The HrpB-HrpA two-partner secretion system is essential for intracellular survival ofNeisseria meningitidis

Abstract

SummaryIn 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 wildtype 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.

Role of HrpA in Biofilm Formation of Neisseria meningitidis and Regulation of the hrpBAS Transcripts

“…HrpA is a factor that is involved in escape from invaded cells (46). We grew biofilms for 48 h on collagen-coated …”

“…The HrpAB two-partner secretion system of N. meningitidis has a role in adherence to tissue culture cells but only in the absence of capsule and with a lipooligosaccharide truncation (42). HrpA also is important in escape from HeLa cells (46). We used an expression-based approach to determine if hrpA was regulated.…”

“…Recently, a type V secretion system was described in N. meningitidis (42,46,48). There are two categories of type V secretion in gram-negative organisms.…”

“…HrpB secretes HrpA, which functions as an adhesin in an unencapsulated and lipooligosaccharide mutant background (42). HrpA also is essential for N. meningitidis escape from the intracellular space after invasion (46). FHA of B. pertussis is known to have multiple roles, which include heparin binding, carbohydrate binding, CR3 and adenylate cyclase interaction, and involvement in adherence, invasion, proinflammatory response, and antiapoptotic characteristics (1,5,19,24,25,31,32,35,38,55).…”

Cooperation between LepA and PlcH Contributes to theIn VivoVirulence and Growth ofPseudomonas aeruginosain Mice

“…For instance, a TpsA of enterotoxigenic E. coli, EtpA, mediates adhesion between flagella and host cells, thereby promoting colonization in the intestine (13,42,43). In addition, a TPS system of Neisseria meningitidis, HrpB-HrpA, contributes to the interaction of meningococci with epithelial cells and is essential for intracellular survival and escape from infected cells (45,51). Although a large number of genes encoding potential TPS systems have been identified through DNA sequencing of microbial genomes, only a limited number of TPS molecules have been characterized so far.…”