Identification of karyopherins involved in the nuclear import of RNA exosome subunit Rrp6 in Saccharomyces cerevisiae
- ↵* Corresponding author; email: ccoliv{at}iq.usp.br
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Author contributions: CCO conceived and coordinated the study. FAGZ designed, performed and analyzed the experiments. EKO contributed to the confocal analysis, protein pull-down experiments and preparation of the figures. FAGZ and JPCDC analyzed the mass spectrometry results. FAGZ, JPCDC and CCO wrote the manuscript. All authors reviewed the results and approved the final version of the manuscript.
Abstract
The exosome is a conserved multiprotein complex essential for RNA processing and degradation. The nuclear exosome is a key factor for pre-rRNA processing through the activity of its catalytic subunits, Rrp6 and Rrp44. In Saccharomyces cerevisiae, Rrp6 is exclusively nuclear and has been shown to interact with exosome cofactors. With the aim of analyzing proteins associated with the nuclear exosome, in this work, we purified the complex with Rrp6-TAP, identified the co-purified proteins by mass spectrometry, and found karyopherins to be one of the major groups of proteins enriched in the samples. By investigating the biological importance of these protein interactions, we identified Kap95 and Sxm1 as the most important karyopherins for Rrp6 nuclear import and the nuclear localization signals recognized by them. Based on the results shown here, we propose a model of multiple pathways for the transport of Rrp6 to the nucleus.
- exosome complex
- protein import
- protein-nucleic acid interaction
- protein-protein interaction
- ribosomal RNA processing (rRNA processing)
- Saccharomyces cerevisiae
- Received December 13, 2016.
- Accepted May 24, 2017.
- Copyright © 2017, The American Society for Biochemistry and Molecular Biology
