A common pyrimidine-rich motif governs trans-splicing and polyadenylation of tubulin polycistronic pre-mRNA in trypanosomes

K R Matthews, C Tschudi, E Ullu
1994 Genes & Development  
In trypanosomes, the generation of monocistronic mRNAs from polycistronic precursors is achieved via RNA processing, namely trans-splicing of the spliced leader sequence at the 5' end and cleavage/polyadenylation at the 3' end of the mRNA coding region. Recent evidence raised the intriguing possibility that these two reactions are coupled. To begin a dissection of the signals required for mRNA 5'-end and 3'-end formation and to uncover potential interactions between trans-splicing and
more » ... ation, we mutagenized the intergenic region between the p-and a-tubulin genes of Trypanosoma brucei. Block substitutions identified the pyrimidine-rich sequences at the a-tubulin 3'-splice-acceptor site as a major determinant for accurate trans-splicing downstream and 3'-end formation upstream. In addition to the utilization of cryptic 3'-splice sites, obliteration of the polypyrimidine tracts led to aberrant polytA)*^ site choice, even in the presence of the wild-type polytA)"^ site and neighboring sequences. Taken together, these results indicate that the polypyrimidine-rich sequences act as a bifunctional element that affects RNA processing both upstream and downstream from itself. This is consistent with the possibility that the polypyrimidine tract is recognized by both the trans-splicing and polyadenylation machineries, either sequentially or simultaneously.
doi:10.1101/gad.8.4.491 pmid:7907303 fatcat:azboqmkhzfaq7mtfxi5goki5ii