Cm. Brown et al., LOCAL AND DISTANT SEQUENCES ARE REQUIRED FOR EFFICIENT READTHROUGH OFTHE BARLEY YELLOW DWARF VIRUS PAV COAT PROTEIN GENE STOP CODON, Journal of virology, 70(9), 1996, pp. 5884-5892
Many viruses use stop codon readthrough as a strategy to produce exten
ded coat or replicase proteins. The stop codon of the barley yellow dw
arf virus (PAV serotype) coat protein gene is read through at a low ra
te. This produces an extended polypeptide which becomes part of the vi
rion. We have analyzed the cis-acting sequences in the barley yellow d
warf virus PAV genome required for this programmed readthrough in vitr
o in wheat germ extracts and reticulocyte lysates and in vivo in oat p
rotoplasts. Two regions 3' to the stop codon were required. Deletion o
f sections containing the first 5 of the 16 CCN NNN repeats located 3'
of the stop codon greatly reduced readthrough in vitro and in vivo. S
urprisingly, readthrough also required a second, more distal element t
hat is located 697 to 758 bases 3' of the stop codon within the readth
rough open reading frame. This element also functioned in vivo in oat
protoplasts when placed more than 2 kb from the coat protein gene stop
in the untranslated region following a GUS reporter gene. This is the
first report of a long-range readthrough signal in viruses.