Regulation of Host Ribonucleic Acid Synthesis in Bacteriophage T3-infected Cells

• Published in: The Journal of biological chemistry 1974-03, Vol.249 (6), p.1787-1791
• Main Authors: Mahadik, S.P., Dharmgrongartama, B., Srinivasan, P.R.
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)42856-1

Recently we described the isolation and partial purification of a protein from T3 phage-infected Escherichia coli B cells. This protein markedly inhibits the activity of E. coli RNA polymerase, but it only slightly diminishes the activity of T3-specific T3 polymerase even when added at high concentrations (Mahadik. S. P., Dharmgrongartama, B., and Srinivasan, P. R. (1972) Proc. Nat. Acad. Sci. U. S. A. 69, 162). This protein has no inhibitory effect on core polymerase activity and requires the presence of sigma factor for eliciting the inhibition. However, further addition of sigma factor failed to overcome the inhibition observed with E. coli RNA polymerase. The protein does not bind directly to DNA or RNA polymerase or RNA polymerase-DNA complex. The presence of ATP and GTP are required for the binding of the inhibitory protein to enzyme-DNA complex. The activity of the inhibitory protein is not observed in nonpermissive cells infected with an amber mutant in gene 1 defective in T3-specific T3 polymerase. Thus, the T3 phage gene responsible for the synthesis of the inhibitory protein is not an early gene and the transcription of this gene is under the control of T3 polymerase.