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Galili-Kostin B, Rajan KS, Ida Ashkenazi Y, Freedman A, Doniger T, Cohen-Chalamish S, Waldman Ben-Asher H, Unger R, Roditi I, Tschudi C, Michaeli S. TblncRNA-23, a long non-coding RNA transcribed by RNA polymerase I, regulates developmental changes in Trypanosoma brucei. Nat Commun 2025; 16:3697. [PMID: 40251171 PMCID: PMC12008373 DOI: 10.1038/s41467-025-58979-w] [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: 03/20/2024] [Accepted: 04/08/2025] [Indexed: 04/20/2025] Open
Abstract
The protozoan parasite Trypanosoma brucei undergoes a complex life cycle, moving between its mammalian host and the blood-feeding tsetse fly vector. The two major surface proteins expressed by procyclic forms in the insect midgut, EP and GPEET procyclin, are transcribed from a polycistronic transcription unit by RNA polymerase I. Here we identify a long non-coding RNA, TblncRNA-23, that is encoded between the two procyclin genes. TblncRNA-23 localizes to the nucleolus and also associates with polysomes. Overexpression of TblncRNA-23 and its down regulation by RNAi or knockout (KO) identify EP and GPEET mRNAs as targets, among other mRNAs that changed abundance in the transition from early to late procyclic forms and from procylic to the metacylic forms, suggesting its role in regulating gene expression which accomapines or dictates of the parasite transitions within in its insect host. TblncRNA-23 interacts with its substrates via base-pairing using different domains. Purification of TblncRNA-23-associated proteins by RaPID identifies hundreds of proteins, including proteins translated from its target mRNAs, suggesting its association with translating ribosomes. Early and late procyclic forms differ in their social motility (SoMo) capabilities, which is essential for migration away from the insect midgut to enable parasite transmission. Overexpression of TblncRNA-23 results in hypermotility, whereas KO compromises this capacity, suggesting a regulatory role in SoMo. Moreover, silencing of the RNA abrogates the ability of the parasite to transform from procylic to the metacyclic forms affecting the parasite's potential to cycle between its hosts.
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Affiliation(s)
- Beathrice Galili-Kostin
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - K Shanmugha Rajan
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Yuval Ida Ashkenazi
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Almog Freedman
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Tirza Doniger
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Smadar Cohen-Chalamish
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Hiba Waldman Ben-Asher
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Ron Unger
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | | | - Christian Tschudi
- Yale School of Public Health, Department of Epidemiology and Microbial Diseases, New Haven, CT, 06536, USA
| | - Shulamit Michaeli
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 52900, Israel.
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Gao J, Wu XJ, Zheng XN, Li TT, Kou YJ, Wang XC, Wang M, Zhu XQ. Functional Characterization of Eight Zinc Finger Motif-Containing Proteins in Toxoplasma gondii Type I RH Strain Using the CRISPR-Cas9 System. Pathogens 2023; 12:1232. [PMID: 37887748 PMCID: PMC10609756 DOI: 10.3390/pathogens12101232] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/03/2023] [Accepted: 10/06/2023] [Indexed: 10/28/2023] Open
Abstract
The Zinc finger protein (ZFP) family is widely distributed in eukaryotes and interacts with DNA, RNA, and various proteins to participate in many molecular processes. In the present study, the biological functions of eight ZFP genes in the lytic cycle and the pathogenicity of Toxoplasma gondii were examined using the CRISPR-Cas9 system. Immunofluorescence showed that four ZFPs (RH248270-HA, RH255310-HA, RH309200-HA, and RH236640-HA) were localized in the cytoplasm, and one ZFP (RH273150-HA) was located in the nucleus, while the expression level of RH285190-HA, RH260870-HA, and RH248450-HA was undetectable. No significant differences were detected between seven RHΔzfp strains (RHΔ285190, RHΔ248270, RHΔ260870, RHΔ255310, RHΔ309200, RHΔ248450, and RHΔ236640) and the wild-type (WT) strain in the T. gondii lytic cycle, including plaque formation, invasion, intracellular replication, and egress, as well as in vitro virulence (p > 0.05). However, the RHΔ273150 strain exhibited significantly lower replication efficiency compared to the other seven RHΔzfp strains and the WT strain, while in vivo virulence in mice was not significantly affected. Comparative expression analysis of the eight zfp genes indicates that certain genes may have essential functions in the sexual reproductive stage of T. gondii. Taken together, these findings expand our current understanding of the roles of ZFPs in T. gondii.
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Affiliation(s)
- Jin Gao
- Laboratory of Parasitic Diseases, College of Veterinary Medicine, Shanxi Agricultural University, Taigu, Jinzhong 030801, China; (J.G.); (X.-J.W.); (X.-N.Z.); (Y.-J.K.)
