Nuclear localization of dengue virus nonstructural protein 5 through its importin alpha/beta-recognized nuclear localization sequences is integral to viral infection.
Dengue virus nonstructural protein 5 (NS5) is a large multifunctional protein with a central role in viral replication. We previously identified two nuclear localization sequences (NLSs) within the central region of dengue virus type-2 (DENV-2) NS5 ('aNLS' and 'bNLS') that are recognized by the importin alpha/beta and importin beta1 nuclear transporters, respectively. Here, we demonstrate the importance of the kinetics of NS5 nuclear localization to virus production for the first time and show that the aNLS is responsible. Site-specific mutations in the bipartite-type aNLS or bNLS region were introduced into a reporter plasmid encoding green fluorescent protein fused to the N-terminus of DENV-2 NS5, as well as into DENV-2 genomic length complementary DNA. Mutation of basic residues in the highly conserved region of the bNLS did not affect nuclear import of NS5. In contrast, mutations in either basic cluster of the aNLS decreased NS5 nuclear accumulation and reduced virus production, with the greatest reduction observed for mutation of the second cluster (K(387)K(388)K(389)); mutagenesis of both clusters abolished NS5 nuclear import and DENV-2 virus production completely. The latter appeared to relate to the impaired ability of virus lacking nuclear-localizing NS5, as compared with wild-type virus expressing nuclear-localizing NS5, to reduce interleukin-8 production as part of the antiviral response. The results overall indicate that NS5 nuclear localization through the aNLS is integral to viral infection, with significant implications for other flaviviruses of medical importance, such as yellow fever and West Nile viruses.
Pryor
Melinda J
MJ
Department of Biochemistry and Molecular Biology, Monash University, Monash, Victoria 3800, Australia.
Rawlinson
Stephen M
SM
Butcher
Rebecca E
RE
Barton
Chenoa L
CL
Waterhouse
Tracey A
TA
Vasudevan
Subhash G
SG
Bardin
Phillip G
PG
Wright
Peter J
PJ
Jans
David A
DA
Davidson
Andrew D
AD
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D006801:Humans; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D017386:Sequence Homology, Amino Acid; D014709:Vero Cells; D017361:Viral Nonstructural Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism; D014777:Virus Diseases / Q000378:metabolism*; D028901:alpha Karyopherins / Q000378:metabolism*; D028961:beta Karyopherins / Q000378:metabolism*
D000998:Antiviral Agents; C096041:NS5 protein, flavivirus; D019913:Nuclear Localization Signals; D017361:Viral Nonstructural Proteins; D028901:alpha Karyopherins; D028961:beta Karyopherins