title: A novel intrinsically disordered outer membrane lipoprotein of Aggregatibacter actinomycetemcomitans binds various cytokines and plays a role in biofilm response to interleukin-1β and interleukin-8.
abstract: Intrinsically disordered proteins (IDPs) do not have a well-defined and stable 3-dimensional fold. Some IDPs can function as either transient or permanent binders of other proteins and may interact with an array of ligands by adopting different conformations. A novel outer membrane lipoprotein, bacterial interleukin receptor I (BilRI) of the opportunistic oral pathogen Aggregatibacter actinomycetemcomitans binds a key gatekeeper proinflammatory cytokine interleukin (IL)-1β. Because the amino acid sequence of the novel lipoprotein resembles that of fibrinogen binder A of Haemophilus ducreyi, BilRI could have the potential to bind other proteins, such as host matrix proteins. However, from the tested host matrix proteins, BilRI interacted with neither collagen nor fibrinogen. Instead, the recombinant non-lipidated BilRI, which was intrinsically disordered, bound various pro/anti-inflammatory cytokines, such as IL-8, tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-10. Moreover, BilRI played a role in the in vitro sensing of IL-1β and IL-8 because low concentrations of cytokines did not decrease the amount of extracellular DNA in the matrix of bilRI-mutant biofilm as they did in the matrix of wild-type biofilm when the biofilms were exposed to recombinant cytokines for 22 hours. BilRI played a role in the internalization of IL-1β in the gingival model system but did not affect either IL-8 or IL-6 uptake. However, bilRI deletion did not entirely prevent IL-1β internalization, and the binding of cytokines to BilRI was relatively weak. Thus, BilRI might sequester cytokines on the surface of A. actinomycetemcomitans to facilitate the internalization process in low local cytokine concentrations.
authors.affiliation: a Department of Biochemistry , University of Turku , Turku , Finland.
authors.forename: Tuuli
authors.initials: T
authors.lastname: Ahlstrand
authors.affiliation: a Department of Biochemistry , University of Turku , Turku , Finland.
authors.forename: Heidi
authors.initials: H
authors.lastname: Tuominen
authors.affiliation: a Department of Biochemistry , University of Turku , Turku , Finland.
authors.forename: Arzu
authors.initials: A
authors.lastname: Beklen
authors.affiliation: a Department of Biochemistry , University of Turku , Turku , Finland.
authors.forename: Annamari
authors.initials: A
authors.lastname: Torittu
authors.affiliation: b Oral Microbiology , Department of Odontology, Umeå University , Umeå , Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Oscarsson
authors.affiliation: c Biocenter Oulu and Department of Pathology , University of Oulu , Oulu Finland.
authors.forename: Raija
authors.initials: R
authors.lastname: Sormunen
authors.affiliation: d Institute of Dentistry, University of Turku , Turku , Finland.
authors.forename: Marja T
authors.initials: MT
authors.lastname: Pöllänen
authors.affiliation: e Program in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki , Helsinki , Finland.|f Department of Biological and Environmental Sciences , Nanoscience Center, University of Jyväskylä , Jyväskylä , Finland.|g Department of Chemistry , Nanoscience Center, University of Jyväskylä , Jyväskylä , Finland.
authors.forename: Perttu
authors.initials: P
authors.lastname: Permi
authors.affiliation: a Department of Biochemistry , University of Turku , Turku , Finland.
authors.forename: Riikka
authors.initials: R
authors.lastname: Ihalin
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D005881:Gingiva / Q000382:microbiology; D006801:Humans; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D064267:Intrinsically Disordered Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D008074:Lipoproteins / Q000276:immunology / Q000378:metabolism; D017472:Receptors, Interleukin-1 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; C508606:CXCL8 protein, human; C508609:IL10 protein, human; D053583:Interleukin-1beta; D016209:Interleukin-8; D064267:Intrinsically Disordered Proteins; D008074:Lipoproteins; D017472:Receptors, Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10
keywords: Aggregatibacter actinomycetemcomitans; bacterial cytokine receptor; biofilm matrix composition; intrinsically disordered protein; outer membrane lipoprotein