8a1s
Structure of murine perforin-2 (Mpeg1) pore in twisted form
Structural highlights
FunctionMPEG1_MOUSE Plays a key role in the innate immune response following bacterial infection by polymerizing and inserting into the bacterial surface to form pores (PubMed:26402460). By breaching the surface of phagocytosed bacteria, allows antimicrobial effectors to enter the bacterial periplasmic space and degrade bacterial proteins such as superoxide dismutase sodC which contributes to bacterial virulence (PubMed:30249808). Shows antibacterial activity against a wide spectrum of Gram-positive, Gram-negative and acid-fast bacteria (PubMed:23257510, PubMed:23753625, PubMed:26402460). Reduces the viability of the intracytosolic pathogen L.monocytogenes by inhibiting acidification of the phagocytic vacuole of host cells which restricts bacterial translocation from the vacuole to the cytosol (PubMed:26831467). Required for the antibacterial activity of reactive oxygen species and nitric oxide (PubMed:26402460).[1] [2] [3] [4] [5] Publication Abstract from PubMedPerforin-2 (PFN2, MPEG1) is a key pore-forming protein in mammalian innate immunity restricting intracellular bacteria proliferation. It forms a membrane-bound pre-pore complex that converts to a pore-forming structure upon acidification; but its mechanism of conformational transition has been debated. Here we used cryo-electron microscopy, tomography and subtomogram averaging to determine structures of PFN2 in pre-pore and pore conformations in isolation and bound to liposomes. In isolation and upon acidification, the pre-assembled complete pre-pore rings convert to pores in both flat ring and twisted conformations. On membranes, in situ assembled PFN2 pre-pores display various degrees of completeness; whereas PFN2 pores are mainly incomplete arc structures that follow the same subunit packing arrangements as found in isolation. Both assemblies on membranes use their P2 beta-hairpin for binding to the lipid membrane surface. Overall, these structural snapshots suggest a molecular mechanism for PFN2 pre-pore to pore transition on a targeted membrane, potentially using the twisted pore as an intermediate or alternative state to the flat conformation, with the capacity to cause bilayer distortion during membrane insertion. Cryo-EM structures of perforin-2 in isolation and assembled on a membrane suggest a mechanism for pore formation.,Yu X, Ni T, Munson G, Zhang P, Gilbert RJC EMBO J. 2022 Dec 1;41(23):e111857. doi: 10.15252/embj.2022111857. Epub 2022 Oct , 17. PMID:36245269[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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