The brace helices of MLKL mediate interdomain communication and oligomerisation to regulate cell death by necroptosis

Davies, KA; Tanzer, MC; Griffin, MDW; Mok, YF; Young, SN; Qin, R; Petrie, EJ; Czabotar, PE; Silke, J; Murphy, JM

Author(s): Davies, KA; Tanzer, MC; Griffin, MDW; Mok, YF; Young, SN; Qin, R; Petrie, EJ; Czabotar, PE; Silke, J; Murphy, JM;
Details: Publication Year 2018-09,Volume 25,Issue #9,Page 1567-1580
Journal Title: Cell Death and Differentiation
Publication Type: Journal Article
Abstract: The programmed cell death pathway, necroptosis, relies on the pseudokinase, Mixed Lineage Kinase domain-Like (MLKL), for cellular execution downstream of death receptor or Toll-like receptor ligation. Receptor-interacting protein kinase-3 (RIPK3)-mediated phosphorylation of MLKL's pseudokinase domain leads to MLKL switching from an inert to activated state, where exposure of the N-terminal four-helix bundle (4HB) 'executioner' domain leads to cell death. The precise molecular details of MLKL activation, including the stoichiometry of oligomer assemblies, mechanisms of membrane translocation and permeabilisation, remain a matter of debate. Here, we dissect the function of the two 'brace' helices that connect the 4HB to the pseudokinase domain of MLKL. In addition to establishing that the integrity of the second brace helix is crucial for the assembly of mouse MLKL homotrimers and cell death, we implicate the brace helices as a device to communicate pseudokinase domain phosphorylation event(s) to the N-terminal executioner 4HB domain. Using mouse:human MLKL chimeras, we defined the first brace helix and adjacent loop as key elements of the molecular switch mechanism that relay pseudokinase domain phosphorylation to the activation of the 4HB domain killing activity. In addition, our chimera data revealed the importance of the pseudokinase domain in conferring host specificity on MLKL killing function, where fusion of the mouse pseudokinase domain converted the human 4HB + brace from inactive to a constitutive killer of mouse fibroblasts. These findings illustrate that the brace helices play an active role in MLKL regulation, rather than simply acting as a tether between the 4HB and pseudokinase domains.
Publisher: Springer Nature
Research Division(s): Structural Biology; Cell Signalling And Cell Death
PubMed ID: 29445128
Link To PubMed Central Version: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6143630/
Publisher's Version: https://doi.org/10.1038/s41418-018-0061-3
NHMRC Grants: NHMRC/1079700, NHMRC/1058190, NHMRC/1105754, NHMRC/1057905, NHMRC/1124735,
Terms of Use/Rights Notice: Refer to copyright notice on published article.

Creation Date: 2018-02-19 11:19:52

Last Modified: 2020-04-07 02:38:28