Studies on the translation mechanism of subgenomic RNA of potato leafroll virus

The expression of open reading frames located on the subgenomic RNA (sgRNA) has been studied in an in vitro transcription and translation system. The obtained results indicate: a) translation of sgRNA occurs according to the scanning model since the insertion of a palindrome (Delta G(0) = -61 kcal/mol) prevents the initiation of translation; b) ORF6 is translated by suppression of the stop codon separating ORF4 from ORF6 and the presence of suppressor tRNA is necessary for the readthrough; c) the presence of leader sequence of sgRNA (212 nucleotides) decreases the translation efficiency of ORFs located downstream and it affects the ratio of products of ORF4 and ORF5; d) 3'UTR does not influence on an expression of genes located on the sgRNA.