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Autoproteolysis in nucleoporin biogenesis
1Laboratory of Cell Biology, Rockefeller University, New York, NY 10021, USA. rosenbj@rockvax.rockefeller.edu
Summary
Nuclear pore complex protein Nup98 undergoes self-cleavage, a process crucial for its biogenesis. This autoproteolytic mechanism, independent of external proteases, ensures proper nuclear pore formation and protein targeting.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Nuclear pore complexes (NPCs) are essential for nucleocytoplasmic transport.
- The biogenesis of certain NPC proteins, like Nup98 and Nup96, involves a conserved proteolytic cleavage.
- This cleavage is critical for the proper function and assembly of NPCs.
Purpose of the Study:
- To elucidate the molecular mechanism of proteolytic cleavage in nuclear pore complex proteins.
- To determine if an external protease is involved in the Nup98 cleavage event.
- To investigate the role of Nup98 self-cleavage in its biogenesis and interaction with Nup96.
Main Methods:
- Domain mapping and site-directed mutagenesis of the human Nup98 protein.
- In vitro cleavage assays using engineered Nup98 mutants.
- Analysis of the interaction between cleaved Nup98 fragments.
Main Results:
- The human Nup98 protein undergoes autoproteolytic self-cleavage between phenylalanine (Phe) 863 and serine (Ser) 864.
- A specific region within Nup98 (amino acids 715-920) mediates this self-cleavage.
- Cleaved Nup98 fragments form a complex, suggesting a mechanism for nuclear targeting of Nup96.
Conclusions:
- Nup98 utilizes an autoproteolytic mechanism for its biogenesis, independent of external proteases.
- This self-cleavage pathway is conserved across species and shares similarities with other protein families like hedgehog proteins and inteins.
- The interaction between cleaved Nup98 fragments plays a role in the nuclear import of Nup96.