title: Bacterial mitosis: ParM of plasmid R1 moves plasmid DNA by an actin-like insertional polymerization mechanism.
abstract: Bacterial DNA segregation takes place in an active and ordered fashion. In the case of Escherichia coli plasmid R1, the partitioning system (par) separates paired plasmid copies and moves them to opposite cell poles. Here we address the mechanism by which the three components of the R1 par system act together to generate the force required for plasmid movement during segregation. ParR protein binds cooperatively to the centromeric parC DNA region, thereby forming a complex that interacts with the filament-forming actin-like ParM protein in an ATP-dependent manner, suggesting that plasmid movement is powered by insertional polymerization of ParM. Consistently, we find that segregating plasmids are positioned at the ends of extending ParM filaments. Thus, the process of R1 plasmid segregation in E. coli appears to be mechanistically analogous to the actin-based motility operating in eukaryotic cells. In addition, we find evidence suggesting that plasmid pairing is required for ParM polymerization.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Møller-Jensen
authors.forename: Jonas
authors.initials: J
authors.lastname: Borch
authors.forename: Mette
authors.initials: M
authors.lastname: Dam
authors.forename: Rasmus B
authors.initials: RB
authors.lastname: Jensen
authors.forename: Peter
authors.initials: P
authors.lastname: Roepstorff
authors.forename: Kenn
authors.initials: K
authors.lastname: Gerdes
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins; D004261:DNA Replication; D004270:DNA, Circular / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D008938:Mitosis / Q000502:physiology*; D011485:Protein Binding; D011487:Protein Conformation; D011815:R Factors / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D020349:Surface Plasmon Resonance
chemical_list: D000199:Actins; D001426:Bacterial Proteins; D004270:DNA, Circular; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; C471255:ParM protein, E coli; C086169:ParR protein, bacteria; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins