Dynamics of fd coat protein in the bacteriophage

The dynamics of the coat protein in fd bacteriophage are described with solid-state 15N and 2H NMR experiments. The virus particles and the coat protein subunits are immobile on the time scales of the 15N chemical shift anisotropy (103 Hz) and 2H quadrupole (106 Hz) interactions. Previously the authors have shown that the Trp-26 side chains is immobile, that the two Tyr and three Phe side chains undergo only rapid two fold jump motions about their C/sub β/-C/sub γ/ bond axis and that most of the backbone peptide linkages are highly constrained but do undergo rapid small amplitude motions in the coat protein subunits in the virus particles. In this paper, the authors demonstrate that the four N-terminal residues of the coat protein subunits are highly mobile, since both backbone and side-chain sites of these residues undergo large amplitude motions that are rapid on the time scales of the solid-state NMR experiments. In addition, the dynamics of the methyl-containing aliphatic residues Ala, Leu, Thr, and Met are analyzed. Large amplitude jump motions are observed in nearly all of these side chains even through, with the exception of the N-terminal residue Ala-1, their backbone peptide linkages are highly constrained. The established information about the dynamics of the structural form of fd coat protein in the virus particle is summarized qualitatively; backbone sites are found to be either immobile or highly mobile, while side-chain sites are found either to be immobile or to undergo apparently well-defined high-frequency jump motions