Ramos-Sáenz, AnaGonzález-Álvarez, DanielRodríguez-Galán, OlgaRodríguez-Gil, AlfonsoGaspar, Sonia GVillalobo, EduardoDosil, Mercedesde la Cruz, Jesús2023-01-252023-01-252019-08-14http://hdl.handle.net/10668/14394In Saccharomyces cerevisiae, more than 250 trans-acting factors are involved in the maturation of 40S and 60S ribosomal subunits. The expression of most of these factors is transcriptionally coregulated to ensure correct ribosome production under a wide variety of environmental and intracellular conditions. Here, we identified the essential nucleolar Pol5 protein as a novel trans-acting factor required for the synthesis of 60S ribosomal subunits. Pol5 weakly and/or transiently associates with early to medium pre-60S ribosomal particles. Depletion of and temperature-sensitive mutations in Pol5 result in a deficiency of 60S ribosomal subunits and accumulation of half-mer polysomes. Both processing of 27SB pre-rRNA to mature 25S rRNA and release of pre-60S ribosomal particles from the nucle(ol)us to the cytoplasm are impaired in the Pol5-depleted strain. Moreover, we identified the genes encoding ribosomal proteins uL23 and eL27A as multicopy suppressors of the slow growth of a temperature-sensitive pol5 mutant. These results suggest that Pol5 could function in ensuring the correct folding of 25S rRNA domain III; thus, favoring the correct assembly of these two ribosomal proteins at their respective binding sites into medium pre-60S ribosomal particles. Pol5 is homologous to the human tumor suppressor Myb-binding protein 1A (MYBBP1A). However, expression of MYBBP1A failed to complement the lethal phenotype of a pol5 null mutant strain though interfered with 60S ribosomal subunit biogenesis.enMYBBP1Anucleoluspre-rRNA processingribosomal proteins uL23 and eL27ribosome biogenesisCell NucleusCytoplasmDNA-Directed DNA PolymeraseRNA Processing, Post-TranscriptionalRibosome Subunits, Large, EukaryoticRibosomesSaccharomyces cerevisiaeSaccharomyces cerevisiae Proteinsresearch article31413149open access10.1261/rna.072116.1191469-9001PMC6795146http://rnajournal.cshlp.org/content/25/11/1561.full.pdfhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC6795146/pdf