An alternative RNA polymerase I structure reveals a dimer hinge.
RNA polymerase I (Pol I) is the central, 14-subunit enzyme that synthesizes the ribosomal RNA (rRNA) precursor in eukaryotic cells. The recent crystal structure of Pol I at 2.8 Å resolution revealed two novel elements: the `expander' in the active-centre cleft and the `connector' that mediates Pol I dimerization [Engel et al. (2013), Nature (London), 502, 650-655]. Here, a Pol I structure in an alternative crystal form that was solved by molecular replacement using the original atomic Pol I structure is reported. The resulting alternative structure lacks the expander but still shows an expanded active-centre cleft. The neighbouring Pol I monomers form a homodimer with a relative orientation distinct from that observed previously, establishing the connector as a hinge between Pol I monomers.
Gene Center Munich and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
Dirk
D
Kostrewa
Elite Network of Bavaria, BIOmac Research Center, University of Bayreuth, 95440 Bayreuth, Germany.
Claus-D
CD
Kuhn
Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Christoph
C
Engel
Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Patrick
P
Cramer
D018360:Crystallography, X-Ray; D019281:Dimerization; D008958:Models, Molecular; D011487:Protein Conformation; D012318:RNA Polymerase I / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*
D029701:Saccharomyces cerevisiae Proteins; D012318:RNA Polymerase I
RNA polymerase I; connector; dimer; hinge