title: QseC controls biofilm formation of non-typeable Haemophilus influenzae in addition to an AI-2-dependent mechanism.
abstract: Non-typeable Haemophilus influenzae (NTHi) is a common pathogen associated with diseases such as acute otitis media or exacerbations in patients with chronic obstructive pulmonary disease. The biofilm-forming capability substantially contributes to the persistence of NTHi. However, the regulation of biofilm formation is not completely understood. Quorum sensing regulated by autoinducer-2 produced by luxS is until now the only described regulatory mechanism. In this study, we show that the two-component signalling system QseB/C is involved in the biofilm formation of NTHi in vitro. An isogenic NTHi mutant of qseC (Hi3655KR2) showed a significant decrease in biofilm formation under static and semi-static conditions as assessed by crystal violet staining. In addition, under constant flow conditions, Hi3655KR2 formed less biofilm after 48 h. The biofilm defects were irrespective of autoinducer-2 levels. Hence, here we suggest for the first time a regulatory circuit in NTHi, which controls biofilm formation by mechanisms other than or in addition to luxS-dependent factors.
authors.affiliation: Medical Microbiology, Department of Laboratory Medicine Malmö, Lund University, Skåne University Hospital, Malmö, Sweden.
authors.forename: Can M
authors.initials: CM
authors.lastname: Unal
authors.forename: Birendra
authors.initials: B
authors.lastname: Singh
authors.forename: Christophe
authors.initials: C
authors.lastname: Fleury
authors.forename: Kalpana
authors.initials: K
authors.lastname: Singh
authors.forename: Luis
authors.initials: L
authors.lastname: Chávez de Paz
authors.forename: Gunnel
authors.initials: G
authors.lastname: Svensäter
authors.forename: Kristian
authors.initials: K
authors.lastname: Riesbeck
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms; D013437:Carbon-Sulfur Lyases / Q000235:genetics / Q000378:metabolism; D003470:Culture Media / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D005840:Gentian Violet; D006193:Haemophilus influenzae / Q000235:genetics / Q000502:physiology*; D059765:Homologous Recombination; D006714:Homoserine / Q000031:analogs & derivatives* / Q000378:metabolism; D007783:Lactones / Q000378:metabolism*; D008163:Luminescent Measurements; D050296:Microbial Viability; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D053038:Quorum Sensing; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D007783:Lactones; C091088:N-octanoylhomoserine lactone; C455504:QseC protein, E coli; D006714:Homoserine; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria; D005840:Gentian Violet