Phosphorus-31 nuclear magnetic resonance of fd virus

31P NMR experiments on the filamentous bacteriophage fd are used to characterize the viral DNA. Because fd is a 16.4 X 10(6) dalton rod-shaped particle, methods of high-resolution solid-state NMR including cross polarization, proton decoupling, and magic angle sample spinning are utilized. The 31P chemical shielding tensor of solid fd is indistinguishable from that of single-stranded or double-stranded DNA in the absence of proteins; therefore the 31P chemical shift does not show evidence of structural changes in DNA upon incorporation into the virus. fd in solution has a very broad 31P resonance line width. The line width is due to static chemical shift anisotropy that is not motionally averaged, as shown by the generation of sidebands with magic angle sample spinning and a linear dependence of line width on magnetic field strength. These results indicate that DNA packaged inside fd is immobilized by the coat proteins.