title: SlmA forms a higher-order structure on DNA that inhibits cytokinetic Z-ring formation over the nucleoid.
abstract: The spatial and temporal control of Filamenting temperature sensitive mutant Z (FtsZ) Z-ring formation is crucial for proper cell division in bacteria. In Escherichia coli, the synthetic lethal with a defective Min system (SlmA) protein helps mediate nucleoid occlusion, which prevents chromosome fragmentation by binding FtsZ and inhibiting Z-ring formation over the nucleoid. However, to perform its function, SlmA must be bound to the nucleoid. To deduce the basis for this chromosomal requirement, we performed biochemical, cellular, and structural studies. Strikingly, structures show that SlmA dramatically distorts DNA, allowing it to bind as an orientated dimer-of-dimers. Biochemical data indicate that SlmA dimer-of-dimers can spread along the DNA. Combined structural and biochemical data suggest that this DNA-activated SlmA oligomerization would prevent FtsZ protofilament propagation and bundling. Bioinformatic analyses localize SlmA DNA sites near membrane-tethered chromosomal regions, and cellular studies show that SlmA inhibits FtsZ reservoirs from forming membrane-tethered Z rings. Thus, our combined data indicate that SlmA DNA helps block Z-ring formation over chromosomal DNA by forming higher-order protein-nucleic acid complexes that disable FtsZ filaments from coalescing into proper structures needed for Z-ring creation.
authors.affiliation: Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA.
authors.forename: Nam K
authors.initials: NK
authors.lastname: Tonthat
authors.forename: Sara L
authors.initials: SL
authors.lastname: Milam
authors.forename: Nagababu
authors.initials: N
authors.lastname: Chinnam
authors.forename: Travis
authors.initials: T
authors.lastname: Whitfill
authors.forename: William
authors.initials: W
authors.lastname: Margolin
authors.forename: Maria A
authors.initials: MA
authors.lastname: Schumacher
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D055503:Protein Multimerization
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C071525:FtsZ protein, Bacteria; C502032:SlmA protein, E coli