Estelle Crozat-brendon

Presentation

I am interested in the organisation and dynamics of bacterial chromosomes and the proteins involved in this process, especially the Nucleoid-Associated-Proteins (NAPs). Using a variety of tools (biochemistry, biophysics, genetics and microscopy), I am trying to understand the binding of proteins such as MatP, Fis, H-NS, and their effect on the structure of the chromosome in E. coli. To do this, I have been combining a biophysical method, the Tethered Particle Motion (TPM) set-up, with short-time microscopy, which allows to generate physical properties of chromosomal loci (MSD, Diffusion Coefficient…) by analysing the motion of foci in the cell in different conditions or mutants.

Example of a TPM set-up to study MatP
a. A bead is attached to a single DNA molecule (*).  When a protein binds (here, MatP binds matS sites), this induces a conformational change (**) or a loop (***), which reduces the apparent length of the DNA, and therefore the Brownian motion of the bead.
b. Example of a trace for a bead linked to a DNA containing 2 matS. Several, short looping events can be observed, indicating the dynamics of the loop formation.

In collaboration with Dr. Catherine Tardin (IPBS).

Example of chromosomal loci movement

A loci near the origin of replication has been tagged with a parS sequence, so that we can observe a focus formed by the fixation of ParB-GFP. We are then using Matlab  scripts to extract the trajectories of each focus, and their properties.

In collaboration with Prof. Pietro Cicuta, Cambridge University.

Our last paper is being advertised on the CNRS webpage

Post-replicative pairing of sister ter regions in Escherichia coli involves multiple activities of MatP
Crozat E, Tardin E, Salhi M, Rousseau P, Lablaine A, Bertoni T, Holcman D, Sclavi B, Cicuta P,  Cornet F
Nature communications 30 July 2020

Publications

• Crozat E, Tardin E, Salhi M, Rousseau P, Lablaine A, Bertoni T, Holcman D, Sclavi B, Cicuta P, Cornet F.
  Post-replicative pairing of sister ter regions in Escherichia coli involves multiple activities of MatP
  Nature Commun
  2020 Jul
• Fournes F, Crozat E, Pages C, Tardin C, Salomé L, Cornet F*, Rousseau P*.
  FtsK translocation inhibits recombination at a Xer site involved in horizontal gene transfer
  Proc Nat Acad Sci USA
  2016 Jan
• 2014 Jan Diagne CT, Salhi M, Crozat E, Salomé L, Cornet F, Rousseau P, Tardin C. (2014) TPM analyses reveal that FtsK contributes both to the assembly and the activation of the XerCD-dif recombination synapse. Nucleic Acids Res 42: 1721–1732.
• Lee JY, Finkelstein IJ, Crozat E, Sherratt DJ, Greene EC .
  Single Molecule Imaging of DNA Curtains Reveals Mechanisms of KOPS Targeting by the DNA Translocase FtsK
  PNAS
  2012 Jan
• Crozat E, Meglio A, Allemand JF, Chivers C, Howarth M, Vénien-Bryan C, Grainge I, Sherratt DJ .
  Separating speed and ability to displace roadblocks during DNA translocation by FtsK
  EMBO J
  2010 Jan