Control of transcriptional fidelity by active center tuning as derived from RNA polymerase endonuclease reaction

Ekaterina Sosunova, Vasily Sosunov, Vitaly Epshtein, Vadim Nikiforov, Arkady Mustaev

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Precise transcription by cellular RNA polymerase requires the efficient removal of noncognate nucleotide residues that are occasionally incorporated. Mis-incorporation causes the transcription elongation complex to backtrack, releasing a single strand 3'-RNA segment bearing a noncognate residue, which is hydrolyzed by the active center that carries two Mg2+ ions. However, in most x-ray structures only one Mg2+ is present. This Mg 2+ is tightly bound to the active center aspartates, creating an inactive stable state. The first residue of the single strand RNA segment in the backtracked transcription elongation complex strongly promotes transcript hydrolytic cleavage by establishing a network of interactions that force a shift of stably bound Mg2+ to release some of its aspartate coordination valences for binding to the second Mg2+ thus enabling catalysis. Such a rearrangement that we call active center tuning (ACT) occurs when all recognition contacts of the active center-bound RNA segment are established and verified by tolerance to stress. Transcription factor Gre builds on the ACT mechanism in the same reaction by increasing the retention of the second Mg 2+ and by activating the attacking water, causing 3000-4000-fold reaction acceleration and strongly reinforcing proofreading. The unified mechanism for RNA synthesis and degradation by RNApolymerase predicts thatACTalso executes NTP selection thereby contributing to high transcription fidelity.

Original languageEnglish (US)
Pages (from-to)6688-6703
Number of pages16
JournalJournal of Biological Chemistry
Issue number9
StatePublished - Mar 1 2013

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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