Oligomerization of type III secretion proteins PopB and PopD precedes pore formation in Pseudomonas
AUTOR(ES)
Schoehn, Guy
FONTE
Oxford University Press
RESUMO
Pseudomonas aeruginosa is the agent of opportunistic infections in immunocompromised individuals and chronic respiratory illnesses in cystic fibrosis patients. Pseudomonas aeruginosa utilizes a type III secretion system for injection of toxins into the host cell cytoplasm through a channel on the target membrane (the ‘translocon’). Here, we have functionally and structurally characterized PopB and PopD, membrane proteins implicated in the formation of the P.aeruginosa translocon. PopB and PopD form soluble complexes with their common chaperone, PcrH, either as stable heterodimers or as metastable heterooligomers. Only oligomeric forms are able to bind to and disrupt cholesterol-rich membranes, which occurs within a pH range of 5–7 in the case of PopB/PcrH, and only at acidic pH for PcrH-free PopD. Electron microscopy reveals that upon membrane association PopB and PopD form 80 Å wide rings which encircle 40 Å wide cavities. Thus, formation of metastable oligomers precedes membrane association and ring generation in the formation of the Pseudomonas translocon, a mechanism which may be similar for other pathogens that employ type III secretion systems.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=204482Documentos Relacionados
- Protein Binding between PcrG-PcrV and PcrH-PopB/PopD Encoded by the pcrGVH-popBD Operon of the Pseudomonas aeruginosa Type III Secretion System
- The V Antigen of Pseudomonas aeruginosa Is Required for Assembly of the Functional PopB/PopD Translocation Pore in Host Cell Membranes
- Pseudomonas syringae Hrp type III secretion system and effector proteins
- A bacterial type III secretion system inhibits actin polymerization to prevent pore formation in host cell membranes
- The Type III Secreted Protein BopD in Bordetella bronchiseptica Is Complexed with BopB for Pore Formation on the Host Plasma Membrane