RNA splicing is required to make the messenger RNA for a variant surface antigen in trypanosomes

Ploeg, Lex H.T. Van der; Liu, A. Y. C.; Michels, Paul A.M.; Lange, Titia de; Borst, Piet; Majumder, Hemanta K.; Weber, Hans; Veeneman, G. H.; Boom, Jacques van

doi:10.1093/nar/10.12.3591

Cited by 184 publications

(81 citation statements)

References 29 publications

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“…Although the oligonucleotides hybridised to DNA of both trypanosomes with equal intensity, the T. bmcei cDNA hybridised only weakly to the T. fig.3) are identical to the spliced leader [8,9], a sequence that is thought to be present on the 5 ' end of all trypanosome mRNAs [lo]. The first ATG, 32 nts 3 ' of the splice junction, has been taken to be the initiator methionine, although there is a second in-frame Fig.3 Nucleotlde sequence of a T brucer cysteme protemase cDNA with its predicted ammo acid sequence As the first 22 nts of the cDNA clone TCP-Fl are ldentlcal to the sphced leader sequence [8,9], the nucleotldes are numbered from the left startmg at the sphce lunctlon.…”

Section: Methodsmentioning

confidence: 97%

A cysteine proteinase cDNA from Trypanosoma brucei predicts an enzyme with an unusual C‐terminal extension

et al. 1989

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of molecular and glo~og~~al Sctences, ~~lverslty of Strrtmg, Stn-lmg FKP 4LA and ~De~art~nt of Zoology, ~~~vers~ty of Gl~gow, Glasgow GIL? 8QQ, Scotland Received 7 September 1989, revtsed version recetved 26 September 1989 A cDNA for a Trypanosoma bnrcer cysteme protemase has been cloned and sequenced The deduced protem can be chuded mto four domains, based on homologies with other cysteme protemases the pre-, pro-and central relpons show considerable homology to the cathepsrn L class of mammahan enzymes, whilst the long C-terminal extension chstmgmshes the trypanosome enzyme from all mammalian cysteme protanases reported This 108 ammo acid extension, wluch includes 9 contiguous prohnes near the Junctron with the central domain, appears likely to be processed m part to produce the mature enzyme, and may be mvolved m targettmg the protein wrthm the cell The trypanosome genome contams more than 20 copies of the cysteme protemase gene arranged m a long tandem array Trypanosome, Cysteme protemase 1, INTRODUCTIONThe cysteine proteinases (EC 3.4.22) are proving a valuable group for investigating the relationship between enzyme structure and function. Mammalian lysosomal cathepsins (B, H, L) and plant proteinases such as papain have been the most extensively studied, but similar enzymes occur widely in invertebrates and protozoa [l]. Notably, they occur at high activity in a number of parasitic protozoa, many of which contain multiple enzymes that in some species are developmentally regulated [2,3]. The abundance of cysteine proteinases in a variety of parasites, their potential role in the host-parasite interaction and virulence, and the advent of families of specific irreversible inhibitors [4], have made these enzymes attractive targets for chemotherapeutic attack. fig.2A and B, lanes 1 and 4), a >23 kb doublet for the T. brucei &rnHl digest (lane 6) and a single >23 kb band for T. cruzi (lane 3). A T. brucei cDNA library in Xgt 11 was also screened and several clones were isolated. The largest insert was subcloned into Bluescript plasmid (pTCP-Fl).On genomic Southerns, the cDNA hybridised to the same fragments as the oligonucleotides for the Hind1 and BamHl digests, with an extra band present in the Pstl digest ( fig.2C). Although the oligonucleotides hybridised to DNA of both trypanosomes with equal intensity, the T. bmcei cDNA hybridised only weakly to the T.

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Section: Methodsmentioning

confidence: 97%

A cysteine proteinase cDNA from Trypanosoma brucei predicts an enzyme with an unusual C‐terminal extension

et al. 1989

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“…This discontinuous transcription was first discovered in African trypanosomes in mRNAs encoding variant surface glycoproteins (9,10), which were found to contain the same leader sequence at their 5Ј end (reviewed in ref. 11).…”

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mRNA maturation by two-step trans-splicing/polyadenylation processing in trypanosomes

