THE COMPLETE NUCLEOTIDE-SEQUENCE OF RNA-3 OF A PEACH ISOLATE OF PRUNUS NECROTIC RINGSPOT VIRUS

The complete nucleotide sequence of RNA 3 of the PE-5 peach isolate of Prunus necrotic ringspot ilarvirus (PNRSV) was obtained from cloned c DNA. The RNA sequence is 1941 nucleotides acid contains two open readi ng frames (ORFs). ORF 1 consisted of 284 amino acids with a calculated molecular weight of 31,729 Da and ORF 2 contained 224 amino acids wit h a calculated molecular weight of 25,018 Da. ORF 2 corresponds to the coat protein gene. Expression of ORF 2 engineered into a pTrcHis vect or in Escherichia coli results in a fusion polypeptide of approximatel y 28 kDa which crossreacts with PNRSV polyclonal antiserum. Analysis o f the coat protein amino acid sequence reveals a putative ''zinc-finge r'' domain at the amino-terminal portion of the protein. Two tetranucl eotide AUGC motifs occur in the 3'-UTR of the RNA and may function in coat protein binding and genome activation. ORF 1 homologies to other ilarviruses and alfalfa mosaic virus are confined to limited regions o f conserved amino acids. The translated amino acid sequence of the coa l protein gene shows 92% similarity to one isolate of apple mosaic vir us, a closely related member of the ilarvirus group of plant viruses, but only 66% similarity to the amino acid sequence of the coat protein gene of a second isolate. These relationships are also reflected at t he nucleotide sequence level. These results in one instance confirm th e close similarities observed at the biophysical and serological level s between these two viruses, but on the other hand call into question the nomenclature used to describe these viruses.