Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
Tomoko Kojidani
Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan; Department of Chemical and Biological Sciences, Faculty of Science, Japan Women’s University, Tokyo, Japan
Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom; Department of Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan; Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan; Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
Non-centrosomal microtubule organizing centers (MTOCs) are important for microtubule organization in many cell types. In fission yeast Schizosaccharomyces pombe, the protein Mto1, together with partner protein Mto2 (Mto1/2 complex), recruits the γ-tubulin complex to multiple non-centrosomal MTOCs, including the nuclear envelope (NE). Here, we develop a comparative-interactome mass spectrometry approach to determine how Mto1 localizes to the NE. Surprisingly, we find that Mto1, a constitutively cytoplasmic protein, docks at nuclear pore complexes (NPCs), via interaction with exportin Crm1 and cytoplasmic FG-nucleoporin Nup146. Although Mto1 is not a nuclear export cargo, it binds Crm1 via a nuclear export signal-like sequence, and docking requires both Ran in the GTP-bound state and Nup146 FG repeats. In addition to determining the mechanism of MTOC formation at the NE, our results reveal a novel role for Crm1 and the nuclear export machinery in the stable docking of a cytoplasmic protein complex at NPCs.
