title: The HrpB-HrpA two-partner secretion system is essential for intracellular survival of Neisseria meningitidis.
abstract: In this study we used HeLa cells to investigate the role of the HrpB-HrpA two-partner secretion (TPS) system in the meningococcal infection cycle. Although there is evidence that several pathogenic microorganisms may use TPS systems to colonize epithelial surfaces, the meningococcal HrpB-HrpA TPS system was not primarily involved in adhesion to or invasion of HeLa cells. Instead, this system was essential for intracellular survival and escape from infected cells. Gentamicin protection assays, immunofluorescence and transmission electron microscopy analyses demonstrated that, in contrast to the wild-type strain, HrpB-HrpA-deficient mutants were primarily confined to late endocytic vacuoles and trapped in HeLa cells. Haemolytic tests using human erythrocytes suggested that the secreted HrpA proteins could act as manganese-dependent lysins directly involved in mediating vacuole escape. In addition, we demonstrated that escape of wild-type meningococci from infected cells required the use of an intact tubulin cytoskeleton and that the hrpB-hrpA genes, which are absent in other Neisseria spp., were upregulated during infection.
authors.affiliation: Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali (DiSTeBA), Università del Salento, Via Provinciale Monteroni, 73100 Lecce, Italy.
authors.forename: Adelfia
authors.initials: A
authors.lastname: Talà
authors.forename: Cinzia
authors.initials: C
authors.lastname: Progida
authors.forename: Mario
authors.initials: M
authors.lastname: De Stefano
authors.forename: Laura
authors.initials: L
authors.lastname: Cogli
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Spinosa
authors.forename: Cecilia
authors.initials: C
authors.lastname: Bucci
authors.forename: Pietro
authors.initials: P
authors.lastname: Alifano
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D015169:Colony Count, Microbial / Q000379:methods; D003599:Cytoskeleton / Q000502:physiology; D005455:Fluorescent Antibody Technique; D017353:Gene Deletion; D005839:Gentamicins / Q000494:pharmacology; D006367:HeLa Cells; D006461:Hemolysis; D006801:Humans; D050296:Microbial Viability; D046529:Microscopy, Electron, Transmission; D009345:Neisseria meningitidis / Q000235:genetics / Q000502:physiology*; D014617:Vacuoles / Q000382:microbiology; D037521:Virulence Factors / Q000235:genetics / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D005839:Gentamicins; C534217:HrpA protein, Neisseria meningitidis; D037521:Virulence Factors