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bioRxiv · 10.1101/2021.07.08.451689

MLKL D144K mutation activates the necroptotic activity of the N-terminal MLKL domain

Hrovat-Schaale, K.·Kalic-Prolinsek, M.·Hadzi, S.·Lah, J.·Guncar, G.
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Abstract

Mixed-lineage kinase domain-like protein (MLKL) is an essential effector protein of necroptotic cell death. The four-helix bundle domain (4HB) presented by the first 125 amino acids of the N-terminal domain is sufficient for its necroptotic activity. However, it has been proposed that the subsequent helix H6 of the brace region has a regulatory effect on its necroptotic activity. How the brace region restrains the necroptotic activity of the N-terminal domain of MLKL is currently unknown. Here, we demonstrate the importance of helix H6 to constrain the necroptotic activity. A single amino acid mutation D144K was able to activate the necroptotic activity of the N-terminal domain of MLKL by removing helix H6 away from 4HB domain. This enabled proteins oligomerization and membrane translocation. Moreover, a biophysical comparison revealed that helix H6 becomes partially unstructured due to D144K mutation, leading to a lower overall thermodynamic stability of the mutant protein compared to the wild type.

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Hrovat-Schaale, K., Kalic-Prolinsek, M., Hadzi, S., Lah, J., Guncar, G.. 2021-07-08. MLKL D144K mutation activates the necroptotic activity of the N-terminal MLKL domain. https://doi.org/10.1101/2021.07.08.451689

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