title: Nuclear export competence of pre-40S subunits in fission yeast requires the ribosomal protein Rps2.
abstract: Ribosome biogenesis is an evolutionarily conserved pathway that requires ribosomal and nonribosomal proteins. Here, we investigated the role of the ribosomal protein S2 (Rps2) in fission yeast ribosome synthesis. As for many budding yeast ribosomal proteins, Rps2 was essential for cell viability in fission yeast and the genetic depletion of Rps2 caused a complete inhibition of 40S ribosomal subunit production. The pattern of pre-rRNA processing upon depletion of Rps2 revealed a reduction of 27SA(2) pre-rRNAs and the concomitant production of 21S rRNA precursors, consistent with a role for Rps2 in efficient cleavage at site A(2) within the 32S pre-rRNA. Importantly, kinetics of pre-rRNA accumulation as determined by rRNA pulse-chases assays indicated that a small fraction of 35S precursors matured into 20S-containing particles, suggesting that most 40S precursors were rapidly degraded in the absence of Rps2. Analysis of steady-state RNA levels revealed that some pre-40S particles were produced in Rps2-depleted cells, but that these precursors were retained in the nucleolus. Our findings suggest a role for Rps2 in a mechanism that monitors pre-40S export competence.
authors.affiliation: RNA Group, Department of Biochemistry, Université de Sherbrooke, Québec, Canada.
authors.forename: Audrey
authors.initials: A
authors.lastname: Perreault
authors.forename: Clément
authors.initials: C
authors.lastname: Bellemer
authors.forename: Francois
authors.initials: F
authors.lastname: Bachand
mesh_terms: D021581:Active Transport, Cell Nucleus; D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D017353:Gene Deletion; D020043:Genes, Essential; D012322:RNA Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012337:RNA, Ribosomal, 18S / Q000096:biosynthesis; D016601:RNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D012269:Ribosomal Proteins / Q000235:genetics / Q000502:physiology*; D054682:Ribosome Subunits, Small, Eukaryotic / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D012322:RNA Precursors; D012337:RNA, Ribosomal, 18S; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; C533187:Rps2 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; C030004:ribosomal protein S2