Interstitial telomeric repeats within the Arabidopsis thaliana genome

The sequence taAACCCTAa, or telo-box, is found at the same location within all known promoters of plant genes encoding the translation elongation factor EF-1 alpha. An analysis of Arabidopsis DNA sequences available in databases revealed that the sequence AAACCCTAA, corresponding to 1.3 units of the plant telomeric repeat AAACCCT, is over-represented within the Arabidopsis genome. These motifs are found both within the transcribed and the untranscribed genome. The examination of their location in the available sequences as well as in selected and partially sequenced cDNA clones suggest that they are preferentially located in the 5' region of genes. We show that a protein present in both maize and Arabidopsis cellular extracts is able to interact specifically with this motif. The putative functions associated with this sequence are discussed. We propose a model involving the telomerase to explain the spreading of this motif within the genome.