Inhibition of host nucleic acid and protein synthesis by bacteriophage T4: Its relation to the physical and functional integrity of host chromosome (original) (raw)

Journal of Molecular Biology, 1962

Abstract

ABSTRACT Infection of E. coli with phage T4 causes a sudden inhibition of the synthesis of host DNA, host RNA, and host protein. Experiments were performed to test the hypothesis that the physical destruction of the host chromosome is a primary cause of this inhibition. Physical destruction of host DNA after infection was studied using sucrose density gradient sedimentation and CsCl equilibrium density gradient centrifugation techniques. No destruction of host DNA was detected after 5 min. However, a definite destruction was observed after 10 min. The addition of Chloromycetin or streptomycin before infection prevented this destruction. Nevertheless, host DNA synthesis and host messenger RNA synthesis are inhibited under such conditions. Therefore, physical destruction of the host chromosome does not seem to be the primary cause of the inhibition. Functional integrity of the host chromosome after infection was studied. During infection in the presence of streptomycin, its functional integrity was demonstrated by introducing the inhibited host chromosome into phage-resistant female cells and observing the subsequent expression of its function to synthesize β-galactosidase. Thus, the primary inhibitory process seems to be reversible in its inherent nature. Some features of such an inhibitory mechanism are briefly discussed.

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