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Barbosa RL, da Cunha JPC, Menezes AT, Melo RDFP, Elias MC, Silber AM, Coltri PP. Proteomic analysis of Trypanosoma cruzi spliceosome complex. J Proteomics 2020; 223:103822. [PMID: 32422275 DOI: 10.1016/j.jprot.2020.103822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 05/01/2020] [Accepted: 05/11/2020] [Indexed: 11/17/2022]
Abstract
The unicellular protists of the group Kinetoplastida include the genera Leishmania and Trypanosoma, which are pathogens of invertebrate and vertebrate animals. Despite their medical and economical importance, critical aspects of their biology such as specific molecular characteristics of gene expression regulation are just beginning to be deciphered. Gene expression regulation also depends on post-transcriptional processing steps, such as the trans-splicing process. Despite being widely used in trypanosomes, trans-splicing is a rare event in other eukaryotes. We sought to describe the protein composition of spliceosomes in epimastigotes of T. cruzi, the etiological agent of Chagas disease. We used two TAP-tagged proteins to affinity purify spliceosomes and analyzed their composition by mass spectrometry. Among the 115 identified proteins we detected conserved spliceosome components, as Sm and LSm proteins, RNA helicases, U2- and U5-snRNP specific proteins. Importantly, by comparing our data with proteomic data of human and T. brucei spliceosome complexes, we observed a core group of proteins common to all spliceosomes. By using amino acid sequence comparisons, we identified RNA-associated proteins that might be involved with splicing regulation in T. cruzi, namely the orthologous of WDR33, PABPCL1 and three different HNRNPs. Data are available via ProteomeXchange with identifier PXD018776.
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Affiliation(s)
- Rosicler L Barbosa
- Department of Cell and Developmental Biology, Institute for Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil
| | - Julia Pinheiro Chagas da Cunha
- Special Laboratory of Cell Cycle, Center of Toxins, Immune Response and Cell Signalling (CeTICS), Butantan Institute, São Paulo 05503-900, Brazil
| | - Arthur T Menezes
- Department of Cell and Developmental Biology, Institute for Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil
| | - Raíssa de F P Melo
- Laboratory of Biochemistry of Tryps - LaBTryps. Department of Parasitology, Institute for Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil
| | - Maria Carolina Elias
- Special Laboratory of Cell Cycle, Center of Toxins, Immune Response and Cell Signalling (CeTICS), Butantan Institute, São Paulo 05503-900, Brazil
| | - Ariel M Silber
- Laboratory of Biochemistry of Tryps - LaBTryps. Department of Parasitology, Institute for Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil
| | - Patricia P Coltri
- Department of Cell and Developmental Biology, Institute for Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil.
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De Gaudenzi JG, Jäger AV, Izcovich R, Campo VA. Insights into the Regulation of mRNA Processing of Polycistronic Transcripts Mediated by DRBD4/PTB2, a Trypanosome Homolog of the Polypyrimidine Tract-Binding Protein. J Eukaryot Microbiol 2016; 63:440-52. [PMID: 26663092 DOI: 10.1111/jeu.12288] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 11/11/2015] [Accepted: 12/02/2015] [Indexed: 12/13/2022]
Abstract
Trypanosomes regulate gene expression mostly by posttranscriptional mechanisms, including control of mRNA turnover and translation efficiency. This regulation is carried out via certain elements located at the 3'-untranslated regions of mRNAs, which are recognized by RNA-binding proteins. In trypanosomes, trans-splicing is of central importance to control mRNA maturation. We have previously shown that TcDRBD4/PTB2, a trypanosome homolog of the human polypyrimidine tract-binding protein splicing regulator, interacts with the intergenic region of one specific dicistronic transcript, referred to as TcUBP (and encoding for TcUBP1 and TcUBP2, two closely kinetoplastid-specific proteins). In this work, a survey of TcUBP RNA processing revealed certain TcDRBD4/PTB2-regulatory elements within its intercistronic region, which are likely to influence the trans-splicing rate of monocistronic-derived transcripts. Furthermore, TcDRBD4/PTB2 overexpression in epimastigote cells notably decreased both UBP1 and UBP2 protein expression. This type of posttranscriptional gene regulatory mechanism could be extended to other transcripts as well, as we identified several other RNA precursor molecules that specifically bind to TcDRBD4/PTB2. Altogether, these findings support a model in which TcDRBD4/PTB2-containing ribonucleoprotein complexes can prevent trans-splicing. This could represent another stage of gene expression regulation mediated by the masking of trans-splicing/polyadenylation signals.
