3QT1: RNA Polymerase II Variant Containing a Chimeric Rpb9-c11 Subunit

Citation:
Abstract
During gene transcription, the RNA polymerase (Pol) active center can catalyze RNA cleavage. This intrinsic cleavage activity is strong for Pol I and Pol III but very weak for Pol II. The reason for this difference is unclear because the active centers of the polymerases are virtually identical. Here we show that Pol II gains strong cleavage activity when the C-terminal zinc ribbon domain (C-ribbon) of subunit Rpb9 is replaced by its counterpart from the Pol III subunit C11. X-ray analysis shows that the C-ribbon has detached from its site on the Pol II surface and is mobile. Mutagenesis indicates that the C-ribbon transiently inserts into the Pol II pore to complement the active center. This mechanism is also used by transcription factor IIS, a factor that can bind Pol II and induce strong RNA cleavage. Together with published data, our results indicate that Pol I and Pol III contain catalytic C-ribbons that complement the active center, whereas Pol II contains a non-catalytic C-ribbon that is immobilized on the enzyme surface. Evolution of the Pol II system may have rendered mRNA transcript cleavage controllable by the dissociable factor transcription factor IIS to enable promoter-proximal gene regulation and elaborate 3'-processing and transcription termination.
PDB ID: 3QT1Download
MMDB ID: 89432
PDB Deposition Date: 2011/2/22
Updated in MMDB: 2012/11 
Experimental Method:
x-ray diffraction
Resolution: 4.3  Å
Source Organism:
Similar Structures:
Biological Unit for 3QT1: dodecameric; determined by author and by software (PISA)
Molecular Components in 3QT1
Label Count Molecule
Proteins (12 molecules)
1
DNA-directed RNA Polymerase II Subunit Rpb1
Molecule annotation
1
DNA-directed RNA Polymerase II Subunit Rpb2
Molecule annotation
1
DNA-directed RNA Polymerase II Subunit Rpb3
Molecule annotation
1
DNA-directed RNA Polymerase II Subunit Rpb4
Molecule annotation
1
DNA-directed RNA Polymerases I, II, and III Subunit Rpabc1
Molecule annotation
1
DNA-directed RNA Polymerases I, II, and III Subunit Rpabc2
Molecule annotation
1
DNA-directed RNA Polymerase II Subunit Rpb7
Molecule annotation
1
DNA-directed RNA Polymerases I, II, and III Subunit Rpabc3
Molecule annotation
1
DNA-directed RNA Polymerase II Subunit Rpb9, DNA-directed RNA Polymerase III Subunit Rpc10
Molecule annotation
1
DNA-directed RNA Polymerases I, II, and III Subunit Rpabc5
Molecule annotation
1
DNA-directed RNA Polymerase II Subunit Rpb11
Molecule annotation
1
DNA-directed RNA Polymerases I, II, and III Subunit Rpabc4
Molecule annotation
Chemicals (8 molecules)
1
7
2
1
* Click molecule labels to explore molecular sequence information.

Citing MMDB
.