title: Expression of the Gene for Autotransporter AutB ofNeisseria meningitidisAffects Biofilm Formation and Epithelial Transmigration.
abstract: Neisseria meningitidisis a Gram-negative bacterium that resides as a commensal in the upper respiratory tract of humans, but occasionally, it invades the host and causes sepsis and/or meningitis. The bacterium can produce eight autotransporters, seven of which have been studied to some detail. The remaining one, AutB, has not been characterized yet. Here, we show that theautBgene is broadly distributed among pathogenicNeisseriaspp. The gene is intact in most meningococcal strains. However, its expression is prone to phase variation due to slipped-strand mispairing at AAGC repeats located within the DNA encoding the signal sequence and is switched off in the vast majority of these strains. Moreover, various genetic disruptions preventautBexpression in most of the strains in which the gene is in phase indicating a strong selection against AutB synthesis. We observed thatautBis expressed in two of the strains examined and that AutB is secreted and exposed at the cell surface. Functionality assays revealed that AutB synthesis promotes biofilm formation and delays the passage of epithelial cell layers invitro. We hypothesize that this autotransporter is produced during the colonization process only in specific niches to facilitate microcolony formation, but its synthesis is switched off probably to evade the immune system and facilitate human tissue invasion.
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University Utrecht, Netherlands.
authors.forename: Jesús
authors.initials: J
authors.lastname: Arenas
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht Utrecht, Netherlands.
authors.forename: Fernanda L
authors.initials: FL
authors.lastname: Paganelli
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University Utrecht, Netherlands.
authors.forename: Patricia
authors.initials: P
authors.lastname: Rodríguez-Castaño
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University Utrecht, Netherlands.
authors.forename: Sara
authors.initials: S
authors.lastname: Cano-Crespo
authors.affiliation: Department of Medical Microbiology, Academic Medical Center Amsterdam, Netherlands.
authors.forename: Arie
authors.initials: A
authors.lastname: van der Ende
authors.affiliation: Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University Utrecht, Netherlands.
authors.forename: Jos P M
authors.initials: JP
authors.lastname: van Putten
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University Utrecht, Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Tommassen
mesh_terms: D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D002460:Cell Line; D004847:Epithelial Cells / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D009345:Neisseria meningitidis / Q000235:genetics / Q000502:physiology*; D000069320:Type V Secretion Systems / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D000069320:Type V Secretion Systems
keywords: Haemophilus influenzae; Neisseria meningitidis; autotransporters; biofilms; infection; pathogenesis; protein secretion