SMC Complexes: Universal DNA Looping Machines with Distinct Regulators

Trends Genet. 2018 Jun;34(6):477-487. doi: 10.1016/j.tig.2018.03.003. Epub 2018 Mar 29.

Abstract

What drives the formation of chromatin loops has been a long-standing question in chromosome biology. Recent work provides major insight into the basic principles behind loop formation. Structural maintenance of chromosomes (SMC) complexes, that are conserved from bacteria to humans, are key to this process. The SMC family includes condensin and cohesin, which structure chromosomes to enable mitosis and long-range gene regulation. We discuss novel insights into the mechanism of loop formation and the implications for how these complexes ultimately shape chromosomes. A picture is emerging in which these complexes form small loops that they then processively enlarge. It appears that SMC complexes act by family-wide basic principles, with complex-specific levels of control.

Keywords: SMC complexes; cohesin; condensin; loop extrusion; loop formation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Adenosine Triphosphatases / genetics
  • CCCTC-Binding Factor / genetics
  • Carrier Proteins / genetics*
  • Cell Cycle Proteins / genetics
  • Chromatin / genetics*
  • Chromosomal Proteins, Non-Histone / genetics
  • Chromosomes / genetics*
  • Cohesins
  • DNA-Binding Proteins / genetics
  • Humans
  • Mitosis / genetics*
  • Multiprotein Complexes / genetics
  • Nuclear Proteins / genetics*

Substances

  • CCCTC-Binding Factor
  • Carrier Proteins
  • Cell Cycle Proteins
  • Chromatin
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Multiprotein Complexes
  • Nuclear Proteins
  • SMC2 protein, human
  • condensin complexes
  • Adenosine Triphosphatases