Biochemistry

Mimicking a Membrane

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Science  01 Mar 2013:
Vol. 339, Issue 6123, pp. 1013
DOI: 10.1126/science.339.6123.1013-a

A challenge in membrane structure determination is selecting membrane-mimicking media that facilitate proper protein folding and function. Detergent micelles are commonly used for structural studies; however, these are often not optimal for protein stability and function. Phospholipid nanodiscs are a promising membrane mimetic; however, the large molecular weight of nanodiscs has hampered their use in structural determination by multidimensional nuclear magnetic resonance (NMR) spectroscopy. Nanodiscs are formed by two copies of a membrane scaffold protein wrapping around a patch of phospholipid bilayer. Hagn et al. engineered a set of shorter variants of the scaffold protein ApoA-I that formed a range of smaller nanodiscs. Using membrane proteins embedded in these smaller nanodiscs together with high deuteration levels of proteins and lipids and advanced NMR methods allowed NMR resonance assignment and high-resolution structure determination of membrane proteins. The set of scaffold proteins could be screened for optimal NMR spectra of small to medium-sized membrane proteins. This method allowed the authors to obtain good-quality spectra for bacteriorhodopsin and to determine the structure of OmpX, a bacterial outer-membrane protein.

CREDIT: F. HAGN ET AL., JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 135, 1919 (1 FEBRUARY 2013) © 2013 AMERICAN CHEMICAL SOCIETY

JACS 135, 1919 (2013).

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