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Structure of the ParM filament at 8.5Å resolution

Pananghat Gayathri1, Takashi Fujii, Keiichi Namba

  • 1MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK.

Journal of Structural Biology
|March 7, 2013
PubMed

Insights

The ParMRC system

Area of Science:

  • Microbiology and Molecular Biology
  • Structural Biology

Background:

  • The ParMRC system is a type II plasmid segregation system in Escherichia coli.
  • The actin-like protein ParM forms the filament crucial for this system's function.

Purpose of the Study:

  • To elucidate the structural basis of ParM filament dynamics.
  • To understand the mechanism of ATP hydrolysis and nucleotide conformational changes within the filament.

Main Methods:

  • Cryo-electron microscopy was used to obtain an 8.5Å resolution reconstruction of the ParM filament.
  • Monomeric crystal structures of ParM were fitted into the 3D density reconstruction.

Main Results:

  • A metastable ParM conformation, stabilized by intrafilament contacts, was identified within the filament.
  • This filament conformation is dependent on the ATP-bound state and alters nucleotide conformation.
  • Structural insights explain the stimulated hydrolysis of ATP upon ParM polymerization.

Conclusions:

  • The study reveals the structural mechanisms underlying ParM filament dynamics and function in plasmid segregation.
  • Understanding these dynamics provides a basis for further research into bacterial cytoskeletal elements and segregation systems.
Keywords:
ActinBacterial cytoskeletonCytomotiveDynamic instability

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