title: The Stability of Ribosome Biogenesis Factor WBSCR22 Is Regulated by Interaction with TRMT112 via Ubiquitin-Proteasome Pathway.
abstract: The human WBSCR22 protein is a 18S rRNA methyltransferase involved in pre-rRNA processing and ribosome 40S subunit biogenesis. Recent studies have shown that the protein function in ribosome synthesis is independent of its enzymatic activity. In this work, we have studied the WBSCR22 protein interaction partners by SILAC-coupled co-immunoprecipitation assay and identified TRMT112 as the interaction partner of WBSCR22. Knock-down of TRMT112 expression decreased the WBSCR22 protein level in mammalian cells, suggesting that the stability of WBSCR22 is regulated through the interaction with TRMT112. The localization of the TRMT112 protein is determined by WBSCR22, and the WBSCR22-TRMT112 complex is localized in the cell nucleus. We provide evidence that the interaction between WBSCR22/Bud23 and TRMT112/Trm112 is conserved between mammals and yeast, suggesting that the function of TRMT112 as a co-activator of methyltransferases is evolutionarily conserved. Finally, we show that the transiently expressed WBSCR22 protein is ubiquitinated and degraded through the proteasome pathway, revealing the tight control of the WBSCR22 protein level in the cells.
authors.affiliation: Institute of Technology, University of Tartu, Tartu, Estonia.
authors.forename: Kadri
authors.initials: K
authors.lastname: Õunap
authors.affiliation: Institute of Technology, University of Tartu, Tartu, Estonia.
authors.forename: Lilian
authors.initials: L
authors.lastname: Leetsi
authors.affiliation: Institute of Technology, University of Tartu, Tartu, Estonia.
authors.forename: Maarja
authors.initials: M
authors.lastname: Matsoo
authors.affiliation: Institute of Technology, University of Tartu, Tartu, Estonia.
authors.forename: Reet
authors.initials: R
authors.lastname: Kurg
mesh_terms: D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000201:enzymology* / Q000235:genetics; D055785:Gene Knockdown Techniques; D006801:Humans; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D012337:RNA, Ribosomal, 18S; D054682:Ribosome Subunits, Small, Eukaryotic / Q000235:genetics / Q000378:metabolism; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000502:physiology*
chemical_list: D012337:RNA, Ribosomal, 18S; D025801:Ubiquitin; C455827:BUD23 protein, human; D008780:Methyltransferases; C000605620:TRMT112 protein, human; D046988:Proteasome Endopeptidase Complex