Transmembrane peptide NB of influenza B: A simulation, structure, and conductance study

The putative transmembrane segment of the ion channel forming peptide NE fr om influenza B was synthesized by standard solid-phase peptide synthesis. I nsertion into the planar lipid bilayer revealed ion channel activity with c onductance levels of 20, 61, 107, and 142 pS in a 0.5 M KCI buffer solution . In addition, levels at -100 mV show conductances of 251 and 413 pS. A lin ear current-voltage relation reveals a voltage-independent channel formatio n. In methanol and in vesicles the peptide appears to adopt an cc-helical-l ike structure. Computational models of ct-helix bundles using N = 4, 5, and 6 NE peptides per bundle revealed water-filled pores after 1 ns of MD simu lation in a solvated lipid bilayer. Calculated conductance values [using HO LE (Smart et al. (1997) Biophys. J. 72, 1 109-1126)] of ca. 20, 60, and 90 pS, respectively, suggested that the multiple conductance levels seen exper imentally must correspond to different degrees of oligomerization of the pe ptide to form channels.