title: The distribution of different classes of nuclear localization signals (NLSs) in diverse organisms and the utilization of the minor NLS-binding site inplantnuclear import factor importin-α.
abstract: The specific recognition between the import receptor importin-α and the nuclear localization signals (NLSs) is crucial to ensure the selective transport of cargoes into the nucleus. NLSs contain 1 or 2 clusters of positively charged amino acids, which usually bind to the major (monopartite NLSs) or both minor and major NLS-binding sites (bipartite NLSs). In our recent study, we determined the structure of importin-α1a from rice (Oryza sativa), and made 2 observations that suggest an increased utilization of the minor NLS-binding site in this protein. First, unlike the mammalian protein, both the major and minor NLS-binding sites are auto-inhibited in the unliganded rice protein. Second, we showed that NLSs of the "plant-specific" class preferentially bind to the minor NLS-binding site of rice importin-α. Here, we show that a distinct group of "minor site-specific" NLSs also bind to the minor site of the rice protein. We further show a greater enrichment of proteins containing these "plant-specific" and "minor site-specific" NLSs in the rice proteome. However, the analysis of the distribution of different classes of NLSs in diverse eukaryotes shows that in all organisms, the minor site-specific NLSs are much less prevalent than the classical monopartite and bipartite NLSs.
authors.affiliation: School of Chemistry and Molecular Biosciences and Institute for Molecular Bioscience; University of Queensland; Brisbane, QLD Australia; Australian Infectious Diseases Research Centre; University of Queensland; Brisbane, QLD Australia.
authors.forename: Chiung-Wen
authors.initials: CW
authors.lastname: Chang
authors.forename: Rafael Miguez
authors.initials: RM
authors.lastname: Couñago
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Williams
authors.forename: Mikael
authors.initials: M
authors.lastname: Boden
authors.forename: Bostjan
authors.initials: B
authors.lastname: Kobe
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D019913:Nuclear Localization Signals / Q000378:metabolism*; D012275:Oryza / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary; D028901:alpha Karyopherins / Q000378:metabolism
chemical_list: D019913:Nuclear Localization Signals; D010940:Plant Proteins; D028901:alpha Karyopherins
keywords: Arabidopsis thaliana; Oryza sativa; importin-α; nuclear localization signal; nuclear-cytoplasmic transport