Nucleotide sequence of Johnsongrass mosaic potyvirus genomic RNA

The complete nucleotide sequence of the RNA genome of Johnsongrass mosaic virus (JGMV), which infects monocotyledonous plant species, has been determined from cloned viral cDNAs. The JGMV genomic RNA is 9,766 nucleotides in length, excluding the poly (A) tail, and contains a large open reading frame that codes for a polyprotein of 3,052 amino acids. The open reading frame is flanked by a 5' untranslated region of 135 and a 3' untranslated region of 475 nucleotides. A comparison of the JGMV polyprotein with the sequences of other members of the Potyvirus genus allowed the delineation of putative proteolytic cleavage sites. This comparison also showed that JGMV has a genome organization that is similar to other members of the genus Potyvirus. As with other potyviruses, the JGMV P1 and P3 proteins were found to be the most variable and the NIb protein the most conserved when compared with the corresponding proteins of other potyviruses. JGMV differed from other members of the genus Potyvirus in the amino acid at the -1 position of the putative cleavage sites of the NIa proteinase. The putative cleavage site for P3/CI, CI/NIa, NIa/NIb, and NIa-VPg/NIa-Pro in the JGMV polyprotein each contained a glutamate at the -1 position which is glutamine in most other potyviruses. Glutamate at the -1 position has also been observed at the CI/NIa-VPg junction of pea seed borne mosaic virus and turnip mosaic virus and at the NIb/CP junction of papaya ringspot virus polyproteins.