INVIVO TRANSCRIPTIONALLY COUPLED ASSEMBLY OF ESCHERICHIA-COLI RIBOSOMAL-SUBUNITS

Evidence is presented that ribosome assembly in bacteria may occur concurrently with transcription of ribosomal RNA. Bacterial folded chromosomes (nucleoids), which contain nascent ribosomal RNA, were isolated and analyzed for the presence of ribosomal proteins by quantitative two-dimensional polyacrylamide gel electrophoresis. For each ribosomal protein on the nucleoid the relative mass, NR1, and the mean frequency of occurrence, F̄, were calculated. These data yield a frequency gradient for ribosomal proteins associated with the transcriptional complex. The possibility that this gradient represents a general in vivo assembly order for the addition of these proteins to 16 S and 23 S RNA is discussed. © 1979.