Smc5/6: a link between DNA repair and unidirectional replication?

Nat Rev Mol Cell Biol. 2008 Feb;9(2):177-82. doi: 10.1038/nrm2309.


Of the three structural maintenance of chromosome (SMC) complexes, two directly regulate chromosome dynamics. The third, Smc5/6, functions mainly in homologous recombination and in completing DNA replication. The literature suggests that Smc5/6 coordinates DNA repair, in part through post-translational modification of uncharacterized target proteins that can dictate their subcellular localization, and that Smc5/6 also functions to establish DNA-damage-dependent cohesion. A nucleolar-specific Smc5/6 function has been proposed because Smc5/6 yeast mutants display penetrant phenotypes of ribosomal DNA (rDNA) instability. rDNA repeats are replicated unidirectionally. Here, we propose that unidirectional replication, combined with global Smc5/6 functions, can explain the apparent rDNA specificity.

MeSH terms

  • Cell Cycle Proteins / metabolism
  • Cell Cycle Proteins / physiology*
  • Chromosomal Proteins, Non-Histone / metabolism
  • DNA Damage
  • DNA Repair*
  • DNA Replication*
  • DNA, Ribosomal / metabolism
  • Gene Expression Regulation*
  • Humans
  • Models, Biological
  • Models, Genetic
  • Nuclear Proteins / metabolism
  • Recombination, Genetic
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / physiology


  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA, Ribosomal
  • Nuclear Proteins
  • SMC5 protein, S cerevisiae
  • SMC5 protein, human
  • SMC6 protein, S cerevisiae
  • SMC6 protein, human
  • Saccharomyces cerevisiae Proteins
  • cohesins