Meta-Biol

• Pathways

Recombinant pseudokinase mixed lineage kinase domain-like (MLKL) exists in both monomeric form (∼30% of total) and tetrameric form (∼70% of total) in solution (Petrie EJ et al. 2018). Higher order oligomersof MLKL mediates necroptosis, an inflammatory form of programmed cell death executed through plasma membrane rupture (Wang H et al. 2014; Dondelinger Y et al. 2014; Tanzer MC et al. 2016; Petrie EJ et al. 2018; Samson AL et al. 2020). Biophysics, mass spectrometry (MS) and cellular assays revealed that the pseudokinase domain of human MLKL functions as a molecular switch in directing the transition of MLKL from a basal monomeric state to a pro-necroptotic tetramer (Petrie EJ et al. 2018). Despite lacking catalytic activity, the pseudokinase domain of MLKL has retained the ability to bind ATP (Murphy JM et al. 2013, 2014; Petrie EJ et al. 2018). The ATP binding has been shown to negatively regulate MLKL-mediated iposome permeabilization by destabilizing the MLKL tetramers and shifting the tetramer:monomer equilibrium toward the monomeric state (Petrie EJ et al. 2018). However, MLKL mutants with defective ATP-binding were still able to induce necroptosis when expressed in MLKL-/- HT-29 cells, suggesting that ATP-binding is most likely reflective of the ancestral function of the pseudokinase domain fold than regulatory in cells (Petrie EJ et al. 2018).