Paper Citing NAMD - Abstract
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, Fasseli; Verschoor, Sandra; Browne, Kylie A.; Ciccone, Annette; Kuiper, Michael J.; Bird, Phillip I.; Trapani, Joseph A.; Saibil, Helen R.; Whisstock, James C.
The structural basis for membrane binding and pore formation by lymphocyte perforin
NATURE, 468:447-U277, NOV 18 2010
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(1-6). 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)(7). 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(8,9) 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, Ca(2+)-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(10,11). 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.
