ParABS system explained

The parABS system is a broadly conserved molecular mechanism for plasmid partitioning and chromosome segregation in bacteria. Originally identified as a genetic element required for faithful partitioning of low-copy-number plasmids, it consists of three components: the ParA ATPase, the ParB DNA-binding protein, and the cis-acting parS sequence. The parA and parB genes are typically found in the same operon, with parS elements located within or adjacent to this operon. Collectively, these components function to ensure accurate partitioning of plasmids or whole chromosomes between bacterial daughter cells prior to cell division.[1]

Mechanism

Based on chromatin immunoprecipitation (ChIP) experiments, ParB has the ability to bind not only to high-affinity parS sites but also to adjacent nonspecific DNA, a behavior known as "spreading".[2] [3] [4] [5] The ParB-DNA complex is thought to be translocated by a Brownian ratchet mechanism involving the ParA ATPase: ParA binds DNA nonspecifically in its ATP-bound state but much more weakly in its ADP-bound state.[6] [7] The ParB-DNA complex binds to ATP-bound ParA,[8] stimulating its ATPase activity and its dissociation from DNA. In this way, the ParB-DNA complex can be translocated by chasing a receding wave.[9] This translocation mechanism has been observed by fluorescence microscopy both in vivo and more recently in vitro with purified components.[10] [11] [12] [13]

Notes and References

  1. Book: Surtees, JA. Funnell, BE. Plasmid and chromosome traffic control: how ParA and ParB drive partition. Current Topics in Developmental Biology. 2003. 56. 145–80. 14584729. 10.1016/s0070-2153(03)01010-x. 9780121531560.
  2. Rodionov. O. Lobocka, M . Yarmolinsky, M . Silencing of genes flanking the P1 plasmid centromere. Science. Jan 22, 1999. 283. 5401. 546–9. 9915704. 10.1126/science.283.5401.546. 1999Sci...283..546R.
  3. Murray. H. Ferreira, H . Errington, J . The bacterial chromosome segregation protein Spo0J spreads along DNA from parS nucleation sites. Molecular Microbiology. Sep 2006. 61. 5. 1352–61. 16925562. 10.1111/j.1365-2958.2006.05316.x. 11449/701. 17530813. free.
  4. Breier. AM. Grossman, AD. Whole-genome analysis of the chromosome partitioning and sporulation protein Spo0J (ParB) reveals spreading and origin-distal sites on the Bacillus subtilis chromosome. Molecular Microbiology. May 2007. 64. 3. 703–18. 17462018. 10.1111/j.1365-2958.2007.05690.x. free.
  5. Sanchez. A. Cattoni, DI. Walter, JC . Rech, J. Parmeggiani, A. Nollmann, M. Bouet, JY . Stochastic Self-Assembly of ParB Proteins Builds the Bacterial DNA Segregation Apparatus. Cell Systems. 2015. 1. 2. 163–73. 27135801. 10.1016/j.cels.2015.07.013. free.
  6. Bouet. JY. Ah-Seng, Y. Benmeradi, N. Lane, D. Polymerization of SopA partition ATPase: regulation by DNA binding and SopB. Molecular Microbiology. 2007. 63. 2. 468–81. 17166176. 10.1111/j.1365-2958.2006.05537.x. free.
  7. Castaing, JP. Bouet, JY. Lane, D. F plasmid partition depends on interaction of SopA with non-specific DNA. Molecular Microbiology. 2008. 70. 4. 1000–11. 18826408. 10.1111/j.1365-2958.2008.06465.x. 26612131. free.
  8. Bouet. JY. Funnell, BE. P1 ParA interacts with the P1 partition complex at parS and an ATP-ADP switch controls ParA activities. EMBO J. 1999. 18. 5. 1415–24. 10064607. 10.1093/emboj/18.5.1415. 1171231.
  9. Walter. JC. Dorignac, J. Lorman, V. Rech, J. Bouet, JY. Nollmann, M. Palmeri, J. Parmeggiani, A. Geniet, F . Surfing on protein waves: proteophoresis as a mechanism for bacterial genome partitioning. Physical Review Letters. 2017. 119. 28101. 028101. 28753349. 10.1103/PhysRevLett.119.028101. 1702.07372. 2017PhRvL.119b8101W. 6762277.
  10. Ptacin. JL. Lee, SF . Garner, EC . Toro, E . Eckart, M . Comolli, LR . Moerner, WE . Shapiro, L . A spindle-like apparatus guides bacterial chromosome segregation. Nature Cell Biology. Aug 2010. 12. 8. 791–8. 20657594. 10.1038/ncb2083 . 3205914.
  11. Ringgaard. S . van Zon, J . Howard, M . Gerdes, K . Movement and equipositioning of plasmids by ParA filament disassembly. Proceedings of the National Academy of Sciences of the United States of America. Nov 17, 2009. 106. 46. 19369–74. 19906997. 10.1073/pnas.0908347106 . 2775997. 2009PNAS..10619369R . free .
  12. Hwang. LC. Vecchiarelli, AG . Han, YW . Mizuuchi, M . Harada, Y . Funnell, BE . Mizuuchi, K . ParA-mediated plasmid partition driven by protein pattern self-organization. The EMBO Journal. May 2, 2013. 32. 9. 1238–49. 23443047. 10.1038/emboj.2013.34 . 3642677.
  13. Vecchiarelli. AG. Hwang, LC . Mizuuchi, K . Cell-free study of F plasmid partition provides evidence for cargo transport by a diffusion-ratchet mechanism. Proceedings of the National Academy of Sciences of the United States of America. Apr 9, 2013. 110. 15. E1390–7. 23479605. 10.1073/pnas.1302745110. 3625265. 2013PNAS..110E1390V. free.

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