Rachel Reichman, Zhuoyue Shi, Robert Malone, Sarit Smolikove

Meiosis is a highly regulated process, partly due to the need to break and then repair DNA as part of the meiotic program. Post-translational modifications are widely used during meiotic events to regulate steps such as protein complex formation, checkpoint activation, and protein attenuation. In this paper, we investigate how proteins that are obligatory components of the SUMO pathway, one such post-translational modification, affect theC. elegansgermline. We show that UBC-9, the E2 conjugation enzyme, and theC. eleganshomolog of SUMO, SMO-1, localized to germline nuclei throughout prophase I. Mutant analysis ofsmo-1andubc-9revealed increased recombination intermediates throughout the germline, originating during the mitotic divisions. SUMOylation mutants also showed late meiotic defects including defects in the restructuring of oocyte bivalents and endomitotic oocytes (Cremonaet al.). Increased rates of non-interfering crossovers (COs) were observed inubc-9heterozygotes, even though interfering COs were unaffected. We have also identified a physical interaction between UBC-9 and DNA repair protein MRE-11.ubc-9andmre-11null mutants exhibited similar phenotypes at germline mitotic nuclei and were synthetically sick. These phenotypes and genetic interactions were specific to MRE-11 null mutants as opposed to RAD-50 or resection-defective MRE-11. We propose that the SUMOylation pathway acts redundantly with MRE-11, and in this process MRE-11 likely plays a structural role.