FIG. 3.

Identification of transcription start sites of each rrn promoter by primer extension on RNA isolated from wild-type cells (RIK350 to RIK356). Cells were grown in LB medium at 37°C and collected at an OD₆₀₀ of approximately 0.20. Thirty micrograms of total RNA extracted from the cells was used for primer extension analysis as described in Materials and Methods. The sequence ladder was generated by PCR cycle sequencing with the same primers used in the primer extension reaction.