Towards decoding the regulation principles of vacuolar processing enzymes.

Plant legumains, or vacuolar processing enzymes, exhibit protease, ligase, and peptide cyclase activities regulated by structural and environmental factors.

• Why it matters: Understanding the regulation of plant legumains is crucial for elucidating their roles in seed development, protein maturation, and programmed cell death, with potential biotechnological applications.
• What they did: The review summarizes current knowledge on how domain architecture, autocatalytic activation, substrate-binding sites, pH, oligomeric state, and inhibitors influence plant legumain activity.
• The result: Despite progress, key questions about the specific regulatory roles of structural elements remain, indicating the need for further research into their mechanisms.