The structure of bacterial ParM filaments

Nat Struct Mol Biol. 2007 Oct;14(10):921-6. doi: 10.1038/nsmb1300. Epub 2007 Sep 16.


Bacterial ParM is a homolog of eukaryotic actin and is involved in moving plasmids so that they segregate properly during cell division. Using cryo-EM and three-dimensional reconstruction, we show that ParM filaments have a different structure from F-actin, with very different subunit-subunit interfaces. These interfaces result in the helical handedness of the ParM filament being opposite to that of F-actin. Like F-actin, ParM filaments have a variable twist, and we show that this involves domain-domain rotations within the ParM subunit. The present results yield new insights into polymorphisms within F-actin, as well as the evolution of polymer families.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Actins / genetics
  • Actins / metabolism
  • Actins / ultrastructure*
  • Cryoelectron Microscopy
  • Escherichia coli / chemistry
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Escherichia coli Proteins / ultrastructure*
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Structure, Quaternary*
  • Protein Subunits / chemistry*
  • Protein Subunits / genetics
  • Protein Subunits / metabolism


  • Actins
  • Escherichia coli Proteins
  • ParM protein, E coli
  • Protein Subunits

Associated data

  • PDB/2QU4