Mutator -like elements identified in melon, Arabidopsis and rice contain ULP1 protease domains.

Abstract  The transposonMutatorwas first identified in maize, and is one of the most active mobile elements in plants. TheArabidopsis thalianagenome contains at least 200Mutator-like elements (MULEs), which contain theMutator-like transposase gene, and often additional genes. We have detected a novel type of MULEs in melon (CUMULE), which, besides the transposase, contains two ubiquitin-like specific protease-like sequences (ULP1). This element is not present in the observed location in some melon cultivars. Multiple copies of this element exist in theCucumis melogenome, and it has been detected in other Cucurbitaceae species. Analysis of theA. thalianagenome revealed more than 90 CUMULE-like elements, containing one or twoUlp1-like sequences, although no evidence of mobility exists for these elements. We detected various putative transposable elements containing ULP1-like sequences in rice. The discovery of these MULEs in melon and Arabidopsis, and the existence of similar elements in rice and maize, suggest that a proteolytic function may be important for this subset of the MULE transposable elements. [ABSTRACT FROM AUTHOR]