NUCLEOTIDE-SEQUENCE, GENOMIC ORGANIZATION AND SYNTHESIS OF INFECTIOUSTRANSCRIPTS FROM A FULL-LENGTH CLONE OF ARTICHOKE MOTTLE CRINKLE VIRUS

The complete nucleotide sequence of the genome of artichoke mottle cri nkle virus (AMCV), a member of the tombusvirus group, has been determi ned. The genome is 4790 nucleotides (nt) in length. A full-length cDNA of the AMCV genome has been cloned in pUC9 downstream of the T7 RNA p olymerase promoter. Transcripts were infective when inoculated onto Ni cotiana clevelandii and N. benthamiana plants. The AMCV genome contain s five open reading frames (ORFs). The first ORF from the 5' terminus (ORF1) encodes a protein with a predicted M(r) of 33K. ORF2 extends th rough the amber termination codon of ORF1 to yield a polypeptide of pr edicted M, 92K and which is the putative RNA-dependent RNA polymerase. ORF3 codes for the coat protein (41K). Two nested ORFs in different r eading frames (ORFs 4 and 5) code for a 22K and a 19K polypeptide resp ectively. Sequence homologies suggest that the 22K protein could be in volved in cell-to-cell movement of virus. ORFs 3, 4 and 5 are translat ed from two 3' coterminal subgenomic (sg) RNAs, the 5' termini of whic h have been mapped. The two sg RNAs are 2155 (sg1) and 934 (sg2) nt in length. ORF3 is expressed from sg1 RNA whereas ORFs 4 and 5 are poten tially expressed from sg2 RNA. Time course experiments with Cynara sco lymus protoplasts indicate that during AMCV infection both positive an d negative strands of genomic and sg RNAs are produced and that sg2 RN A is produced before and at a higher level than sg1 RNA.