Investigation of the Functional Role of the Conserved Sequence at the 5'-End of the Fourth Intron of the mod(mdg4) Gene in Trans-Splicing in Drosophila melanogaster

Alternative splicing is an important mechanism that provides genetic diversity of proteins. Unique loci have been identified in Drosophila melanogaster, where mRNA diversity arises as a result of trans-splicing—a process in which exons from different pre-mRNAs are joined together. The trans-splicing in the mod(mdg4) locus, which encodes more than 31 isoforms, has been studied in detail. Important elements for this process include previously described conserved sequences in the fourth intron. The aim of this study is to further characterize the conserved motifs of the fourth intron, specifically the element at the 5'-end of the intron. Using model transgenic lines, it has been shown that introduced changes in the sequence of the studied element lead to a disruption of trans-splicing. In contrast, similar changes in the endogenous locus did not result in a disruption of trans-splicing. Thus, the conserved element plays a role in trans-splicing but is not critical.