Structural Insight into the Central Element Assembly of the Synaptonemal Complex

The key step in meiosis is synaptonemal complex formation, which mediates homologous chromosome alignment and synapsis. False pairing between homologous chromosomes produces infertility. Here, we present a crystal structure of the mouse meiosis-specific protein SYCE3, which is a component of the synaptonemal complex central element. Our studies show that functional SYCE3 most likely forms a dimer or higher order oligomer in cells. Furthermore, we demonstrate that the SYCE3 N-helix interacts with the SYCE1 C-helix, which is another central element component. Our results suggest that helical packing may mediate intra- or inter-association of each central element protein component, thereby playing an essential role in forming the synaptonemal complex central elements.