Abstract
Densovirus genome replication and capsid assembly take place in the nucleus of the infected cells. However, the mechanisms underlying such processes as the delivery of virus proteins to the nucleus and the export of progeny virus from the nucleus remain elusive. It is evident that nuclear transport signals should be involved in these processes. We performed an in silico search for the putative nuclear localization signal (NLS) and nuclear export signal (NES) motifs in the capsid proteins of the Blattella germanica Densovirus 1 (BgDV1) densovirus. A high probability NLS motif was found in the common C-terminal of capsid proteins together with a NES motif in the unique N-terminal of VP2. We also performed a global search for the nuclear traffic signals in the densoviruses belonging to five Densovirinae genera, which revealed high diversity in the patterns of NLSs and NESs. Using a heterologous system, the HeLa mammalian cell line expressing GFP-fused BgDV1 capsid proteins, we demonstrated that both signals are functionally active. We suggest that the NLS shared by all three BgDV1 capsid proteins drives the trafficking of the newly-synthesized proteins into the nucleus, while the NES may play a role in the export of the newly-assembled BgDV1 particles into the cytoplasm through nuclear pore complexes.
Highlights
Densoviruses comprise the subfamily Densovirinae of invertebrate-infecting viruses within the family Parvoviridae
Using the same approach as with Blattella germanica Densovirus 1 (BgDV1), we performed a global search for the intracellular traffic signals in representatives of all five Densovirinae genera, which demonstrated that capsid proteins of all analyzed densoviruses contain nuclear localization signal (NLS) motifs, whereas nuclear export signal (NES) motifs were predicted in most densoviruses with the exception for the lepidopteran genera Ambidensovirus, Iteravirus, and Penstyldensovirus
We demonstrated earlier that the German cockroach densovirus BgDV1 possesses three capsid proteins (VP1-VP3) with VP1 (97 kDa) and VP2 (80/85 kDa) proteins sharing a common C-terminal corresponding to the entire VP3 protein (57 kDa) and differing by their unique N-terminals [51]
Summary
Densoviruses comprise the subfamily Densovirinae of invertebrate-infecting viruses within the family Parvoviridae. Using the same approach as with BgDV1, we performed a global search for the intracellular traffic signals in representatives of all five Densovirinae genera, which demonstrated that capsid proteins of all analyzed densoviruses contain NLS motifs ( the probability score of the detected NLSs varied significantly among different types of densoviruses), whereas NES motifs were predicted in most densoviruses with the exception for the lepidopteran genera Ambidensovirus, Iteravirus, and Penstyldensovirus. By introducing amino acid substitutions in the in silico-predicted intracellular traffic signals, we experimentally demonstrated that both the high-probability NLS and NES are functionally active and mediate respectively the nuclear import and the nuclear export of BgDV1 capsid proteins. The latter finding may be of significance for future studies of the intracellular trafficking of densovirus particles, especially in those cases where the corresponding host organism cell cultures are difficult to obtain or recalcitrant to laboratory conditions, or when carrying out experimental manipulation with the host cell culture is intractable for some other reason
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
