Neisseria meningitidis is a frequent commensal of the human nasopharynx causing severe invasive infections in rare cases. A functional two-partner secretion (TPS) system in N. meningitidis, composed of the secreted effector protein HrpA and its cognate transporter HrpB, is identified and characterized in this study. Although all meningococcal strains harbor at least one TPS system, the hrpA genes display significant C-terminal sequence variation. Meningococcal genes encoding the TPS effector proteins and their transporters are closely associated and transcribed into a single mRNA. HrpA proteins are translocated across the meningococcal outer membrane by their cognate transporters HrpB and mainly released into the environment. During this process, HrpA is proteolytically processed to a mature 180-kDa form. In contrast to other known TPS systems, immature HrpA proteins are stable in the absence of HrpB and accumulate within the bacterial cell. A small percentage of mature HrpA remains associated with the bacteria and contributes to the interaction of meningococci with epithelial cells.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2168671PMC
http://dx.doi.org/10.1128/JB.00851-07DOI Listing

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Article Synopsis
  • * A study using a reference strain and a knockout mutant showed that the HrpA/HrpB system is essential for disease progression, as the mutant exhibited impaired spreading and replication in the brain of infected mice.
  • * Analysis of infected brain samples revealed that the mutant had reduced activation of key pyroptosis pathways and inflammatory markers, indicating that HrpA/HrpB is crucial for inducing pyroptosis during meningococcal infection.
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