A comparison of trans-RNA splicing in trypanosomes and nematodes

Donelson, John E.; Zeng, Wenlin

doi:10.1016/0169-4758(90)90177-6

Cited by 31 publications

(16 citation statements)

References 53 publications

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“…4B. All conserved features of other SL-RNAs (4,6,8,9), including three stem-loop structures, a putative Sm binding sequence between stemloops 2 and 3, and the typical location of the SL within the first stem-loop, are present.…”

Section: Identification Of Alternatively Spliced Elp Transcripts-wementioning

confidence: 94%

“…SL trans-splicing was first described in kinetoplastid protozoans where all mature mRNAs contain an identical leader sequence at the 5Ј end (6). Among metazoans, SL trans-splicing is known for several parasitic and non-parasitic nematodes (1)(2)(3)(4)(5)(6) and, in the phylum Platyhelminthes, for parasitic trematodes (7)(8)(9) and free-living turbellarians (9). In contrast to kinetoplastids, where trans-splicing is the predominant form of splicing, transcripts of metazoans are generally spliced both cis, usually at introns within the coding region, and trans at the 5Ј end (1)(2)(3)(4)(5).…”

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confidence: 99%

“…In all cases investigated so far, the SL donor molecule is a small, non-polyadenylated nuclear RNA (the SL-RNA) with structural properties similar to the snRNAs that function in "conventional" cis-splicing (1)(2)(3)(4)(5). SL trans-splicing was first described in kinetoplastid protozoans where all mature mRNAs contain an identical leader sequence at the 5Ј end (6). Among metazoans, SL trans-splicing is known for several parasitic and non-parasitic nematodes (1)(2)(3)(4)(5)(6) and, in the phylum Platyhelminthes, for parasitic trematodes (7)(8)(9) and free-living turbellarians (9).…”

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confidence: 99%

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mRNA Trans-splicing in the Human Parasitic CestodeEchinococcus multilocularis

Brehm

Jensen

Frosch

2000

Journal of Biological Chemistry

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An identical 36-nucleotide exon was identified at the 5 termini of different mRNAs from the cestode Echinococcus multilocularis. We provide evidence that this exon constitutes a new spliced leader (SL) that is obviously trans-spliced to echinococcal pre-mRNAs, donated by a non-polyadenylated, trimethylguanosine-capped SL-RNA of 104 nucleotides. Sequence comparisons indicated that cestode and trematode SLs are likely to be derived from a common ancestor gene. No conservation was, however, observed concerning the spectrum of mRNAs that is trans-spliced in cestodes and trematodes, indicating that trans-splicing of a particular flatworm mRNA is not correlated with the function of the encoded protein. We also show that the echinococcal gene elp, encoding a member of the ezrin/radixin/moesin protein family, is expressed via two alternative transcripts, spliced either cis or trans at an identical splice acceptor site. This was accompanied by the formation of different elp primary transcripts, harboring a complete or a truncated upstream intron, which supports the hypothesis that alternative cis/trans-splicing depends on the presence or absence of an upstream splice donor site. A putative SL gene was also identified on chromosomal DNA of Echinococcus granulosus, indicating widespread utilization of trans-splicing in the genus.Trans-splicing is a mechanism of mRNA processing that involves the fusion of exons from independent primary transcripts to form a mature mRNA (for recent reviews, see Refs. 1-5). In the most common form of trans-splicing, called SL 1 trans-splicing, a small "mini-exon" (or SL) is added to the 5Ј ends of pre-mRNA molecules, eventually forming the 5Ј-terminal exon of the mature mRNA. In all cases investigated so far, the SL donor molecule is a small, non-polyadenylated nuclear RNA (the SL-RNA) with structural properties similar to the snRNAs that function in "conventional" cis-splicing (1-5). SL trans-splicing was first described in kinetoplastid protozoans where all mature mRNAs contain an identical leader sequence at the 5Ј end (6). Among metazoans, SL trans-splicing is known for several parasitic and non-parasitic nematodes (1-6) and, in the phylum Platyhelminthes, for parasitic trematodes (7-9) and free-living turbellarians (9). In contrast to kinetoplastids, where trans-splicing is the predominant form of splicing, transcripts of metazoans are generally spliced both cis, usually at introns within the coding region, and trans at the 5Ј end (1-5). A further difference is that in metazoans not all mRNAs are trans-spliced. In Caenorhabditis elegans, for example, around 60% of all transcripts contain one leader, called SL1, and about 10 -15% contain an alternative mini-exon, called SL2 (1-5). Besides SL1 and SL2, three additional SLs were identified in C. elegans that are, however, less frequently found at mRNA 5Ј ends (10).Although significant data has been obtained on the biochemistry of the trans-splicing mechanism itself (1-6), the biological in vivo functions of SLs are less well understood. At ...

