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ParG, a protein required for active partition of bacterial plasmids, has a dimeric ribbon-helix-helix structure

Alexander P Golovanov1, Daniela Barillà, Marina Golovanova

  • 1Department of Biomolecular Sciences, University of Manchester Institute of Science and Technology (UMIST), PO Box 88, Manchester M60 1QD, UK.

Molecular Microbiology
|November 19, 2003
PubMed

Insights

The ParG protein, crucial for DNA partitioning in plasmid TP228, forms a dimer with a ribbon-helix-helix structure. This structure suggests ParG may act as a transcriptional repressor, binding DNA via its folded domain.

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Genetics

Background:

  • The ParG protein is essential for DNA partitioning in the multidrug resistance plasmid TP228.
  • ParG functions as a dimer and interacts with DNA and the ParF protein.

Purpose of the Study:

  • To determine the solution nuclear magnetic resonance (NMR) structure of the ParG protein.
  • To elucidate the DNA-binding mechanism and potential transcriptional repressor activity of ParG.

Main Methods:

  • Solution nuclear magnetic resonance (NMR) spectroscopy to determine the 3D structure of ParG.
  • Analysis of protein-DNA and protein-protein interactions.

Main Results:

  • The ParG dimer exhibits a ribbon-helix-helix (RHH) architecture, similar to Arc/MetJ repressors.
  • ParG binds DNA via its folded domain, coupled with oligomerization.
  • A new classification for Arc/MetJ superfamily proteins and ParG homologues is proposed based on conserved residues.

Conclusions:

  • ParG's RHH structure suggests DNA binding in the major groove, akin to transcriptional repressors.
  • ParG may possess intrinsic transcriptional repressor activity.
  • Structural insights facilitate a refined classification of DNA-binding proteins.

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