The HrpB-HrpA two-partner secretion system is essential for intracellular survival of Neisseria meningitidis.
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.
Talà
Adelfia
A
Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali (DiSTeBA), Università del Salento, Via Provinciale Monteroni, 73100 Lecce, Italy.
Progida
Cinzia
C
De Stefano
Mario
M
Cogli
Laura
L
Spinosa
Maria Rita
MR
Bucci
Cecilia
C
Alifano
Pietro
P
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*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D005839:Gentamicins; C534217:HrpA protein, Neisseria meningitidis; D037521:Virulence Factors