PolySUMOylation of PCNA and Rad52 restricts centromeric recombination in fission yeast

SUMOylation, a conserved post-translational modification in eukaryotes, regulates protein function, localization, and stability. However, the role of SUMO chains in genome maintenance is still emerging. Using Schizosaccharomyces pombe, we show that loss of SUMO chains results in spontaneous replication stress, DNA damage, and elevated centromeric recombination. To investigate SUMO-dependent interactome at the sites of Rad52 repair, we used split-SUMO-ID proteomics approach. It allowed analysis of local SUMOylation content at the Rad52 repair sites, and enabled identification of the essential replication factor PCNA. We found that SUMO chain-modified PCNA antagonizes Rad8-mediated PCNA polyubiquitination, modulating the choice of post-replication repair pathways at stalled forks within centromeres. In the absence of polySUMOylation, excessive PCNA polyubiquitination drives elevated recombination at centromeres. Artificial tethering of a SUMO chain to Rad52 suppresses this defect. Our findings uncover an essential role for SUMO chains in centromere maintenance by modulating DNA repair pathway choice under endogenous replication stress. Overall design: Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) for CFP-Cnp1 histone variant (human CENP-A) from fission yeast Schizosaccharomyces pombe. Please note that additional data processing was carried out to remove background more stringently for the GSM8506073, GSM8506075, and GSM8506077 ChIP-seq samples. The processed data files and data processing description have been updated on May 29, 2025.