Jäger

Gaudenzi

Cassola

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Trypanosomes are unique eukaryotic cells, in that they virtually lack mechanisms to control gene expression at the transcriptional level. These microorganisms mostly control protein synthesis by posttranscriptional regulation processes, like mRNA stabilization and degradation. Transcription in these cells is polycistronic. Tens to hundreds of protein-coding genes of unrelated function are arrayed in long clusters on the same DNA strand. Polycistrons are cotranscriptionally processed by trans-splicing at the 5 end and polyadenylation at the 3 end, generating monocistronic units ready for degradation or translation. In this work, we show that some trans-splicing/polyadenylation sites may be skipped during normal polycistronic processing. As a consequence, dicistronic units or monocistronic transcripts having long 3 UTRs are produced. Interestingly, these unspliced transcripts can be processed into mature mRNAs by the conventional trans-splicing/ polyadenylation events leading to translation. To our knowledge, this is a previously undescribed mRNA maturation by trans-splicing uncoupled from transcription. We identified an RNA-recognition motif-type protein, homologous to the mammalian polypyrimidine tract-binding protein, interacting with one of the partially processed RNAs analyzed here that might be involved in exon skipping. We propose that splice-site skipping might be part of a posttranscriptional mechanism to regulate gene expression in trypanosomes, through the generation of premature nontranslatable RNA molecules.gene expression ͉ posttranscriptional regulation ͉ RNA processing R egulation of gene expression is central in defining the phenotype of a cell or organism. In the vast majority of cases, this regulation is controlled by transcriptional regulation in which DNA sequence elements, together with DNA-binding proteins, target genes for transcription by RNA polymerase II. In addition to regulating single genes, master regulators of transcription may give rise to a gene expression phenotype, a trait that may be inherited (1). Mature transcripts can also be regulated in their expression at the posttranscriptional level. A number of cis-motifs mainly located in the 5Ј and 3Ј UTRs determine the fate of the transcript by the use of highly specific and sometimes evolutionarily conserved machineries. This process is essentially achieved through RNA-binding proteins (RBPs) forming, together with the mRNA, ribonucleoprotein (RNP) complexes. It is the composition of the RNP complex that determines whether an mRNA is transported to the cytoplasm for translation, degradation, or other processing events (2, 3).Posttranscriptional regulation is common among Kinetoplastid parasites, like trypanosomes and Leishmania (4, 5), which are the causative agents of several infections affecting both humans and domestic animals worldwide (6). In these parasites, transcription by RNA polymerase II starts at a few genomic locations within chromosomes. In contrast to operons in bacteria, polycistronic units in trypanosomatids requir...

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“…[1][2][3][4][5][6]. This form of RNA maturation was first described in trypanosomes (7,8) and subsequently in other kinetoplastida and the flagellated protozoan Euglena (9). The identification of trans-splicing in two divergent invertebrate phyla, first in nematodes (10) and then in flatworms (11), suggests that this particular form of RNA processing may be an important form of gene expression common in early metazoa.…”

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RNA Trans-splicing in Flatworms

Davis

Hardwick

Tavernier

et al. 1995

Journal of Biological Chemistry

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Characteristics of trans-splicing in Schistosoma mansoni were examined to explore the significance and determinants of spliced leader (SL) addition in flatworms. Only a small subset of mRNAs acquire the SL. Analysis of 30 trans-spliced mRNAs and four genes revealed no discernable patterns or common characteristics in the genes, mRNAs, or their encoded proteins that might explain the functional significance of SL addition. While the mRNA encoding the glycolytic enzyme enolase is trans-spliced, mRNAs encoding four other glycolytic enzymes are not, indicating trans-splicing is not prevalent throughout this metabolic pathway. Although the 3 end of flatworm SLs contribute an AUG to mRNAs, the SL AUG does not typically serve to provide a methionine for translation initiation of reading frames in recipient mRNAs. SL RNA expression exhibits no apparent sex, tissue, or cell specificity. Trans-spliced genes undergo both cis-and trans-splicing, and the sequence contexts for these respective acceptor sites are very similar. These results suggest trans-splicing in flatworms is most likely associated either with some property conferred on recipient mRNAs by SL addition or related to some characteristic of the primary transcripts or transcription of trans-spliced genes.Trans-splicing is an RNA processing event that accurately joins sequences derived from independently transcribed RNAs. In one form of trans-splicing, a leader sequence (the spliced leader, SL) 1 is donated from the 5Ј end of a small, non-polyadenylated RNA (the spliced leader RNA, SL RNA) to pre-mRNAs to form the 5Ј-terminal exon of mature mRNAs (for recent reviews see Refs. 1-6). This form of RNA maturation was first described in trypanosomes (7,8) and subsequently in other kinetoplastida and the flagellated protozoan Euglena (9). The identification of trans-splicing in two divergent invertebrate phyla, first in nematodes (10) and then in flatworms (11), suggests that this particular form of RNA processing may be an important form of gene expression common in early metazoa.The general distribution of trans-splicing and its origin in metazoa is currently not known. Furthermore, both the origin of early metazoan groups and the phylogenetic relationships between flatworms, nematodes, and other early invertebrates have been difficult to delineate (12, 13). Trans-splicing may have arisen independently in several invertebrate lineages (6) and, if true, the characteristics and functional significance of spliced leader addition might also be different in diverse metazoan groups. Trans-splicing is of particular interest in flatworms (Phylum Platyhelminthes) as these metazoa may represent the earliest bilateral animals, and one possible evolutionary tree places a flatworm-like ancestor as the progenitor of a number of other early invertebrate groups (12, 13). We have recently shown that trans-splicing is present in diverse trematode flatworms and in a predominantly free-living group generally considered to represent primitive flatworms (14). 2 This suggests that spliced ...

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RNA splicing is required to make the messenger RNA for a variant surface antigen in trypanosomes

Cited by 184 publications

References 29 publications

A cysteine proteinase cDNA from Trypanosoma brucei predicts an enzyme with an unusual C‐terminal extension

A cysteine proteinase cDNA from Trypanosoma brucei predicts an enzyme with an unusual C‐terminal extension

mRNA maturation by two-step trans-splicing/polyadenylation processing in trypanosomes

RNA Trans-splicing in Flatworms

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