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Spronken MI, van de Sandt CE, de Jongh EP, Vuong O, van der Vliet S, Bestebroer TM, Olsthoorn RCL, Rimmelzwaan GF, Fouchier RAM, Gultyaev AP. A compensatory mutagenesis study of a conserved hairpin in the M gene segment of influenza A virus shows its role in virus replication. RNA Biol 2017; 14:1606-1616. [PMID: 28662365 PMCID: PMC5785231 DOI: 10.1080/15476286.2017.1338243] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
RNA structures are increasingly recognized to be of importance during influenza A virus replication. Here, we investigated a predicted conserved hairpin in the M gene segment (nt 967-994) within the region of the vRNA 5′ packaging signal. The existence of this RNA structure and its possible role in virus replication was investigated using a compensatory mutagenesis approach. Mutations were introduced in the hairpin stem, based on natural variation. Virus replication properties were studied for the mutant viruses with disrupted and restored RNA structures. Viruses with structure-disrupting mutations had lower virus titers and a significantly reduced median plaque size when compared with the wild-type (WT) virus, while viruses with structure restoring-mutations replicated comparable to WT. Moreover, virus replication was also reduced when mutations were introduced in the hairpin loop, suggesting its involvement in RNA interactions. Northern blot and FACS experiments were performed to study differences in RNA levels as well as production of M1 and M2 proteins, expressed via alternative splicing. Stem-disruptive mutants caused lower vRNA and M2 mRNA levels and reduced M2 protein production at early time-points. When the RNA structure was restored, vRNA, M2 mRNA and M2 protein levels were increased, demonstrating a compensatory effect. Thus, this study provides evidence for functional importance of the predicted M RNA structure and suggests its role in splicing regulation.
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Affiliation(s)
- M I Spronken
- a Department of Viroscience , Erasmus Medical Centre , Rotterdam , the Netherlands
| | - C E van de Sandt
- a Department of Viroscience , Erasmus Medical Centre , Rotterdam , the Netherlands
| | - E P de Jongh
- a Department of Viroscience , Erasmus Medical Centre , Rotterdam , the Netherlands
| | - O Vuong
- a Department of Viroscience , Erasmus Medical Centre , Rotterdam , the Netherlands
| | - S van der Vliet
- a Department of Viroscience , Erasmus Medical Centre , Rotterdam , the Netherlands
| | - T M Bestebroer
- a Department of Viroscience , Erasmus Medical Centre , Rotterdam , the Netherlands
| | - R C L Olsthoorn
- c Group Supramolecular and Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University , Leiden , the Netherlands
| | - G F Rimmelzwaan
- a Department of Viroscience , Erasmus Medical Centre , Rotterdam , the Netherlands
| | - R A M Fouchier
- a Department of Viroscience , Erasmus Medical Centre , Rotterdam , the Netherlands
| | - A P Gultyaev
- a Department of Viroscience , Erasmus Medical Centre , Rotterdam , the Netherlands.,b Group Imaging and Bioinformatics, Leiden Institute of Advanced Computer Science, Leiden University , Leiden , the Netherlands
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