Dynamic ParB–DNA interactions initiate and maintain a partition condensate for bacterial chromosome segregation
Miloš Tišma (Kavli institute of nanoscience Delft, BN/Cees Dekker Lab)
Richard Janissen (TU Delft - BN/Bionanoscience, Kavli institute of nanoscience Delft)
Hammam Antar (University of Lausanne)
Alejandro Martin-Gonzalez (Kavli institute of nanoscience Delft, BN/Cees Dekker Lab)
Roman Barth (BN/Cees Dekker Lab, Kavli institute of nanoscience Delft)
T.G.T. Beekman (Student TU Delft)
Jaco Torre (BN/Cees Dekker Lab)
Davide Michieletto (The University of Edinburgh)
Stephan Gruber (University of Lausanne)
C Dekker (BN/Cees Dekker Lab)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
In most bacteria, chromosome segregation is driven by the ParABS system where the CTPase protein ParB loads at the parS site to trigger the formation of a large partition complex. Here, we present in vitro studies of the partition complex for Bacillus subtilis ParB, using single-molecule fluorescence microscopy and AFM imaging to show that transient ParB–ParB bridges are essential for forming DNA condensates. Molecular Dynamics simulations confirm that condensation occurs abruptly at a critical concentration of ParB and show that multimerization is a prerequisite for forming the partition complex. Magnetic tweezer force spectroscopy on mutant ParB proteins demonstrates that CTP hydrolysis at the N-terminal domain is essential for DNA condensation. Finally, we show that transcribing RNA polymerases can steadily traverse the ParB–DNA partition complex. These findings uncover how ParB forms a stable yet dynamic partition complex for chromosome segregation that induces DNA condensation and segregation while enabling replication and transcription.
help_outline