THE NUCLEOTIDE-SEQUENCE OF APPLE MOSAIC-VIRUS COAT PROTEIN GENE HAS NO SIMILARITY WITH OTHER BROMOVIRIDAE COAT PROTEIN GENES

A double-stranded cDNA was synthesized from in vitro polyadenylated ap ple mosaic virus (ApMV) RNA 3 using oligo(dT) and sequence-specific pr imers, and was cloned into plasmid vectors. A set of overlapping cDNA clones was used to determine the nucleotide sequence of RNA 4. ApMV RN A 4 was found to contain an open reading frame (ORF) of 666 nucleotide s, which was flanked by 5' and 3' non-translated sequences of 55 and 2 64 nucleotides, respectively. The ORF encoding the coat protein was id entified by comparing the predicted amino acid sequence with that obta ined from direct protein microsequencing of the native viral coat prot ein. The ORF encodes a protein with an M(r) of 25056. The nucleotide s equence of the ApMV coat protein gene showed no similarity to those of alfalfa mosaic virus, tobacco streak virus (TSV), brome mosaic virus or cucumber mosaic virus. The predicted amino acid sequence of the ami no-terminal region of the ApMV coat protein is basic, rich in cysteine residues and may contain a zinc finger motif similar to that found in TSV.