The Saccharomyces cerevisiae Nucleoporin Nup2p Is a Natively Unfolded Protein

Little is known about the structure of the individual nucleoporins that form eukaryotic nuclear pore complexes (NPCs). We report here in vitro physical and structural characterizations of a full-length nucleoporin, the Saccharomyces cerevisiae protein Nup2p. Analyses of the Nup2p structure by far-UV...

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Bibliographic Details
Published in:The Journal of biological chemistry 2002-09, Vol.277 (36), p.33447-33455
Main Authors: Denning, Daniel P., Uversky, Vladimir, Patel, Samir S., Fink, Anthony L., Rexach, Michael
Format: Article
Language:English
Subjects:
Blotting, Western
Centrifugation, Density Gradient
Chromatography, Gel
Circular Dichroism
Cytoplasm - metabolism
Endopeptidase K - pharmacology
Hot Temperature
Nuclear Pore Complex Proteins - metabolism
Protein Conformation
Protein Folding
Protein Structure, Secondary
Protein Transport
Recombinant Proteins - metabolism
Saccharomyces cerevisiae - metabolism
Saccharomyces cerevisiae Proteins - metabolism
Spectroscopy, Fourier Transform Infrared
Sucrose - pharmacology
Time Factors
Ultraviolet Rays
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Summary:Little is known about the structure of the individual nucleoporins that form eukaryotic nuclear pore complexes (NPCs). We report here in vitro physical and structural characterizations of a full-length nucleoporin, the Saccharomyces cerevisiae protein Nup2p. Analyses of the Nup2p structure by far-UV circular dichroism (CD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, protease sensitivity, gel filtration, and sedimentation velocity experiments indicate that Nup2p is a “natively unfolded protein,” belonging to a class of proteins that exhibit little secondary structure, high flexibility, and low compactness. Nup2p possesses a very large Stokes radius (79 Å) in gel filtration columns, sediments slowly in sucrose gradients as a 2.9 S particle, and is highly sensitive to proteolytic digestion by proteinase K; these characteristics suggest a structure of low compactness and high flexibility. Spectral analyses (CD and FTIR spectroscopy) provide additional evidence that Nup2p contains extensive regions of structural disorder with comparatively small contributions of ordered secondary structure. We address the possible significance of natively unfolded nucleoporins in the mechanics of nucleocytoplasmic trafficking across NPCs.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M203499200