Intramolecular interaction of NEP regulated by CRM1 ensures the unidirectional transport of M1 for the nuclear export of influenza viral ribonucleoprotein

IntroductionThe influenza virus genome consists of single-stranded RNAs and forms viral ribonucleoprotein (RNP) complexes. After viral genome replication in the nucleus, the viral RNP interacts with viral protein M1. The M1-viral RNP complex is exported to the cytoplasm via the CRM1-dependent pathwa...

Full description

Bibliographic Details
Main Authors: Mikako Hirohama, Shun Yamashita, Masamitsu N. Asaka, Takahiro Kuroki, Atsushi Kawaguchi
Format: Article
Language:English
Published: Frontiers Media S.A. 2023-08-01
Series:Frontiers in Virology
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fviro.2023.1232906/full
_version_ 1797741444380753920
author Mikako Hirohama
Shun Yamashita
Masamitsu N. Asaka
Takahiro Kuroki
Atsushi Kawaguchi
Atsushi Kawaguchi
Atsushi Kawaguchi
Atsushi Kawaguchi
author_facet Mikako Hirohama
Shun Yamashita
Masamitsu N. Asaka
Takahiro Kuroki
Atsushi Kawaguchi
Atsushi Kawaguchi
Atsushi Kawaguchi
Atsushi Kawaguchi
author_sort Mikako Hirohama
collection DOAJ
description IntroductionThe influenza virus genome consists of single-stranded RNAs and forms viral ribonucleoprotein (RNP) complexes. After viral genome replication in the nucleus, the viral RNP interacts with viral protein M1. The M1-viral RNP complex is exported to the cytoplasm via the CRM1-dependent pathway using NS2/NEP as an export adaptor protein. NEP is a 14 kDa protein and diffusely localizes in the nucleus and cytoplasm. Upon binding to the NLS motif of M1, NEP inhibits the nuclear accumulation of M1 and promotes the nuclear export of M1-viral RNP complex. However, the detail mechanism by which NEP binds to M1 only in the nucleus remains unclear.MethodsTo visualize the interaction of NEP with M1 in the formation of vRNP export complexes, we performed in situ proximity ligation assays. The close proximity of N-terminal and C-terminal domains of NEP was tested by split Renilla luciferase complementation assays in which the N-terminal and C-terminal fragments of Renilla luciferase were fused to the N-terminus and C-terminus of NEP, respectively.Results and discussionWe found that the intramolecular interaction of NEP inhibits the interaction of NEP with M1. The intramolecular interaction of NEP was mediated through the interaction of the N-terminal NES motif with the M1-binding domain at the C-terminus. By adding leptomycin B, a potent inhibitor of CRM1, the interaction of NEP with M1 was impaired. These results suggest that CRM1 disrupts the intramolecular interaction of NEP by recognizing the NES motif at the N-terminus of NEP, thereby promoting the interaction of NEP with M1. We also found that NEP mutant deficient in the intramolecular interaction was co-localized with M1 at the plasma membrane and did not show nuclear localization with M1. Based on these results, we propose that the intramolecular interaction of NEP regulated by CRM1 ensures the unidirectional transport of M1.
first_indexed 2024-03-12T14:26:48Z
format Article
id doaj.art-e7a687dafaea4fbeb7706bc544e2ed7e
institution Directory Open Access Journal
issn 2673-818X
language English
last_indexed 2024-03-12T14:26:48Z
publishDate 2023-08-01
publisher Frontiers Media S.A.
record_format Article
series Frontiers in Virology
spelling doaj.art-e7a687dafaea4fbeb7706bc544e2ed7e2023-08-18T07:01:42ZengFrontiers Media S.A.Frontiers in Virology2673-818X2023-08-01310.3389/fviro.2023.12329061232906Intramolecular interaction of NEP regulated by CRM1 ensures the unidirectional transport of M1 for the nuclear export of influenza viral ribonucleoproteinMikako Hirohama0Shun Yamashita1Masamitsu N. Asaka2Takahiro Kuroki3Atsushi Kawaguchi4Atsushi Kawaguchi5Atsushi Kawaguchi6Atsushi Kawaguchi7Department of Infection Biology, Faculty of Medicine, University of Tsukuba, Tsukuba, JapanGraduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, JapanDepartment of Infection Biology, Faculty of Medicine, University of Tsukuba, Tsukuba, JapanGraduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, JapanDepartment of Infection Biology, Faculty of Medicine, University of Tsukuba, Tsukuba, JapanGraduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, JapanTransborder Medical Research Center, University of Tsukuba, Tsukuba, JapanMicrobiology Research Center for Sustainability, University of Tsukuba, Tsukuba, JapanIntroductionThe influenza virus genome consists of single-stranded RNAs and forms viral ribonucleoprotein (RNP) complexes. After viral genome replication in the nucleus, the viral RNP