MAC5, an RNA-binding protein, protects pri-miRNAs from SERRATE-dependent exoribonuclease activities

Significance In Arabidopsis , MAC5, a component of the conserved MOS4-associated complex, is required for development and immunity. This study shows that MAC5 interacts with Serrate (SE) and the stem loop of pri-miRNAs, facilitates pri-miRNA processing, and protects pri-miRNAs from SE-dependent 5′-to-3′ exoribonuclease activities. Consequently, this study provides insights into the mechanism regulating miRNA biogenesis. Since MAC5 is a conserved protein, this study may have a broader impact.