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RNA polymerase mutants defective in the initiation of transcription-coupled DNA repair

A J Smith1, N J Savery

  • 1Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk Bristol BS8 1TD, UK.

Nucleic Acids Research
|February 3, 2005
PubMed

Insights

The bacterial Mfd protein is crucial for DNA repair by removing stalled RNA polymerase (RNAP). Specific RNAP beta subunit changes disrupt this interaction, impacting DNA repair and transcription processes.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • The Mfd protein acts as a transcription-repair coupling factor in bacteria.
  • Mfd facilitates DNA repair by removing stalled RNA polymerase (RNAP) and recruiting repair proteins.
  • Mfd also handles transcription complexes stalled by roadblocks or backtracking.

Purpose of the Study:

  • To identify the specific interactions between Mfd and RNAP.
  • To understand how Mfd mediates transcription-coupled DNA repair.
  • To define the role of RNAP's beta subunit in Mfd-mediated processes.

Main Methods:

  • Site-directed mutagenesis was used to introduce amino acid substitutions in the Escherichia coli RNAP beta subunit.
  • In vivo and in vitro assays were performed to assess the impact of these mutations on Mfd-RNAP interactions.
  • Analysis of Mfd's ability to displace stalled RNAP, enhance roadblock repression, and reactivate backtracked complexes.

Main Results:

  • Specific amino acid substitutions in the RNAP beta subunit were found to disrupt the direct interaction with Mfd.
  • These mutations prevent Mfd from displacing stalled RNAP from DNA.
  • A conserved surface-exposed patch on the RNAP beta1 domain was identified as essential for Mfd's function in DNA repair and transcription regulation.

Conclusions:

  • The identified RNAP beta1 domain patch is critical for Mfd's role in transcription-coupled DNA repair.
  • This interaction is essential for Mfd to manage stalled transcription complexes, including those stalled by roadblocks or backtracking.
  • Understanding this Mfd-RNAP interface provides insights into bacterial DNA repair mechanisms.

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