interacts with viral protein M1. The M1-viral RNP complex is exported to the cytoplasm via the CRM1-dependent pathway using NS2/NEP as an export adaptor protein. NEP is a 14 kDa protein and diffusely localizes in the nucleus and cytoplasm. Upon binding to the NLS motif of M1, NEP inhibits the nuclear accumulation of M1 and promotes the nuclear export of M1-viral RNP complex. However, the detail mechanism by which NEP binds to M1 only in the nucleus remains unclear.MethodsTo visualize the interaction of NEP with M1 in the formation of vRNP export complexes, we performed in situ proximity ligation assays. The close proximity of N-terminal and C-terminal domains of NEP was tested by split Renilla luciferase complementation assays in which the N-terminal and C-terminal fragments of Renilla luciferase were fused to the N-terminus and C-terminus of NEP, respectively.Results and discussionWe found that the intramolecular interaction of NEP inhibits the interaction of NEP with M1. The intramolecular interaction of NEP was mediated through the interaction of the N-terminal NES motif with the M1-binding domain at the C-terminus. By adding leptomycin B, a potent inhibitor of CRM1, the interaction of NEP with M1 was impaired. These results suggest that CRM1 disrupts the intramolecular interaction of NEP by recognizing the NES motif at the N-terminus of NEP, thereby promoting the interaction of NEP with M1. We also found that NEP mutant deficient in the intramolecular interaction was co-localized with M1 at the plasma membrane and did not show nuclear localization with M1. Based on these results, we propose that the intramolecular interaction of NEP regulated by CRM1 ensures the unidirectional transport of M1.https://www.frontiersin.org/articles/10.3389/fviro.2023.1232906/fullCRM1nuclear exportNEPintramolecular interactioninfluenza A virus
spellingShingle Mikako Hirohama
Shun Yamashita
Masamitsu N. Asaka
Takahiro Kuroki
Atsushi Kawaguchi
Atsushi Kawaguchi
Atsushi Kawaguchi
Atsushi Kawaguchi
Intramolecular interaction of NEP regulated by CRM1 ensures the unidirectional transport of M1 for the nuclear export of influenza viral ribonucleoprotein
Frontiers in Virology
CRM1
nuclear export
NEP
intramolecular interaction
influenza A virus
title Intramolecular interaction of NEP regulated by CRM1 ensures the unidirectional transport of M1 for the nuclear export of influenza viral ribonucleoprotein
title_full Intramolecular interaction of NEP regulated by CRM1 ensures the unidirectional transport of M1 for the nuclear export of influenza viral ribonucleoprotein
title_fullStr Intramolecular interaction of NEP regulated by CRM1 ensures the unidirectional transport of M1 for the nuclear export of influenza viral ribonucleoprotein
title_full_unstemmed Intramolecular interaction of NEP regulated by CRM1 ensures the unidirectional transport of M1 for the nuclear export of influenza viral ribonucleoprotein
title_short Intramolecular interaction of NEP regulated by CRM1 ensures the unidirectional transport of M1 for the nuclear export of influenza viral ribonucleoprotein
title_sort intramolecular interaction of nep regulated by crm1 ensures the unidirectional transport of m1 for the nuclear export of influenza viral ribonucleoprotein
topic CRM1
nuclear export
NEP
intramolecular interaction
influenza A virus
url https://www.frontiersin.org/articles/10.3389/fviro.2023.1232906/full
work_keys_str_mv AT mikakohirohama intramolecularinteractionofnepregulatedbycrm1ensurestheunidirectionaltransportofm1forthenuclearexportofinfluenzaviralribonucleoprotein
AT shunyamashita intramolecularinteractionofnepregulatedbycrm1ensurestheunidirectionaltransportofm1forthenuclearexportofinfluenzaviralribonucleoprotein
AT masamitsunasaka intramolecularinteractionofnepregulatedbycrm1ensurestheunidirectionaltransportofm1forthenuclearexportofinfluenzaviralribonucleoprotein
AT takahirokuroki intramolecularinteractionofnepregulatedbycrm1ensurestheunidirectionaltransportofm1forthenuclearexportofinfluenzaviralribonucleoprotein
AT atsushikawaguchi intramolecularinteractionofnepregulatedbycrm1ensurestheunidirectionaltransportofm1forthenuclearexportofinfluenzaviralribonucleoprotein
AT atsushikawaguchi intramolecularinteractionofnepregulatedbycrm1ensurestheunidirectionaltransportofm1forthenuclearexportofinfluenzaviralribonucleoprotein
AT atsushikawaguchi intramolecularinteractionofnepregulatedbycrm1ensurestheunidirectionaltransportofm1forthenuclearexportofinfluenzaviralribonucleoprotein
AT atsushikawaguchi intramolecularinteractionofnepregulatedbycrm1ensurestheunidirectionaltransportofm1forthenuclearexportofinfluenzaviralribonucleoprotein