Rrp5p, Noc1p and Noc2p form a protein module which is part of early large ribosomal subunit precursors in S. cerevisiae.

Nucleic acids research 2013 Jan

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Eukaryotic ribosome biogenesis requires more than 150 auxiliary proteins, which transiently interact with pre-ribosomal particles. Previous studies suggest that several of these biogenesis factors function together as modules. Using a heterologous expression system, we show that the large ribosomal subunit (LSU) biogenesis factor Noc1p of Saccharomyces cerevisiae can simultaneously interact with the LSU biogenesis factor Noc2p and Rrp5p, a factor required for biogenesis of the large and the small ribosomal subunit. Proteome analysis of RNA polymerase-I-associated chromatin and chromatin immunopurification experiments indicated that all members of this protein module and a specific set of LSU biogenesis factors are co-transcriptionally recruited to nascent ribosomal RNA (rRNA) precursors in yeast cells. Further ex vivo analyses showed that all module members predominantly interact with early pre-LSU particles after the initial pre-rRNA processing events have occurred. In yeast strains depleted of Noc1p, Noc2p or Rrp5p, levels of the major LSU pre-rRNAs decreased and the respective other module members were associated with accumulating aberrant rRNA fragments. Therefore, we conclude that the module exhibits several binding interfaces with pre-ribosomes. Taken together, our results suggest a co- and post-transcriptional role of the yeast Rrp5p-Noc1p-Noc2p module in the structural organization of early LSU precursors protecting them from non-productive RNase activity.

Citation

Thomas Hierlmeier, Juliane Merl, Martina Sauert, Jorge Perez-Fernandez, Patrick Schultz, Astrid Bruckmann, Stephan Hamperl, Uli Ohmayer, Reinhard Rachel, Anja Jacob, Kristin Hergert, Rainer Deutzmann, Joachim Griesenbeck, Ed Hurt, Philipp Milkereit, Jochen Baßler, Herbert Tschochner. Rrp5p, Noc1p and Noc2p form a protein module which is part of early large ribosomal subunit precursors in S. cerevisiae. Nucleic acids research. 2013 Jan;41(2):1191-210