The replication of bacteriophage MS2: VI. Interaction between bacteriophage RNA and cellular components in MS2-infected Escherichia coli

Abstract

Almost immediately after infection of Escherichia coli cells with [^(32)P]MS2, parental RNA appears in cell lysates associated with the 30 s ribosome subunit and with polysomes; a small amount is found as unbound, free RNA. At early times after infection (zero to four minutes) no parental RNA is associated with the 70 s monosomes or with the 50 s ribosome subunits. After four to five minutes of infection, the distribution of these components is such that approximately 30% of the total [^(32)P]parental RNA in the cells is associated with the polysomes, 38% is associated with the 30 s ribosome subunit, 15% is free RNA and 16% is residual whole phage. At later times (four to ten minutes), coincident with the time of increase in ribonuclease-resistant parental RNA, a new component containing [^(32)P]parental RNA appears, sedimenting just in front of the 50 s ribosome subunit. The ribonuclease-resistant 12 s RNA (“core” RNA, Fenwick, Erikson & Franklin, 1964) is present in both this 50 s region and in the polysomes: none is present in the 30 s or free RNA regions. The ribonuclease-resistant 12 s RNA probably appears first in the 50 s region and later in the polysome region. The [^(32)P]parental RNA of cells infected for eight minutes can be dissociated, in low Mg^(2+) concentration, from the polysomes (and can also be derived from the 50 s component) as a fast sedimenting component of 40 s.