FIG. 3.
Effect of the spacer length on transcription. (A) In vitro transcription by C. trachomatis σ28 RNA polymerase of hctB promoter templates containing a spacer of 9 to 13 nt as indicated. The 12-nt wild-type (wt) spacer is marked for reference. (B) Graph showing quantification of the transcription results for C. trachomatis and E. coli RNA polymerases. Reactions were performed in triplicate, and standard deviations are marked by error bars. Results for each RNA polymerase were normalized to a promoter activity of 100% for the wild-type hctB promoter.