Ibars, EvaCodina-Fabra, JoanBellí, GemmaCasas, CeliaTarrés, MarcSolé-Soler, RogerLorite, Neus PXimenez-Embun, PilarMuñoz, JavierColomina, NeusTorres-Rosell, Jordi2024-09-162024-09-162023-05-30Cell Rep . 2023 ;42(5):112463.https://hdl.handle.net/20.500.12105/23103Ubiquitination controls numerous cellular processes, and its deregulation is associated with many pathologies. The Nse1 subunit in the Smc5/6 complex contains a RING domain with ubiquitin E3 ligase activity and essential functions in genome integrity. However, Nse1-dependent ubiquitin targets remain elusive. Here, we use label-free quantitative proteomics to analyze the nuclear ubiquitinome of nse1-C274A RING mutant cells. Our results show that Nse1 impacts the ubiquitination of several proteins involved in ribosome biogenesis and metabolism that, importantly, extend beyond canonical functions of Smc5/6. In addition, our analysis suggests a connection between Nse1 and RNA polymerase I (RNA Pol I) ubiquitination. Specifically, Nse1 and the Smc5/6 complex promote ubiquitination of K408 and K410 in the clamp domain of Rpa190, a modification that induces its degradation in response to blocks in transcriptional elongation. We propose that this mechanism contributes to Smc5/6-dependent segregation of the rDNA array, the locus transcribed by RNA Pol I.engVoRhttp://creativecommons.org/licenses/by-nc-nd/4.0/RNA Polymerase IUbiquitinAmino Acid SequenceProteomicsCell Cycle ProteinsRNAUbiquitin-Protein LigasesAttribution-NonCommercial-NoDerivatives 4.0 Internacional3714109642511246310.1016/j.celrep.2023.1124632211-1247Cell reportsopen access