Partial Nucleotide Sequence of Potato Virus M RNA Shows Similarities to Potexviruses in Gene Arrangement and the Encoded Amino Acid Sequences

The nucleotide sequence of the 3'-proximal 2630 nucleotides of potato virus M (PVM) genomic RNA was determined. The sequenced region contained five long open reading frames (ORFs). The ORF nearest to the 3'-terminal pol(A) tail corresponds to a polypeptide of Mr 10,848. This ORF is preceded by one which encodes a protein of Mr 33,906 (34K) which has an amino acid sequence that is very similar in its carboxyterminal part to that of the coat proteins of some potexviruses. Three other ORFs encoding polypeptides of Mr 24,615, 11,983 and 6739 are present in the region 5' to the 34K protein gene. There is extensive similarity between these proteins and the corresponding proteins encoded by the conserved triple gene block in the RNA of potexviruses.