Spliced-leader RNA trans splicing in a chordate, Oikopleura dioica, with a compact genome.
trans splicing of a spliced-leader RNA (SL RNA) to the 5' ends of mRNAs has been shown to have a limited and sporadic distribution among eukaryotes. Within metazoans, only nematodes are known to process polycistronic pre-mRNAs, produced from operon units of transcription, into mature monocistronic mRNAs via an SL RNA trans-splicing mechanism. Here we demonstrate that a chordate with a highly compact genome, Oikopleura dioica, now joins Caenorhabditis elegans in coupling trans splicing with processing of polycistronic transcipts. We identified a single SL RNA which associates with Sm proteins and has a trimethyl guanosine cap structure reminiscent of spliceosomal snRNPs. The same SL RNA, estimated to be trans-spliced to at least 25% of O. dioica mRNAs, is used for the processing of both isolated or first cistrons and downstream cistrons in a polycistronic precursor. Remarkably, intercistronic regions in O. dioica are far more reduced than those in either nematodes or kinetoplastids, implying minimal cis-regulatory elements for coupling of 3'-end formation and trans splicing.
Ganot
Philippe
P
Sars International Centre for Marine Molecular Biology, Bergen High Technology Centre, Thormøhlensgt. 55, N-5008 Bergen, Norway.
Kallesøe
Torben
T
Reinhardt
Richard
R
Chourrout
Daniel
D
Thompson
Eric M
EM
D000818:Animals; D001483:Base Sequence; D056743:Cyclin D3; D016213:Cyclins / Q000235:genetics; D005796:Genes; D016678:Genome; D008969:Molecular Sequence Data; D005810:Multigene Family; D009690:Nucleic Acid Conformation; D012315:RNA Caps; D012326:RNA Splicing; D020038:RNA, Spliced Leader / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014561:Urochordata / Q000235:genetics*
D056743:Cyclin D3; D016213:Cyclins; D012315:RNA Caps; D020038:RNA, Spliced Leader; D017411:Ribonucleoproteins, Small Nuclear