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China; (T.-T.L.); (X.-C.W.)
| | - Xiao-Jing Wu
- Laboratory of Parasitic Diseases, College of Veterinary Medicine, Shanxi Agricultural University, Taigu, Jinzhong 030801, China; (J.G.); (X.-J.W.); (X.-N.Z.); (Y.-J.K.)
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China; (T.-T.L.); (X.-C.W.)
| | - Xiao-Nan Zheng
- Laboratory of Parasitic Diseases, College of Veterinary Medicine, Shanxi Agricultural University, Taigu, Jinzhong 030801, China; (J.G.); (X.-J.W.); (X.-N.Z.); (Y.-J.K.)
| | - Ting-Ting Li
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China; (T.-T.L.); (X.-C.W.)
| | - Yong-Jie Kou
- Laboratory of Parasitic Diseases, College of Veterinary Medicine, Shanxi Agricultural University, Taigu, Jinzhong 030801, China; (J.G.); (X.-J.W.); (X.-N.Z.); (Y.-J.K.)
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China; (T.-T.L.); (X.-C.W.)
| | - Xin-Cheng Wang
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China; (T.-T.L.); (X.-C.W.)
| | - Meng Wang
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China; (T.-T.L.); (X.-C.W.)
| | - Xing-Quan Zhu
- Laboratory of Parasitic Diseases, College of Veterinary Medicine, Shanxi Agricultural University, Taigu, Jinzhong 030801, China; (J.G.); (X.-J.W.); (X.-N.Z.); (Y.-J.K.)
- Key Laboratory of Veterinary Public Health of Higher Education of Yunnan Province, College of Veterinary Medicine, Yunnan Agricultural University, Kunming 650201, China
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3
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Licon MH, Giuliano CJ, Chan AW, Chakladar S, Eberhard JN, Shallberg LA, Chandrasekaran S, Waldman BS, Koshy AA, Hunter CA, Lourido S. A positive feedback loop controls Toxoplasma chronic differentiation. Nat Microbiol 2023; 8:889-904. [PMID: 37081202 PMCID: PMC10520893 DOI: 10.1038/s41564-023-01358-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 03/07/2023] [Indexed: 04/22/2023]
Abstract
Successful infection strategies must balance pathogen amplification and persistence. In the obligate intracellular parasite Toxoplasma gondii this is accomplished through differentiation into dedicated cyst-forming chronic stages that avoid clearance by the host immune system. The transcription factor BFD1 is both necessary and sufficient for stage conversion; however, its regulation is not understood. In this study we examine five factors that are transcriptionally activated by BFD1. One of these is a cytosolic RNA-binding protein of the CCCH-type zinc-finger family, which we name bradyzoite formation deficient 2 (BFD2). Parasites lacking BFD2 fail to induce BFD1 and are consequently unable to fully differentiate in culture or in mice. BFD2 interacts with the BFD1 transcript under stress, and deletion of BFD2 reduces BFD1 protein levels but not messenger RNA abundance. The reciprocal effects on BFD2 transcription and BFD1 translation outline a positive feedback loop that enforces the chronic-stage gene-expression programme. Thus, our findings help explain how parasites both initiate and commit to chronic differentiation. This work provides new mechanistic insight into the regulation of T. gondii persistence, and can be exploited in the design of strategies to prevent and treat these key reservoirs of human infection.
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Affiliation(s)
| | - Christopher J Giuliano
- Whitehead Institute, Cambridge, MA, USA
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Alex W Chan
- Whitehead Institute, Cambridge, MA, USA
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sundeep Chakladar
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Julia N Eberhard
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Lindsey A Shallberg
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Benjamin S Waldman
- Whitehead Institute, Cambridge, MA, USA
- Department of Microbiology and Immunology, School of Medicine, Stanford University, Stanford, CA, USA
| | - Anita A Koshy
- BIO5 Institute, University of Arizona, Tucson, AZ, USA
- Department of Neurology, Department of Immunobiology, University of Arizona, Tucson, AZ, USA
| | - Christopher A Hunter
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sebastian Lourido
- Whitehead Institute, Cambridge, MA, USA.
