BACKBONE DYNAMICS OF THE MAJOR COAT PROTEIN OF BACTERIOPHAGE M13 IN DETERGENT MICELLES BY 15N NUCLEAR MAGNETIC RESONANCE RELAXATION MEASUREMENTS USING THE MODEL-FREE APPROACH AND REDUCED SPECTRAL DENSITY MAPPING

The backbone dynamics of the major coat protein (gVIIIp) of the filamentous bacteriophage M13, solubilized in detergent micelles, have been studied using 15N nuclear magnetic resonance spectroscopy at three frequencies. Motional parameters and overall and internal correlation times were derived with the model-free approach. It was also checked whether these parameters had to be modified due to anisotropic motion of the protein/micelle complex. Reduced spectral density mapping was used to calculate the spectral densities at J(0), J(ωN), and 〈J(ωH)〉. The spectral densities were interpreted by mapping a linear or scaled linear combination of two Lorentzians onto a J(0) − J(ω) plot. The major coat protein of bacteriophage M13 consists of two α -helices, one of which is hydrophobic and located within the micelle, while the other is amphipathic and located on the surface of the micelle. Our results indicate that the motion of the hydrophobic helix is restricted such that it corresponds to the overall tumbling o...