Identification of an E3 ligase that targets the catalytic subunit of RNA Polymerase I upon transcription stress

• Published in: The Journal of biological chemistry 2022-12, Vol.298 (12), p.102690-102690, Article 102690
• Main Authors: Pitts, Stephanie, Liu, Hester, Ibrahim, Adel, Garg, Amit, Felgueira, Catarina Mendes, Begum, Asma, Fan, Wenjun, Teh, Selina, Low, Jin-Yih, Ford, Brittany, Schneider, David A., Hay, Ronald, Laiho, Marikki
• Format: Article
• Language: English
• Subjects: cancer; Catalytic Domain; F-Box Proteins - genetics; F-Box Proteins - metabolism; Humans; proteasome; RNA Polymerase I - genetics; RNA Polymerase I - metabolism; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; SKP Cullin F-Box Protein Ligases - genetics; SKP Cullin F-Box Protein Ligases - metabolism; small molecule; transcription; Transcription, Genetic - genetics; ubiquitin; Ubiquitination
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/j.jbc.2022.102690

RNA Polymerase I (Pol I) synthesizes rRNA, which is the first and rate-limiting step in ribosome biogenesis. Factors governing the stability of the polymerase complex are not known. Previous studies characterizing Pol I inhibitor BMH-21 revealed a transcriptional stress-dependent pathway for degradation of the largest subunit of Pol I, RPA194. To identify the E3 ligase(s) involved, we conducted a cell-based RNAi screen for ubiquitin pathway genes. We establish Skp–Cullin–F-box protein complex F-box protein FBXL14 as an E3 ligase for RPA194. We show that FBXL14 binds to RPA194 and mediates RPA194 ubiquitination and degradation in cancer cells treated with BMH-21. Mutation analysis in yeast identified lysines 1150, 1153, and 1156 on Rpa190 relevant for the protein degradation. These results reveal the regulated turnover of Pol I, showing that the stability of the catalytic subunit is controlled by the F-box protein FBXL14 in response to transcription stress.