[Investigation of the Dependence of Escherichia coli RNA Polymerase σ70-Subunit Structure on Ionic Strength by Molecular Dynamics Simulation Method].

The σ70-subunit of E. coli RNA polymerase (a small protein, being a part of RNA holoenzyme, and responsible for initiation of transcription of constitutive genes) is modeled at different ionic strengths. Two variants of the location of C-end domain 4 are obtained. At low ionic strength domain 4 interacts with the region of high negative charge 190-210 AK within NCR domain. At high ionic strength this region was screened and domain 4 was free and set away from domain NCR. We suppose that this leads to the increase in polymerization rate. Simulation data do not confirm any hypothesis about a self-inhibition mechanism.