%0 Journal Article
%A Olombrada, Miriam
%A Peña, Cohue
%A Rodríguez Galán, Olga
%A Klingauf Nerurkar, Purnima
%A Portugal Calisto, Daniela
%A Oborská Oplová, Michaela
%A Altvater, Martin
%A Gavilanes, José G.
%A Martínez del Pozo, Álvaro
%A De la Cruz, Jesús
%A García Ortega, Lucía
%A Govind Panse, Vikram
%T The ribotoxin α-sarcin can cleave the sarcin/ricin loop on late 60S pre-ribosomes
%D 2020
%@ 1362-4962
%U https://hdl.handle.net/20.500.14352/6552
%X The ribotoxin -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 -sarcin targets the SRL only in mature 60S subunits remains unresolved. Here, we show that, in yeast, -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 -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 -sarcin cleaved SRL might be assessed only during translation.
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