Modified vaccinia virus Ankara protein F1L is a novel BH3-domain-binding protein and acts together with the early viral protein E3L to block virus-associated apoptosis.
Infection with viruses often protects the infected cell against external stimuli to apoptosis. Here we explore the balance of apoptosis induction and inhibition for infection with the modified vaccinia virus Ankara (MVA), using two MVA mutants with experimentally introduced deletions. Deletion of the E3L-gene from MVA transformed the virus from an inhibitor to an inducer of apoptosis. Noxa-deficient mouse embryonic fibroblasts (MEF) were resistant to MVA-DeltaE3L-induced apoptosis. When the gene encoding F1L was deleted from MVA, apoptosis resulted that required Bak or Bax. MVA-DeltaF1L-induced apoptosis was blocked by Bcl-2. When expressed in HeLa cells, F1L blocked apoptosis induced by forced expression of the BH3-only proteins, Bim, Puma and Noxa. Finally, biosensor analysis confirmed direct binding of F1L to BH3 domains. These data describe a molecular framework of how a cell responds to MVA infection by undergoing apoptosis, and how the virus blocks apoptosis by interfering with critical steps of its signal transduction.
Institute for Medical Microbiology, Technical University Munich, Germany.
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SF
Fischer
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H
Ludwig
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J
Holzapfel
M
M
Kvansakul
L
L
Chen
D C S
DC
Huang
G
G
Sutter
M
M
Knese
G
G
Häcker
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002478:Cells, Cultured; D017353:Gene Deletion; D005814:Genes, Viral; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D014616:Vaccinia virus / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology*; D014774:Virulence / Q000235:genetics / Q000502:physiology; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000235:genetics / Q000378:metabolism
C494772:BAK1 protein, human; C474007:Bax protein (53-86); C081374:E3L protein, Vaccinia virus; C507356:F1L protein, vaccinia virus; C498702:PMAIP1 protein, human; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016601:RNA-Binding Proteins; D014764:Viral Proteins; D050998:bcl-2 Homologous Antagonist-Killer Protein