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Affiliation(s)
- Javier G De Gaudenzi
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Sede San Martín, Prov. de Buenos Aires, Argentina
| | - Adriana V Jäger
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Sede San Martín, Prov. de Buenos Aires, Argentina
| | - Ronan Izcovich
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Sede San Martín, Prov. de Buenos Aires, Argentina
| | - Vanina A Campo
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Sede San Martín, Prov. de Buenos Aires, Argentina
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Vasquez JJ, Hon CC, Vanselow JT, Schlosser A, Siegel TN. Comparative ribosome profiling reveals extensive translational complexity in different Trypanosoma brucei life cycle stages. Nucleic Acids Res 2014; 42:3623-37. [PMID: 24442674 PMCID: PMC3973304 DOI: 10.1093/nar/gkt1386] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
While gene expression is a fundamental and tightly controlled cellular process that is regulated at multiple steps, the exact contribution of each step remains unknown in any organism. The absence of transcription initiation regulation for RNA polymerase II in the protozoan parasite Trypanosoma brucei greatly simplifies the task of elucidating the contribution of translation to global gene expression. Therefore, we have sequenced ribosome-protected mRNA fragments in T. brucei, permitting the genome-wide analysis of RNA translation and translational efficiency. We find that the latter varies greatly between life cycle stages of the parasite and ∼100-fold between genes, thus contributing to gene expression to a similar extent as RNA stability. The ability to map ribosome positions at sub-codon resolution revealed extensive translation from upstream open reading frames located within 5' UTRs and enabled the identification of hundreds of previously un-annotated putative coding sequences (CDSs). Evaluation of existing proteomics and genome-wide RNAi data confirmed the translation of previously un-annotated CDSs and suggested an important role for >200 of those CDSs in parasite survival, especially in the form that is infective to mammals. Overall our data show that translational control plays a prevalent and important role in different parasite life cycle stages of T. brucei.
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Affiliation(s)
- Juan-José Vasquez
- Research Center for Infectious Diseases, University of Wuerzburg, Wuerzburg 97080, Germany, Département Biologie cellulaire et infection, Institut Pasteur, Unité Biologie Cellulaire du Parasitisme, Paris 75015, France, INSERM U786, Paris 75015, France and Rudolf Virchow Center, University of Wuerzburg, Wuerzburg 97080, Germany
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Mayer MG, Santos MGD, Silva MFLD, Floeter-Winter LM. Footprints of a trypanosomatid RNA world: pre-small subunit rRNA processing by spliced leader addition trans-splicing. Mem Inst Oswaldo Cruz 2013; 107:522-31. [PMID: 22666864 DOI: 10.1590/s0074-02762012000400013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 01/11/2012] [Indexed: 11/22/2022] Open
Abstract
The addition of a capped mini-exon [spliced leader (SL)] through trans-splicing is essential for the maturation of RNA polymerase (pol) II-transcribed polycistronic pre-mRNAs in all members of the Trypanosomatidae family. This process is an inter-molecular splicing reaction that follows the same basic rules of cis-splicing reactions. In this study, we demonstrated that mini-exons were added to precursor ribosomal RNA (pre-rRNA) are transcribed by RNA pol I, including the 5' external transcribed spacer (ETS) region. Additionally, we detected the SL-5'ETS molecule using three distinct methods and located the acceptor site between two known 5'ETS rRNA processing sites (A' and A1) in four different trypanosomatids. Moreover, we detected a polyadenylated 5'ETS upstream of the trans-splicing acceptor site, which also occurs in pre-mRNA trans-splicing. After treatment with an indirect trans-splicing inhibitor (sinefungin), we observed SL-5'ETS decay. However, treatment with 5-fluorouracil (a precursor of RNA synthesis that inhibits the degradation of pre-rRNA) led to the accumulation of SL-5'ETS, suggesting that the molecule may play a role in rRNA degradation. The detection of trans-splicing in these molecules may indicate broad RNA-joining properties, regardless of the polymerase used for transcription.