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Ashby E, Paddock L, Betts HL, Liao J, Miller G, Porter A, Rollosson LM, Saada C, Tang E, Wade SJ, Hardin J, Schulz D. Genomic Occupancy of the Bromodomain Protein Bdf3 Is Dynamic during Differentiation of African Trypanosomes from Bloodstream to Procyclic Forms. mSphere 2022; 7:e0002322. [PMID: 35642518 PMCID: PMC9241505 DOI: 10.1128/msphere.00023-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 05/05/2022] [Indexed: 12/05/2022] Open
Abstract
Trypanosoma brucei, the causative agent of human and animal African trypanosomiasis, cycles between a mammalian host and a tsetse fly vector. The parasite undergoes huge changes in morphology and metabolism during adaptation to each host environment. These changes are reflected in the different transcriptomes of parasites living in each host. However, it remains unclear whether chromatin-interacting proteins help mediate these changes. Bromodomain proteins localize to transcription start sites in bloodstream parasites, but whether the localization of bromodomain proteins changes as parasites differentiate from bloodstream to insect stages remains unknown. To address this question, we performed cleavage under target and release using nuclease (CUT&RUN) against bromodomain protein 3 (Bdf3) in parasites differentiating from bloodstream to insect forms. We found that Bdf3 occupancy at most loci increased at 3 h following onset of differentiation and decreased thereafter. A number of sites with increased bromodomain protein occupancy lie proximal to genes with altered transcript levels during differentiation, such as procyclins, procyclin-associated genes, and invariant surface glycoproteins. Most Bdf3-occupied sites are observed throughout differentiation. However, one site appears de novo during differentiation and lies proximal to the procyclin gene locus housing genes essential for remodeling surface proteins following transition to the insect stage. These studies indicate that occupancy of chromatin-interacting proteins is dynamic during life cycle stage transitions and provide the groundwork for future studies on the effects of changes in bromodomain protein occupancy. Additionally, the adaptation of CUT&RUN for Trypanosoma brucei provides other researchers with an alternative to chromatin immunoprecipitation (ChIP). IMPORTANCE The parasite Trypanosoma brucei is the causative agent of human and animal African trypanosomiasis (sleeping sickness). Trypanosomiasis, which affects humans and cattle, is fatal if untreated. Existing drugs have significant side effects. Thus, these parasites impose a significant human and economic burden in sub-Saharan Africa, where trypanosomiasis is endemic. T. brucei cycles between the mammalian host and a tsetse fly vector, and parasites undergo huge changes in morphology and metabolism to adapt to different hosts. Here, we show that DNA-interacting bromodomain protein 3 (Bdf3) shows changes in occupancy at its binding sites as parasites transition from the bloodstream to the insect stage. Additionally, a new binding site appears near the locus responsible for remodeling of parasite surface proteins during transition to the insect stage. Understanding the mechanisms behind host adaptation is important for understanding the life cycle of the parasite.
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Affiliation(s)
- Ethan Ashby
- Department of Mathematics and Statistics, Pomona College, Claremont, California, USA
| | - Lucinda Paddock
- Department of Biology, Harvey Mudd College, Claremont, California, USA
| | - Hannah L. Betts
- Department of Biology, Harvey Mudd College, Claremont, California, USA
| | - Jingwen Liao
- Department of Biology, Harvey Mudd College, Claremont, California, USA
| | - Geneva Miller
- Department of Biology, Harvey Mudd College, Claremont, California, USA
| | - Anya Porter
- Department of Biology, Harvey Mudd College, Claremont, California, USA
| | | | - Carrie Saada
- Department of Biology, Harvey Mudd College, Claremont, California, USA
| | - Eric Tang
- Department of Biology, Harvey Mudd College, Claremont, California, USA
| | - Serenity J. Wade
- Department of Biology, Harvey Mudd College, Claremont, California, USA
| | - Johanna Hardin
- Department of Mathematics and Statistics, Pomona College, Claremont, California, USA
| | - Danae Schulz
- Department of Biology, Harvey Mudd College, Claremont, California, USA
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5
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Oldrieve GR, Malacart B, López-Vidal J, Matthews KR. The genomic basis of host and vector specificity in non-pathogenic trypanosomatids. Biol Open 2022; 11:bio059237. [PMID: 35373253 PMCID: PMC9099014 DOI: 10.1242/bio.059237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/25/2022] [Indexed: 11/20/2022] Open
Abstract
Trypanosoma theileri, a non-pathogenic parasite of bovines, has a predicted surface protein architecture that likely aids survival in its mammalian host. Their surface proteins are encoded by genes which account for ∼10% of their genome. A non-pathogenic parasite of sheep, Trypanosoma melophagium, is transmitted by the sheep ked and is closely related to T. theileri. To explore host and vector specificity between these species, we sequenced the T. melophagium genome and transcriptome and an annotated draft genome was assembled. T. melophagium was compared to 43 kinetoplastid genomes, including T. theileri. T. melophagium and T. theileri have an AT biased genome, the greatest bias of publicly available trypanosomatids. This trend may result from selection acting to decrease the genomic nucleotide cost. The T. melophagium genome is 6.3Mb smaller than T. theileri and large families of proteins, characteristic of the predicted surface of T. theileri, were found to be absent or greatly reduced in T. melophagium. Instead, T. melophagium has modestly expanded protein families associated with the avoidance of complement-mediated lysis. We propose that the contrasting genomic features of these species is linked to their mode of transmission from their insect vector to their mammalian host. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Guy R. Oldrieve
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, UK
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Cheng X, Tian B, Gao C, Gao W, Yan S, Yao H, Wang X, Jiang Y, Hu L, Pan X, Cao J, Lu J, Ma C, Chang C, Zhang H. Identification and expression analysis of candidate genes related to seed dormancy and germination in the wheat GATA family. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 169:343-359. [PMID: 34837867 DOI: 10.1016/j.plaphy.2021.11.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/21/2021] [Accepted: 11/10/2021] [Indexed: 06/13/2023]
