Auto-Regulation of a Rice Mariner-like Element By a Subterminal Transposase Binding Site

Successful class II transposable elements undergo initial burst amplifications followed by strong limitations on their transposition. Auto-regulation of transposition activity is an important mechanism for attenuation of transposition. A previously identified highly repressive motif on the 3’ subterminal region of a rice Mariner-like element Osmar14 was found to be a transposase binding site. However, surprisingly, this binding site can also significantly enhance transposition if it is located at certain positions in the subterminal region. Further analyses indicated that the role of this subterminal transposase binding site on transposition is correlated with its rotational phasing on DNA. Evolutionary analyses of sequences related to Osmar14 elements in rice genomes suggest that the subterminal transposase binding site is a molecular tuner of transposition activity during evolution: facilitating the initial amplification of the element when in an enhancing location and attenuating the transposition of the element when in a repressive location. Such a role of the subterminal transposase binding site may be usefule to tune transposition efficiency of TE based tools.