Movement and equipositioning of plasmids by ParA filament disassembly
Author(s)
Ringgaard, Simon; van Zon, Jeroen Sebastiaan; Howard, Martin; Gerdes, Kenn
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Bacterial plasmids encode partitioning (par) loci that confer stable plasmid inheritance. We showed previously that, in the presence of ParB and parC encoded by the par2 locus of plasmid pB171, ParA formed cytoskeletal-like structures that dynamically relocated over the nucleoid. Simultaneously, the par2 locus distributed plasmids regularly over the nucleoid. We show here that the dynamic ParA patterns are not simple oscillations. Rather, ParA nucleates and polymerizes in between plasmids. When a ParA assembly reaches a plasmid, the assembly reaction reverses into disassembly. Strikingly, plasmids consistently migrate behind disassembling ParA cytoskeletal structures, suggesting that ParA filaments pull plasmids by depolymerization. The perpetual cycles of ParA assembly and disassembly result in continuous relocation of plasmids, which, on time averaging, results in equidistribution of the plasmids. Mathematical modeling of ParA and plasmid dynamics support these interpretations. Mutational analysis supports a molecular mechanism in which the ParB/parC complex controls ParA filament depolymerization.
Date issued
2009-11Department
Massachusetts Institute of Technology. Department of PhysicsJournal
Proceedings of the National Academy of Sciences of the United States of America
Publisher
National Academy of Sciences
Citation
Ringaard, van Zon, Howard, and Gerdes (2009). Movement and equipositioning of plasmids by ParA filament disassembly. Proceedings of the National Academy of Sciences of the United States of America 106:19369-19374. Copyright ©2009 by the National Academy of Sciences
Version: Final published version
ISSN
0027-8424
Keywords
cytoskeleton, DNA segregation, mathematical modeling, pulling, ParA ParB