Wise, Helen M., Barbezange, Cyril, Jagger, Brett W., Dalton, Rosa Maria, Gog, Julia R., Curran, Martin D., Taubenberger, Jeffery, Anderson, Emma C. and Digard, Paul (2011) Overlapping signals for translational regulation and packaging of influenza A virus segment 2. Nucleic Acids Research, Vol.39 (No.17). pp. 7775-7790. doi:10.1371/journal.pone.0023630

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Abstract

Influenza A virus segment 2 mRNA expresses three
polypeptides: PB1, PB1-F2 and PB1-N40, from AUGs
1, 4 and 5 respectively. Two short open reading
frames (sORFs) initiated by AUGs 2 and 3 are also
present. To understand translational regulation in
this system, we systematically mutated AUGs 1–4
and monitored polypeptide synthesis from
plasmids and recombinant viruses. This identified
sORF2 as a key regulatory element with opposing
effects on PB1-F2 and PB1-N40 expression. We
propose a model in which AUGs 1–4 are accessed
by leaky ribosomal scanning, with sORF2 repressing
synthesis of downstream PB1-F2. However, sORF2
also up-regulates PB1-N40 expression, most likely
by a reinitiation mechanism that permits skipping of
AUG4. Surprisingly, we also found that in contrast to
plasmid-driven expression, viruses with improved
AUG1 initiation contexts produced less PB1 in
infected cells and replicated poorly, producing
virions with elevated particle:PFU ratios. Analysis
of the genome content of virus particles showed
reduced packaging of the mutant segment
2 vRNAs. Overall, we conclude that segment
2 mRNA translation is regulated by a combination
of leaky ribosomal scanning and reinitiation, and
that the sequences surrounding the PB1 AUG
codon are multifunctional, containing overlapping
signals for translation initiation and for segmentspecific
packaging.

Item Type:	Journal Article
Subjects:	Q Science > QR Microbiology > QR355 Virology
Divisions:	Faculty of Science > Life Sciences (2010- ) > Biological Sciences ( -2010) Faculty of Science > Life Sciences (2010- )
Library of Congress Subject Headings (LCSH):	Influenza A virus -- Genetics, Genetic translation
Journal or Publication Title:	Nucleic Acids Research
Publisher:	Oxford University Press
ISSN:	1362-4962
Official Date:	21 June 2011
Dates:	Date Event 21 June 2011 Published
Volume:	Vol.39
Number:	No.17
Page Range:	pp. 7775-7790
DOI:	10.1371/journal.pone.0023630
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Open Access
Funder:	Medical Research Council (Great Britain) (MRC), National Institutes of Health (U.S.) (NIH), Oxford/Cambridge Research Scholars Program, National Institute of Allergy and Infectious Diseases (U.S.) (NIAID)
Grant number:	G0700815 (MRC), G0701220 (MRC)

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