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Characterization of MLKL-mediated Plasma Membrane Rupture in Necroptosis
08:55

Characterization of MLKL-mediated Plasma Membrane Rupture in Necroptosis

Published on: August 7, 2018

11.1K

Conformational interconversion of MLKL and disengagement from RIPK3 precede cell death by necroptosis

Sarah E Garnish1,2, Yanxiang Meng1,2, Akiko Koide3,4

  • 1Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.

Nature Communications
|April 14, 2021
PubMed

Insights

Researchers developed synthetic Monobodies to study MLKL activation in necroptosis. Monobody-27 reveals MLKL disengages from RIPK3, a key step in cell death.

Area of Science:

  • Cellular Biology
  • Molecular Mechanisms of Cell Death
  • Protein-Protein Interactions

Background:

  • Necroptotic cell death is a programmed form of lysis, crucial in immunity and development.
  • The mixed lineage kinase domain-like (MLKL) protein is the key executioner of necroptosis.
  • MLKL activation, triggered by RIPK3 kinase, involves its oligomerization and membrane permeabilization, but the precise steps are unclear.

Purpose of the Study:

  • To investigate the conformational changes and regulatory steps in MLKL activation during necroptosis.
  • To develop novel molecular tools for studying MLKL function in human cells.

Main Methods:

  • Generation and characterization of Monobodies, synthetic binding proteins targeting MLKL.
  • X-ray crystallography of MLKL pseudokinase domain in complex with Monobodies.
  • In cellulo binding studies of Monobodies to MLKL.

Main Results:

  • Monobodies were developed that bind the MLKL pseudokinase domain.
  • Monobody-27 binds an epitope exposed only after MLKL disengages from RIPK3.
  • Crystal structures revealed distinct MLKL pseudokinase domain conformations, supporting a major conformational transition.
  • MLKL disengagement from RIPK3 is identified as a critical regulatory step.

Conclusions:

  • MLKL undergoes a significant conformational change upon activation, preceding plasma membrane permeabilization.
  • The disengagement of phosphorylated MLKL from RIPK3 is a key regulatory event in the necroptosis pathway.
  • Monobodies targeting MLKL provide valuable tools for dissecting necroptosis mechanisms.

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