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Journal of General Virology header logo Journal of General Virology

Volume 107, Issue 4

Identification of the nucleolar localization signal in multiple nucleopolyhedrovirus multifunctional protein Ac16 Open Access

Abstract

multiple nucleopolyhedrovirus (AcMNPV) Ac16 (BV/ODV-E26) is a multifunctional protein found exclusively in group I NPV genomes. Here, we report a novel role for Ac16 in nucleolar localization. Using protein truncation and subcellular localization analysis, we characterized that the residues 78–113 of Ac16 contain nuclear (NLS) and nucleolar (NoLS) localization signals. Further multiple point mutation analysis within this region demonstrated that two basic-amino-acid-rich clusters, L and TT , function as NLSs, and together, they constitute a functional NoLS. However, Ac16 itself was not observed to localize to nucleoli, while it displayed an overlapping distribution with IE1 during AcMNPV infection. Co-expression assay revealed that IE1, an Ac16-interacting protein, alters the subcellular localization of Ac16, and this effect is independent of the Ac16 NoLS. By yeast two-hybrid library screening, vacuolar (H)-ATPase subunit D (SfVhaD) was identified as a candidate interaction partner of Ac16, which was further confirmed by co-immunoprecipitation. Ac16 affected the localization of SfVhaD; both proteins predominantly colocalized in nucleoli in transient co-expression assays, while they primarily colocalized within the virogenic stroma during AcMNPV infection. Together, these data suggest that Ac16 contains a functional NoLS and may facilitate the transport of its interaction partners from nucleoli to viral replication centres during AcMNPV infection.

  • Received:
  • Accepted:
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Keyword(s): Ac16 , baculovirus , IE1 and nucleolar localization signal
Funding
This study was supported by the:
  • National Natural Science Foundation of China (Award 31972983)
    • Principal Award Recipient: GuozhongFeng
  • National Natural Science Foundation of China (Award 32072487)
    • Principal Award Recipient: GuoqingChen
  • Zhejiang Provincial Natural Science Foundation of China (Award LY23C140001)
    • Principal Award Recipient: GuoqingChen
  • Central Public-interest Scientific Institution Basal Research Fund (Award CPSIBRF-CNRRI-202115)
    • Principal Award Recipient: GuozhongFeng
© 2026 The Authors
  • This is an open-access article distributed under the terms of the Creative Commons Attribution License. This article was made open access via a Publish and Read agreement between the Microbiology Society and the corresponding author’s institution.
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2026-04-01
2026-04-22

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Identification of the nucleolar localization signal in Autographa californica multiple nucleopolyhedrovirus multifunctional protein Ac16
J. Gen. Virol. 107, 002246 (2026); https://doi.org/10.1099/jgv.0.002246
/content/journal/jgv/10.1099/jgv.0.002246
/content/journal/jgv/10.1099/jgv.0.002246
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