Transcription of ribosomal protein genes carried on F' plasmids of Escherichia coli.

The transcriptional activity of the DNA sequences coding for certain ribosomal proteins has been measured in Escherichia coli. Two partial diploid strains were isolated from mating of a recA, argD, aroE recipient and an Hfr with an origin at 69.5 min. One contained an F' element carrying the genes from 69.5 to 72.7 min including the rpsL locus (72.4) and the second was diploid for the genes from 69.5 to 71.5 min but did not include any mapped ribosomal protein loci. The molecular weights of the plasmids were estimated to be 140 and 110 x 10(6) daltons, respectively. The extent of in vivo transcription of the chromosomal genes on the plasmid and the ribosomal protein mRNA fraction of the total cellular RNA weer calculated from DNA-RNA liquid hybridization experiments using both DNA and RNA excess procedures. The results indicated a high degree of transcriptional activity concentrated in the ribosomal protein sequences with 83% of the F' chromosomal sequences transcribed into mRNA products representing about 0.12% of the total cellular RNA.