A short interspersed repetitive element provides a new 3' acceptor site for trans-splicing in certain ribosomal P2 beta protein genes of Trypanosoma cruzi.
Four Trypanosoma cruzi genomic DNA fragments carrying different TcP2 beta genes have been isolated and sequenced. Three of them had a single TcP2 beta gene, while the 3.8-kb-long DNA segment encoding the TcP2 beta-H1.8 locus showed two TcP2 beta genes arranged in tandem. These genes were physically connected by a 428-bp-long DNA sequence that was also located immediately 5' to the first gene and immediately 3' to the second. Comparison of the 4 TcP2 beta gene loci, suggested that the insertion of this repeated element originated the duplication of its target sequence, a poly(dT) stretch. Approximately 1200 copies of this short sequence, named short interspersed repetitive element (SIRE), were found scattered in the genome. Analysis of the 5' non-coding regions of different TcP2 beta mRNAs, and RNA-PCR experiments suggested that the insertion of a SIRE upstream of a TcP2 beta-H1.8 gene introduced a new 3' spliced leader (SL) acceptor site in the TcP2 beta-H1.8 pre-mRNAs, encoded within the SIRE. Consequently, in the mature H1.8 mRNA the SL sequence is followed by 38 bases directly transcribed from the SIRE. Structural and functional features of this repeated element reveal similarity to the short interspersed repetitive DNA sequences detected in the genomes of several microorganisms.
Vazquez
M P
MP
Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Buenos Aires, Argentina.
Schijman
A G
AG
Levin
M J
MJ
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D016054:DNA, Protozoan / Q000235:genetics; D017125:Genes, Protozoan; D008969:Molecular Sequence Data; D005810:Multigene Family; D010750:Phosphoproteins / Q000235:genetics*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D012269:Ribosomal Proteins / Q000235:genetics*; D014349:Trypanosoma cruzi / Q000235:genetics* / Q000378:metabolism
D016054:DNA, Protozoan; D010750:Phosphoproteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D012269:Ribosomal Proteins; C031937:phosphoprotein P2, ribosomal