BACKGROUND/AIMS: The Hepatitis C Virus (HCV) nonstructural protein 5A (NS5A) is an essential part of the ER-localized HCV-replicon complex. Although NS5A harbours a conserved NLS in its C-terminal domain, NS5A is associated with the cytoplasmic face of the ER by an amphipathic helix close to its N-terminus. METHODS: Intracellular distribution of NS5A in HCV replicating cells was analyzed by confocal microscopy and subcellular fractionation. The effect on HCV replication was analyzed using the JFH-1-based infection/replication system. RESULTS: During viral life cycle N-terminally truncated NS5A fragments are caspase-dependent formed that lack the ER-attachment signal and are localized within the nucleus. These N-terminally truncated fragments inhibit HCV replication. If their formation is blocked by inhibition of caspases HCV replication is increased. The C-terminal domain of NS5A binds to c-Raf and thereby localizes it to the replicon complex. This interaction is essential for HCV replication. The N-terminally truncated NS5A fragments are still able to bind c-Raf. However, due to their nuclear localization they withdraw c-Raf from the replicon complex into the nucleus resulting in an impaired HCV replication. CONCLUSIONS: Formation of N-terminally truncated NS5A fragments could represent a mechanism to regulate HCV replication by withdrawal of essential factors from the replicon complex.
BACKGROUND/AIMS: The Hepatitis C Virus (HCV) nonstructural protein 5A (NS5A) is an essential part of the ER-localized HCV-replicon complex. Although NS5A harbours a conserved NLS in its C-terminal domain, NS5A is associated with the cytoplasmic face of the ER by an amphipathic helix close to its N-terminus. METHODS: Intracellular distribution of NS5A in HCV replicating cells was analyzed by confocal microscopy and subcellular fractionation. The effect on HCV replication was analyzed using the JFH-1-based infection/replication system. RESULTS: During viral life cycle N-terminally truncated NS5A fragments are caspase-dependent formed that lack the ER-attachment signal and are localized within the nucleus. These N-terminally truncated fragments inhibit HCV replication. If their formation is blocked by inhibition of caspases HCV replication is increased. The C-terminal domain of NS5A binds to c-Raf and thereby localizes it to the replicon complex. This interaction is essential for HCV replication. The N-terminally truncated NS5A fragments are still able to bind c-Raf. However, due to their nuclear localization they withdraw c-Raf from the replicon complex into the nucleus resulting in an impaired HCV replication. CONCLUSIONS: Formation of N-terminally truncated NS5A fragments could represent a mechanism to regulate HCV replication by withdrawal of essential factors from the replicon complex.
Authors: Lilian Ht Yamasaki; Helen A Arcuri; Ana Carolina G Jardim; Cintia Bittar; Isabel Maria Vg de Carvalho-Mello; Paula Rahal Journal: Virol J Date: 2012-01-12 Impact factor: 4.099
Authors: Liang Guo; Suresh D Sharma; Jose D Debes; Daniel Beisang; Bernd Rattenbacher; Irina Vlasova-St Louis; Darin L Wiesner; Craig E Cameron; Paul R Bohjanen Journal: Nucleic Acids Res Date: 2018-03-16 Impact factor: 16.971
Authors: Muhammad Ahmad Maqbool; Mohamed R Imache; Martin R Higgs; Sophie Carmouse; Jean-Michel Pawlotsky; Hervé Lerat Journal: J Virol Date: 2013-03-06 Impact factor: 5.103
Authors: Ana C G Jardim; Cíntia Bittar; Renata P A Matos; Lílian H T Yamasaki; Rafael A Silva; João R R Pinho; Roberta M Fachini; Claudia M A Carareto; Isabel M V G de Carvalho-Mello; Paula Rahal Journal: BMC Infect Dis Date: 2013-02-01 Impact factor: 3.090