| Autor: |
Lezzhov AA; A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia., Tolstyko EA; Konstantinov St.-Petersburg Nuclear Physics Institute, National Research Center «Kurchatov Institute», 188300 Gatchina, Russia., Atabekova AK; A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia.; Department of Virology, Biological Faculty, Moscow State University, 119234 Moscow, Russia., Chergintsev DA; Department of Virology, Biological Faculty, Moscow State University, 119234 Moscow, Russia., Morozov SY; A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia.; Department of Virology, Biological Faculty, Moscow State University, 119234 Moscow, Russia., Solovyev AG; A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia.; Department of Virology, Biological Faculty, Moscow State University, 119234 Moscow, Russia. |
| Abstrakt: |
Retrozymes are nonautonomous retrotransposons with hammerhead ribozymes in their long terminal repeats (LTRs). Retrozyme transcripts can be self-cleaved by the LTR ribozyme, circularized, and can undergo RNA-to-RNA replication. Here, we demonstrate that the Nicotiana benthamiana genome contains hundreds of retrozyme loci, of which nine represent full-length retrozymes. The LTR contains a promoter directing retrozyme transcription. Although retrozyme RNA is easily detected in plants, the LTR region is heavily methylated, pointing to its transcriptional silencing, which can be mediated by 24 nucleotide-long retrozyme-specific RNAs identified in N. benthamiana . A transcriptome analysis revealed that half of the retrozyme-specific RNAs in plant leaves have no exact matches to genomic retrozyme loci, containing up to 13% mismatches with the closest genomic sequences, and could arise as a result of many rounds of RNA-to-RNA replication leading to error accumulation. Using a cloned retrozyme copy, we show that retrozyme RNA is capable of replication and systemic transport in plants. The presented data suggest that retrozyme loci in the N. benthamiana genome are transcriptionally inactive, and that circular retrozyme RNA can persist in cells due to its RNA-to-RNA replication and be transported systemically, emphasizing functional and, possibly, evolutionary links of retrozymes to viroids-noncoding circular RNAs that infect plants. |
