title: A cytotoxic ribonuclease variant with a discontinuous nuclear localization signal constituted by basic residues scattered over three areas of the molecule.
abstract: Nuclear import of proteins is determined by specific signals that allow them to bind to receptors that mediate their energy-dependent transport through the nuclear pore. These signals are termed nuclear localization signals and do not constitute a specific consensus sequence. Among them, the most characterized correspond to monopartite and bipartite nuclear localization signals, which interact with the importin alpha/beta heterodimer. We previously described a cytotoxic variant of human pancreatic-ribonuclease that is actively transported into the nucleus. Here, we show that this protein interacts with importin alpha through different basic residues, including Lys1 and the arginine clusters 31-33 and 89-91. Although these residues are scattered along the sequence, they are close in the three-dimensional structure of the protein and their topological disposition strongly resembles that of a classical bipartite nuclear localization signal.
authors.affiliation: Laboratori d'Enginyeria de Proteïnes, Departament de Biologia, Facultat de Ciències, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Rodríguez
authors.forename: A
authors.initials: A
authors.lastname: Benito
authors.forename: P
authors.initials: P
authors.lastname: Tubert
authors.forename: J
authors.initials: J
authors.lastname: Castro
authors.forename: M
authors.initials: M
authors.lastname: Ribó
authors.forename: B
authors.initials: B
authors.lastname: Beaumelle
authors.forename: M
authors.initials: M
authors.lastname: Vilanova
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D024361:Amino Acids, Basic / Q000737:chemistry*; D016923:Cell Death; D002467:Cell Nucleus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D019913:Nuclear Localization Signals / Q000737:chemistry*; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012259:Ribonuclease, Pancreatic / Q000737:chemistry / Q000378:metabolism*; D051901:Smad4 Protein / Q000378:metabolism; D014407:Tumor Cells, Cultured; D028901:alpha Karyopherins / Q000378:metabolism
chemical_list: D024361:Amino Acids, Basic; D019913:Nuclear Localization Signals; D051901:Smad4 Protein; D028901:alpha Karyopherins; D012259:Ribonuclease, Pancreatic