Escherichia coli RNA polymerase cove and holoenzyme structures

Multisubunit RNA polymerase is an essential enzyme for regulated gene expression. Here we report two Escherichia coli RNA polymerase structures: an 11.0 Angstrom structure of the core RNA polymerase and a 9.5 Angstrom structure of the sigma (70) holoenzyme. Both structures were obtained by cryo-electron microscopy and angular reconstitution. Core RNA polymerase exists in an open conformation. Extensive conformational changes occur between the core and the holoenzyme forms of the RNA polymerase, which are largely associated with movements in beta'. An common RNA polymerase subunits (alpha (2), beta, beta') could be localized in both structures, thus suggesting the position of sigma (70) in the holoenzyme.