title: The internal organization of mycobacterial partition assembly: does the DNA wrap a protein core?
abstract: Before cell division in many bacteria, the ParBs spread on a large segment of DNA encompassing the origin-proximal parS site(s) to form the partition assembly that participates in chromosome segregation. Little is known about the structural organization of chromosomal partition assembly. We report solution X-ray and neutron scattering data characterizing the size parameters and internal organization of a nucleoprotein assembly formed by the mycobacterial chromosomal ParB and a 120-meric DNA containing a parS-encompassing region from the mycobacterial genome. The cross-sectional radii of gyration and linear mass density describing the rod-like ParB-DNA assembly were determined from solution scattering. A "DNA outside, protein inside" mode of partition assembly organization consistent with the neutron scattering hydrogen/deuterium contrast variation data is discussed. In this organization, the high scattering DNA is positioned towards the outer region of the partition assembly. The new results presented here provide a basis for understanding how ParBs organize the parS-proximal chromosome, thus setting the stage for further interactions with the DNA condensins, the origin tethering factors and the ParA.
authors.affiliation: Center for Structural Molecular Biology, Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA.
authors.forename: Shuo
authors.initials: S
authors.lastname: Qian
authors.forename: Rebecca
authors.initials: R
authors.lastname: Dean
authors.forename: Volker S
authors.initials: VS
authors.lastname: Urban
authors.forename: Barnali N
authors.initials: BN
authors.lastname: Chaudhuri
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D020090:Chromosome Segregation; D002876:Chromosomes, Bacterial; D004269:DNA, Bacterial / Q000378:metabolism*; D046911:Macromolecular Substances / Q000378:metabolism; D009161:Mycobacterium / Q000235:genetics* / Q000378:metabolism*; D010957:Plasmids
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D046911:Macromolecular Substances; C052883:chromosome partition proteins, bacterial