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Section: Identification Of Alternatively Spliced Elp Transcripts-wementioning

confidence: 94%

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confidence: 99%

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confidence: 99%

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mRNA Trans-splicing in the Human Parasitic CestodeEchinococcus multilocularis

Brehm

Jensen

Frosch

2000

Journal of Biological Chemistry

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“…In addition, there are several genetic features that are unique to the kinetoplastid group. T. cruzi genes are intronless, but individual genes are trans-spliced from polycistronic mRNAs to a splice leader RNA (DeLange et al 1984;McCarthy-Burke et al 1989;Donelson and Zeng 1990). Many housekeeping genes are present in large tandemly repeated clusters containing two to >100 copies.…”

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confidence: 99%

Complete Sequence of a 93.4-kb Contig from Chromosome 3 of Trypanosoma cruzi Containing a Strand-Switch Region

et al. 1998

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We have initiated large-scale sequencing of the third smallest chromosome of the CL Brener strain of Trypanosoma cruzi and we report here the complete sequence of a contig consisting of three cosmids. This contig covers 93.4 kb and has been found to contain 20-30 novel genes and several repeat elements, including a novel chromosome 3-specific 400-bp repeat sequence. The intergenic sequences were found to be rich in di-and trinucleotide repeats of varying lengths and also contained several known T. cruzi repeat elements. The sequence contains 29 open reading frames (ORFs) longer than 700 bp, the longest being 5157 bp, and a large number of shorter ORFs. Of the long ORFs, seven show homology to known genes in parasites and other organisms, whereas four ORFs were confirmed by sequencing of cDNA clones. Two shorter ORFs were confirmed by a database homology and a cDNA clone, respectively, and one RNA gene was identified. The identified genes include two copies of the gene for alanine-aminotransferase as well as genes for glucose-6-phosphate isomerase, protein kinases and phosphatases, and an ATP synthase subunit. An interesting feature of the sequence was that the genes appear to be organized in two long clusters containing multiple genes on the same strand. The two clusters are transcribed in opposite directions and they are separated by an ∼20-kb long, relatively GC-rich sequence, that contains two large repetitive elements as well as a pseudogene for cruzipain and a gene for U2snRNA. It is likely that this strand switch region contains one or more regulatory and promoter regions. The reported sequence provides the first insight into the genome organization of T. cruzi and shows the potential of this approach for rapid identification of novel genes.

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“…In trypanosomatids, however, transcription is polycistronic, there are no introns and, therefore, no cis-splicing reactions. Processing of pre-mRNA into singlegene units is effected by trans-splicing reactions, a process that has been found to operate only in trypanosomatids, Euglena and in nematode and trematode worms (2). In addition to these differences, other cellular and molecular novelties were discovered in trypanosomes: i) during cell division, chromosome condensation and nuclear membrane disruption do not occur; ii) peculiar organelles are found, such as glycosomes which concentrate the enzymes and the intermediates of the glycolytic pathway; iii) an extensive post-transcriptional modification of mitochondrial RNA known as RNA editing is required for the correct expression of mitochondrial enzymes, and, finally, iv) transcription of protein-coding genes can be achieved by RNA polymerase I (or an enzyme with similar properties).…”

Section: Introduction: General Mechanisms Of Gene Expression In Trypamentioning

confidence: 99%

Control of gene expression in Trypanosomatidae

Teixeira

1998

Braz J Med Biol Res

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The study of mechanisms which control gene expression in trypanosomatids has developed at an increasing rate since 1989 when the first successful DNA transfection experiments were reported. Using primarily Trypanosoma brucei as a model, several groups have begun to elucidate the basic control mechanisms and to define the cellular factors involved in mRNA transcription, processing and translation in these parasites. This review focuses on the most recent studies regarding a subset of genes that are expressed differentially during the life cycle of three groups of parasites. In addition to T. brucei, I will address studies on gene regulation in a few species of Leishmania and the results obtained by a much more limited group of laboratories studying gene expression in Trypanosoma cruzi. It is becoming evident that the regulatory strategies chosen by different species of trypanosomatids are not similar, and that for these very successful parasites it is probably advantageous to employ multiple mechanisms simultaneously. In addition, with the increasing numbers of parasite genes that have now been submitted to molecular dissection, it is also becoming evident that, among the various strategies for gene expression control, there is a predominance of regulatory pathways acting at the post-transcriptional level.

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A comparison of trans-RNA splicing in trypanosomes and nematodes

Cited by 31 publications

References 53 publications

mRNA Trans-splicing in the Human Parasitic CestodeEchinococcus multilocularis

mRNA Trans-splicing in the Human Parasitic CestodeEchinococcus multilocularis

Complete Sequence of a 93.4-kb Contig from Chromosome 3 of Trypanosoma cruzi Containing a Strand-Switch Region

Control of gene expression in Trypanosomatidae

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