Multiple Non-Ltr Retrotransposons in the Genome of Arabidopsis Thaliana
Wright, D. A.
DNA sequence analysis near the Arabidopsis thaliana ABI3 gene revealed the presence of a non-LTR retrotransposon insertion that we have designated Ta11-1. This insertion is 6.2 kb in length and encodes two overlapping reading frames with similarity to non-LTR retrotransposon proteins, including reverse transcriptase. A polymerase chain reaction assay was developed based on conserved amino acid sequences shared between the Ta11-1 reverse transcriptase and those of non-LTR retrotransposons from other species. Seventeen additional A. thaliana reverse transcriptases were identified that range in nucleotide similarity from 48-88% (Ta12-Ta28). Phylogenetic analyses indicated that the A. thaliana sequences are more closely related to each other than to elements from other organisms, consistent with the vertical evolution of these sequences over most of their evolutionary history. One sequence, Ta17, is located in the mitochondrial genome. The remaining are nuclear and of low copy number among 17 diverse A. thaliana ecotypes tested, suggesting that they are not highly active in transposition. The paucity of retrotransposons and the small genome size of A. thaliana support the hypothesis that most repetitive sequences have been lost from the genome and that mechanisms may exist to prevent amplification of extant element families.
ACESSO AO ARTIGOhttp://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1206989
- A search for reverse transcriptase-coding sequences reveals new non-LTR retrotransposons in the genome of Drosophila melanogaster
- The non-LTR retrotransposons in Ciona intestinalis: new insights into the evolution of chordate genomes
- An Active Non-LTR Retrotransposon With Tandem Structure in the Compact Genome of the Pufferfish Tetraodon nigroviridis
- A new non-LTR retrotransposon provides evidence for multiple distinct site-specific elements in Crithidia fasciculata miniexon arrays.
- R4, a non-LTR retrotransposon specific to the large subunit rRNA genes of nematodes.