The structure of bacterial ParM filaments

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Albina Orlova1, Ethan C Garner, Vitold E Galkin

  • 1Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia 22908-0733, USA.

Nature Structural & Molecular Biology
|September 18, 2007
PubMed

Insights

Bacterial ParM protein filaments, essential for plasmid segregation, exhibit distinct structures and opposite helical handedness compared to eukaryotic actin filaments. This reveals insights into actin evolution and polymer family diversity.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Microbiology

Background:

  • Bacterial ParM protein is a homolog of eukaryotic actin.
  • ParM plays a crucial role in plasmid segregation during bacterial cell division.

Purpose of the Study:

  • To elucidate the structural differences between bacterial ParM filaments and eukaryotic F-actin.
  • To understand the molecular basis for ParM filament formation and its implications for polymer evolution.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) was employed.
  • Three-dimensional reconstruction techniques were utilized to determine filament structures.

Main Results:

  • ParM filaments possess distinct subunit-subunit interfaces compared to F-actin.
  • The helical handedness of ParM filaments is opposite to that of F-actin.
  • Variable twist in ParM filaments arises from domain-domain rotations within subunits.

Conclusions:

  • The structural divergence of ParM from F-actin highlights unique evolutionary paths within actin-like polymers.
  • Findings provide new perspectives on F-actin polymorphisms and the broader evolution of protein polymer families.

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