Identification of karyopherins involved in the nuclear import of RNA exosome subunit Rrp6 in Saccharomyces cerevisiae

• Published in: The Journal of biological chemistry Vol. 292; no. 29; pp. 12267 - 12284
• Main Authors: Gonzales-Zubiate, Fernando A., Okuda, Ellen K., Da Cunha, Julia P.C., Oliveira, Carla Columbano
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 21.07.2017; American Society for Biochemistry and Molecular Biology
• Subjects: Active Transport, Cell Nucleus; beta Karyopherins - chemistry; beta Karyopherins - genetics; beta Karyopherins - metabolism; exosome complex; Exosome Multienzyme Ribonuclease Complex - chemistry; Exosome Multienzyme Ribonuclease Complex - genetics; Exosome Multienzyme Ribonuclease Complex - metabolism; Exosomes - enzymology; Exosomes - metabolism; Gene Deletion; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Karyopherins - chemistry; Karyopherins - genetics; Karyopherins - metabolism; Microscopy, Confocal; Microscopy, Fluorescence; Nuclear Localization Signals - chemistry; Nuclear Localization Signals - genetics; Nuclear Localization Signals - metabolism; Peptide Fragments - chemistry; Peptide Fragments - genetics; Peptide Fragments - metabolism; protein import; Protein Interaction Domains and Motifs; protein-nucleic acid interaction; protein-protein interaction; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; ribosomal RNA processing (rRNA processing); RNA; Saccharomyces cerevisiae; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; exosome complex; protein-nucleic acid interaction; protein-protein interaction; ribosomal RNA processing (rRNA processing); protein import; Saccharomyces cerevisiae
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M116.772376

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 Srp1, 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.