Abstract
GATA transcription factors have been reported to function in plant growth and development and during various biotic/abiotic stresses in Arabidopsis and rice. However, the functions of wheat GATAs, particularly in the regulation of seed dormancy and germination, remain unclear. Here, we identified 78 TaGATAs in wheat and divided them into five subfamilies. Sixty-four paralogous pairs and 52 orthologous pairs were obtained, and Ka/Ks ratios showed that the TaGATAs had undergone strong purifying election during the evolutionary process. Triplet analysis indicated that a high homologue retention rate could explain the large number of TaGATAs in wheat. Gene structure analysis revealed that most members of the same subfamily had similar structures, and subcellular localization prediction indicated that most TaGATAs were located in the nucleus. Gene ontology annotation results showed that most TaGATAs had molecular functions in DNA and zinc binding, and promoter analysis suggested that they may play important roles in growth, development, and biotic/abiotic stress response. We combined three microarray datasets with qRT-PCR expression data from wheat varieties of contrasting dormancy and pre-harvest sprouting resistance levels during imbibition in order to identify ten candidate genes (TaGATA17/-25/-34/-37/-40/-46/-48/-51/-72/-73) that may be involved in the regulation of seed dormancy and germination in wheat. These findings provide valuable information for further dissection of TaGATA functions in the regulation of seed dormancy and germination, thereby enabling the improvement of wheat pre-harvest sprouting resistance by gene pyramiding.
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Affiliation(s)
- Xinran Cheng
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China; National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, China
| | - Bingbing Tian
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Chang Gao
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Wei Gao
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Shengnan Yan
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Hui Yao
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Xuyang Wang
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Yating Jiang
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Leixue Hu
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Xu Pan
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Jiajia Cao
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Jie Lu
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Chuanxi Ma
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Cheng Chang
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China.
| | - Haiping Zhang
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China.
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Abstract
Abstract
In Trypanosoma brucei and related Kinetoplastids, regulation of gene expression occurs mostly post-transcriptionally, and RNA-binding proteins play a critical role in the regulation of mRNA and protein abundance. Trypanosoma brucei ZC3H28 is a 114 KDa cytoplasmic mRNA-binding protein with a single C(x)7C(x)5C(x)sH zinc finger at the C-terminus and numerous proline-, histidine- or glutamine-rich regions. ZC3H28 is essential for normal bloodstream-form trypanosome growth, and when tethered to a reporter mRNA, ZC3H28 increased reporter mRNA and protein levels. Purification of N-terminally tagged ZC3H28 followed by mass spectrometry showed enrichment of ribosomal proteins, various RNA-binding proteins including both poly(A) binding proteins, the translation initiation complex EIF4E4/EIF4G3, and the activator MKT1. Tagged ZC3H28 was preferentially associated with long RNAs that have low complexity sequences in their 3′-untranslated regions; their coding regions also have low ribosome densities. In agreement with the tethering results, after ZC3H28 depletion, the levels of a significant proportion of its bound mRNAs decreased. We suggest that ZC3H28 is implicated in the stabilization of long mRNAs that are poorly translated.
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Cheng X, Cao J, Gao C, Gao W, Yan S, Yao H, Xu K, Liu X, Xu D, Pan X, Lu J, Chang C, Zhang H, Ma C. Identification of the wheat C3H gene family and expression analysis of candidates associated with seed dormancy and germination. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 156:524-537. [PMID: 33053501 DOI: 10.1016/j.plaphy.2020.09.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/28/2020] [Indexed: 05/01/2023]
Abstract
C3H zinc finger transcription factors play important roles in managing various biotic/abiotic stresses in Aarabidopsis, rice, and maize. The functions of these factors in wheat, however, remain largely unclear. We identified 88 TaC3H genes that were divided into four subfamilies in this analysis. Gene structure and conserved domain analyses indicate that most members of the same subfamily have similar structures. A total of 76 paralogous and 48 orthologous pairs were identified and Ka/Ks values were used to analyze replication relationships amongst wheat, rice, and Arabidopsis. Gene ontology (GO) annotation analysis showed that most TaC3H genes possessed molecular functions, while transcriptome results showed that the 88 TaC3H genes responded to water imbibition. Microarray data for 53 TaC3H genes were obtained and heat maps were generated; these results indicate that these genes are expressed in 13 wheat tissues. Subcellular localization prediction analysis indicates that most TaC3H genes are located in the nucleus. Promoter analysis indicates that most TaC3H genes contained cis-elements including ABRE, GARE-motif, and MBS, indicating that these can respond to various biotic/abiotic stresses. Transcriptome data and quantitative real-time PCR analysis of wheat cultivars with contrasting seed dormancy phenotypes show that five genes TaC3H4/-18/-37/-51/-72 were very likely involved in seed dormancy and germination. Exogenous ABA treatment further indicated that these five genes were responsive to ABA, suggesting that there may be a crosstalk between these genes and ABA signaling pathway in controlling seed dormancy and germination. These results provide a theoretical basis for subsequent studies on TaC3H gene function and also contribute to studies on the C3H gene in other species.
