Functional characterization of a Nup159p-containing nuclear pore subcomplex

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Nup159p/Rat7p is a crucial FG-repeat nucleoporin at the cytoplasmic face of the nuclear pore complex (NPC).
• It plays vital roles in poly(A)+ RNA export and NPC organization.
• Previous studies established Nup159p's NPC anchoring via its carboxyl-terminal domain.

Purpose of the Study:

• To investigate the interactions of Nup159p within the NPC.
• To elucidate the role of Nup82p in the Nup159p/Nsp1p subcomplex.
• To understand the molecular basis of poly(A)+ RNA export defects in nup82 mutants.

Main Methods:

• Structural-functional analysis of Nup159p interactions.
• Yeast genetics using nup82Delta108 and nup159-1/rat7-1 mutant strains.
• Immunofluorescence microscopy to assess Nup159p localization.
• In vivo transport assays for nuclear protein import and export.

Main Results:

• Nup159p directly interacts with Nsp1p and Nup82p via its carboxyl-terminal domain.
• A deletion in Nup82p (nup82Delta108) disrupts Nsp1p binding but not Nup159p-Nsp1p interaction.
• Nup159p delocalizes from the NPC in nup82Delta108 cells at 37°C, correlating with Nup82Delta108p degradation.
• Nup82p appears to function as a docking site for the Nup159p-Nsp1p complex.
• Mutant strains showed minimal defects in nuclear protein import/export.

Conclusions:

• Nup82p is essential for anchoring Nup159p at the NPC.
• The poly(A)+ RNA export defect in nup82 mutants is likely caused by Nup159p dissociation from the NPC.
• This study clarifies the role of Nup82p in NPC structure and function, particularly in RNA export.