title: Polymerization of SopA partition ATPase: regulation by DNA binding and SopB.
abstract: In bacteria, mitotic stability of plasmids and many chromosomes depends on replicon-specific systems which comprise a centromere, a centromere-binding protein and an ATPase. Dynamic self-assembly of the ATPase appears to enable active partition of replicon copies into cell-halves, but for most ATPases (the Walker-box type) the mechanism is unknown. Also unknown is how the host cell contributes to partition. We have examined the effects of non-sequence-specific DNA on in vitro self-assembly of the SopA partition ATPase of plasmid F. SopA underwent polymerization provided ATP was present. DNA inhibited this polymerization and caused breakdown of pre-formed polymers. Centromere-binding protein SopB counteracted DNA-mediated inhibition by itself binding to and masking the DNA, as well as by stimulating polymerization directly. The results suggest that in vivo, SopB smothers DNA by spreading from sopC, allowing SopA-ATP polymerization which initiates plasmid displacement. We propose that SopB and nucleoid DNA regulate SopA polymerization and hence partition.
authors.affiliation: Laboratoire de Microbiologie et de Génétique Moléculaire, UMR5100 CNRS, Toulouse, France. jean-yves.bouet@ibcg.biotoul.fr
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Bouet
authors.forename: Yoan
authors.initials: Y
authors.lastname: Ah-Seng
authors.forename: Nacer
authors.initials: N
authors.lastname: Benmeradi
authors.forename: David
authors.initials: D
authors.lastname: Lane
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D029968:Escherichia coli Proteins / Q000378:metabolism / Q000502:physiology*; D005144:F Factor / Q000378:metabolism*; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D008954:Models, Biological; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; C489223:SopB protein, E coli; D000255:Adenosine Triphosphate; C060971:SopA protein, Bacteria