Bacterial mitosis: ParM of plasmid R1 moves plasmid DNA by an actin-like insertional polymerization mechanism.
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.
Møller-Jensen
Jakob
J
Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
Borch
Jonas
J
Dam
Mette
M
Jensen
Rasmus B
RB
Roepstorff
Peter
P
Gerdes
Kenn
K
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
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