Nucleotide sequence of potato virus Y (N Strain) genomic RNA.

The complete nucleotide sequence of the genomic RNA of the potyvirus potato virus Y strain N (PVYn) was obtained from cloned cDNAs. This sequence is 9704 nucleotides long and can encode a polyprotein of 3063 amino acids. The positions of the cleavage sites at the N terminus of the capsid and cytoplasmic inclusion proteins have been determined. Other putative protein cleavage sites have been deduced by searching for consensus sequences and by analogy with the polyprotein of the tobacco vein mottling virus and of the tobacco etch virus. Comparison of the PVY polyprotein sequence with that of other potyvirus polyproteins shows similarities in genome organization and a high level of identity along most of the polyprotein, except for the putative proteins flanking the helper component. A search for specific protein motifs has revealed the existence of a potential metal-binding site at the putative N terminus of the helper component in potyviruses. The possible functions of this structure are discussed.