title: Central domain of DivIB caps the C-terminal regions of the FtsL/DivIC coiled-coil rod.
abstract: DivIB(FtsQ), FtsL, and DivIC(FtsB) are enigmatic membrane proteins that are central to the process of bacterial cell division. DivIB(FtsQ) is dispensable in specific conditions in some species, and appears to be absent in other bacterial species. The presence of FtsL and DivIC(FtsB) appears to be conserved despite very low sequence conservation. The three proteins form a complex at the division site, FtsL and DivIC(FtsB) being associated through their extracellular coiled-coil region. We report here structural investigations by NMR, small-angle neutron and x-ray scattering, and interaction studies by surface plasmon resonance, of the complex of DivIB, FtsL, and DivIC from Streptococcus pneumoniae, using soluble truncated forms of the proteins. We found that one side of the "bean"-shaped central beta-domain of DivIB interacts with the C-terminal regions of the dimer of FtsL and DivIC. This finding is corroborated by sequence comparisons across bacterial genomes. Indeed, DivIB is absent from species with shorter FtsL and DivIC proteins that have an extracellular domain consisting only of the coiled-coil segment without C-terminal conserved regions (Campylobacterales). We propose that the main role of the interaction of DivIB with FtsL and DivIC is to help the formation, or to stabilize, the coiled-coil of the latter proteins. The coiled-coil of FtsL and DivIC, itself or with transmembrane regions, could be free to interact with other partners.
authors.affiliation: Laboratoire d'Ingénierie des Macromolécules, Institut de Biologie Structurale, UMR 5075, Université Joseph Fourier, CNRS, Commissariat à l'Energie Atomique, 38027 Grenoble, France.
authors.forename: Soizic
authors.initials: S
authors.lastname: Masson
authors.forename: Thomas
authors.initials: T
authors.lastname: Kern
authors.forename: Audrey
authors.initials: A
authors.lastname: Le Gouëllec
authors.forename: Cécile
authors.initials: C
authors.lastname: Giustini
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Simorre
authors.forename: Philip
authors.initials: P
authors.lastname: Callow
authors.forename: Thierry
authors.initials: T
authors.lastname: Vernet
authors.forename: Frank
authors.initials: F
authors.lastname: Gabel
authors.forename: André
authors.initials: A
authors.lastname: Zapun
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D033363:Neutron Diffraction; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D053838:Scattering, Small Angle; D016415:Sequence Alignment; D012995:Solubility; D013296:Streptococcus pneumoniae / Q000166:cytology / Q000378:metabolism; D020349:Surface Plasmon Resonance; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; C531001:DivIB protein, Streptococcus pneumoniae; D008565:Membrane Proteins; D010446:Peptide Fragments