Fig. 8.

GroEL enhanced transcriptional repression by full-length but not truncated rHrcA in vitro. In vitro transcription of the C. trachomatis dnaK promoter with E. coli RNA polymerase in the presence of 350 nM full-length rHrcA or 100 nM truncated rHrcA, which produced similar baseline repression in the absence of rGroEL (lanes 3 and 5). rGroEL (170 nM) was added to reactions in lanes 2, 4, and 6. These rHrcA preparations were purified by metal affinity chromatography without further purification by DNA affinity chromatography. The graph shows quantification of the transcription results as measured by phosphorimager analysis. Transcription levels were normalized to the amount of transcription produced by RNA polymerase alone, which was defined as 100%, and the percentage change in transcription due to the addition of rHrcA and/or rGroEL is reported. Reactions were performed in triplicate, and error bars represent standard deviations.