Bacterial mitosis: partitioning protein ParA oscillates in spiral-shaped structures and positions plasmids at mid-cell

Mol Microbiol. 2004 Apr;52(2):385-98. doi: 10.1111/j.1365-2958.2004.04002.x.


The par2 locus of Escherichia coli plasmid pB171 encodes oscillating ATPase ParA, DNA binding protein ParB and two cis-acting DNA regions to which ParB binds (parC1 and parC2). Three independent techniques were used to investigate the subcellular localization of plasmids carrying par2. In cells with a single plasmid focus, the focus located preferentially at mid-cell. In cells with two foci, these located at quarter-cell positions. In the absence of ParB and parC1/parC2, ParA-GFP formed stationary helices extending from one end of the nucleoid to the other. In the presence of ParB and parC1/parC2, ParA-GFP oscillated in spiral-shaped structures. Amino acid substitutions in ParA simultaneously abolished ParA spiral formation, oscillation and either plasmid localization or plasmid separation at mid-cell. Therefore, our results suggest that ParA spirals position plasmids at the middle of the bacterial nucleoid and subsequently separate them into daughter cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • DNA, Bacterial / metabolism
  • Escherichia coli / cytology*
  • Escherichia coli / genetics*
  • Green Fluorescent Proteins
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Mitosis*
  • Plasmids*
  • Recombinant Fusion Proteins / metabolism


  • Bacterial Proteins
  • DNA, Bacterial
  • Luminescent Proteins
  • Recombinant Fusion Proteins
  • chromosome partition proteins, bacterial
  • Green Fluorescent Proteins