Virology. Frameshifting to PA-X influenza

Abstract

The genome of influenza A virus encodes a newly discovered protein that diminishes its pathogenicity.

Figure. Ribosomal shift

As the ribosome (60S subunit shown) transits PA mRNA in the standard reading frame (F0), the codon in the ribosomal A site is matched to the cognate aminoacyl tRNA, whose amino acid cargo is bonded to the elongating polypeptide. Deacylated tRNA is ejected from the E (exit) site. Ribosomal pausing as the slowly decoded arginine (R) codon CGU enters the A site and waits for its rare ^3′GCA^5′ anticodon allows the upstream phenylalanine (F) anticodon ^3′AAG^5′ to occasionally slip into the preferred +1 UUC codon, thus changing the reading frame to F+1 and altering the C-terminal peptide to generate the PA-X fusion protein.