SCF Cdc4 ubiquitin ligase regulates synaptonemal complex formation during meiosis

Abstract Homologous chromosomes pair with each other during meiosis, culminating in the formation of the synaptonemal complex (SC), which is coupled with meiotic recombination. In this study, we showed that a meiosis-specific depletion mutant of a cullin (Cdc53) of the SCF (Skp-Cullin-F-box) ubiquitin ligase, which plays a critical role in cell cycle regulation during mitosis, is deficient in SC formation, but is proficient in the formation of crossovers, indicating uncoupling of meiotic recombination with SC formation in the mutant. Furthermore, the deletion of the PCH2 gene encoding a meiosis-specific AAA+ ATPase suppresses SC-assembly defect induced by CDC53 depletion. On the other hand, the pch2 cdc53 double mutant is defective in meiotic crossover formation, suggesting the SC assembly with unrepaired DSBs. A temperature-sensitive mutant of the CDC4 , which encodes a F-box protein of the SCF, shows similar meiotic defects to the CDC53 depletion mutant. These suggest that SCF Cdc4 , probably SCF Cdc4 -dependnet protein ubiquitylation, regulates and collaborates with Pch2 in SC assembly and meiotic recombination. Summary During meiosis, homologous chromosomes pair with each other and form the synaptonemal complex (SC). In this study, components of the SCF (Skp-Cullin-F-box) ubiquitin ligase, Cdc53 and Cdc4, are required for SC formation. A meiosis-specific AAA+ ATPase Pch2 antagonize the functions of Cdc53 and Cdc4 for proper SC assembly.