Membrane permeabilization is mediated by distinct epitopes in mouse and human orthologs of the necroptosis effector, MLKL
- Author(s)
- Sethi, A; Horne, CR; Fitzgibbon, C; Wilde, K; Davies, KA; Garnish, SE; Jacobsen, AV; Samson, AL; Hildebrand, JM; Wardak, A; Czabotar, PE; Petrie, EJ; Gooley, PR; Murphy, JM;
- Journal Title
- Cell Death and Differentiation
- Publication Type
- epub ahead of print
- Abstract
- Necroptosis is a lytic programmed cell death pathway with origins in innate immunity that is frequently dysregulated in inflammatory diseases. The terminal effector of the pathway, MLKL, is licensed to kill following phosphorylation of its pseudokinase domain by the upstream regulator, RIPK3 kinase. Phosphorylation provokes the unleashing of MLKL's N-terminal four-helix bundle (4HB or HeLo) domain, which binds and permeabilizes the plasma membrane to cause cell death. The precise mechanism by which the 4HB domain permeabilizes membranes, and how the mechanism differs between species, remains unclear. Here, we identify the membrane binding epitope of mouse MLKL using NMR spectroscopy. Using liposome permeabilization and cell death assays, we validate K69 in the alpha3 helix, W108 in the alpha4 helix, and R137/Q138 in the first brace helix as crucial residues for necroptotic signaling. This epitope differs from the phospholipid binding site reported for human MLKL, which comprises basic residues primarily located in the alpha1 and alpha2 helices. In further contrast to human and plant MLKL orthologs, in which the alpha3-alpha4 loop forms a helix, this loop is unstructured in mouse MLKL in solution. Together, these findings illustrate the versatility of the 4HB domain fold, whose lytic function can be mediated by distinct epitopes in different orthologs.
- Publisher
- NPG
- Research Division(s)
- Inflammation; Structural Biology
- PubMed ID
- 35264780
- Publisher's Version
- https://doi.org/10.1038/s41418-022-00965-6
- NHMRC Grants
- NHMRC/9000653, NHMRC/1142669, NHMRC/1079700, NHMRC/1142669, NHMRC/2002965,
- Terms of Use/Rights Notice
- Refer to copyright notice on published article.
Creation Date: 2022-03-15 10:53:33
Last Modified: 2022-07-13 01:49:47