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Abstract
The parasitic unicellular trypanosomatids are responsible for several fatal diseases in humans and livestock. Regarding their biochemistry and molecular biology, they possess a multitude of special features such as polycistronic transcription of protein-coding genes. The resulting long primary transcripts need to be processed by coupled trans-splicing and polyadenylation reactions, thereby generating mature mRNAs. Catalyzed by a large ribonucleoprotein complex termed the spliceosome, trans-splicing attaches a 39-nucleotide leader sequence, which is derived from the Spliced Leader (SL) RNA, to each protein-coding gene. Recent genome-wide studies demonstrated that alternative trans-splicing increases mRNA and protein diversity in these organisms. In this mini-review we give an overview of the current state of research on trans-splicing.
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Affiliation(s)
- Christian Preußer
- Institute of Biochemistry, Justus Liebig University of Giessen, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany
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Spliced leader trapping reveals widespread alternative splicing patterns in the highly dynamic transcriptome of Trypanosoma brucei. PLoS Pathog 2010; 6:e1001037. [PMID: 20700444 PMCID: PMC2916883 DOI: 10.1371/journal.ppat.1001037] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 07/12/2010] [Indexed: 11/19/2022] Open
Abstract
Trans-splicing of leader sequences onto the 5′ends of mRNAs is a widespread phenomenon in protozoa, nematodes and some chordates. Using parallel sequencing we have developed a method to simultaneously map 5′splice sites and analyze the corresponding gene expression profile, that we term spliced leader trapping (SLT). The method can be applied to any organism with a sequenced genome and trans-splicing of a conserved leader sequence. We analyzed the expression profiles and splicing patterns of bloodstream and insect forms of the parasite Trypanosoma brucei. We detected the 5′ splice sites of 85% of the annotated protein-coding genes and, contrary to previous reports, found up to 40% of transcripts to be differentially expressed. Furthermore, we discovered more than 2500 alternative splicing events, many of which appear to be stage-regulated. Based on our findings we hypothesize that alternatively spliced transcripts present a new means of regulating gene expression and could potentially contribute to protein diversity in the parasite. The entire dataset can be accessed online at TriTrypDB or through: http://splicer.unibe.ch/. Some organisms like the human and animal parasite Trypanosoma brucei add a leader sequence to their mRNAs through a reaction called trans-splicing. Until now the splice sites for most mRNAs were unknown in T. brucei. Using high throughput sequencing we have developed a method to identify the splice sites and at the same time measure the abundance of the corresponding mRNAs. Analyzing three different life cycle stages of the parasite we identified the vast majority of splice sites in the organism and, to our great surprise, uncovered more than 2500 alternative splicing events, many of which appeared to be specific for one of the life cycle stages. Alternative splicing is a result of the addition of the leader sequence to different positions on the mRNA, leading to mixed mRNA populations that can encode for proteins with varying properties. One of the most obvious changes caused by alternative splicing is the gain or loss of targeting signals, leading to differential localization of the corresponding proteins. Based on our findings we hypothesize that alternative splicing is a major mechanism to regulate gene expression in T. brucei and could contribute to protein diversity in the parasite.
