tailieunhanh - Báo cáo khoa học: Nop53p interacts with 5.8S rRNA co-transcriptionally, and regulates processing of pre-rRNA by the exosome

In eukaryotes, pre-rRNA processing depends on a large number of nonrib-osomal trans-acting factors that form intriguingly organized complexes. One of the early stages of pre-rRNA processing includes formation of the two intermediate complexes pre-40S and pre-60S, which then form the mature ribosome subunits. | ễFEBS Journal Nop53p interacts with rRNA co-transcriptionally and regulates processing of pre-rRNA by the exosome Daniela C. Granato1 Glaucia M. Machado-Santelli2 and Carla C. Oliveira1 1 Department of Biochemistry Institute of Chemistry University of Sao Paulo Brazil 2 Department of Cellular and Development Biology Institute of BiomedicalSciences University of Scio Paulo Brazil Keywords exosome activation pre-60S pre-rRNA processing protein-RNA interaction ribosome biogenesis Correspondence C. C. Oliveira Department of Biochemistry Institute of Chemistry University of Sao Paulo Av. Prof. Lineu Prestes 748 Sao Paulo CEP 05508-900 Brazil Fax 55 11 38155579 Tel 55 11 30913810 ext. 208 E-mail ccoliv@ Received 2 April2008 revised 22 May 2008 accepted 20 June 2008 doi In eukaryotes pre-rRNA processing depends on a large number of nonrib-osomal trans-acting factors that form intriguingly organized complexes. One of the early stages of pre-rRNA processing includes formation of the two intermediate complexes pre-40S and pre-60S which then form the mature ribosome subunits. Each of these complexes contains specific pre-rRNAs ribosomal proteins and processing factors. The yeast nucleolar protein Nop53p has previously been identified in the pre-60S complex and shown to affect pre-rRNA processing by directly binding to rRNA and to interact with Nop17p and Nip7p which are also involved in this process. Here we show that Nop53p binds rRNA co-transcriptionally through its N-terminal region and that this protein portion can also partially complement growth of the conditional mutant strain Dnop53 GAL -NOP53. Nop53p interacts with Rrp6p and activates the exosome in vitro. These results indicate that Nop53p may recruit the exosome to 7S pre-rRNA for processing. Consistent with this observation and similar to the observed in exosome mutants depletion of Nop53p leads to accumulation of polyadenylated pre-rRNAs. Synthesis of .