Binding of the Drosophila Sex-lethal gene product to the alternative splice site of transformer primary transcript

Abstract

Somatic sexual differentiation in Drosophila melanogaster is accomplished by a hierarchy of genes of which one, Sex-lethal (Sxl), is required for the functional female-specific splicing of the transcripts of the immediately downstream regulatory gene, transformer (tra). The first exon of the tra primary transcript is spliced to one of two acceptor sites. Splicing to the upstream site yields a messenger RNA which is neither sex-specific nor functional, but that produced after splicing to the downstream acceptor site yields a functional female-specific mRNA. Here we address the question of how the Sxl gene product determines the alternative splicing of tra primary transcripts. One suggestion is that non-sex-specific splicing to the upstream acceptor is blocked in female flies by sex-specific factors, but neither the identity of the female-specific factors nor the mechanism of the blockage has been specified. We have now performed co-transfection experiments in which Sxl complementary DNA and the tra gene are expressed in Drosophila Kc cells. Moreover, we find that female Sxl-encoded protein binds specifically to the tra transcript at or near the non-sex-specific acceptor site, implying that the female Sxl gene product is the trans-acting factor that regulates the alternative splicing.

Specific RNP capture with antisense LNA/DNA mixmers

“…The interaction of Sxl with poly(U) motifs has been well-characterized biochemically and structurally (Inoue et al 1990;Valcárcel et al 1993;Handa et al 1999;Hennig et al 2014). In addition to its interaction with msl-2 mRNA (Bashaw and Baker 1995;Kelley et al 1995Kelley et al , 1997Bashaw and Baker 1997), Sxl also binds to poly(U) motifs present in its own mRNA (Cline 1984;Bell et al 1991) and in the transformer mRNA (tra) (Boggs et al, 1987).…”

The complexity of alternative splicing of hagoromo mRNAs is increased in an explosively speciated lineage in East African cichlids

“…resulting in alternative splicing (35)(36)(37). Thus, a few mutations in the splicing motif may change the alternative splicing pattern, thereby dramatically altering the phenotype.…”

Insect sex determination: it all evolves around transformer

“…SXL also directs cryptic splicing of tra by binding to a polypyrimidine tract in the first tra intron and forces the general splicing factor U2AF to use the female-specific 3 0 splice site in exon 3 instead of the nonsex-specific 3 0 splice site in exon 2. This tra transcript yields a functional TRA protein [12][13][14], which interacts with the nonsex-specific transformer2 protein (TRA2) [15] and binds to the dsx transcript in the middle of exon 4, called the dsx repeat element (dsxRE). This dsxRE contains six copies of the 13 nucleotide sequence TC(T/A) (T/A)C(A/G)ATCAACA [16].…”