The Axial Element Protein DESYNAPTIC2 Mediates Meiotic Double-Strand Break Formation and Synaptonemal Complex Assembly in Maize

摘要

During meiosis, homologous chromosomes pair and recombine via repair of programmed DNA double-strand breaks (). are formed in the context of chromatin loops, which are anchored to the proteinaceous axial element (). The later serves as a framework to assemble the synaptonemal complex () that provides a transient but tight connection between homologous chromosomes. Here, we showed that DESYNAPTIC2 (DSY2), a coiled-coil protein, mediates formation and is directly involved in assembly in maize (Zea mays). The dsy2 mutant exhibits homologous pairing defects, leading to sterility. Analyses revealed that formation and the number of RADIATION SENSITIVE51 (RAD51) foci are largely reduced, and synapsis is completely abolished in dsy2 meiocytes. Super-resolution structured illumination microscopy showed that DSY2 is located on the and forms a distinct alternating pattern with the HORMA-domain protein ASYNAPTIC1 (ASY1). In the dsy2 mutant, localization of ASY1 is affected, and loading of the central element ZIPPER1 (ZYP1) is disrupted. Yeast two-hybrid and bimolecular fluorescence complementation experiments further demonstrated that ZYP1 interacts with DSY2 but does not interact with ASY1. Therefore, DSY2, an protein, not only mediates formation but also bridges the and central element of during meiosis.