title: Role of attenuation in growth rate-dependent regulation of the S10 r-protein operon of E. coli.
abstract: We have investigated the transcription of the 11 gene S10 ribosomal protein operon of Escherichia coli under various growth conditions. The differential synthesis rate of structural gene message increases 2- to 2.5-fold immediately after a shift-up from glycerol minimal medium to glucose plus amino acids. After the initial increase, the transcription rate goes through several oscillations before reaching the new steady-state rate. By comparing the rates of transcription of leader and structural genes, we conclude that these oscillations are due predominantly to changes in the level of read-through at the S10 attenuator. This regulation of attenuation can account for most of the variations in protein synthesis from the S10 operon after a shift. We also measured the level of read-through in cells growing exponentially in different growth media. Over a 2.5-fold range in growth rates, the read-through changed less than 50%. Thus, regulation of attenuation cannot explain the growth-dependent regulation of ribosomal protein synthesis during steady-state growth. Apparently, additional mechanisms are required to control the expression of the S10 operon in exponentially growing cells.
mesh_terms: D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D005786:Gene Expression Regulation; D005796:Genes; D009876:Operon; D012269:Ribosomal Proteins / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D012269:Ribosomal Proteins