Post-translational modification of proteins is an important way of regulating the life activities of organisms. The ubiquitination and SUMOization of proteins are hotspots in the field of post-translational modification of proteins. Studies have found that there is an interaction between ubiquitination and SUMOization of proteins. Among them, SUMO targeting ubiquitin ligase is an important ubiquitination-SUMOization interaction regulator. The interaction between protein ubiquitination and SUMOization greatly enriches the complexity of the two post-translational modification functions. SUMO targets ubiquitin ligase in gene regulation, maintenance of genome stability, embryonic development, cancer, etc. These physiological processes all play important roles. However, the role of protein ubiquitination and SUMO modification in the meiosis process, and how SUMO targeting ubiquitin ligase participates in meiosis regulation is still poorly understood.



In 1996, the ubiquitin-like protein modification molecule SUMO1 and SUMOylation were first reported. In the past 20 years, various eukaryotic cells from yeast to humans have found their modified substrate proteins. A very common way of protein post-translational modification.



In higher eukaryotic cells, there are at least three SUMO proteins and six SUMO-specific proteins—SENP1 / 2/3/5/6/7.



SUMO is mainly distributed in the nucleus, of which SUMO1 is distributed in the nuclear membrane, nucleolus, and cytoplasm, while SUMO2 / 3 is mainly distributed in the nucleus.



SUMO modification is a dynamic reversible process. SUMO molecules regulate the structure and function of substrate proteins by covalently binding to lysine residues of substrate proteins with the participation of E1 activating enzyme, E2 binding enzyme and E3 ligase. However, SENPs specifically modify the substrate protein's SUMOization state by specifically de-SUMOizing the substrate target protein, thereby regulating cell function.



In order to study the mechanism of the interaction between protein ubiquitination and SUMOization modification in meiosis, the researchers first screened the SUMO-targeted ubiquitin ligase during yeast meiosis and found that the complex Slx5p-Slx8p was The loss of a protein will affect the normal progress of meiosis. Further studies have found that knockout SLX8 affects the degradation of the meiotic homologous chromosomal synaptic complex component protein degradation, while the failure to effectively degrade the synaptic complex protein affects the correct separation of homologous chromosomes. Slx8p's ubiquitin ligase activity and the SUMO recognition domain are critical to its function in meiosis, predicting that the interaction of ubiquitination and SUMOization mediated by Slx8p-mediated proteins in the correct separation of meiotic homologous chromosomes Play an important role. To further verify this conclusion, the researchers expressed the fused ubiquitin-SUMO protein in the SLX8 knockout strain, artificially linked ubiquitination with the SUMO modification, and found that the ubiquitin-SUMO fusion protein can partially rescue the SLX8 knockout caused Meiosis is abnormal. In order to further clarify the key role of Slx5p-Slx8p in the meiosis process, the researchers reconstructed the Slx5p-Slx8p ubiquitination system in vitro and found that Slx5p-Slx8p can be used in SUMO-modified synaptic complex proteins Zip1p and Ecm11p Directly catalyzes ubiquitination modification. In the process of meiosis of SLX8 knockout strains, the degradation of Ecm11p protein induced by the AID system can partially rescue its meiotic abnormalities. Therefore, SUMO-targeted ubiquitin ligase Slx5p-Slx8p can catalyze ubiquitination and mediate its degradation on the SUMO-modified synaptone complex protein Ecm11p, thereby regulating the correct separation of homologous chromosomes.



The above work clarified for the first time that SUMO targeted ubiquitin ligase Slx5p-Slx8p mediates the interaction of protein ubiquitination and SUMO modification during meiosis, promotes the degradation of protein sumoylation synaptic complex proteins and regulates homologous chromosomes Correct separation. It provides new ideas for people to further understand the complex regulation of protein post-translational modification. Related results were published in Advanced Science on January 1, 2020 under the heading "Slx5p-Slx8p promotes accurate chromosome segregation by mediating the degradation of synaptonemal complex components during meiosis".