A Classical Bipartite Nuclear Localization Signal on Thogoto and Influenza A Virus Nucleoproteins

摘要: Abstract We have previously shown that the nucleoprotein (NP) of Thogoto virus (THOV), a tick-borne member Orthomyxoviridae family, accumulates in cell nucleus. Here we demonstrate THOV NP contains motif (KRxxxxxxxxxKTKK) at amino acid positions 179–193 represents classical bipartite nuclear localization signal (NLS). This sequence (named cNLS) was able to translocate cytoplasmic 80-kDa reporter protein into Targeted mutations substituting lysines for alanines downstream cluster abolished capacity cNLS mediate import. In contrast, identical had no effect on when introduced NP, indicating additional transport signals are present NP. Amino-acid comparisons revealed lacks N-terminal nonconvential NLS here nNLS), which has been implicated import influenza A Accordingly, failed interact coprecipitation assays with cellular NPI-1/3 factors karyopherin α family. highly conserved identified so-called accumulation (NAS). Mutating NAS alone, or combination cNLS, gross intracellular distribution protein, functional is not required mammalian cells. also studied A/PR/8/34 Interestingly, found 198–216 addition described nonconventional nNLS. To further assess role nNLS, and NAS, analyzed single, double, triple mutants When nNLS destroyed, stayed cytoplasm as expected. disrupted double mutant accumulated nucleus, suggesting active. Indeed, inactivated, localized again predominantly cytoplasm. These findings suggest orthomyxoviruses two independent NLSs, namely They NLSs may assume opposing roles nucleocytoplasmic