title: Visualization and functional dissection of coaxial paired SpoIIIE channels across the sporulation septum.
abstract: SpoIIIE is a membrane-anchored DNA translocase that localizes to the septal midpoint to mediate chromosome translocation and membrane fission during Bacillus subtilis sporulation. Here we use cell-specific protein degradation and quantitative photoactivated localization microscopy in strains with a thick sporulation septum to investigate the architecture and function of the SpoIIIE DNA translocation complex in vivo. We were able to visualize SpoIIIE complexes with approximately equal numbers of molecules in the mother cell and the forespore. Cell-specific protein degradation showed that only the mother cell complex is required to translocate DNA into the forespore, whereas degradation in either cell reverses membrane fission. Our data suggest that SpoIIIE assembles a coaxially paired channel for each chromosome arm comprised of one hexamer in each cell to maintain membrane fission during DNA translocation. We show that SpoIIIE can operate, in principle, as a bi-directional motor that exports DNA.
authors.affiliation: Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States.
authors.forename: Jae
authors.initials: J
authors.lastname: Yen Shin
authors.affiliation: Division of Biological Sciences, University of California, San Diego, La Jolla, United States.
authors.forename: Javier
authors.initials: J
authors.lastname: Lopez-Garrido
authors.affiliation: Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States.
authors.forename: Sang-Hyuk
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States.
authors.forename: Cesar
authors.initials: C
authors.lastname: Diaz-Celis
authors.affiliation: Division of Biological Sciences, University of California, San Diego, La Jolla, United States.
authors.forename: Tinya
authors.initials: T
authors.lastname: Fleming
authors.affiliation: Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States.
authors.forename: Carlos
authors.initials: C
authors.lastname: Bustamante
authors.affiliation: Division of Biological Sciences, University of California, San Diego, La Jolla, United States.
authors.forename: Kit
authors.initials: K
authors.lastname: Pogliano
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D002876:Chromosomes, Bacterial / Q000737:chemistry* / Q000648:ultrastructure; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D008853:Microscopy / Q000379:methods; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D055503:Protein Multimerization; D059748:Proteolysis; D013171:Spores, Bacterial / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C030069:spore-specific proteins, Bacillus
keywords: B. subtilis; biophysics; cell biology; chromosome segregation; membrane fission; sporulation; structural biology; superresolution microscopy