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Structure and dynamics of polymyxin-resistance-associated response regulator PmrA in complex with promoter DNA

Yuan-Chao Lou1, Tsai-Hsuan Weng2, Yi-Chuan Li2

  • 1Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan, ROC.

Nature Communications
|November 14, 2015
PubMed

Insights

PmrA protein

Area of Science:

  • Microbiology
  • Molecular Biology
  • Structural Biology

Background:

  • PmrA is a response regulator in the OmpR/PhoB family, controlling antibiotic resistance genes.
  • Phosphorylation of OmpR/PhoB regulators leads to dimerization and DNA binding for adaptive responses.
  • Previous studies suggested an REC-DBD interface in KdpE is crucial for transcription activation.

Purpose of the Study:

  • To determine the structure of the PmrA-DNA complex.
  • To investigate the role of the REC-DBD interface in PmrA function.
  • To elucidate the mechanism of PmrA-mediated transcription activation.

Main Methods:

  • X-ray crystallography to determine the PmrA-DNA complex structure at 3.2-Å resolution.
  • Nuclear Magnetic Resonance (NMR) spectroscopy to study domain dynamics in solution.
  • Reporter gene assays to assess the function of PmrA variants.

Main Results:

  • The PmrA-DNA complex structure revealed a REC-DBD interface, distinct from KdpE.
  • NMR studies indicated transient REC-DBD interactions and independent domain tumbling in solution.
  • Reporter gene analyses showed that altered interface residues did not significantly impact gene expression.

Conclusions:

  • The REC-DBD interface is not essential for PmrA-mediated gene expression.
  • Interdomain dynamics and DBD-DBD interactions likely facilitate PmrA's interaction with RNA polymerase holoenzyme.
  • These findings suggest a dynamic mechanism for PmrA-dependent transcription activation.

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