Olombrada, MiriamPena, CohueRodríguez Galán, OlgaKlingauf Nerurkar, PurnimaPortugal Calisto, DanielaOborska Oplová, MichaelaAltvater, MartínGavilanes, Jose G.Martínez del Pozo, ÁlvaroCruz Díaz, Jesús de la2020-05-052020-05-052020Olombrada, M., Pena, C., Rodríguez Galán, O., Klingauf Nerurkar, P., Portugal Calisto, D., Oborska Oplová, M.,...,Cruz Díaz, J.d.l. (2020). The ribotoxin α-sarcin can cleave the sarcin/ricin loop on late 60S pre-ribosomes. Nucleic Acids Research, 48 (11), 6210-6222.1362-4962https://hdl.handle.net/11441/96123The ribotoxin α-sarcin belongs to a family of ribonucleases that cleave the sarcin/ricin loop (SRL), a critical functional rRNA element within the large ribosomal subunit (60S), thereby abolishing translation. Whether α-sarcin targets the SRL only in mature 60S subunits remains unresolved. Here, we show that, in yeast, α-sarcin can cleave SRLs within late 60S pre-ribosomes containing mature 25S rRNA but not nucleolar/nuclear 60S pre-ribosomes containing 27S pre-rRNA in vivo. Conditional expression of α-sarcin is lethal, but does not impede early pre-rRNA processing, nuclear export and the cytoplasmic maturation of 60S pre-ribosomes. Thus, SRL-cleaved containing late 60S pre-ribosomes seem to escape cytoplasmic proofreading steps. Polysome analyses revealed that SRL-cleaved 60S ribosomal subunits form 80S initiation complexes, but fail to progress to the step of translation elongation. We suggest that the functional integrity of a α-sarcin cleaved SRL might be assessed only during translation.application/pdf13 p.engAttribution-NonCommercial-NoDerivatives 4.0 Internacionalhttp://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccesshttps://doi.org/10.1093/nar/gkaa315