Solid-state NMR studies of the membrane-bound closed state of the colicin E1 channel domain in lipid bilayers.
The colicin E1 channel polypeptide was shown to be organized anisotropically in membranes by solid-state NMR analysis of samples of uniformly 15N-labeled protein in oriented planar phospholipid bilayers. The 190 residue C-terminal colicin E1 channel domain is the largest polypeptide to have been characterized by 15N solid-state NMR spectroscopy in oriented membrane bilayers. The 15N-NMR spectra of the colicin E1 show that: (1) the structure and dynamics are independent of anionic lipid content in both oriented and unoriented samples; (2) assuming the secondary structure of the polypeptide is helical, there are both trans-membrane and in-plane helical segments; (3) trans-membrane helices account for approximately 20-25% of the channel polypeptide, which is equivalent to 38-48 residues of the 190-residue polypeptide. The results of the two-dimensional PISEMA spectrum are interpreted in terms of a single trans-membrane helical hairpin inserted into the bilayer from each channel molecule. These data are also consistent with this helical hairpin being derived from the 38-residue hydrophobic segment near the C-terminus of the colicin E1 channel polypeptide.
Kim
Y
Y
Department of Chemistry, University of Pennsylvania, Philadelphia 19104, USA.
Valentine
K
K
Opella
S J
SJ
Schendel
S L
SL
Cramer
W A
WA
D000595:Amino Acid Sequence; D003087:Colicins / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000737:chemistry
D003087:Colicins; D008051:Lipid Bilayers; D008565:Membrane Proteins; D010743:Phospholipids