A link between the synthesis of nucleoporins and the biogenesis of the nuclear envelope

TitleA link between the synthesis of nucleoporins and the biogenesis of the nuclear envelope
Publication TypeJournal Article
Year of Publication2001
AuthorsMarelli M, Lusk CP, Chan H, Aitchison JD, Wozniak RW
JournalJ Cell Biol
Date PublishedMay 14
Keywords*Membrane Transport Proteins, *Nuclear Pore Complex Proteins, *Saccharomyces cerevisiae Proteins, Active Transport, Cell Nucleus/*physiology, Fungal Proteins/metabolism, Gene Expression Regulation, Fungal/physiology, Membrane Glycoproteins/metabolism, Membrane Proteins/metabolism, Microscopy, Electron, Nuclear Envelope/*metabolism/ultrastructure, Nuclear Proteins/chemistry/*genetics/*metabolism, Plasmids, Porins/chemistry/*genetics/*metabolism, Protein Structure, Secondary, Protein Structure, Tertiary, Receptors, Cytoplasmic and Nuclear/metabolism, Yeasts
AbstractThe nuclear pore complex (NPC) is a multicomponent structure containing a subset of proteins that bind nuclear transport factors or karyopherins and mediate their movement across the nuclear envelope. By altering the expression of a single nucleoporin gene, NUP53, we showed that the overproduction of Nup53p altered nuclear transport and had a profound effect on the structure of the nuclear membrane. Strikingly, conventional and immunoelectron microscopy analysis revealed that excess Nup53p entered the nucleus and associated with the nuclear membrane. Here, Nup53p induced the formation of intranuclear, tubular membranes that later formed flattened, double membrane lamellae structurally similar to the nuclear envelope. Like the nuclear envelope, the intranuclear double membrane lamellae enclosed a defined cisterna that was interrupted by pores but, unlike the nuclear envelope pores, they lacked NPCs. Consistent with this observation, we detected only two NPC proteins, the pore membrane proteins Pom152p and Ndc1p, in association with these membrane structures. Thus, these pores likely represent an intermediate in NPC assembly. We also demonstrated that the targeting of excess Nup53p to the NPC and its specific association with intranuclear membranes were dependent on the karyopherin Kap121p and the nucleoporin Nup170p. At the nuclear envelope, the abilities of Nup53p to associate with the membrane and drive membrane proliferation were dependent on a COOH-terminal segment containing a potential amphipathic alpha-helix. The implications of these results with regards to the biogenesis of the nuclear envelope are discussed.
Short TitleThe Journal of cell biology
Alternate JournalThe Journal of cell biology