title: Nucleoid occlusion protein Noc recruits DNA to the bacterial cell membrane.
abstract: To proliferate efficiently, cells must co-ordinate division with chromosome segregation. In Bacillus subtilis, the nucleoid occlusion protein Noc binds to specific DNA sequences (NBSs) scattered around the chromosome and helps to protect genomic integrity by coupling the initiation of division to the progression of chromosome replication and segregation. However, how it inhibits division has remained unclear. Here, we demonstrate that Noc associates with the cell membrane via an N-terminal amphipathic helix, which is necessary for function. Importantly, the membrane-binding affinity of this helix is weak and requires the assembly of nucleoprotein complexes, thus establishing a mechanism for DNA-dependent activation of Noc. Furthermore, division inhibition by Noc requires recruitment of NBS DNA to the cell membrane and is dependent on its ability to bind DNA and membrane simultaneously. Indeed, Noc production in a heterologous system is sufficient for recruitment of chromosomal DNA to the membrane. Our results suggest a simple model in which the formation of large membrane-associated nucleoprotein complexes physically occludes assembly of the division machinery.
authors.affiliation: Centre for Bacterial Cell Biology, Medical School, Newcastle University, Newcastle Upon Tyne, UK.
authors.forename: David William
authors.initials: DW
authors.lastname: Adams
authors.affiliation: Centre for Bacterial Cell Biology, Medical School, Newcastle University, Newcastle Upon Tyne, UK.
authors.forename: Ling Juan
authors.initials: LJ
authors.lastname: Wu
authors.affiliation: Centre for Bacterial Cell Biology, Medical School, Newcastle University, Newcastle Upon Tyne, UK jeff.errington@ncl.ac.uk.
authors.forename: Jeff
authors.initials: J
authors.lastname: Errington
mesh_terms: D001412:Bacillus subtilis / Q000166:cytology / Q000235:genetics* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002876:Chromosomes, Bacterial / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D008954:Models, Biological
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins
keywords: Bacillus subtilis; FtsZ; Noc; ParB; nucleoid occlusion