Evidence for trans splicing in trypanosomes.
The 5' ends of trypanosome mRNAs consist of an identical sequence of 35 nucleotides. This "mini-exon" sequence is derived from the 5' end of a 137 nucleotide RNA (medRNA). The remainder of each mRNA is derived from a protein-coding exon that is not linked to the mini-exon. We propose that medRNA is spliced in trans to de-novo-initiated transcripts of protein-coding genes. This trans splicing model predicts that the downstream portion of medRNA will be part of a branched structure and then be released as a free product (minRNA). We demonstrate that significant levels of minRNA exist in trypanosome RNA. Furthermore, minRNA can be released from high molecular weight RNA by a HeLa cell S100 "debranching" extract. We conclude that trans splicing is the physiological process by which mature mRNA molecules are synthesized in trypanosomes.
D000818:Animals; D001483:Base Sequence; D004720:Endonucleases; D005091:Exons; D009694:Nucleic Acid Precursors / Q000235:genetics*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics*; D015719:Single-Strand Specific DNA and RNA Endonucleases; D014345:Trypanosoma / Q000235:genetics*
D009694:Nucleic Acid Precursors; D012333:RNA, Messenger; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases