The structural basis for membrane binding and pore formation by lymphocyte perforin

Natural killer cells and cytotoxic T lymphocytes accomplish the critically important function of killing virus-infected and neoplastic cells. They do this by releasing the pore-forming protein perforin and granzyme proteases from cytoplasmic granules into the cleft formed between the abutting killer...

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Bibliographic Details
Published in:	Nature (London) 2010-11, Vol.468 (7322), p.447-451
Main Authors:	Trapani, Joseph A, Saibil, Helen R, Whisstock, James C, Law, Ruby H. P, Lukoyanova, Natalya, Voskoboinik, Ilia, Caradoc-Davies, Tom T, Baran, Katherine, Dunstone, Michelle A, D'Angelo, Michael E, Orlova, Elena V, Coulibaly, Fasséli, Verschoor, Sandra, Browne, Kylie A, Ciccone, Annette, Kuiper, Michael J, Bird, Phillip I
Format:	Article
Language:	eng
Subjects:	Animals Binding sites Biological and medical sciences Cell Membrane - metabolism Chemical properties Cholesterol - metabolism Cryoelectron Microscopy Crystal structure Crystallography, X-Ray Crystals Epidermal growth factor Epidermal Growth Factor - chemistry Fundamental and applied biological sciences. Psychology Granzymes - metabolism Humans Labeling Lipids Lymphocytes - metabolism Mice Models, Molecular Molecular biophysics Pore Forming Cytotoxic Proteins - chemistry Pore Forming Cytotoxic Proteins - genetics Pore Forming Cytotoxic Proteins - metabolism Pore Forming Cytotoxic Proteins - ultrastructure Proteases Protein Structure, Tertiary Proteins Structure Structure in molecular biology T cells Tridimensional structure
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Summary:	Natural killer cells and cytotoxic T lymphocytes accomplish the critically important function of killing virus-infected and neoplastic cells. They do this by releasing the pore-forming protein perforin and granzyme proteases from cytoplasmic granules into the cleft formed between the abutting killer and target cell membranes. Perforin, a 67-kilodalton multidomain protein, oligomerizes to form pores that deliver the pro-apoptopic granzymes into the cytosol of the target cell. The importance of perforin is highlighted by the fatal consequences of congenital perforin deficiency, with more than 50 different perforin mutations linked to familial haemophagocytic lymphohistiocytosis (type 2 FHL). Here we elucidate the mechanism of perforin pore formation by determining the X-ray crystal structure of monomeric murine perforin, together with a cryo-electron microscopy reconstruction of the entire perforin pore. Perforin is a thin 'key-shaped' molecule, comprising an amino-terminal membrane attack complex perforin-like (MACPF)/cholesterol dependent cytolysin (CDC) domain followed by an epidermal growth factor (EGF) domain that, together with the extreme carboxy-terminal sequence, forms a central shelf-like structure. A C-terminal C2 domain mediates initial, Ca2+-dependent membrane binding. Most unexpectedly, however, electron microscopy reveals that the orientation of the perforin MACPF domain in the pore is inside-out relative to the subunit arrangement in CDCs. These data reveal remarkable flexibility in the mechanism of action of the conserved MACPF/CDC fold and provide new insights into how related immune defence molecules such as complement proteins assemble into pores.
ISSN:	0028-0836 1476-4687