title: Computational and biochemical identification of a nuclear pore complex binding site on the nuclear transport carrier NTF2.
abstract: Nuclear transport carriers interact with proteins of the nuclear pore complex (NPC) to transport their cargo across the nuclear envelope. One such carrier is nuclear transport factor 2 (NTF2), whose import cargo is the small GTPase Ran. A domain highly homologous to the small NTF2 protein (14kDa) is also found in a number of additional proteins, which together make up the NTF2 domain containing superfamily of proteins. Using structural, computational and biochemical analysis we have identified a functional site that is present throughout this superfamily, and our results indicate that this site functions as an NPC binding site in NTF2. Previously we showed that a D23A mutant of NTF2 exhibits increased affinity for the NPC. The mechanism of this mutation, however, was unknown as this region of NTF2 had not been implicated in binding to NPC proteins. Here we show that the D23A mutation in NTF2 does not result in gross structural changes affecting other known NPC binding sites. Instead, the D23 residue is located in an evolutionarily important region in the NTF2 domain containing superfamily, that in NTF2, is involved in binding to the NPC.
authors.affiliation: Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA. ian.cushman@duke.edu
authors.forename: Ian
authors.initials: I
authors.lastname: Cushman
authors.forename: Brian R
authors.initials: BR
authors.lastname: Bowman
authors.forename: Mathew E
authors.initials: ME
authors.lastname: Sowa
authors.forename: Olivier
authors.initials: O
authors.lastname: Lichtarge
authors.forename: Florante A
authors.initials: FA
authors.lastname: Quiocho
authors.forename: Mary Shannon
authors.initials: MS
authors.lastname: Moore
mesh_terms: D021581:Active Transport, Cell Nucleus; D000409:Alanine / Q000378:metabolism; D019943:Amino Acid Substitution; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism*; D019295:Computational Biology; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics; D019143:Evolution, Molecular; D006367:HeLa Cells; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D022022:Nuclear Pore / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D020931:ran GTP-Binding Protein / Q000378:metabolism
chemical_list: D029543:Nucleocytoplasmic Transport Proteins; D020931:ran GTP-Binding Protein; D000409:Alanine