Determination of the promoter strength in the mixed transcription system, II. Promoters of ribosomal RNA, ribosomal protein S1 and recA protein operons from Escherichia coli

摘要

Using the in vitro mixed transcription system (Kajitani, M. and Ishihama, A. (1983) Nucleic Acids Res. 11, 671–686), we determined the two parameters of the promoter strength, i.e., the rate of open complex formation between RNA poly= merase and promoter, and the saturation level of the open complex formation at equilibrium, for the promoters of ribosomal RNA (rrnE), ribosomal protein S1 (rpsA) and recA protein (recA) operons from Escherichia coli. Taken together with the previous determinations for lactose (lac(UV5)), tryptophan (trp) and ribosomal protein L10 (rplJ) operons, these studies revealed that the relative promoter strengths with respect to the kinetic parameter are 200, 70, 50, 40, 30, 20 and 2% of the reference promoter lacP(UV5) for recA_p, rplJ_p, rpsA_p3, trpP, rpsA_p1, rrnE_pl and rrnE_p2, respectively, under our standard reaction conditions (50 mM NaCl and 37°C); and those with respect to the thermodynamic parameter are 70, 35, 20, 10, 10, 10 and 5% the level of lacP(UV5) for rrnE_p2, trpP, rpsAp3, rplJ_p, rpsA_p1, rrnE_pl and recA_p, respectively. The order of the promoter strength, however, changes with variation of the salt concentration or reaction temperature.