Details

Autor(en) / Beteiligte

• Liu, Bin
• Zuo, Yuhong
• Steitz, Thomas A.

Titel

Structural basis for transcription reactivation by RapA

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2015-02, Vol.112 (7), p.2006-2010

Ort / Verlag

United States: National Academy of Sciences

Erscheinungsjahr

2015

Link zum Volltext

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• Significance Transcription is the first and most regulated step of gene expression. During transcription, RNA polymerase (RNAP) translocates along DNA while processively synthesizing RNA molecules hundreds of nucleotides long. Excessive translocation in either direction halts RNA synthesis. Here, we present a structure of the Escherichia coli RNA polymerase in complex with ATPase RapA, a large DNA translocase that is involved in transcriptional reactivation. The structural insights gained from this study suggest an alternative mechanism for transcription regulation in which backward translocation (backtranslocation) might be promoted by a DNA translocase and also lead us to propose a model for how RapA reactivates RNA polymerases and stimulates transcription. This active backtranslocation proposed here could be a general mechanism for regulating transcription and transcription-related processes. RNA polymerase (RNAP) loses activity during transcription as it stalls at various inactive states due to erratic translocation. Reactivation of these stalled RNAPs is essential for efficient RNA synthesis. Here we report a 4.7-Å resolution crystal structure of the Escherichia coli RNAP core enzyme in complex with ATPase RapA that is involved in reactivating stalled RNAPs. The structure reveals that RapA binds at the RNA exit channel of the RNAP and makes the channel unable to accommodate the formation of an RNA hairpin. The orientation of RapA on the RNAP core complex suggests that RapA uses its ATPase activity to propel backward translocation of RNAP along the DNA template in an elongation complex. This structure provides insights into the reactivation of stalled RNA polymerases and helps support ATP-driven backward translocation as a general mechanism for transcriptional regulation.