Originally published as Genetics Published Articles Ahead of Print on August 22, 2005.

Genetics, Vol. 171, 935-947, November 2005, Copyright © 2005
doi:10.1534/genetics.104.036319

Nuclear Pore Complex Function in Saccharomyces cerevisiae Is Influenced by Glycosylation of the Transmembrane Nucleoporin Pom152p

Kenneth D. Belanger*,1, Amitabha Gupta*,2, Kristy M. MacDonald*, Christina M. Ott*,3, Christine A. Hodge{dagger}, Charles M. Cole{dagger} and Laura I. Davis{ddagger}

* Department of Biology, Colgate University, Hamilton, New York 13346, {dagger} Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755 and {ddagger} Department of Biology, Brandeis University, Waltham, Massachusetts 02453

1 Corresponding author: Department of Biology, Colgate University, 13 Oak Dr., Hamilton, NY 13346.
E-mail: kbelanger{at}mail.colgate.edu

The regulated transport of proteins across the nuclear envelope occurs through nuclear pore complexes (NPCs), which are composed of >30 different protein subunits termed nucleoporins. While some nucleoporins are glycosylated, little about the role of glycosylation in NPC activity is understood. We have identified loss-of-function alleles of ALG12, encoding a mannosyltransferase, as suppressors of a temperature-sensitive mutation in the gene encoding the FXFG-nucleoporin NUP1. We observe that nup1{Delta} cells import nucleophilic proteins more efficiently when ALG12 is absent, suggesting that glycosylation may influence nuclear transport. Conditional nup1 and nup82 mutations are partially suppressed by the glycosylation inhibitor tunicamycin, while nic96 and nup116 alleles are hypersensitive to tunicamycin treatment, further implicating glycosylation in NPC function. Because Pom152p is a glycosylated, transmembrane nucleoporin, we examined genetic interactions between pom152 mutants and nup1{Delta}. A nup1 deletion is lethal in combination with pom152{Delta}, as well as with truncations of the N-terminal and transmembrane regions of Pom152p. However, truncations of the N-glycosylated, lumenal domain of Pom152p and pom152 mutants lacking N-linked glycosylation sites are viable in combination with nup1{Delta}, suppress nup1{Delta} temperature sensitivity, and partially suppress the nuclear protein import defects associated with the deletion of NUP1. These data provide compelling evidence for a role for glycosylation in influencing NPC function.