The ribosomal protein Rps15p is required for nuclear exit of the 40S subunit precursors in yeast.
We have conducted a genetic screen in order to identify ribosomal proteins of Saccharomyces cerevisiae involved in nuclear export of the small subunit precursors. This has led us to distinguish Rps15p as a protein dispensable for maturation of the pre-40S particles, but whose assembly into the pre-ribosomes is a prerequisite to their nuclear exit. Upon depletion of Rps15p, 20S pre-rRNA is released from the nucleolus and retained in the nucleus, without alteration of the pre-rRNA early cleavages. In contrast, Rps18p, which contacts Rps15p in the small subunit, is required upstream for pre-rRNA processing at site A2. Most pre-40S specific factors are correctly associated with the intermediate particles accumulating in the nucleus upon Rps15p depletion, except the late-binding proteins Tsr1p and Rio2p. Here we show that these two proteins are dispensable for nuclear exit; instead, they participate in 20S pre-rRNA processing in the cytoplasm. We conclude that, during the final maturation steps in the nucleus, incorporation of the ribosomal protein Rps15p is specifically required to render the pre-40S particles competent for translocation to the cytoplasm.
Léger-Silvestre
Isabelle
I
Laboratoire de Biologie Moléculaire Eucaryote, CNRS and Université Paul Sabatier, Toulouse, France.
Milkereit
Philipp
P
Ferreira-Cerca
Sébastien
S
Saveanu
Cosmin
C
Rousselle
Jean-Claude
JC
Choesmel
Valérie
V
Guinefoleau
Cécile
C
Gas
Nicole
N
Gleizes
Pierre-Emmanuel
PE
D002467:Cell Nucleus / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D021381:Protein Transport; D012322:RNA Precursors / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
D009687:Nuclear Proteins; D012322:RNA Precursors; D012335:RNA, Ribosomal