Abstract
Bacillus subtilis ParB forms multimeric networks involving non-specific DNA binding leading to DNA condensation. Previously, we found that an excess of the free C-terminal domain (CTD) of ParB impeded DNA condensation or promoted decondensation of pre-assembled networks (Fisher et al., 2017). However, interpretation of the molecular basis for this phenomenon was complicated by our inability to uncouple protein binding from DNA condensation. Here, we have combined lateral magnetic tweezers with TIRF microscopy to simultaneously control the restrictive force against condensation and to visualise ParB protein binding by fluorescence. At non-permissive forces for condensation, ParB binds non-specifically and highly dynamically to DNA. Our new approach concluded that the free CTD blocks the formation of ParB networks by heterodimerisation with full length DNA-bound ParB. This strongly supports a model in which the CTD acts as a key bridging interface between distal DNA binding loci within ParB networks.
Original language | English |
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Article number | e43812 |
Number of pages | 19 |
Journal | eLife |
Volume | 8 |
DOIs | |
Publication status | Published - 25 Mar 2019 |
Keywords
- B. subtilis
- bacterial chromosome dynamics
- chromosomes
- gene expression
- magnetic tweezers
- molecular biophysics
- ParB
- single molecule
- Spo0J
- structural biology
- TIRF microscopy
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Profiles
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Professor Mark S Dillingham
- Fundamental Bioscience
- School of Biochemistry - Professor of Biochemistry
Person: Academic , Member