Formation of multimers of linear satellite RNAs.

A 22-base region of turnip crinkle virus satellite-RNA C (sat-RNA C) is involved in the accumulation of monomeric and dimeric forms. Deletions within the region inhibited the accumulation of sat-RNA C monomers. However, normal ratios of dimers to monomers occurred if the 22 bases were replaced by 22 unrelated bases or if the location of this region was altered. Therefore, these specific 22 bases are not involved in the accumulation of sat-RNA C monomers. Examination of the sequences at the junctions of multimers of all three turnip crinkle virus sat-RNAs revealed the deletion of bases corresponding to the 3' and 5' ends of monomeric units as well as the addition of nucleotides not present in monomers. Based on these results, we present a model to explain the formation of multimers of linear subviral RNAs associated with turnip crinkle virus. Our model suggests that multimers are formed by the reinitiation of replication by the replicase before release of the nascent strand. We have previously proposed the same mechanism for the formation of defective interfering RNAs, chimeric sat-RNAs, and sat-RNA recombinants in the turnip crinkle virus system (Cascone, Carpenter, Li, and Simon. (1990). EMBO J. 9, 1709-1715).