The unnamed complex: what do we know about Smc5-Smc6?
The structural maintenance of chromosome (SMC) proteins constitute the cores of three protein complexes involved in chromosome metabolism; cohesin, condensin and the Smc5-Smc6 complex. While the roles of cohesin and condensin in sister chromatid cohesion and chromosome condensation respectively have been described, the cellular function of Smc5-Smc6 is as yet not understood, consequently the less descriptive name. The complex is involved in a variety of DNA repair pathways. It contains activities reminiscent of those described for cohesin and condensin, as well as several DNA helicases and endonucleases. It is required for sister chromatid recombination, and smc5-smc6 mutants suffer from the accumulation of unscheduled recombination intermediates. The complex contains a SUMO-ligase and potentially an ubiquitin-ligase; thus Smc5-Smc6 might presently have a dull name, but it seems destined to be recognized as a key player in the maintenance of chromosome stability. In this review we summarize our present understanding of this enigmatic protein complex.
De Piccoli
Giacomo
G
Cell Cycle Group, MRC Clinical Sciences Centre, Imperial College, Du Cane Road, London W12 0NN, UK.
Torres-Rosell
Jordi
J
Aragón
Luis
L
D000251:Adenosine Triphosphatases / Q000502:physiology; D000818:Animals; D018797:Cell Cycle Proteins / Q000502:physiology*; D002842:Chromatids / Q000502:physiology / Q000648:ultrastructure; D002868:Chromosomal Proteins, Non-Histone / Q000502:physiology; D002875:Chromosomes / Q000502:physiology* / Q000648:ultrastructure; D015825:Chromosomes, Fungal / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D004260:DNA Repair / Q000502:physiology; D004261:DNA Replication / Q000502:physiology; D004271:DNA, Fungal / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D004268:DNA-Binding Proteins / Q000502:physiology; D006801:Humans; D046912:Multiprotein Complexes / Q000502:physiology*; D011995:Recombination, Genetic / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology; D012568:Schizosaccharomyces / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D029702:Schizosaccharomyces pombe Proteins / Q000502:physiology; D044767:Ubiquitin-Protein Ligases / Q000502:physiology; D029867:Xenopus Proteins / Q000502:physiology; D014982:Xenopus laevis / Q000235:genetics; D000097722:Cohesins
D000251:Adenosine Triphosphatases; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004271:DNA, Fungal; D004275:DNA, Ribosomal; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D044767:Ubiquitin-Protein Ligases; D029867:Xenopus Proteins; D000097722:Cohesins; C108312:condensin complexes