SMC is recruited to oriC by ParB and promotes chromosome segregation in Streptococcus pneumoniae

Mol Microbiol. 2011 Aug;81(3):676-88. doi: 10.1111/j.1365-2958.2011.07722.x. Epub 2011 Jun 22.


Segregation of replicated chromosomes is an essential process in all organisms. How bacteria, such as the oval-shaped human pathogen Streptococcus pneumoniae, efficiently segregate their chromosomes is poorly understood. Here we show that the pneumococcal homologue of the DNA-binding protein ParB recruits S. pneumoniae condensin (SMC) to centromere-like DNA sequences (parS) that are located near the origin of replication, in a similar fashion as was shown for the rod-shaped model bacterium Bacillus subtilis. In contrast to B. subtilis, smc is not essential in S. pneumoniae, and Δsmc cells do not show an increased sensitivity to gyrase inhibitors or high temperatures. However, deletion of smc and/or parB results in a mild chromosome segregation defect. Our results show that S. pneumoniae contains a functional chromosome segregation machine that promotes efficient chromosome segregation by recruitment of SMC via ParB. Intriguingly, the data indicate that other, as of yet unknown mechanisms, are at play to ensure proper chromosome segregation in this organism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Chromosome Segregation*
  • Chromosomes, Bacterial / metabolism*
  • DNA-Binding Proteins / metabolism*
  • Gene Deletion
  • Origin Recognition Complex*
  • Protein Binding
  • Streptococcus pneumoniae / enzymology*
  • Streptococcus pneumoniae / genetics
  • Streptococcus pneumoniae / growth & development
  • Streptococcus pneumoniae / metabolism*


  • Bacterial Proteins
  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • OriC chromosomal replication origin
  • Origin Recognition Complex
  • SMC protein, Bacteria