title: The outer membrane secretin PilQ from Neisseria meningitidis binds DNA.
abstract: Neisseria meningitidis is naturally competent for transformation throughout its growth cycle. Transformation in neisserial species is coupled to the expression of type IV pili, which are present on the cell surface as bundled filamentous appendages, and are assembled, extruded and retracted by the pilus biogenesis components. During the initial phase of the transformation process, binding and uptake of DNA takes place with entry through a presumed outer-membrane channel into the periplasm. This study showed that DNA associates only weakly with purified pili, but binds significantly to the PilQ complex isolated directly from meningococcal membranes. By assessing the DNA-binding activity of the native complex PilQ, as well as recombinant truncated PilQ monomers, it was shown that the N-terminal region of PilQ is involved in the interaction with DNA. It was evident that the binding of ssDNA to PilQ had a higher affinity than the binding of dsDNA. The binding of DNA to PilQ did not, however, depend on the presence of the neisserial DNA-uptake sequence. It is suggested that transforming DNA is introduced into the cell through the outer-membrane channel formed by the PilQ complex, and that DNA uptake occurs by non-specific introduction of DNA coupled to pilus retraction, followed by presentation to DNA-binding component(s), including PilQ.
authors.affiliation: Centre for Molecular Biology and Neuroscience and Institute of Microbiology, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway.|Centre for Molecular Biology and Neuroscience and Institute of Microbiology, University of Oslo, Oslo, Norway.
authors.forename: Reza
authors.initials: R
authors.lastname: Assalkhou
authors.affiliation: Centre for Molecular Biology and Neuroscience and Institute of Microbiology, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway.|Centre for Molecular Biology and Neuroscience and Institute of Microbiology, University of Oslo, Oslo, Norway.
authors.forename: Seetha
authors.initials: S
authors.lastname: Balasingham
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Manchester Interdisciplinary Biocentre, 131 Princess Street, Manchester M1 7DN, UK.
authors.forename: Richard F
authors.initials: RF
authors.lastname: Collins
authors.affiliation: Centre for Molecular Biology and Neuroscience and Institute of Microbiology, University of Oslo, Oslo, Norway.
authors.forename: Stephan A
authors.initials: SA
authors.lastname: Frye
authors.affiliation: Centre for Molecular Biology and Neuroscience and Institute of Microbiology, University of Oslo, Oslo, Norway.
authors.forename: Tonje
authors.initials: T
authors.lastname: Davidsen
authors.affiliation: Centre for Molecular Biology and Neuroscience and Institute of Microbiology, University of Oslo, Oslo, Norway.
authors.forename: Afsaneh V
authors.initials: AV
authors.lastname: Benam
authors.affiliation: Centre for Molecular Biology and Neuroscience and Institute of Microbiology, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway.|Centre for Molecular Biology and Neuroscience and Institute of Microbiology, University of Oslo, Oslo, Norway.
authors.forename: Magnar
authors.initials: M
authors.lastname: Bjørås
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Manchester Interdisciplinary Biocentre, 131 Princess Street, Manchester M1 7DN, UK.
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Derrick
authors.affiliation: Centre for Molecular Biology and Neuroscience and Institute of Microbiology, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway.|Centre for Molecular Biology and Neuroscience and Institute of Microbiology, University of Oslo, Oslo, Norway.
authors.forename: Tone
authors.initials: T
authors.lastname: Tønjum
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D009345:Neisseria meningitidis / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D013379:Substrate Specificity; D014169:Transformation, Bacterial
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004277:DNA, Single-Stranded; C084295:pilQ protein, bacteria; D036781:Fimbriae Proteins; D004247:DNA