Transcription unit mapping in bacteriophage T7. II. Proportionality of number of gene copies, mRNA, and gene product.

The effect of UV irradiation of bacteriophage T7 on in vivo early RNA synthesis has been studied by direct quantitation of the gene-specific RNA transcripts. The results show that the early region of phage T7 is transcribed from left to right as a single unit. Furthermore, gene inactivation, the UV sensitivity of synthesis of gene-specific RNA, and the UV sensitivity of synthesis of the corresponding proteins all follow pseudo first-order kinetics in multiply infected cells, demonstrating a random statistical correlation between both transcriptional sampling of gene copies and translational sampling of the resultant RNA transcripts. In addition, these simple kinetics imply an absence of positive feedback mechanisms compensating for the differential decline of individual early gene products in cells multiply infected with phage T7.