title: Functional characterization of the role of the chromosome I partitioning system in genome segregation in Deinococcus radiodurans.
abstract: Deinococcus radiodurans, a radiation-resistant bacterium, harbors a multipartite genome. Chromosome I contains three putative centromeres (segS1, segS2, and segS3), and ParA (ParA1) and ParB (ParB1) homologues. The ParB1 interaction with segS was sequence specific, and ParA1 was shown to be a DNA binding ATPase. The ATPase activity of ParA1 was stimulated when segS elements were coincubated with ParB1, but the greatest increase was observed with segS3. ParA1 incubated with the segS-ParB1 complex showed increased light scattering in the absence of ATP. In the presence of ATP, this increase was continued with segS1-ParA1B1 and segS2-ParA1B1 complexes, while it decreased rapidly after an initial increase for 30 min in the case of segS3. D. radiodurans cells expressing green fluorescent protein (GFP)-ParB1 produced foci on nucleoids, and the ΔparB1 mutant showed growth retardation and ∼13%-higher anucleation than the wild type. Unstable mini-F plasmids carrying segS1 and segS2 showed inheritance in Escherichia coli without ParA1B1, while segS3-mediated plasmid stability required the in trans expression of ParA1B1. Unlike untransformed E. coli cells, cells harboring pDAGS3, a plasmid carrying segS3 and also expressing ParB1-GFP, produced discrete GFP foci on nucleoids. These findings suggested that both segS elements and the ParA1B1 proteins of D. radiodurans are functionally active and have a role in genome segregation.
authors: Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai, India.
authors: Vijay Kumar
authors: VK
authors: Charaka
authors: Hari S
authors: HS
authors: Misra
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism*; D002876:Chromosomes, Bacterial / Q000378:metabolism*; D034301:Deinococcus / Q000235:genetics* / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; C052883:chromosome partition proteins, bacterial