Stimulatory Effect of Trehalose on Formation and Activity of Escherichia coli RNA Polymerase Es Holoenzyme

The intracellular concentration of trehalose increases in the stationary-phase cells of Escherichia coli. The effects of trehalose on transcription in vitro by E. coli RNA polymerase were compared for two holoenzymes, Es and Es, which were reconstituted from purified core enzyme and either s (the major s at the exponential growth phase) or s (the essential s at the stationary growth phase), respectively. The optimum trehalose concentration giving maximum transcription by Es was higher than that by Es. Transcription activation by trehalose was attributed to both increased formation of Es holoenzyme and increased transcription initiation by Es from s-dependent promoters. The activation of Es by trehalose was additive with the transcription enhancement by decreased superhelicity of template DNA prepared from stationaryphase cells. We thus propose that the selective activation of transcription by Es holoenzyme takes place in the presence of specific conditions and factors present under stress conditions.