Higle is A Bifunctional Homing Endonuclease That Directly Interacts with Hyl1 and Serrate in Arabidopsis Thaliana

A highly coordinated complex known as the microprocessor precisely processes primary transcripts of MIRNA genes into mature miRNAs. In plants, the microprocessor minimally consists of three components: Dicer‐like protein 1 (DCL1), HYPONASTIC LEAF 1 (HYL1), and SERRATE (SE). To precisely modulate miRNA maturation, the microprocessor cooperates with at least 12 proteins in plants. In addition, we here show the involvement of a novel gene, HYL1‐interacting GIY‐YIG‐like endonuclease (HIGLE). The encoded protein has a GIY‐YIG domain that is generally found within a class of homing endonucleases. HIGLE directly interacts with the microprocessor components HYL1 and SE. Unlike the functions of other GIY‐YIG endonucleases, the catalytic core of HIGLE has both DNase and RNase activities that sufficiently processes miRNA precursors into short fragments in vitro.