STUDIES ON POLYPROTEIN OF COCKSFOOT MOTTLE SOBEMOVIRUS
K MÄKINEN1, J LUCCHESI1, T TAMM2, S ZAVRIEV3 and M SAARMA1
1Institute of Biotechnology, Univeristy of Helsinki, Viikki Biocenter 1, PO Box 56, FIN-00014, Finland; 2Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE00026 Tallinn, Estonia; 3Institute of Agricultural Biotechnology, Timiryazevskaya st. 42, Moscow 127550, Russia
Background and objectives
Results and conclusions
The frameshifting signal directing the ribosomes from 0-frame to -1-frame is composed of UUUAAAC, a slippery heptamer and a hairpin loop starting seven nucleotides downstream. Deletion mutants were created to identify sequences necessary for frameshifting. Deletion-destabilizing the hairpin loop prevents the frameshifting. However, deletion of 442 nucleotides starting 10 nucleotides after the stem-loop structure does not prevent frameshifting. Also, a construct containing only 12 nucleotides of CfMV sequences upstream from the slippery heptanucleotide and having the rest of the 5' region of the polyprotein coding region deleted, is translated by -1 ribosomal frameshift.
In conclusion, our preliminary data suggest that 70 nucleotides of CfMV sequence, including the frameshifting signal, is enough to direct the ribosomes to translational shift. We are analysing the effect of these deletions on the frameshifting efficiency, when the polyprotein coding ORFs are translated in wheat germ extract at the level of 12-16%. This efficiency is high if compared to the frameshifting efficiencies of related luteoviruses.