Nuclear export receptor Xpo1/Crm1 is physically and functionally linked to the spindle pole body in budding yeast.
The spindle pole body (SPB) represents the microtubule organizing center in the budding yeast Saccharomyces cerevisiae. It is a highly structured organelle embedded in the nuclear membrane, which is required to anchor microtubules on both sides of the nuclear envelope. The protein Spc72, a component of the SPB, is located at the cytoplasmic face of this organelle and serves as a receptor for the gamma-tubulin complex. In this paper we show that it is also a binding partner of the nuclear export receptor Xpo1/Crm1. Xpo1 binds its cargoes in a Ran-dependent fashion via a short leucine-rich nuclear export signal (NES). We show that binding of Spc72 to Xpo1 depends on Ran-GTP and a functional NES in Spc72. Mutations in this NES have severe consequences for mitotic spindle morphology in vivo. This is also the case for xpo1 mutants, which show a reduction in cytoplasmic microtubules. In addition, we find a subpopulation of Xpo1 localized at the SPB. Based on these data, we propose a functional link between Xpo1 and the SPB and discuss a role for this exportin in spindle biogenesis in budding yeast.
Max Delbrück Centrum für Molekulare Medizin, Robert Rössle Str. 10, 13092 Berlin, Germany.
Anja
A
Neuber
Jacqueline
J
Franke
Angelika
A
Wittstruck
Gabriel
G
Schlenstedt
Thomas
T
Sommer
Katrin
K
Stade
D021581:Active Transport, Cell Nucleus; D002467:Cell Nucleus / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D028884:Karyopherins / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D049790:Nuclear Export Signals; D009687:Nuclear Proteins / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism*; D000097606:Exportin 1 Protein
D006160:Guanosine Triphosphate; D028884:Karyopherins; D008869:Microtubule-Associated Proteins; D020559:Monomeric GTP-Binding Proteins; D049790:Nuclear Export Signals; D009687:Nuclear Proteins; D010446:Peptide Fragments; D018160:Receptors, Cytoplasmic and Nuclear; D029701:Saccharomyces cerevisiae Proteins; D000097606:Exportin 1 Protein; C080324:GSP1 protein, S cerevisiae; C418484:SPC72 protein, S cerevisiae