[NMR paper] Solution-NMR Characterization of Outer-Membrane Protein A from E. coli in Lipid Bilayer Nanodiscs and Detergent Micelles.

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Solution-NMR Characterization of Outer-Membrane Protein A from E. coli in Lipid Bilayer Nanodiscs and Detergent Micelles.

Related Articles Solution-NMR Characterization of Outer-Membrane Protein A from E. coli in Lipid Bilayer Nanodiscs and Detergent Micelles.

Chembiochem. 2014 Apr 1;

Authors: Sušac L, Horst R, Wüthrich K

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 ?-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 ?-barrel prevented complete structural characterization. Here, we show that this NMR-invisible ring around the ?-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.


PMID: 24692152 [PubMed - as supplied by publisher]



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