The vaccinia virus N1L protein is an intracellular homodimer that promotes virulence.
The vaccinia virus (VV) N1L gene encodes a protein of 14 kDa that was identified previously in the concentrated supernatant of virus-infected cells. Here we show that the protein is present predominantly (>90%) within cells rather than in the culture supernatant and it exists as a non-glycosylated, non-covalent homodimer. The N1L protein present in the culture supernatant was uncleaved at the N terminus and was released from cells more slowly than the VV A41L gene product, a secreted glycoprotein that has a conventional signal peptide. Bioinformatic analyses predict that the N1L protein is largely alpha-helical and show that it is conserved in many VV strains, in other orthopoxviruses and in members of other chordopoxvirus genera. However, database searches found no non-poxvirus proteins with significant amino acid similarity to N1L. A deletion mutant lacking the N1L gene replicated normally in cell culture, but was attenuated in intranasal and intradermal murine models compared to wild-type and revertant controls. The conservation of the N1L protein and the attenuated phenotype of the deletion mutant indicate an important role in the virus life-cycle.
Bartlett
Nathan
N
Department of Virology, The Wright-Fleming Institute, Faculty of Medicine, Imperial College, St Mary's Campus, Norfolk Place, London W2 1PG, UK2.|Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK1.
Symons
Julian A
JA
Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK1.
Tscharke
David C
DC
Department of Virology, The Wright-Fleming Institute, Faculty of Medicine, Imperial College, St Mary's Campus, Norfolk Place, London W2 1PG, UK2.|Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK1.
Smith
Geoffrey L
GL
Department of Virology, The Wright-Fleming Institute, Faculty of Medicine, Imperial College, St Mary's Campus, Norfolk Place, London W2 1PG, UK2.|Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK1.
D000818:Animals; D002460:Cell Line; D019295:Computational Biology; D020405:Dermis / Q000821:virology; D019281:Dimerization; D004195:Disease Models, Animal; D005260:Female; D005455:Fluorescent Antibody Technique; D017353:Gene Deletion; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009666:Nose / Q000821:virology; D011995:Recombination, Genetic; D014615:Vaccinia / Q000503:physiopathology* / Q000821:virology*; D014616:Vaccinia virus / Q000254:growth & development / Q000472:pathogenicity*; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014774:Virulence; D014779:Virus Replication
C464479:N1L protein, Vaccinia virus; D014764:Viral Proteins