In vivo assembly of bacterial partition condensates on circular supercoiled and linear DNA

Abstract In bacteria, faithful DNA segregation of chromosomes and plasmids is mainly mediated by ParABS systems. These systems, consisting of a ParA ATPase, a DNA binding ParB CTPase, and centromere sites parS , orchestrate the separation of newly replicated DNA copies and their intracellular positi...

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Bibliographic Details
Published in:Molecular microbiology 2024-08
Main Authors: Alaoui, Hicham Sekkouri, Quèbre, Valentin, Delimi, Linda, Rech, Jérôme, Debaugny‐Diaz, Roxanne, Labourdette, Delphine, Campos, Manuel, Cornet, François, Walter, Jean‐Charles, Bouet, Jean‐Yves
Format: Article
Language:English
Subjects:
Bacteriology
Biochemistry, Molecular Biology
Life Sciences
Microbiology and Parasitology
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Summary:Abstract In bacteria, faithful DNA segregation of chromosomes and plasmids is mainly mediated by ParABS systems. These systems, consisting of a ParA ATPase, a DNA binding ParB CTPase, and centromere sites parS , orchestrate the separation of newly replicated DNA copies and their intracellular positioning. Accurate segregation relies on the assembly of a high‐molecular‐weight complex, comprising a few hundreds of ParB dimers nucleated from parS sites. This complex assembles in a multi‐step process and exhibits dynamic liquid‐droplet properties. Despite various proposed models, the complete mechanism for partition complex assembly remains elusive. This study investigates the impact of DNA supercoiling on ParB DNA binding profiles in vivo, using the ParABS system of the plasmid F. We found that variations in DNA supercoiling does not significantly affect any steps in the assembly of the partition complex. Furthermore, physical modeling, leveraging ChIP‐seq data from linear plasmids F, suggests that ParB sliding is restricted to approximately 2 Kbp from parS , highlighting the necessity for additional mechanisms beyond ParB sliding over DNA for concentrating ParB into condensates nucleated at parS . Finally, explicit simulations of a polymer coated with bound ParB suggest a dominant role for ParB‐ParB interactions in DNA compaction within ParB condensates.
ISSN:0950-382X
1365-2958
1365-2958
DOI:10.1111/mmi.15297