Phosphorylation of the influenza A virus protein PB1-F2 by PKC is crucial for apoptosis promoting functions in monocytes
| Autor: | Karsten Bruns, Alok Sharma, David Mitzner, Ulrich S. Schubert, Sabine Eva Dudek, Ludmilla Wixler, Igor Mazur, Josef Wissing, Stephan Ludwig, Nicole Studtrucker, Victor Wray, Peter Henklein, Darisuren Anhlan, Lothar Jänsch |
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| Rok vydání: | 2009 |
| Předmět: |
animal structures
viruses Immunology PKC Phosphorylation Site Caspase 3 Apoptosis Saccharomyces cerevisiae Biology medicine.disease_cause Microbiology Monocytes Cell Line Viral Proteins Virology Two-Hybrid System Techniques Protein Interaction Mapping Influenza A virus medicine Humans Phosphorylation Protein kinase C Protein Kinase C Activator (genetics) virus diseases Transfection biochemical phenomena metabolism and nutrition Molecular biology Phosphoprotein |
| Zdroj: | Cellular microbiology. 11(10) |
| ISSN: | 1462-5822 |
| Popis: | The 11(th) influenza A virus (IAV) protein PB1-F2 is encoded by an alternative reading frame of the PB1 polymerase gene and found in the nucleus, cytosol and at the mitochondria of infected cells, the latter is consistent with experimental evidence for its pro-apoptotic function. Here, the function of PB1-F2 as a phosphoprotein was characterized. PB1-F2 derived from isolate IAV(PR8) and synthetic fragments thereof were phosphorylated in vitro by purified protein kinase C (PKC) and cellular extract. Constitutively active PKCalpha interacts with PB1-F2 in yeast two-hybrid assays. (32)P radiolabelling of transfected 293T cells revealed that phosphorylation of PB1-F2 is sensitive to inhibitors of PKC and could be increased by the PKC activator PMA. ESI-MS analysis and cellular expression of PB1-F2 mutants identified the positions Ser-35 as the major and the Thr-27 as an alternative PKC phosphorylation site. Infection of MDCK cells with recombinant IAV(PR8) lacking these PKC sites abrogated phosphorylation of PB1-F2 in vivo. Furthermore, infection of primary human monocytes with mutant viruses lacking these PB1-F2 phosphorylation sites resulted in impaired caspase 3 activation and reduced progeny virus titres, indicating that the integrity of the identified phosphorylation sites is crucial for a cell-specific function of PB1-F2 during virus replication. |
| Databáze: | OpenAIRE |
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