Coupled termination/reinitiation for translation of the downstream open reading frame B of the prototypic hypovirus CHV1-EP713

Li Hua Guo, Liying Sun, Sotaro Chiba, Hiroyuki Araki, Nobuhiro Suzuki

    Research output: Contribution to journalArticlepeer-review

    29 Citations (Scopus)

    Abstract

    Cryphonectria hypovirus 1 (CHV1), associated with the picorna-like superfamily, infects the chestnut blight fungus and attenuates the virulence of the host fungus. The genomic RNA of the virus has two continuous open reading frames, A and B, separated by the pentanucleotide UAAUG. We present here evidence suggesting that ORF B is translated from genome-sized virus mRNA by a coupled termination/ reinitiation mechanism mediated by the pentamer. In the coupled translation, the overlapping UAA and AUG triplets serve as the stop codon of ORF A and the initiator of ORF B, respectively. This was established by the use of a luciferase assay with a basic construct containing the ORF A sequence and the firefly luciferase gene while retaining the pentamer between the two coding sequences. The proportion of ribosomes reinitiating translation after terminating was determined to be 2.5-4.4% by three independent assay systems in fungal and insect cells. Use of a series of mutant constructs identified two sequence elements, the pentamer and the p40 sequence, that affect the efficiency of coupled translation and virus replication. Together, these results provide the first example of coupled translation facilitated by the pentanucleotide UAAUG in the kingdom Fungi. The mechanism by which the preceding p40-coding sequence promotes reinitiation is discussed.

    Original languageEnglish
    Pages (from-to)3645-3659
    Number of pages15
    JournalNucleic acids research
    Volume37
    Issue number11
    DOIs
    Publication statusPublished - 2009

    ASJC Scopus subject areas

    • Genetics

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