ATHILA, A NEW RETROELEMENT FROM ARABIDOPSIS-THALIANA

An analysis of Arabidopsis thaliana heterochromatic regions allowed th e identification of a new family of retroelements called Athila. These 10.5 kb elements, representing ca. 0.3% of the genome, present severa l features of retrotransposons and retroviruses. Athila elements are f lanked by 1.5 kb long terminal repeats (LTR) that are themselves bound ed by 5 bp perfect inverted repeats. These LTRs start and end with the retroviral consensus 5'TG....CA3' nucleotides. A putative tRNA-bindin g site and a polypurine tract are found adjacent to the 5' and 3' LTR respectively. The central domain is composed of two long open reading frames (ORFs) of 935 and 694 amino acids. Despite several indications of recent transposition activity, the translation of these ORFs failed to reveal significant homology with proteins associated to retrotrans position. We suggest that the Athila family could result from the tran sduction and dispersion of a cellular gene by a retrotransposon.