Managing the bacterial chromosome

Transregio TRR 174 Seminar

  • Date: Aug 19, 2019
  • Time: 13:15
  • Speaker: Prof. David Sherrat
  • University of Oxford, Dept. of Biochemistry
  • Location: MPI for Terrestrial Microbiology
  • Room: Lecture hall
  • Host: TRR 174
  • Contact: thanbichler@uni-marburg.de

Our mission is to understand how the E. coli chromosome is managed in living cells, in order that the chromosome can be a template for gene expression, DNA replication and repair, and chromosome segregation. We track the action of single protein complexes over time in cells and determine their stoichiometry in steady state and perturbed conditions. Our work is directed at chromosome organisation and unlinking, with two major players, the SMC complex, MukBEF, and the decatenase, Topoisomerase IV, coordinating these processes through their interaction. We demonstrate that the circular chromosome is organised as series of loops around a thin (<130 nm) axial MukBEF core whose length is ~1100 times shorter than the chromosomal DNA. The core is linear (1 µm), but in the absence of MatP, becomes circular (1.5 µm). Our findings illustrate how MukBEF compacts the chromosome lengthwise while avoiding links between chromosome arms and demonstrate how displacement of MukBEF from ter promotes enrichment with the replication origin. Individualisation and separation of chromosome arms by MukBEF demonstrates a chromosome organisation mechanism akin to the action of condensin in mitotic chromosome formation, one likely used in all domains of life.

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