Caulobacter requires a dedicated mechanism to initiate chromosome segregation.
Chromosome segregation in bacteria is rapid and directed, but the mechanisms responsible for this movement are still unclear. We show that Caulobacter crescentus makes use of and requires a dedicated mechanism to initiate chromosome segregation. Caulobacter has a single circular chromosome whose origin of replication is positioned at one cell pole. Upon initiation of replication, an 8-kb region of the chromosome containing both the origin and parS moves rapidly to the opposite pole. This movement requires the highly conserved ParABS locus that is essential in Caulobacter. We use chromosomal inversions and in vivo time-lapse imaging to show that parS is the Caulobacter site of force exertion, independent of its position in the chromosome. When parS is moved farther from the origin, the cell waits for parS to be replicated before segregation can begin. Also, a mutation in the ATPase domain of ParA halts segregation without affecting replication initiation. Chromosome segregation in Caulobacter cannot occur unless a dedicated parS guiding mechanism initiates movement.
Toro
Esteban
E
Department of Developmental Biology, Stanford University School of Medicine, Beckman Center, B300, Stanford, CA 94305, USA.
Hong
Sun-Hae
SH
McAdams
Harley H
HH
Shapiro
Lucy
L
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D016935:Caulobacter crescentus / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division; D002478:Cells, Cultured; D020090:Chromosome Segregation / Q000502:physiology*; D002876:Chromosomes, Bacterial / Q000378:metabolism*; D004261:DNA Replication; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D018741:Replication Origin
D001426:Bacterial Proteins