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J Virol. 1972 January; 9(1): 75-84
Copyright © 1972 American Society for Microbiology. All Rights Reserved.

Polysomal Localization of R17 Bacteriophage-Specific Protein Synthesis

^a Department of Molecular Biophysics, The Public Health Research Institute of the City of New York, Inc., New York, New York 10016

ABSTRACT

Synthesis of viral ribonucleic acid (RNA) polymerase, maturation protein, and coat protein in Escherichia coli infected with bacteriophage R17 occurs mainly on polysomes containing four or more ribosomes. The 30S ribosomal subunits through trimer-size polysomes, which are associated with all of the R17-specific proteins and are predominant in the infected cell, synthesize only coat protein. These structures may accumulate as products derived from larger polysomes as a result of failure in the release of nascent polypeptides after termination of chain growth. Appreciable amounts of viral coat protein remain attached to ribosomes and polysomes during R17 bacteriophage replication, supporting the hypothesis of the repressor role of this protein. The time course of synthesis of virus-specific proteins obtained from the polysomes of infected cells demonstrated regulated R17 messenger RNA translation consistent with the idea that coat protein is preferentially synthesized whereas the synthesis of noncoat proteins is suppressed.

¹ Present address: Biozentrum der Universität, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.