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Affiliation(s)
- Xinran Cheng
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Jiajia Cao
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Chang Gao
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Wei Gao
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Shengnan Yan
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Hui Yao
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Kangle Xu
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Xue Liu
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Dongmei Xu
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Xu Pan
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Jie Lu
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
| | - Cheng Chang
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China.
| | - Haiping Zhang
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China.
| | - Chuanxi Ma
- College of Agronomy, Anhui Agricultural University, Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, Ministry of Agriculture and Rural Affairs, Hefei, 230036, Anhui, China
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9
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Ferreira TR, Dowle AA, Parry E, Alves-Ferreira EVC, Hogg K, Kolokousi F, Larson TR, Plevin MJ, Cruz AK, Walrad PB. PRMT7 regulates RNA-binding capacity and protein stability in Leishmania parasites. Nucleic Acids Res 2020; 48:5511-5526. [PMID: 32365184 PMCID: PMC7261171 DOI: 10.1093/nar/gkaa211] [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: 08/12/2019] [Revised: 03/17/2020] [Accepted: 04/16/2020] [Indexed: 12/12/2022] Open
Abstract
RNA binding proteins (RBPs) are the primary gene regulators in kinetoplastids as transcriptional control is nearly absent, making Leishmania an exceptional model for investigating methylation of non-histone substrates. Arginine methylation is an evolutionarily conserved protein modification catalyzed by Protein aRginine Methyl Transferases (PRMTs). The chromatin modifier PRMT7 is the only Type III PRMT found in higher eukaryotes and a restricted number of unicellular eukaryotes. In Leishmania major, PRMT7 is a cytoplasmic protein implicit in pathogenesis with unknown substrates. Using comparative methyl-SILAC proteomics for the first time in protozoa, we identified 40 putative targets, including 17 RBPs hypomethylated upon PRMT7 knockout. PRMT7 can modify Alba3 and RBP16 trans-regulators (mammalian RPP25 and YBX2 homologs, respectively) as direct substrates in vitro. The absence of PRMT7 levels in vivo selectively reduces Alba3 mRNA-binding capacity to specific target transcripts and can impact the relative stability of RBP16 in the cytoplasm. RNA immunoprecipitation analyses demonstrate PRMT7-dependent methylation promotes Alba3 association with select target transcripts and thus indirectly stabilizes mRNA of a known virulence factor, δ-amastin surface antigen. These results highlight a novel role for PRMT7-mediated arginine methylation of RBP substrates, suggesting a regulatory pathway controlling gene expression and virulence in Leishmania. This work introduces Leishmania PRMTs as epigenetic regulators of mRNA metabolism with mechanistic insight into the functional manipulation of RBPs by methylation.
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Affiliation(s)
- Tiago R Ferreira
- York Biomedical Research Institute, Department of Biology, University of York, York, UK
| | - Adam A Dowle
- Metabolomics and Proteomics Lab, Bioscience Technology Facility, Department of Biology, University of York, UK
| | - Ewan Parry
- York Biomedical Research Institute, Department of Biology, University of York, York, UK
| | | | - Karen Hogg
- Imaging and Cytometry Lab, Bioscience Technology Facility, Department of Biology, University of York, UK
| | - Foteini Kolokousi
- York Biomedical Research Institute, Department of Biology, University of York, York, UK
| | - Tony R Larson
- Metabolomics and Proteomics Lab, Bioscience Technology Facility, Department of Biology, University of York, UK
| | - Michael J Plevin
- York Biomedical Research Institute, Department of Biology, University of York, York, UK
| | - Angela K Cruz
- Cell and Molecular Biology Department, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Pegine B Walrad
- York Biomedical Research Institute, Department of Biology, University of York, York, UK
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10
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Walsh ME, Naudzius EM, Diaz SJ, Wismar TW, Martchenko Shilman M, Schulz D. Identification of clinically approved small molecules that inhibit growth and affect transcript levels of developmentally regulated genes in the African trypanosome. PLoS Negl Trop Dis 2020; 14:e0007790. [PMID: 32168320 PMCID: PMC7094864 DOI: 10.1371/journal.pntd.0007790] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 03/25/2020] [Accepted: 01/21/2020] [Indexed: 01/08/2023] Open
Abstract
