Structure of the Escherichia coli RNA polymerase subunit C-terminal domain

Abstract

The subunit C-terminal domain (CTD) of RNA polymerase (RNAP) is a key element in transcription activation in Escherichia coli, possessing determinants responsible for the interaction of RNAP with DNA and with transcription factors. Here, the crystal structure of E. coli CTD ( α subunit residues 245-329) determined to 2.0 Å resolution is reported. Crystals were obtained after reductive methylation of the recombinantly expressed domain. The crystals belonged to space group P21 and possessed both pseudo-translational symmetry and pseudo-merohedral twinning. The refined coordinate model (R factor = 0.193, Rfree = 0.236) has improved geometry compared with prior lower resolution determinations of the CTD structure [Jeon et al. (1995), Science, 270, 1495-1497; Benoff et al. (2002), Science, 297, 1562-1566]. An extensive dimerization interface formed primarily by N- and C-terminal residues is also observed. The new coordinates will facilitate the improved modeling of αCTD-containing multi-component complexes visualized at lower resolution using X-ray crystallo-graphy and electron-microscopy reconstruction. © 2010 International Union of Crystallography.