Structure and assembly of the Nup84p complex.

Area of Science:

• Cell Biology
• Molecular Biology
• Structural Biology

Background:

• The Nup84p complex is a key component of the nuclear pore complex (NPC).
• Sec13p is a known subunit of the COPII coat complex involved in vesicular transport.
• The precise role of Sec13p within the Nup84p complex and its contribution to NPC biogenesis are not fully understood.

Purpose of the Study:

• To investigate the role of Sec13p in the Nup84p complex and its function in nuclear pore complex (NPC) organization and biogenesis.
• To characterize the structural and functional relationship between Sec13p and the Nup84p complex.

Main Methods:

• Localization studies using green fluorescent protein (GFP)-tagged Sec13p in vivo.
• Genetic analysis of sec13 mutant alleles for synthetic lethality with nup85Delta.
• Electron microscopy to assess nuclear pore complex (NPC) and nuclear envelope organization in sec13 mutants.
• Biochemical purification of the Nup84p complex.
• Quantitative scanning transmission electron microscopy and analytical ultracentrifugation to determine molecular mass and morphology.

Main Results:

• Sec13p localizes to nuclear pores in vivo.
• Specific sec13 mutant alleles exhibit synthetic lethality with nup85Delta and disrupt NPC structure.
• The Nup84p complex was purified, revealing a molecular mass of 375 kD and a Y-shaped, triskelion-like morphology.
• Nup85p, Nup120p, and Nup145p-C are essential for Nup84p complex assembly.

Conclusions:

• The Nup84p complex is a distinct structural module of the nuclear pore complex (NPC).
• Sec13p plays a critical role in nuclear mRNA export and NPC biogenesis.
• The Nup84p complex's composition and structure are essential for its function in nuclear transport.