Reconstitution of DNA segregation driven by assembly of a prokaryotic actin homolog

Science. 2007 Mar 2;315(5816):1270-4. doi: 10.1126/science.1138527.


Multiple unrelated polymer systems have evolved to partition DNA molecules between daughter cells at division. To better understand polymer-driven DNA segregation, we reconstituted the three-component segregation system of the R1 plasmid from purified components. We found that the ParR/parC complex can construct a simple bipolar spindle by binding the ends of ParM filaments, inhibiting dynamic instability, and acting as a ratchet permitting incorporation of new monomers and riding on the elongating filament ends. Under steady-state conditions, the dynamic instability of unattached ParM filaments provides the energy required to drive DNA segregation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / chemistry*
  • Actins / metabolism*
  • Actins / ultrastructure
  • Adenosine Triphosphate / metabolism
  • Bacterial Proteins / metabolism
  • Biopolymers
  • DNA Topoisomerase IV / metabolism
  • DNA, Bacterial / metabolism*
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / metabolism*
  • Escherichia coli Proteins / ultrastructure
  • Microspheres
  • Protein Binding
  • R Factors / genetics
  • R Factors / metabolism*
  • Repressor Proteins / metabolism


  • Actins
  • Bacterial Proteins
  • Biopolymers
  • DNA, Bacterial
  • Escherichia coli Proteins
  • ParM protein, E coli
  • ParR protein, bacteria
  • Repressor Proteins
  • Adenosine Triphosphate
  • DNA Topoisomerase IV