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Circular oligomeric particles formed by Ros/MucR family members mediate DNA organization in α-proteobacteria

Antonio Chaves-Sanjuan1,2, Gianluca D'Abrosca3, Veronica Russo4

  • 1Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milano, Italy.

Nucleic Acids Research
|November 26, 2024
PubMed

Insights

The Ros/MucR protein family, including Brucella

Area of Science:

  • Microbiology
  • Molecular Biology
  • Structural Biology

Background:

  • The transcriptional regulator MucR controls virulence gene expression in Brucella by binding AT-rich DNA.
  • MucR and homologs form the Ros/MucR family in α-proteobacteria, functionally resembling histone-like nucleoid structuring (H-NS) proteins.
  • H-NS proteins globally regulate transcription by structuring the bacterial genome.

Purpose of the Study:

  • To elucidate the functional architecture of MucR from Brucella abortus and its homolog Ml5 from Mesorhizobium loti.
  • To understand how Ros/MucR family members function as novel H-NS-like proteins.
  • To establish a model linking nucleoid structure and transcription regulation in α-proteobacteria.

Main Methods:

  • Integrated cryogenic electron microscopy (cryo-EM).
  • Nuclear magnetic resonance (NMR) spectroscopy.
  • Molecular modeling.
  • Biochemical assays.

Main Results:

  • MucR and Ml5 form circular quaternary assemblies.
  • These assemblies bridge and condense DNA by binding AT-rich sequences.
  • Ros/MucR proteins represent a novel class of H-NS-like proteins.

Conclusions:

  • MucR and Ml5 possess a unique circular quaternary structure enabling DNA binding and condensation.
  • The Ros/MucR family are a novel type of H-NS-like proteins.
  • This study provides a model for nucleoid structure and transcription regulation in α-proteobacteria.

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