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Gosavi U, Srivastava A, Badjatia N, Günzl A. Rapid block of pre-mRNA splicing by chemical inhibition of analog-sensitive CRK9 in Trypanosoma brucei. Mol Microbiol 2020; 113:1225-1239. [PMID: 32068297 PMCID: PMC7299817 DOI: 10.1111/mmi.14489] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 02/13/2020] [Accepted: 02/14/2020] [Indexed: 12/24/2022]
Abstract
Trypanosoma brucei CRK9 is an essential cyclin-dependent kinase for the parasite-specific mode of pre-mRNA processing. In trypanosomes, protein coding genes are arranged in directional arrays that are transcribed polycistronically, and individual mRNAs are generated by spliced leader trans-splicing and polyadenylation, processes that are functionally linked. Since CRK9 silencing caused a decline of mRNAs, a concomitant increase of unspliced pre-mRNAs and the disappearance of the trans-splicing Y structure intermediate, CRK9 is essential for the first step of splicing. CRK9 depletion also caused a loss of phosphorylation in RPB1, the largest subunit of RNA polymerase (pol) II. Here, we established cell lines that exclusively express analog-sensitive CRK9 (CRK9AS ). Inhibition of CRK9AS in these cells by the ATP-competitive inhibitor 1-NM-PP1 reproduced the splicing defects and proved that it is the CKR9 kinase activity that is required for pre-mRNA processing. Since defective trans-splicing was detected as early as 5 min after inhibitor addition, CRK9 presumably carries out reversible phosphorylation on the pre-mRNA processing machinery. Loss of RPB1 phosphorylation, however, took 12-24 hr. Surprisingly, RNA pol II-mediated RNA synthesis in 24 hr-treated cells was upregulated, indicating that, in contrast to other eukaryotes, RPB1 phosphorylation is not a prerequisite for transcription in trypanosomes.
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Affiliation(s)
- Ujwala Gosavi
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
| | - Ankita Srivastava
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
| | - Nitika Badjatia
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
- Current address: Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Arthur Günzl
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
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Manzano-Román R, Fuentes M. Relevance and proteomics challenge of functional posttranslational modifications in Kinetoplastid parasites. J Proteomics 2020; 220:103762. [PMID: 32244008 DOI: 10.1016/j.jprot.2020.103762] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/06/2020] [Accepted: 03/23/2020] [Indexed: 02/06/2023]
Abstract
Protozoan parasitic infections are health, social and economic issues impacting both humans and animals, with significant morbidity and mortality worldwide. Protozoan parasites have complicated life cycles with both intracellular and extracellular forms. As a consequence, protozoan adapt to changing environments in part through a dynamic enzyme-catalyzed process leading to reversible posttranslational modifications (PTMs). The characterization by proteomics approaches reveals the critical role of the PTMs of the proteins involved in host-pathogen interaction. The complexity of PTMs characterization is increased by the high diversity, stoichiometry, dynamic and also co-existence of several PTMs in the same moieties which crosstalk between them. Here, we review how to understand the complexity and the essential role of PTMs crosstalk in order to provide a new hallmark for vaccines developments, immunotherapies and personalized medicine. In addition, the importance of these motifs in the biology and biological cycle of kinetoplastid parasites is highlighted with key examples showing the potential to act as targets against protozoan diseases.
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Affiliation(s)
- R Manzano-Román
- Proteomics Unit, Cancer Research Centre (IBMCC/CSIC/USAL/IBSAL), 37007, Salamanca, Spain..
