Cleave and Unleash: Metacaspases Prepare Peps for Work.

Plant elicitor peptide 1 (Pep1) is a versatile immune modulator that is involved in plant defense against herbivores and pathogens. A recent study (Hander et al., Science, 2019) has uncovered that Arabidopsis thaliana Pep1 is released from the C-terminus of the tonoplast-resident precursor protein, PROPEP1, by Ca2+-activated metacaspases upon cell membrane rupture in damaged tissues.