TY - JOUR
T1 - Structural basis for Ca2+-mediated interaction of the perforin C2 domain with lipid membranes
AU - Yagi, Hiromasa
AU - Conroy, Paul J
AU - Leung, Eleanor W W
AU - Law, Ruby H P
AU - Trapani, Joseph A
AU - Voskoboinik, Ilia
AU - Whisstock, James
AU - Norton, Raymond S
PY - 2015
Y1 - 2015
N2 - 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.
AB - 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.
UR - http://www.jbc.org.ezproxy.lib.monash.edu.au/content/290/42/25213.full.pdf+html
U2 - 10.1074/jbc.M115.668384
DO - 10.1074/jbc.M115.668384
M3 - Article
VL - 290
SP - 25213
EP - 25226
JO - The Journal of Biological Chemistry
JF - The Journal of Biological Chemistry
SN - 1083-351X
IS - 42
ER -