Functional modulation of Escherichia coli RNA polymerase

The promoter recognition specificity of Escherichia coli RNA polymerase is modulated by replacement of the a subunit in the first step and by interaction with transcription factors in the second step. The overall differentiated state of similar to 2000 molecules of the RNA polymerase in a single cell can be estimated after measurement of both the intracellular concentrations and the RNA polymerase-binding affinities for all seven species of the a subunit and 100-150 transcription factors. The anticipated impact from this line of systematic approach is that the prediction of the expression hierarchy of similar to 4000 genes on the E. coli genome can be estimated.