Bacteriophage-host interaction and restriction of nonglucosylated T6

Nonglucosylated T6 phage (T6gtam 16am30, hereafter called T6alpha gt-) were found to have two structural anomalies when compared with wild-type T6. The DNA of T6alpha gt- phage contains single-strand interruptions. These can be seen both during infection, in the pool of replicating DNA, and in DNA extracted from purified phage. In addition, the sodium dodecyl sulfate-polyacrylamide gel pattern of T6alpha gt- phage structural proteins reveals a protein band not found in T6. The altered protein has a mobility slightly faster than that of the major head protein, and it is not removed by osmotic shock. The restriction activity of Escherichia coli B directed against T6alpha gt- phage is abolished by preinfection of the cells for 4 min with T4 im m2. The shut-off of restriction is observed either by the rescue of superinfecting T6alpha gt- or by the failure to detect degradation of incoming T6alpha gt- DNA. This effect is resistant to rifampin and chloramphenicol.