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Bacterial actin: architecture of the ParMRC plasmid DNA partitioning complex.

Abstract

The R1 plasmid employs ATP-driven polymerisation of the actin-like protein ParM to move newly replicated DNA to opposite poles of a bacterial cell. This process is essential for ensuring accurate segregation of the low-copy number plasmid and is the best characterised example of DNA partitioning in prokaryotes. In vivo, ParM only forms long filaments when capped at both ends by attachment to a centromere-like region parC, through a small DNA-binding protein ParR. Here, we present biochemical and electron microscopy data leading to a model for the mechanism by which ParR-parC complexes bind and stabilise elongating ParM filaments. We propose that the open ring formed by oligomeric ParR dimers with parC DNA wrapped around acts as a rigid clamp, which holds the end of elongating ParM filaments while allowing entry of new ATP-bound monomers. We propose a processive mechanism by which cycles of ATP hydrolysis in polymerising ParM drives movement of ParR-bound parC DNA. Importantly, our model predicts that each pair of plasmids will be driven apart in the cell by just a single double helical ParM filament.

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    Source

    The EMBO journal 27:16 2008 Aug 20 pg 2230-8

    MeSH

    Actins
    DNA Topoisomerase IV
    DNA, Bacterial
    Escherichia coli Proteins
    Models, Molecular
    Peptides
    Plasmids
    Promoter Regions, Genetic
    Protein Binding
    Protein Structure, Secondary

    Pub Type(s)

    Journal Article

    Language

    eng

    PubMed ID

    18650930

    Citation

    TY - JOUR T1 - Bacterial actin: architecture of the ParMRC plasmid DNA partitioning complex. AU - Salje,Jeanne, AU - Löwe,Jan, Y1 - 2008/07/24/ PY - 2008/5/27/received PY - 2008/7/07/accepted PY - 2008/7/24/aheadofprint PY - 2008/7/25/pubmed PY - 2008/9/11/medline PY - 2008/7/25/entrez SP - 2230 EP - 8 JF - The EMBO journal JO - EMBO J. VL - 27 IS - 16 N2 - The R1 plasmid employs ATP-driven polymerisation of the actin-like protein ParM to move newly replicated DNA to opposite poles of a bacterial cell. This process is essential for ensuring accurate segregation of the low-copy number plasmid and is the best characterised example of DNA partitioning in prokaryotes. In vivo, ParM only forms long filaments when capped at both ends by attachment to a centromere-like region parC, through a small DNA-binding protein ParR. Here, we present biochemical and electron microscopy data leading to a model for the mechanism by which ParR-parC complexes bind and stabilise elongating ParM filaments. We propose that the open ring formed by oligomeric ParR dimers with parC DNA wrapped around acts as a rigid clamp, which holds the end of elongating ParM filaments while allowing entry of new ATP-bound monomers. We propose a processive mechanism by which cycles of ATP hydrolysis in polymerising ParM drives movement of ParR-bound parC DNA. Importantly, our model predicts that each pair of plasmids will be driven apart in the cell by just a single double helical ParM filament. SN - 1460-2075 UR - https://www.unboundmedicine.com/medline/citation/18650930/Bacterial_actin:_architecture_of_the_ParMRC_plasmid_DNA_partitioning_complex_ L2 - http://emboj.embopress.org/cgi/pmidlookup?view=long&pmid=18650930 ER -