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Palmitoylation of the influenza A virus M2 protein
R J Sugrue1, R B Belshe, A J Hay
1Virology Division, National Institute for Medical Research, Mill Hill, London, United Kingdom.
Abstract:
The M2 proteins of a variety of influenza A viruses of different subtypes were shown to possess associated palmitate. Susceptibility to removal by reduction or treatment with hydroxylamine is consistent with attachment via a thioester linkage to cysteine. The absence of the acyl group from the M2 proteins of several equine viruses of the H3N8 subtype correlates with the replacement of cysteine 50 with phenylalanine and points to this as the site of palmitate attachment.
Insights
Influenza A virus M2 proteins are palmitoylated via a thioester linkage to cysteine. This palmitoylation site, cysteine 50, is replaced by phenylalanine in equine H3N8 viruses, preventing acylation.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Influenza A virus M2 protein is a vital ion channel.
- Post-translational modifications of viral proteins influence their function and pathogenesis.
- Palmitoylation is a lipid modification that can affect protein localization and activity.
Purpose of the Study:
- To investigate the palmitoylation of influenza A virus M2 proteins.
- To identify the site and nature of palmitate attachment to M2.
- To explore variations in M2 palmitoylation across different influenza A subtypes.
Main Methods:
- Analysis of M2 proteins from various influenza A virus subtypes.
- Treatment with reducing agents and hydroxylamine to assess thioester linkage.
- Site-directed mutagenesis to investigate cysteine 50's role.
Main Results:
- M2 proteins from multiple influenza A virus subtypes were found to be palmitoylated.
- Palmitate removal by reduction and hydroxylamine suggests a thioester linkage to cysteine.
- Equine H3N8 influenza A viruses showed absent palmitoylation, correlating with Cys50-Phe substitution.
Conclusions:
- Influenza A virus M2 protein undergoes palmitoylation through a thioester linkage to cysteine.
- Cysteine 50 is identified as the primary site of palmitoylation.
- Substitution of Cys50 with phenylalanine in equine H3N8 viruses abrogates M2 palmitoylation.