| | - M Fuentes
- Proteomics Unit, Cancer Research Centre (IBMCC/CSIC/USAL/IBSAL), 37007, Salamanca, Spain.; Proteomics Unit, Cancer Research Centre (IBMCC/CSIC/USAL/IBSAL), 37007 Salamanca, Spain; Department of Medicine and General Cytometry Service-Nucleus, Cancer Research Centre (IBMCC/CSIC/USAL/IBSAL), 37007, Salamanca, Spain
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Kieft R, Zhang Y, Marand AP, Moran JD, Bridger R, Wells L, Schmitz RJ, Sabatini R. Identification of a novel base J binding protein complex involved in RNA polymerase II transcription termination in trypanosomes. PLoS Genet 2020; 16:e1008390. [PMID: 32084124 PMCID: PMC7055916 DOI: 10.1371/journal.pgen.1008390] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 03/04/2020] [Accepted: 01/08/2020] [Indexed: 11/18/2022] Open
Abstract
Base J, β-D-glucosyl-hydroxymethyluracil, is a modification of thymine DNA base involved in RNA Polymerase (Pol) II transcription termination in kinetoplastid protozoa. Little is understood regarding how specific thymine residues are targeted for J-modification or the mechanism of J regulated transcription termination. To identify proteins involved in J-synthesis, we expressed a tagged version of the J-glucosyltransferase (JGT) in Leishmania tarentolae, and identified four co-purified proteins by mass spectrometry: protein phosphatase (PP1), a homolog of Wdr82, a potential PP1 regulatory protein (PNUTS) and a protein containing a J-DNA binding domain (named JBP3). Gel shift studies indicate JBP3 is a J-DNA binding protein. Reciprocal tagging, co-IP and sucrose gradient analyses indicate PP1, JGT, JBP3, Wdr82 and PNUTS form a multimeric complex in kinetoplastids, similar to the mammalian PTW/PP1 complex involved in transcription termination via PP1 mediated dephosphorylation of Pol II. Using RNAi and analysis of Pol II termination by RNA-seq and RT-PCR, we demonstrate that ablation of PNUTS, JBP3 and Wdr82 lead to defects in Pol II termination at the 3'-end of polycistronic gene arrays in Trypanosoma brucei. Mutants also contain increased antisense RNA levels upstream of transcription start sites, suggesting an additional role of the complex in regulating termination of bi-directional transcription. In addition, PNUTS loss causes derepression of silent Variant Surface Glycoprotein genes involved in host immune evasion. Our results suggest a novel mechanistic link between base J and Pol II polycistronic transcription termination in kinetoplastids.
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Affiliation(s)
- Rudo Kieft
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Yang Zhang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Alexandre P. Marand
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Jose Dagoberto Moran
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Robert Bridger
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Lance Wells
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Robert J. Schmitz
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Robert Sabatini
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
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Srivastava A, Badjatia N, Lee JH, Hao B, Günzl A. An RNA polymerase II-associated TFIIF-like complex is indispensable for SL RNA gene transcription in Trypanosoma brucei. Nucleic Acids Res 2019; 46:1695-1709. [PMID: 29186511 PMCID: PMC5829719 DOI: 10.1093/nar/gkx1198] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 11/17/2017] [Indexed: 12/23/2022] Open
Abstract
Trypanosomes are protistan parasites that diverged early in evolution from most eukaryotes. Their streamlined genomes are packed with arrays of tandemly linked genes that are transcribed polycistronically by RNA polymerase (pol) II. Individual mRNAs are processed from pre-mRNA by spliced leader (SL) trans splicing and polyadenylation. While there is no strong evidence that general transcription factors are needed for transcription initiation at these gene arrays, a RNA pol II transcription pre-initiation complex (PIC) is formed on promoters of SLRNA genes, which encode the small nuclear SL RNA, the SL donor in trans splicing. The factors that form the PIC are extremely divergent orthologues of the small nuclear RNA-activating complex, TBP, TFIIA, TFIIB, TFIIH, TFIIE and Mediator. Here, we functionally characterized a heterodimeric complex of unannotated, nuclear proteins that interacts with RNA pol II and is essential for PIC formation, SL RNA synthesis in vivo, SLRNA transcription in vitro, and parasite viability. These functional attributes suggest that the factor represents TFIIF although the amino acid sequences are too divergent to firmly make this conclusion. This work strongly indicates that early-diverged trypanosomes have orthologues of each and every general transcription factor, requiring them for the synthesis of SL RNA.
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Affiliation(s)
- Ankita Srivastava
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
| | - Nitika Badjatia
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
| | - Ju Huck Lee
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
| | - Bing Hao
- Department of Molecular Biology and Biophysics, UConn Health, 263 Farmington Avenue, Farmington, CT 06030-3305, USA
| | - Arthur Günzl
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
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Abstract
In trypanosomes, RNA polymerase II transcription is polycistronic and individual mRNAs are excised by trans-splicing and polyadenylation. The lack of individual gene transcription control is compensated by control of mRNA processing, translation and degradation. Although the basic mechanisms of mRNA decay and translation are evolutionarily conserved, there are also unique aspects, such as the existence of six cap-binding translation initiation factor homologues, a novel decapping enzyme and an mRNA stabilizing complex that is recruited by RNA-binding proteins. High-throughput analyses have identified nearly a hundred regulatory mRNA-binding proteins, making trypanosomes valuable as a model system to investigate post-transcriptional regulation.
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Affiliation(s)
- Christine Clayton
- University of Heidelberg Center for Molecular Biology (ZMBH), Im Neuenheimer Feld 282, D69120 Heidelberg, Germany
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