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Chembiochem. 2014 May 5;15(7):995-1000. doi: 10.1002/cbic.201300729. Epub 2014 Apr 1.

Solution-NMR characterization of outer-membrane protein A from E. coli in lipid bilayer nanodiscs and detergent micelles.

Author information

1
Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037 (USA).

Abstract

X-ray crystallography and solution NMR of detergent-reconstituted OmpA (outer membrane protein A from E. coli) had shown that this protein forms an eight-stranded transmembrane β-barrel, but only limited information was obtained for the extracellular loops. In NMR studies of OmpA in two different detergent micelles, "NMR-invisible" amino acid residues in-between the extracellular loops and the β-barrel prevented complete structural characterization. Here, we show that this NMR-invisible ring around the β-barrel of OmpA is also present in lipid bilayer nanodiscs and in mixed micelles with a third detergent, thus suggesting that the implicated rate processes have a functional role rather than representing an artifact of the protein reconstitution. In addition to sequence-specific NMR assignments for OmpA in the nanodiscs, the present results are based on a protocol of micro-coil TROSY- and CRINEPT-type NMR diffusion measurements for studying the hydrodynamic properties and the foldedness of [(2)H,(15)N]-labeled membrane proteins in nanodiscs. This protocol can be applied under conditions closely similar to those used for NMR structure determinations or crystallization trials.

KEYWORDS:

NMR spectroscopy; membrane protein reconstitution; membrane proteins; nanodiscs; structural biology

PMID:
24692152
PMCID:
PMC4105301
DOI:
10.1002/cbic.201300729
[Indexed for MEDLINE]
Free PMC Article

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