Yeast nuclear pore complexes have a cytoplasmic ring and internal filaments

Abstract

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThe nuclear pore complex (NPC) controls transport of macromolecules across the nuclear envelope. It is large and complex but appears to consist of only ~30 different proteins despite its mass of >60 MDa. Vertebrate NPC structure has been analyzed by several methods giving a comprehensive architectural model. Despite our knowledge of yeast nucleoporins, structural data is more limited and suggests the basic organization is similar to vertebrates, but may lack some peripheral and other components. Using field emission scanning electron microscopy to probe NPC structure we found that the yeast, like higher eukaryotic, NPCs contain similar peripheral components. We can detect cytoplasmic rings and evidence of nucleoplasmic rings in yeasts. A filamentous basket is present on the nucleoplasmic face and evidence for cytoplasmic filaments is shown. We observe a central structure, possibly the transporter, that which may be linked to the cytoplasmic ring by internal filaments. Immuno-gold labeling suggests that Nup159p may be attached to the cytoplasmic ring, whereas Nup116p may be associated, partly, with the cytoplasmic filaments. Analysis of a Nup57p mutant suggested a role in maintaining the stability of cytoplasmic components of the NPC. We conclude that peripheral NPC components appear similar in yeasts compared to higher organisms and present a revised model for yeast NPC structural composition.4

Nuclear Membrane Disassembly and Rupture

“…Movement of macromolecules across the NE is regulated through the NPCs. NPCs are channels of ~120 MD and ~120 nm diameter in vertebrates (3) and may be smaller in yeast (4,5), but in many respects are conserved. The NPC has an eightfold rotational symmetry and comprises multiple copies of ~ 30 or more (6,7) nucleoporins.…”

Entry into the nuclear pore complex is controlled by a cytoplasmic exclusion zone containing dynamic GLFG-repeat nucleoporin domains

“…It also extended up to ,80 nm from the central plane, into the cytoplasm or nucleoplasm. This is further than the extent of the cytoplasmic filaments or nuclear baskets (Goldberg and Allen, 1992;Kiseleva et al, 2004). Some NPCs have cytoplasmic GLFG labelling ( Fig.…”

“…We modified a previous procedure to study yeast NPCs by field emission scanning electron microscopy (feSEM) (Kiseleva et al, 2004), leaving ribosomes in place (Fig. 1A).…”

Multiple Conserved Domains of the Nucleoporin Nup124p and Its Orthologs Nup1p and Nup153 Are Critical for Nuclear Import and Activity of the Fission Yeast Tf1 Retrotransposon

“…Despite differences in both size and composition, yeast and vertebrate NPCs have a number of common features including their general overall structure, protein composition, and mechanism of nuclear transport (Fabre and Hurt, 1997;Yang et al, 1998;Stoffler et al, 1999;Ryan and Wente, 2000;Wente, 2000;Cronshaw et al, 2002;Suntharalingam and Wente, 2003;Kiseleva et al, 2004;Devos et al, 2006;Tran and Wente, 2006). Fission yeast has NPC features and transport factors comparable to S. cerevisiae and vertebrate systems and the appropriate tools to study these features are now available (Ding et al, 2000;Chen et al, 2004;Kiseleva et al, 2004;Yoshida and Sazer, 2004). In general, the bulk of macromolecular traffic through the NPC is mediated by a system of mobile transporter proteins, multiple importins ␣ and ␤ and the nucleoporins (Nups), the latter, a unique and conserved group of structural proteins of the pore complex.…”