L.B., Franks, W.T., van Rossum, B.J., Vinothkumar, K.R., Handel, L., de Palma, G.G., Bardiaux, B., Pintacuda, G., Emsley, L., Kuhlbrandt, W., Oschkinat, H.(2017) Nat Commun 8: 2073-2073
- PubMed: 29233991 
- DOI: https://doi.org/10.1038/s41467-017-02228-2
- Primary Citation of Related Structures:  
5MWV - PubMed Abstract: 
β-barrel proteins mediate nutrient uptake in bacteria and serve vital functions in cell signaling and adhesion. For the 14-strand outer membrane protein G of Escherichia coli, opening and closing is pH-dependent. Different roles of the extracellular loops in this process were proposed, and X-ray and solution NMR studies were divergent. Here, we report the structure of outer membrane protein G investigated in bilayers of E. coli lipid extracts by magic-angle-spinning NMR. In total, 1847 inter-residue 1 H- 1 H and 13 C- 13 C distance restraints, 256 torsion angles, but no hydrogen bond restraints are used to calculate the structure. The length of β-strands is found to vary beyond the membrane boundary, with strands 6-8 being the longest and the extracellular loops 3 and 4 well ordered. The site of barrel closure at strands 1 and 14 is more disordered than most remaining strands, with the flexibility decreasing toward loops 3 and 4. Loop 4 presents a well-defined helix.
Organizational Affiliation: 
Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125, Berlin, Germany.