Structure of the nucleocapsid protein gene of sonchus yellow net virus.

The structure of the gene adjacent to the "leader RNA" gene of sonchus yellow net virus (SYNV), a plant rhabdovirus, was deduced by dideoxyribonucleotide sequence analysis of SYNV genomic (g) RNA and a series of plasmids constructed from SYNV gRNA or polyadenylated [poly(A)+] RNA from SYNV-infected plants. Evidence that this gene encodes the nucleocapsid (N) protein was obtained by reaction of SYNV N protein with polyclonal antibodies raised against recombinant proteins derived from the cloned gene. Experiments in which defined oligodeoxyribonucleotides were used to initiate reverse transcription of poly(A)+ RNA from SYNV-infected tobacco revealed that the N protein messenger (m) RNA gene begins at position 147 from the 3' end of the SYNV genome. Inspection of the sequence shows that this mRNA has a 56 nucleotide (NT) untranslated region followed by a 1425 NT open reading frame that is terminated by tandem UAA stop codons at positions 1628 to 1633 relative to the 3' end of SYNV gRNA. Little direct sequence homology is evident between the 475 amino acid polypeptide predicted from the SYNV sequence and the nucleocapsid (N) proteins deduced from nucleotide sequences of the Indiana and New Jersey serotypes of vesicular stomatitis virus (VSV) and rabies virus. However, a short region of possible importance contains a small group of chemically similar amino acids common to all four N proteins.