Beschreibung:
<jats:p>The α subunit C-terminal domain (αCTD) of RNA polymerase (RNAP) is a key element in transcription activation in<jats:italic>Escherichia coli</jats:italic>, possessing determinants responsible for the interaction of RNAP with DNA and with transcription factors. Here, the crystal structure of<jats:italic>E. coli</jats:italic>αCTD (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<jats:italic>P</jats:italic>2<jats:sub>1</jats:sub>and possessed both pseudo-translational symmetry and pseudo-merohedral twinning. The refined coordinate model (<jats:italic>R</jats:italic>factor = 0.193,<jats:italic>R</jats:italic><jats:sub>free</jats:sub>= 0.236) has improved geometry compared with prior lower resolution determinations of the αCTD structure [Jeon<jats:italic>et al.</jats:italic>(1995),<jats:italic>Science</jats:italic>,<jats:bold>270</jats:bold>, 1495–1497; Benoff<jats:italic>et al.</jats:italic>(2002),<jats:italic>Science</jats:italic>,<jats:bold>297</jats:bold>, 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 crystallography and electron-microscopy reconstruction.</jats:p>