Trypanosoma brucei are unicellular parasites endemic to Sub-Saharan Africa that cause fatal disease in humans and animals. Infection with these parasites is caused by the bite of the tsetse fly vector, and parasites living extracellularly in the blood of infected animals evade the host immune system through antigenic variation. Existing drugs for Human and Animal African Trypanosomiasis are difficult to administer and can have serious side effects. Resistance to some drugs is also increasing, creating an urgent need for alternative trypanosomiasis therapeutics. We screened a library of 1,585 U.S. or foreign-approved drugs and identified 154 compounds that inhibit trypanosome growth. As all of these compounds have already undergone testing for human toxicity, they represent good candidates for repurposing as trypanosome therapeutics. In addition to identifying drugs that inhibit trypanosome growth, we wished to identify small molecules that can induce bloodstream form parasites to differentiate into forms adapted for the insect vector. These insect stage parasites lack the immune evasion mechanisms prevalent in bloodstream forms, making them vulnerable to the host immune system. To identify drugs that increase transcript levels of an invariant, insect-stage specific surface protein called procyclin, we engineered bloodstream reporter parasites that express Green Fluorescent Protein (GFP) following induction or stabilization of the procyclin transcript. Using these bloodstream reporter strains in combination with automated flow cytometry, we identified eflornithine, spironolactone, and phenothiazine as small molecules that increase abundance of procyclin transcript. Both eflornithine and spironolactone also affect transcript levels for a subset of differentiation associated genes. While we failed to identify compounds that increase levels of procyclin protein on the cell surface, this study is proof of principle that these fluorescent reporter parasites represent a useful tool for future small molecule or genetic screens aimed at identifying molecules or processes that initiate remodeling of the parasite surface during life cycle stage transitions.
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Affiliation(s)
- Madison Elle Walsh
- Department of Biology, Harvey Mudd College, Claremont, California, United States of America
| | - Eleanor Mary Naudzius
- Department of Biology, Harvey Mudd College, Claremont, California, United States of America
| | - Savanah Jessica Diaz
- Department of Biology, Harvey Mudd College, Claremont, California, United States of America
| | | | - Mikhail Martchenko Shilman
- School of Applied Life Sciences, Keck Graduate Institute, Claremont, California, United States of America
| | - Danae Schulz
- Department of Biology, Harvey Mudd College, Claremont, California, United States of America
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11
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Szöőr B, Silvester E, Matthews KR. A Leap Into the Unknown - Early Events in African Trypanosome Transmission. Trends Parasitol 2020; 36:266-278. [PMID: 32014419 DOI: 10.1016/j.pt.2019.12.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/19/2019] [Accepted: 12/25/2019] [Indexed: 01/09/2023]
Abstract
African trypanosomes are mainly transmitted by tsetse flies. In recent years there has been good progress in understanding how the parasites prepare for transmission, detect their changed environment through the perception of different environmental cues, and respond by changing their developmental gene expression. In this review, we discuss the different signals and signaling mechanisms used by the parasites to carry out the early events necessary for their establishment in the fly. We also compare Trypanosoma brucei and Trypanosoma congolense, parasites that share a common pathway in the early stages of fly colonization but apparently use different mechanisms to achieve this.
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Affiliation(s)
- Balázs Szöőr
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK.
| | - Eleanor Silvester
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Keith R Matthews
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK.
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12
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de Pablos LM, Ferreira TR, Dowle AA, Forrester S, Parry E, Newling K, Walrad PB. The mRNA-bound Proteome of Leishmania mexicana: Novel Genetic Insight into an Ancient Parasite. Mol Cell Proteomics 2019; 18:1271-1284. [PMID: 30948621 PMCID: PMC6601212 DOI: 10.1074/mcp.ra118.001307] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 02/23/2019] [Indexed: 01/08/2023] Open
Abstract
Leishmania parasite infections, termed the leishmaniases, cause significant global infectious disease burden. The lifecycle of the parasite embodies three main stages that require precise coordination of gene regulation to survive environmental shifts between sandfly and mammalian hosts. Constitutive transcription in kinetoplastid parasites means that gene regulation is overwhelmingly reliant on post-transcriptional mechanisms, yet strikingly few Leishmania trans-regulators are known. Using optimized crosslinking and deep, quantified mass spectrometry, we present a comprehensive analysis of 1400 mRNA binding proteins (mRBPs) and whole cell proteomes from the three main Leishmania lifecycle stages. Supporting the validity, although the crosslinked RBPome is magnitudes more enriched, the protein identities of the crosslinked and non-crosslinked RBPomes were nearly identical. Moreover, multiple candidate RBPs were endogenously tagged and found to associate with discrete mRNA target pools in a stage-specific manner. Results indicate that in L. mexicana parasites, mRNA levels are not a strong predictor of the whole cell expression or RNA binding potential of encoded proteins. Evidence includes a low correlation between transcript and corresponding protein expression and stage-specific variation in protein expression versus RNA binding potential. Unsurprisingly, RNA binding protein enrichment correlates strongly with relative replication efficiency of the specific lifecycle stage. Our study is the first to quantitatively define and compare the mRBPome of multiple stages in kinetoplastid parasites. It provides novel, in-depth insight into the trans-regulatory mRNA:Protein (mRNP) complexes that drive Leishmania parasite lifecycle progression.
