Characterization of a mitochondrial-targeting signal in the PB2 protein of influenza viruses

Simon M. Carr, Elena Carnero, Adolfo García-Sastre, George G. Brownlee, Ervin Fodor

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


Influenza virus RNA polymerase is a heterotrimeric complex consisting of PB1, PB2, and PA subunits. These polymerase subunits accumulate in the nucleus of infected cells. We report here that PB2, from both human and avian influenza viruses, could also localize to mitochondria in transfected cells. Importantly, cells infected with influenza A virus also displayed mitochondrial PB2. We show that an N-terminal motif composed of 120 amino acids is sufficient for localization of PB2 to mitochondria. In particular, leucine residues at positions 7 and 10 were essential for mitochondrial targeting. Recombinant influenza A/WSN/33 viruses expressing PB2 proteins with L7A and/or L10A mutations showed reduced viral titers, but unaffected levels of transcription, replication, and protein expression. The introduction of L7A and/or L10A mutations into recombinant viruses correlated with reduced mitochondrial membrane potential in infected cells, suggesting that mitochondrial localization of PB2 contributes to the preservation of mitochondrial function during influenza virus infection.

Original languageEnglish
Pages (from-to)492-508
Number of pages17
Issue number2
StatePublished - 20 Jan 2006


  • Apoptosis
  • Influenza virus
  • Mitochondria
  • Mitochondrial membrane potential
  • Mitochondrial-targeting signal
  • Polymerase basic protein 2 (PB2)
  • RNA polymerase
  • Transcription


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