Abstract:
:The S4 segments of voltage-gated sodium channels are important parts of the voltage-sensing elements of these proteins. Furthermore, the addition of the isolated S4 polypeptide to planar lipid bilayers results in stepwise increases of ion conductivity. In order to gain insight into the mechanisms of pore formation by amphipathic peptides, the structure and orientation of the S4 segment of the first internal repeat of the rat brain II sodium channel was investigated in the presence of DPC micelles by multidimensional solution NMR spectroscopy and solid-state NMR spectroscopy on oriented phospholipid bilayers. Both the anisotropic chemical shift observed by proton-decoupled (15)N solid-state NMR spectroscopy and the attenuating effects of DOXYL-stearates on TOCSY crosspeak intensities of micelle-associated S4 indicate that the central alpha-helical portion of this peptide is oriented approximately parallel to the membrane surface. Simulated annealing and molecular dynamics calculations of the peptide in a biphasic tetrachloromethane-water environment indicate that the peptide alpha-helix extends over approximately 12 residues. A less regular structure further toward the C-terminus allows for the hydrophobic residues of this part of the peptide to be positioned in the tetrachloromethane environment. The implications for possible pore-forming mechanisms are discussed.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Mattila K,Kinder R,Bechinger Bdoi
10.1016/S0006-3495(99)77051-7subject
Has Abstractpub_date
1999-10-01 00:00:00pages
2102-13issue
4eissn
0006-3495issn
1542-0086pii
S0006-3495(99)77051-7journal_volume
77pub_type
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