A nuclear envelope protein linking nuclear pore basket assembly, SUMO protease regulation, and mRNA surveillance.
The nuclear pore complex (NPC) is both the major conduit for nucleocytoplasmic trafficking and a platform for organizing macromolecules at the nuclear envelope. We report that yeast Esc1, a non-NPC nuclear envelope protein, is required both for proper assembly of the nuclear basket, a structure extending into the nucleus from the NPC, and for normal NPC localization of the Ulp1 SUMO protease. In esc1Delta cells, Ulp1 and nuclear basket components Nup60 and Mlp1 no longer distribute broadly around the nuclear periphery, but co-localize in a small number of dense-staining perinuclear foci. Loss of Esc1 (or Nup60) alters SUMO conjugate accumulation and enhances ulp1 mutant defects. Similar to previous findings with Mlp1, both Esc1 and Ulp1 help retain unspliced pre-mRNAs in the nucleus. Therefore, these proteins are essential for proper nuclear basket function, which includes mRNA surveillance and regulation of SUMO protein dynamics. The results raise the possibility that NPC-localized protein desumoylation may be a key regulatory event preventing inappropriate pre-mRNA export.
Lewis
Alaron
A
Departments of Cell Biology, Yale University, New Haven, CT 06520, USA.
Felberbaum
Rachael
R
Hochstrasser
Mark
M
D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D022022:Nuclear Pore / Q000378:metabolism* / Q000648:ultrastructure; D028861:Nuclear Pore Complex Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012322:RNA Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism*; D014452:Ubiquitins / Q000378:metabolism
C495981:Esc1 protein, S cerevisiae; C080988:MLP1 protein, S cerevisiae; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; C495208:Nup60 protein, S cerevisiae; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D014452:Ubiquitins; D003546:Cysteine Endopeptidases; C118083:Ulp1 protease