Regensburg 2022 – scientific programme

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BP: Fachverband Biologische Physik

BP 13: Cytoskeleton

BP 13.2: Talk

Wednesday, September 7, 2022, 10:00–10:15, H15

Dynamic bridging explains sub-diffusive movement of chromosomal loci — •Srikanth Subramanian and Seán Murray — Max Planck Institute for Terrestrial Microbiology, Marburg, Germany

Chromosomal loci in bacterial cells show a robust sub-diffusive scaling of the mean square displacement (MSD) ∼ τ^α, with α < 0.5 under various growth conditions and antibiotic treatments. Recent experiments have also shown that DNA-bridging Nucleoid Associated Proteins (NAPs) play an important role in chromosome organisation and compaction. Here, using polymer simulations we investigate the role of DNA bridging in determining the dynamics of chromosomal loci. We find that bridging compacts the polymer and reproduces the sub-diffusive dynamics of monomers at timescales shorter than the bridge lifetime. Furthermore, the measured scaling exponent defines a relationship between chromosome compaction and bridge lifetime. Importantly, measuring the MSD of tagged chromosomal loci in WT and NAP mutant (ΔH-NS) we find that the decompacted mutant has a higher scaling exponent as expected. Based on the observed mobility of chromosomal loci and our simulations, we predict a lower bound on the average bridge lifetime of NAPs to be around 5 seconds.