Lipid-tail group dependent structure of the fd gene 8 protein

Using circular dichroism several laboratories have shown that the fd coat protein can assume three distinct conformations depending on the conditions. We have reinvestigated these three conformations using laser Raman spectroscopy and the quantitative estimates of alpha-helix by Raman agree fairly well with the earlier estimates obtained by CD. In addition, we have studied in more detail the conditions governing the 3 conformations. To our surprise, the nature f the lipid tail group seems to be the determining factor for two of the conformations. A lipid tail group dependence of protein structure is without precedent and has potential consequences for the assembly of filamentous phages as well as for the structure and function of cell membranes.