Cryo-Structural Insights into Enzymatic Peptide Self-Assembly Driving Extrinsic Lytic Cell Death.

Area of Science:

• Biochemistry
• Supramolecular Chemistry
• Cell Biology

Background:

• Programmed lytic cell death pathways like pyroptosis and necroptosis rely on intracellular enzymes.
• Tumor-associated ectoenzymes, such as alkaline phosphatase (ALP), present an opportunity for extrinsic induction of cell death.

Purpose of the Study:

• To design a novel peptide precursor that utilizes tumor-specific ALP for initiating programmed cell death.
• To investigate the mechanism of enzyme-instructed peptide self-assembly (EISA) for targeted cancer cell elimination.

Main Methods:

• Design of a phospho-biphenyl-capped peptide precursor.
• Selective dephosphorylation by cancer cell surface ALP to trigger EISA.
• Cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET) for structural and mechanistic analysis.

Main Results:

• The peptide precursor self-assembles into supramolecular filaments upon ALP activation.
• These filaments breach the plasma membrane, overwhelm repair mechanisms, and induce cell death.
• Cryo-EM revealed ordered dimeric packing responsible for mechanical rigidity and membrane rupture.
• Cryo-ET visualized filament penetration of the plasma membrane in live cells.

Conclusions:

• Reprogramming ALP from an immune checkpoint ectoenzyme into a pro-death catalyst is feasible.
• A molecular mechanism linking enzymatic catalysis, supramolecular assembly, and membrane failure was established.
• This work presents a supramolecular chemical-biology framework for enzyme-triggered cell death execution.