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ParB dynamics and the critical role of the CTD in DNA condensation unveiled by combined force-fluorescence measurements

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). Howeve...

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Autores principales: Madariaga-Marcos, Julene, Pastrana, Cesar L, Fisher, Gemma LM, Dillingham, Mark Simon, Moreno-Herrero, Fernando
Formato: Online Artículo Texto
Lenguaje:English
Publicado: eLife Sciences Publications, Ltd 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6433461/
https://www.ncbi.nlm.nih.gov/pubmed/30907359
http://dx.doi.org/10.7554/eLife.43812
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author Madariaga-Marcos, Julene
Pastrana, Cesar L
Fisher, Gemma LM
Dillingham, Mark Simon
Moreno-Herrero, Fernando
author_facet Madariaga-Marcos, Julene
Pastrana, Cesar L
Fisher, Gemma LM
Dillingham, Mark Simon
Moreno-Herrero, Fernando
author_sort Madariaga-Marcos, Julene
collection PubMed
description 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.
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spelling pubmed-64334612019-03-27 ParB dynamics and the critical role of the CTD in DNA condensation unveiled by combined force-fluorescence measurements Madariaga-Marcos, Julene Pastrana, Cesar L Fisher, Gemma LM Dillingham, Mark Simon Moreno-Herrero, Fernando eLife Chromosomes and Gene Expression 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. eLife Sciences Publications, Ltd 2019-03-25 /pmc/articles/PMC6433461/ /pubmed/30907359 http://dx.doi.org/10.7554/eLife.43812 Text en © 2019, Madariaga-Marcos et al http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/This article is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use and redistribution provided that the original author and source are credited.
spellingShingle Chromosomes and Gene Expression
Madariaga-Marcos, Julene
Pastrana, Cesar L
Fisher, Gemma LM
Dillingham, Mark Simon
Moreno-Herrero, Fernando
ParB dynamics and the critical role of the CTD in DNA condensation unveiled by combined force-fluorescence measurements
title ParB dynamics and the critical role of the CTD in DNA condensation unveiled by combined force-fluorescence measurements
title_full ParB dynamics and the critical role of the CTD in DNA condensation unveiled by combined force-fluorescence measurements
title_fullStr ParB dynamics and the critical role of the CTD in DNA condensation unveiled by combined force-fluorescence measurements
title_full_unstemmed ParB dynamics and the critical role of the CTD in DNA condensation unveiled by combined force-fluorescence measurements
title_short ParB dynamics and the critical role of the CTD in DNA condensation unveiled by combined force-fluorescence measurements
title_sort parb dynamics and the critical role of the ctd in dna condensation unveiled by combined force-fluorescence measurements
topic Chromosomes and Gene Expression
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6433461/
https://www.ncbi.nlm.nih.gov/pubmed/30907359
http://dx.doi.org/10.7554/eLife.43812
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