Metacaspase-Mediated Cell Death Mechanisms in Plant Systems

Metacaspases are cysteine-dependent proteases ubiquitously present in plants, fungi and protozoa that share structural homology with animal caspases yet diverge in substrate specificity and activation modes. In higher plants, metacaspases are classified into type I and type II subfamilies, distinguished by the presence or absence of an N-terminal prodomain. These enzymes are synthesised as inactive zymogens and undergo proteolytic or conformational activation in response to developmental cues or environmental stresses. Active metacaspases cleave substrates after basic residues, triggering a cascade of events that culminate in programmed cell death (PCD), a genetically regulated process essential for tissue remodelling, defence against pathogens and removal of damaged cells. Beyond their canonical proteolytic role, some metacaspases assume non-proteolytic functions, such as modulation of membrane properties or interaction with signalling proteins, thereby integrating cell death with broader physiological processes. Central to metacaspase activation is calcium binding, which induces intramolecular autoprocessing and conformational rearrangements. Metacaspase-dependent PCD interfaces with reactive oxygen species (ROS) signalling, hormone pathways (notably abscisic acid during drought) and autophagic responses, ensuring spatial confinement of cellular demise in organs such as the vasculature. Studies in unicellular algae and multicellular plants have revealed evolutionary conservation as well as lineage-specific innovations, underlining the global significance of metacaspase research for crop improvement and resilience to climate-driven stresses.

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Metacaspase-Mediated Cell Death Mechanisms in Plant Systems publication trend

The graph below shows the total number of articles in metacaspase-mediated cell death mechanisms in plant systems across all publications each year (not limited to Nature Index journals).

Technical terms

Metacaspase: A clan CD cysteine protease in plants and other non-metazoans that cleaves substrates after arginine or lysine residues, driving programmed cell death and related processes.

Zymogen: An inactive precursor of an enzyme that requires proteolytic or conformational change for activation.

Programmed cell death (PCD): A genetically controlled sequence of events leading to organized cellular dismantling, crucial for development, defence and stress adaptation.

Plasma membrane fluidity: The viscosity of the lipid bilayer, influencing membrane protein function and cellular responses to temperature stress.

Phloem: The vascular tissue responsible for translocation of photoassimilates and signalling molecules, instrumental in stress adaptation and systemic regulation.

References

1. Thermoprotection by a cell membrane–localized metacaspase in a green alga. The Plant Cell (2023).
2. A phloem‐localized Arabidopsis metacaspase (AtMC3) improves drought tolerance. New Phytologist (2023).
3. Structural and functional diversity of caspase homologues in non-metazoan organisms. Protoplasma (2017).
4. Calcium-dependent Activation and Autolysis of Arabidopsis Metacaspase 2d*. Journal of Biological Chemistry (2011).
5. METACASPASE9 modulates autophagy to confine cell death to the target cells during Arabidopsis vascular xylem differentiation. Biology Open (2016).