Dynamics of fd coat protein in the bacteriophage

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Abstract
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 immobilie on the time scales of the 15N chemical shift anisotropy (103 Hz) and P2H quadrupole (106 Hz) interactions. Previously we have shown that the Trp-26 side chain is immobile, that the two Tyr and three Phe side chains undergo only rapid twofold jump motions about their C.beta.-C.gamma. bond axis [Gall, C. M., Cross, T. A., DiVerdi, J. A., and Opella, S. J. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 101-105], and that most of the backbone peptide linkages are highly constrained but do undergo rapid small amplitude motions 7(Cross, T. A., and Opella, S. J. (1982) J. Mol. Biol. 159, 543-549] in the coat protein subunits in the virus particles. In this paper, we 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, Val, Thr, and Met are analyzed. Large amplitude jump motions are oberved in nearly all of these side chains even though, 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.