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Affiliation(s)
| | | | - Adam A Dowle
- §Metabolomics and Proteomics Lab, Bioscience Technology Facility, and
| | | | - Ewan Parry
- From the ‡Centre for Immunology and Infection
| | - Katherine Newling
- ¶Genomics and Bioinformatics Lab, Bioscience Technology Facility, Department of Biology, University of York, UK
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13
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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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14
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Abstract
To satisfy its fatty acid needs, the extracellular eukaryotic parasite Trypanosoma brucei relies on two mechanisms: uptake of fatty acids from the host and de novo synthesis. We hypothesized that T. brucei modulates fatty acid synthesis in response to environmental lipid availability. The first committed step in fatty acid synthesis is catalyzed by acetyl coenzyme A (acetyl-CoA) carboxylase (ACC) and serves as a key regulatory point in other organisms. To test our hypothesis, T. brucei mammalian bloodstream and insect procyclic forms were grown in low-, normal-, or high-lipid media and the effect on T. brucei ACC (TbACC) mRNA, protein, and enzymatic activity was examined. In bloodstream form T. brucei, media lipids had no effect on TbACC expression or activity. In procyclic form T. brucei, we detected no change in TbACC mRNA levels but observed 2.7-fold-lower TbACC protein levels and 37% lower TbACC activity in high-lipid media than in low-lipid media. Supplementation of low-lipid media with the fatty acid stearate mimicked the effect of high lipid levels on TbACC activity. In procyclic forms, TbACC phosphorylation also increased 3.9-fold in high-lipid media compared to low-lipid media. Phosphatase treatment of TbACC increased activity, confirming that phosphorylation represented an inhibitory modification. Together, these results demonstrate a procyclic-form-specific environmental lipid response pathway that regulates TbACC posttranscriptionally, through changes in protein expression and phosphorylation. We propose that this environmental response pathway enables procyclic-form T. brucei to monitor the host lipid supply and downregulate fatty acid synthesis when host lipids are abundant and upregulate fatty acid synthesis when host lipids become scarce.IMPORTANCETrypanosoma brucei is a eukaryotic parasite that causes African sleeping sickness. T. brucei is transmitted by the blood-sucking tsetse fly. In order to adapt to its two very different hosts, T. brucei must sense the host environment and alter its metabolism to maximize utilization of host resources and minimize expenditure of its own resources. One key nutrient class is represented by fatty acids, which the parasite can either take from the host or make themselves. Our work describes a novel environmental regulatory pathway for fatty acid synthesis where the parasite turns off fatty acid synthesis when environmental lipids are abundant and turns on synthesis when the lipid supply is scarce. This pathway was observed in the tsetse midgut form but not the mammalian bloodstream form. However, pharmacological activation of this pathway in the bloodstream form to turn fatty acid synthesis off may be a promising new avenue for sleeping sickness drug discovery.
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15
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Romaniuk MA, Frasch AC, Cassola A. Translational repression by an RNA-binding protein promotes differentiation to infective forms in Trypanosoma cruzi. PLoS Pathog 2018; 14:e1007059. [PMID: 29864162 PMCID: PMC6002132 DOI: 10.1371/journal.ppat.1007059] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 06/14/2018] [Accepted: 04/25/2018] [Indexed: 01/08/2023] Open
Abstract
Trypanosomes, protozoan parasites of medical importance, essentially rely on post-transcriptional mechanisms to regulate gene expression in insect vectors and vertebrate hosts. RNA binding proteins (RBPs) that associate to the 3'-UTR of mature mRNAs are thought to orchestrate master developmental programs for these processes to happen. Yet, the molecular mechanisms by which differentiation occurs remain largely unexplored in these human pathogens. Here, we show that ectopic inducible expression of the RBP TcUBP1 promotes the beginning of the differentiation process from non-infective epimastigotes to infective metacyclic trypomastigotes in Trypanosoma cruzi. In early-log epimastigotes TcUBP1 promoted a drop-like phenotype, which is characterized by the presence of metacyclogenesis hallmarks, namely repositioning of the kinetoplast, the expression of an infective-stage virulence factor such as trans-sialidase, increased resistance to lysis by human complement and growth arrest. Furthermore, TcUBP1-ectopic expression in non-infective late-log epimastigotes promoted full development into metacyclic trypomastigotes. TcUBP1-derived metacyclic trypomastigotes were infective in cultured cells, and developed normally into amastigotes in the cytoplasm. By artificial in vivo tethering of TcUBP1 to the 3' untranslated region of a reporter mRNA we were able to determine that translation of the reporter was reduced by 8-fold, while its mRNA abundance was not significantly compromised. Inducible ectopic expression of TcUBP1 confirmed its role as a translational repressor, revealing significant reduction in the translation rate of multiple proteins, a reduction of polysomes, and promoting the formation of mRNA granules. Expression of TcUBP1 truncated forms revealed the requirement of both N and C-terminal glutamine-rich low complexity sequences for the development of the drop-like phenotype in early-log epimastigotes. We propose that a rise in TcUBP1 levels, in synchrony with nutritional deficiency, can promote the differentiation of T. cruzi epimastigotes into infective metacyclic trypomastigotes.
