title: ParAB Partition Dynamics in Firmicutes: Nucleoid Bound ParA Captures and Tethers ParB-Plasmid Complexes.
abstract: In Firmicutes, small homodimeric ParA-like (δ2) and ParB-like (ω2) proteins, in concert with cis-acting plasmid-borne parS and the host chromosome, secure stable plasmid inheritance in a growing bacterial population. This study shows that (ω:YFP)2 binding to parS facilitates plasmid clustering in the cytosol. (δ:GFP)2 requires ATP binding but not hydrolysis to localize onto the cell's nucleoid as a fluorescent cloud. The interaction of (δ:CFP)2 or δ2 bound to the nucleoid with (ω:YFP)2 foci facilitates plasmid capture, from a very broad distribution, towards the nucleoid and plasmid pairing. parS-bound ω2 promotes redistribution of (δ:GFP)2, leading to the dynamic release of (δ:GFP)2 from the nucleoid, in a process favored by ATP hydrolysis and protein-protein interaction. (δD60A:GFP)2, which binds but cannot hydrolyze ATP, also forms unstable complexes on the nucleoid. In the presence of ω2, (δD60A:GFP)2 accumulates foci or patched structures on the nucleoid. We propose that (δ:GFP)2 binding to different nucleoid regions and to ω2-parS might generate (δ:GFP)2 gradients that could direct plasmid movement. The iterative pairing and unpairing cycles may tether plasmids equidistantly on the nucleoid to ensure faithful plasmid segregation by a mechanism compatible with the diffusion-ratchet mechanism as proposed from in vitro reconstituted systems.
authors.affiliation: Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain.
authors.forename: Virginia S
authors.initials: VS
authors.lastname: Lioy
authors.affiliation: Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Volante
authors.affiliation: Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain.
authors.forename: Nora E
authors.initials: NE
authors.lastname: Soberón
authors.affiliation: Max Planck Institute for Molecular Genetics, Ihnestrasse 73, D-1000 Berlin, Germany.
authors.forename: Rudi
authors.initials: R
authors.lastname: Lurz
authors.affiliation: Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Ayora
authors.affiliation: Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Alonso
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D049452:Green Fluorescent Proteins / Q000378:metabolism; D009707:Nucleosomes / Q000235:genetics; D010957:Plasmids / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D059008:Time-Lapse Imaging
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D009707:Nucleosomes; C052883:chromosome partition proteins, bacterial; D049452:Green Fluorescent Proteins