We have performed a genome-wide analysis of the
mimp family of miniature inverted-repeat transposable elements, taking advantage of the recent release of the
F. oxysporum genome sequence. Using different approaches, we detected 103
mimp elements, corresponding to 75 nonredundant copies, half of which are located on a single small chromosome. Phylogenetic analysis
identified at least six subfamilies, all remarkably homogeneous in size and sequence. Based on high sequence identity in the
terminal inverted repeats (TIRs),
mimp elements were connected to different
impala members. To gain insights into the mechanisms at the origin and amplification of
mimps, we studied the potential of
impala to cross-mobilize different
mimps, native but also created de novo by inserting a short DNA segment between two TIRs. Our results show that TIR sequences are
the main requirement for mobilization but that additional parameters in the internal region are likely to influence transposition
efficiency. Finally, we show that integration site preference of native versus newly transposed
mimps greatly varies in the host genomes used in this study.
Keywords Miniature inverted-repeat transposable element (MITE) - Mobilization - De novo origin -
Fusarium
Nucleotide sequences of novel mimp3 and mimp4 elements are available under GenBank accession numbers EU833100 and EU833101, respectively. Coordinates of mimp5, mimp6 and of non-classified mimp copies are indicated in Supplementary Table 1.