Trans splicing in Leishmania enriettii and identification of ribonucleoprotein complexes containing the spliced leader and U2 equivalent RNAs
The 5' ends of Leishmania mRNAs contain an identical 35-nucleotide sequence termed the spliced leader (SL) or 5' mini-exon. The SL sequence is at the 5' end of an 85-nucleotide primary transcript that contains a consensus eucaryotic 5' intron-exon splice junction immediately 3' to the SL. The SL is added to protein-coding genes immediately 3' to a consensus eucaryotic 3' intron-exon splice junction. The authors' previous work demonstrated possible intermediates in discontinuous mRNA processing that contain the 50 nucleotides of the SL primary transcript 3' to the SL, the SL intron sequence (SLIS). These RNAs have a 5' terminus at the splice junction of the SL and the SLIS. The authors examined a Leishmania nuclear extract for these RNAs in ribonucleoprotein (RNP) particles. Density centrifugation analysis showed that the SL RNA is predominately in RNP complexes at 60S, while the SLIS-containing RNAs are in complexes at 40S. They also demonstrated that the SLIS can be released from polyadenylated RNA by incubation with a HeLa cell extract containing debranching enzymatic activity. These data suggested that Leishmania enriettii mRNAs are assembled by bimolecular or trans splicing as has been recently demonstrated for Trypanosoma brucei. Furthermore, they determined the partial sequence of the Leishmania U2 equivalent RNA and demonstrated that it cosediments with the SL RNA at 60S in a nuclear extract. These RNP particles may be analogous to so-called spliceosomes that have been demonstrated in other systems.
- Research Organization:
- Dept. of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA (US)
- OSTI ID:
- 6829946
- Journal Information:
- Mol. Cell. Biol.; (United States), Vol. 8:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NUCLEOPROTEINS
FRACTIONATION
RNA PROCESSING
MOLECULAR BIOLOGY
CHEMICAL ANALYSIS
DNA SEQUENCING
ENZYME ACTIVITY
HELA CELLS
MESSENGER-RNA
MOLECULAR STRUCTURE
PROTOZOA
ANIMALS
INVERTEBRATES
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PROTEINS
RNA
SEPARATION PROCESSES
STRUCTURAL CHEMICAL ANALYSIS
550200* - Biochemistry