Probing the transmembrane structure and topology of microsomal cytochrome-p450 by solid-state NMR on temperature-resistant bicelles

Sci Rep. 2013:3:2556. doi: 10.1038/srep02556.

Abstract

Though the importance of high-resolution structure and dynamics of membrane proteins has been well recognized, optimizing sample conditions to retain the native-like folding and function of membrane proteins for Nuclear Magnetic Resonance (NMR) or X-ray measurements has been a major challenge. While bicelles have been shown to stabilize the function of membrane proteins and are increasingly utilized as model membranes, the loss of their magnetic-alignment at low temperatures makes them unsuitable to study heat-sensitive membrane proteins like cytochrome-P450 and protein-protein complexes. In this study, we report temperature resistant bicelles that can magnetically-align for a broad range of temperatures and demonstrate their advantages in the structural studies of full-length microsomal cytochrome-P450 and cytochrome-b5 by solid-state NMR spectroscopy. Our results reveal that the N-terminal region of rabbit cytochrome-P4502B4, that is usually cleaved off to obtain crystal structures, is helical and has a transmembrane orientation with ~17° tilt from the lipid bilayer normal.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cytochrome P-450 Enzyme System / analysis
  • Cytochrome P-450 Enzyme System / chemistry*
  • Humans
  • Lipid Bilayers / chemistry*
  • Magnetic Resonance Spectroscopy / methods
  • Microsomes, Liver / chemistry*
  • Specimen Handling / methods*

Substances

  • Lipid Bilayers
  • Cytochrome P-450 Enzyme System