Structure and Synthesis of a Lipid‐Containing Bacteriophage

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Abstract
The lipid-containing bacteriophage PM2 was dissociated stepwise in 1 M NaCl (pH 7.2) with increasing urea concentrations. In 2 M urea the following substructures could be identified: a nucleocapsid containing all of the viral lipid, the DNA, proteins III and IV, plus a fraction of protein II, and a 2nd substructure representing particles which contained all viral elements except protein I, the spike protein. In 4 M urea the viral nucleocapsid containing all of proteins III and IV, the DNA, plus a fraction of protein II, was isolated. Upon increasing the urea concentration further, this nucleocapsid is stable up to 8.5 M urea; in 9 M urea protein III was partly dissociated from the nucleocapsid. The nucleocapsid in 4-8.5 M urea is stabliized by the addition of 0.1-3 M NaCl but dissociates if the NaCl concentration is less than 0.1 M. The nucleocapsid was also dissociated in 4-8.5 M urea at pH 4.5. The nucleocapsid structures and some intermediate morphological subunits were analyzed by physical methods, giving some conclusions about the structure and hydration of the virus.