Thermodynamic analysis of the transcription cycle in E. coli (original) (raw)

1990, Biophysical Chemistry

The E. coli RNA transcription cycle can be divided into three major phases, which are generafly called initiation, elongation, and termiuation. In this paper, we review recent biophysical studies of the interactions of the transcriptional regulatory proteins, sigma7o and NusA, with tbemsefves and with core RNA polymerase in solution, as well as with core polymerase within the transcription complex. The different affinities of sigma70 and NusA for core RNA polymerase at various stages in the transcription cycle, together with other quantitative data, are then used to construct a partial free energy diagram for the overall transcription process. 'Ibis thermodynamic framework, which is interrupted by at least two irreversible steps, can be used to rationalize physiological aspects of the transcription cycle and its regulation, as well as to identify crucial points at which our knowledge is still incomplete.