Structural basis for Ca2+-mediated interaction of the perforin C2 domain with lipid membranes

Hiromasa Yagi, Paul J Conroy, Eleanor W W Leung, Ruby H P Law, Joseph A Trapani, Ilia Voskoboinik, James Whisstock, Raymond S Norton

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16 Citations (Scopus)


Natural killer cells and cytotoxic T-lymphocytes deploy perforin and granzymes to kill infected host cells. Perforin, secreted by immune cells, binds target membranes to form pores that deliver pro-apoptotic granzymes into the target cell. A crucial first step in this process is interaction of its C2 domain with target cell membranes, which is a calcium-dependent event. Some aspects of this process are understood, but many molecular details remain unclear. To address this, we investigated the mechanism of Ca2+ and lipid binding to the C2 domain by NMR spectroscopy and x-ray crystallography. Calcium titrations, together with do decylphosphocholine micelle experiments, confirmed that multiple Ca2+ ions bind within the calcium-binding regions, activating perforin with respect to membrane binding. We have also determined the affinities of several of these binding sites and have shown that this interaction causes a significant structural rearrangement in CBR1. Thus, it is proposed that Ca2+ binding at the weakest affinity site triggers changes in the C2 domain that facilitate its interaction with lipid membranes.
Original languageEnglish
Pages (from-to)25213-25226
Number of pages14
JournalJournal of Biological Chemistry
Issue number42
Publication statusPublished - 2015

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