TRANSCRIPTION AND TRANSLATION OF R-PLASMID 538-1 DNA - EFFECTS OF MERCURY INDUCTION AND ANALYSIS OF POLYPEPTIDES CODED FOR BY THE R-DETERMINANT REGION

In vivo transcription and translation of R-plasmid 538-1 in Escherichia coli was analyzed. Transcription of individual restriction fragments was determined qualitatively by utilizing the techniques developed by Southern J. Mol. Biol. 98, 503-517, 1975 and quantitatively by carrying out DNA-RNA filter hybridization. The most active region of R-plasmid transcription in strains repressed for conjugal transfer was found to occur in the region of the R-plasmid carrying the antibiotic resistance genes. In plasmids derepressed for conjugal transfer, a high level of transcription from the transfer gene region was also observed. When strains carrying R538-1 were induced with Hg2+ a high level of transcription was observed from the region of the R-plasmid carrying the genes for Hgr. Hybrid ColE1 plasmids carrying restriction fragments from the antibiotic resistance region of R538-1 were segregated into minicells. Labeling of the minicells with [35S]methionine or [14C]amino acids allowed identification of the proteins coded by the fragments. A limited number of proteins were detected, and several of these have been correlated with the antibiotic resistance genes carried by R538-1. © 1979.