Dynamic architecture of the Escherichia coli structural maintenance of chromosomes (SMC) complex, MukBEF

Nucleic Acids Res. 2019 Oct 10;47(18):9696-9707. doi: 10.1093/nar/gkz696.

Abstract

Ubiquitous Structural Maintenance of Chromosomes (SMC) complexes use a proteinaceous ring-shaped architecture to organize and individualize chromosomes, thereby facilitating chromosome segregation. They utilize cycles of adenosine triphosphate (ATP) binding and hydrolysis to transport themselves rapidly with respect to DNA, a process requiring protein conformational changes and multiple DNA contact sites. By analysing changes in the architecture and stoichiometry of the Escherichia coli SMC complex, MukBEF, as a function of nucleotide binding to MukB and subsequent ATP hydrolysis, we demonstrate directly the formation of dimer of MukBEF dimer complexes, dependent on dimeric MukF kleisin. Using truncated and full length MukB, in combination with MukEF, we show that engagement of the MukB ATPase heads on nucleotide binding directs the formation of dimers of heads-engaged dimer complexes. Complex formation requires functional interactions between the C- and N-terminal domains of MukF with the MukB head and neck, respectively, and MukE, which organizes the complexes by stabilizing binding of MukB heads to MukF. In the absence of head engagement, a MukF dimer bound by MukE forms complexes containing only a dimer of MukB. Finally, we demonstrate that cells expressing MukBEF complexes in which MukF is monomeric are Muk-, with the complexes failing to associate with chromosomes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosomal Proteins, Non-Histone / chemistry*
  • Chromosomal Proteins, Non-Histone / genetics
  • Chromosomes / chemistry
  • Chromosomes / genetics
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • Escherichia coli / chemistry
  • Escherichia coli / genetics
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / genetics*
  • Multiprotein Complexes / chemistry
  • Multiprotein Complexes / genetics
  • Protein Binding
  • Repressor Proteins / chemistry
  • Repressor Proteins / genetics*

Substances

  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • MukB protein, E coli
  • Multiprotein Complexes
  • Repressor Proteins
  • mukE protein, E coli
  • mukF protein, E coli