FIG 3.

The bioY P1 promoter is transcriptionally active and supercoiling dependent. (A) Sequence of bioY P1. The predicted −35 and −10 elements are underlined, and the preferred C. trachomatis σ⁶⁶ promoter sequences are shown below for comparison. (B) In vitro transcription of bioY P1 by E. coli RNA polymerase σ⁷⁰ holoenzyme and partially purified C. trachomatis σ⁶⁶ RNA polymerase, as indicated. bioY P1 was present on a supercoiled transcription template. (C) Comparison of bioY P1 transcription from supercoiled and relaxed plasmid templates. As controls, a supercoiling-independent promoter (omcAB) and a supercoiling-dependent promoter (dnaK P1) were also tested. Transcription reactions were performed with E. coli σ⁷⁰ RNA polymerase.