HECT-type ligases facilitate autoubiquitination and degradation of other ubiquitin ligases to activate plant immunity

The study, posted on bioRxiv, investigates the role of HECT-type UPL3/4 ligases in plant immunity. It shows that after substrates are ubiquitinated by pathway-specific E3 ligases, they are physically relayed to proteasome-associated UPL3/4 ligases for further modification, which is necessary for their proteasome-mediated degradation. This mechanism involves autoubiquitination and degradation of other ubiquitin ligases, suggesting a feed-forward loop that amplifies immune responses. The findings highlight a conserved yet underappreciated step in ubiquitin-mediated proteolysis, with implications for understanding plant defense and potentially engineering disease-resistant crops. Further research is needed to identify specific substrates and confirm the in vivo relevance across plant species.