ParMRC is known as one of the best systems for bacterial segregation. This system uses actin-like filaments to push plasmids, small DNA molecules within a cell that are physically separated from a chromosomal DNA and can replicate independently, to opposite poles of the cell.


There the plasmids are segregated and can replicate without interference from the chromosomal DNA.[1] During cell division many plasmids are plagued with low copy numbers and thus evolved active segregation to avoid plasmid loss during cell division [2] The process of this segregation is carried out by a small number of components, three to be exact, in the DNA, with incredible efficiency.[3] The three components, a parC DNA site, and two proteins parR and parM all combine to create the ParMRC system, a type II plasmid partitioning system.[3]

The process by which the plasmids are segregated from the chromosomal DNA is not an extremely complicated one and contains just three components. The first component ParM is an actin-like protein. The second is a DNA-binding adaptor protein known as ParR. The last component is a centromere-like region called ParC.[4] The process works using all three of these components and has been evolved to work extremely efficiently. In the cell the ParM protein filaments search for plasmids. Next, they find the ParR and ParC that are headed to DNA molecules and push them to opposite poles of the cell in order to segregate them.[5]

This type of process using filament forming actin-like protein (ParM) to move DNA to opposite sides of the cell has been adopted by several Bacteria as their main plasmid segregation systems, due to its efficiency. This discovery as well as improvements in technology, such as higher resolution in light microscopy, will soon allow scientists to track individual molecules in cells to reveal even more about this ParMRC system.[4]


  1. ^ Salje, Leanne; Gayathri, Pananghat (Oct 2010). "Loewe". Jan. 8 (Nature Reviews Microbiology).
  2. ^ Salje, Jeanne; et al. (8 October 2010). "The ParMRC system: molecular mechanisms of plasmid segregation by actin-like filaments". Nature Reviews Microbiology. 8 (10): 683–692. doi:10.1038/nrmicro2425. PMID 20844556.
  3. ^ a b "Structural studies on the ParMRC plasmid DNA partitioning complex". European Commission: Cordis. 31 March 2011. Retrieved 28 May 2015.
  4. ^ a b Kenn, Gerdes; Howard, Martin; Szardenings, Florian (11 June 2010). "Pushing and Pulling in Prokaryotic DNA Segregation". Science. 141 (11): 927–942. doi:10.1016/j.cell.2010.05.033. PMID 20550930.
  5. ^ Salje, Jeanne; Lowe, Jan (20 Aug 2008). "Bacterial actin: architecture of the ParMRC plasmid DNA partitioning complex". EMBO Journal. 27 (16): 2230–2238. doi:10.1038/emboj.2008.152. PMC 2519105. PMID 18650930. Retrieved 28 May 2015.