Membrane dynamics in the intact PM2 phage and its host cells as monitored by T1rho(H).

Temperature dependence of the spin-lattice relaxation time of proton in the rotating frame (T1rho(H)) was examined for the membranes of the intact PM2 phage, its host bacterial cells, and the phospholipids extracted from the cells. The relevant motions of the phospholipid molecules in all lipid membranes were found in the fast-motional regime (tauc < 1.7 x 10(-6) s) in the temperature range from 0 to 34 degrees C. The motions responsible for the relaxation in the intact biomembranes are more suppressed than those of the extracted phospholipid bilayers, suggesting that the lipid-protein interactions induce slow motions of the phospholipids in the membrane. Especially, the membrane of the intact PM2 phage showed a cooperative change in the motional state, being consistent with the reported change in the phosphorus chemical shift anisotropies of DNA and phospholipids of the phage particle.