ISOLATION OF A PHOSPHOLIPID-FREE PROTEIN SHELL OF BACTERIOPHAGE-PRD1, AN ESCHERICHIA-COLI VIRUS WITH AN INTERNAL MEMBRANE

PRD1 is a double-stranded DNA virus infecting Escherichia coli and Salmonella typhimurium. It has an icosahedral outer protein capsid which encloses the viral membrane, inside of which resides the phage genome. In this investigation we demonstrate the detergent resistance of the intact virus particles. The membrane of empty DNA-free particles, however, is very sensitive to detergent action. We assume that their sensitivity is due to the access of detergents through a portal structure to the virus interior. Using the anionic detergent sodium dodecyl sulfate, it is possible to obtain a shell structure composed of the major coat protein P3 alone. The treatment of empty particles with the milder nonionic detergents n-octyl β-D-glucopyranoside and Triton X-100 yielded P3 particles which retained the membrane associated proteins P7 and P11. Deoxycholic acid treatment yielded shells of intermediate composition between those obtained with the nonionic detergents and sodium dodecyl sulfate. © 1993 Academic Press. All rights reserved.