Download MendeleyStructural Basis for Ca2+-mediated Interaction of the Perforin C2 Domain with Lipid Membranes.
Yagi, H., Conroy, P.J., Leung, E.W., Law, R.H., Trapani, J.A., Voskoboinik, I., Whisstock, J.C., Norton, R.S.(2015) J Biol Chem 290: 25213-25226
- PubMed: 26306037
- DOI: https://doi.org/10.1074/jbc.M115.668384
- Primary Citation of Related Structures:
4Y1S, 4Y1T - PubMed Abstract:
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 Ca(2+) and lipid binding to the C2 domain by NMR spectroscopy and x-ray crystallography. Calcium titrations, together with dodecylphosphocholine micelle experiments, confirmed that multiple Ca(2+) 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 Ca(2+) binding at the weakest affinity site triggers changes in the C2 domain that facilitate its interaction with lipid membranes.
Organizational Affiliation:
From the Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052.