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Siegel TN, Hekstra DR, Wang X, Dewell S, Cross GAM. Genome-wide analysis of mRNA abundance in two life-cycle stages of Trypanosoma brucei and identification of splicing and polyadenylation sites. Nucleic Acids Res 2010; 38:4946-57. [PMID: 20385579 PMCID: PMC2926603 DOI: 10.1093/nar/gkq237] [Citation(s) in RCA: 256] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Transcription of protein-coding genes in trypanosomes is polycistronic and gene expression is primarily regulated by post-transcriptional mechanisms. Sequence motifs in the untranslated regions regulate mRNA trans-splicing and RNA stability, yet where UTRs begin and end is known for very few genes. We used high-throughput RNA-sequencing to determine the genome-wide steady-state mRNA levels (‘transcriptomes’) for ∼90% of the genome in two stages of the Trypanosoma brucei life cycle cultured in vitro. Almost 6% of genes were differentially expressed between the two life-cycle stages. We identified 5′ splice-acceptor sites (SAS) and polyadenylation sites (PAS) for 6959 and 5948 genes, respectively. Most genes have between one and three alternative SAS, but PAS are more dispersed. For 488 genes, SAS were identified downstream of the originally assigned initiator ATG, so a subsequent in-frame ATG presumably designates the start of the true coding sequence. In some cases, alternative SAS would give rise to mRNAs encoding proteins with different N-terminal sequences. We could identify the introns in two genes known to contain them, but found no additional genes with introns. Our study demonstrates the usefulness of the RNA-seq technology to study the transcriptional landscape of an organism whose genome has not been fully annotated.
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Affiliation(s)
- Tim Nicolai Siegel
- Laboratory of Molecular Parasitology, The Rockefeller University, New York, NY 10065, USA
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Brandão A. Trypanosomatid EST: a neglected information resource regarding flagellated protozoa? Mem Inst Oswaldo Cruz 2009; 103:622-6. [PMID: 18949338 DOI: 10.1590/s0074-02762008000600021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Adeilton Brandão
- Laboratório de Epidemiologia Molecular de Doenças Infecciosas, Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro, RJ, Brasil.
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Helm JR, Wilson ME, Donelson JE. Differential expression of a protease gene family in African trypanosomes. Mol Biochem Parasitol 2008; 163:8-18. [PMID: 18848586 DOI: 10.1016/j.molbiopara.2008.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 09/04/2008] [Accepted: 09/12/2008] [Indexed: 12/01/2022]
Abstract
During their life cycle African trypanosomes must quickly adapt to the different environments of the tsetse fly midgut and the mammalian bloodstream by modulating expression of many of their genes. One group of these differentially expressed genes encodes different forms of a major surface protease. Using a luciferase reporter gene transiently or permanently transfected into trypanosomes, we show here that the 3'-UTRs of these protease genes are responsible for their differential expression. Deletion analysis of the 389-bp 3'-UTR of one of the protease genes, MSP-B, demonstrated that it contains a U-rich regulatory region of about 23bp (UCGUCUGUUAUUUCUUAGUCCAG), which suppresses expression of the reporter protein in bloodstream trypanosomes by as much as 25-fold, but has little effect on the reporter expression in procyclic (tsetse fly) trypanosomes. Replacing the entire 3'-UTR with just this 23-bp element mimicked most of the suppression effect of the complete 3'-UTR. Northern blots showed that the 23-bp element influences the steady state RNA level, but not enough to account for the 25-fold suppression effect. Polysome analyses showed that in procyclic trypanosomes more of the total protease mRNA is associated with intermediate-sized and large polysomes than in bloodstream trypanosomes. Thus, the 23-bp element of this protease gene affects both the level of RNA and its translation.
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Affiliation(s)
- Jared R Helm
- Department of Biochemistry, University of Iowa, 4-339 Bowen Science Bldg., Iowa City, IA 52242, USA
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