Bacterial mitosis: partitioning protein ParA oscillates in spiral-shaped structures and positions plasmids at mid-cell.
The par2 locus of Escherichia coli plasmid pB171 encodes oscillating ATPase ParA, DNA binding protein ParB and two cis-acting DNA regions to which ParB binds (parC1 and parC2). Three independent techniques were used to investigate the subcellular localization of plasmids carrying par2. In cells with a single plasmid focus, the focus located preferentially at mid-cell. In cells with two foci, these located at quarter-cell positions. In the absence of ParB and parC1/parC2, ParA-GFP formed stationary helices extending from one end of the nucleoid to the other. In the presence of ParB and parC1/parC2, ParA-GFP oscillated in spiral-shaped structures. Amino acid substitutions in ParA simultaneously abolished ParA spiral formation, oscillation and either plasmid localization or plasmid separation at mid-cell. Therefore, our results suggest that ParA spirals position plasmids at the middle of the bacterial nucleoid and subsequently separate them into daughter cells.
Ebersbach
Gitte
G
Department of Biochemistry and Molecular Biology, Campusvej 55, DK-5230 Odense M, University of Southern Denmark, Denmark.
Gerdes
Kenn
K
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000166:cytology* / Q000235:genetics*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008938:Mitosis; D010957:Plasmids; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; C052883:chromosome partition proteins, bacterial; D049452:Green Fluorescent Proteins