Caspase-Dependent N-Terminal Cleavage of Influenza Virus Nucleocapsid Protein in Infected Cells

摘要: The nucleocapsid protein (NP) (56 kDa) of human influenza A viruses is cleaved in infected cells into a 53-kDa form. Likewise, B virus NP (64 55-kDa with 62-kDa intermediate (O. P. Zhirnov and A. G. Bukrinskaya, Virology 109:174–179, 1981). We show now that an antibody specific for the N terminus reacted uncleaved 56-kDa form but not truncated NP53 form, indicating removal 3-kDa peptide from terminus. Amino acid sequencing revealed cleavage sites ETD16*G A/Aichi/68 DID7*G EAD61*V B/Hong Kong/72 NP. With D at position −1, acidic amino acids −3, aliphatic ones positions −2 +1, recognition motif typical caspases, key enzymes apoptosis. These caspase demonstrated evolutionary stability were retained NPs all viruses. avian viruses, which cells, contains G instead 16. Oligopeptide DEVD derivatives, inhibitors, shown to prevent intracellular All three events, cleavage, increase activity, development apoptosis, coincide data suggest exerted by host caspases associated apoptosis late stages infection.