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Affiliation(s)
- Maria Albertina Romaniuk
- Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, San Martín, Provincia de Buenos Aires, Argentina
| | - Alberto Carlos Frasch
- Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, San Martín, Provincia de Buenos Aires, Argentina
| | - Alejandro Cassola
- Instituto de Investigaciones Biotecnológicas, UNSAM-CONICET, San Martín, Provincia de Buenos Aires, Argentina
- * E-mail:
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16
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Kelly S, Ivens A, Mott GA, O'Neill E, Emms D, Macleod O, Voorheis P, Tyler K, Clark M, Matthews J, Matthews K, Carrington M. An Alternative Strategy for Trypanosome Survival in the Mammalian Bloodstream Revealed through Genome and Transcriptome Analysis of the Ubiquitous Bovine Parasite Trypanosoma (Megatrypanum) theileri. Genome Biol Evol 2018; 9:2093-2109. [PMID: 28903536 PMCID: PMC5737535 DOI: 10.1093/gbe/evx152] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2017] [Indexed: 12/19/2022] Open
Abstract
There are hundreds of Trypanosoma species that live in the blood and tissue spaces of their vertebrate hosts. The vast majority of these do not have the ornate system of antigenic variation that has evolved in the small number of African trypanosome species, but can still maintain long-term infections in the face of the vertebrate adaptive immune system. Trypanosoma theileri is a typical example, has a restricted host range of cattle and other Bovinae, and is only occasionally reported to cause patent disease although no systematic survey of the effect of infection on agricultural productivity has been performed. Here, a detailed genome sequence and a transcriptome analysis of gene expression in bloodstream form T. theileri have been performed. Analysis of the genome sequence and expression showed that T. theileri has a typical kinetoplastid genome structure and allowed a prediction that it is capable of meiotic exchange, gene silencing via RNA interference and, potentially, density-dependent growth control. In particular, the transcriptome analysis has allowed a comparison of two distinct trypanosome cell surfaces, T. brucei and T. theileri, that have each evolved to enable the maintenance of a long-term extracellular infection in cattle. The T. theileri cell surface can be modeled to contain a mixture of proteins encoded by four novel large and divergent gene families and by members of a major surface protease gene family. This surface composition is distinct from the uniform variant surface glycoprotein coat on African trypanosomes providing an insight into a second mechanism used by trypanosome species that proliferate in an extracellular milieu in vertebrate hosts to avoid the adaptive immune response.
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Affiliation(s)
- Steven Kelly
- Department of Plant Sciences, University of Oxford, United Kingdom
| | - Alasdair Ivens
- Centre for Immunity, Infection and Evolution and Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - G Adam Mott
- Centre for Immunity, Infection and Evolution and Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Ellis O'Neill
- Department of Plant Sciences, University of Oxford, United Kingdom
| | - David Emms
- Department of Plant Sciences, University of Oxford, United Kingdom
| | - Olivia Macleod
- Department of Biochemistry, University of Cambridge, United Kingdom
| | - Paul Voorheis
- School of Biochemistry and Immunology, Trinity College, Dublin, Ireland
| | - Kevin Tyler
- Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Matthew Clark
- Earlham Institute, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Jacqueline Matthews
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, United Kingdom
| | - Keith Matthews
- Centre for Immunity, Infection and Evolution and Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, United Kingdom
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17
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Knockout of the CCCH zinc finger protein TcZC3H31 blocks Trypanosoma cruzi differentiation into the infective metacyclic form. Mol Biochem Parasitol 2018; 221:1-9. [DOI: 10.1016/j.molbiopara.2018.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 01/21/2018] [Accepted: 01/29/2018] [Indexed: 01/23/2023]
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18
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de Freitas Nascimento J, Kelly S, Sunter J, Carrington M. Codon choice directs constitutive mRNA levels in trypanosomes. eLife 2018; 7:e32467. [PMID: 29543152 PMCID: PMC5896880 DOI: 10.7554/elife.32467] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/27/2018] [Indexed: 11/13/2022] Open
Abstract
Selective transcription of individual protein coding genes does not occur in trypanosomes and the cellular copy number of each mRNA must be determined post-transcriptionally. Here, we provide evidence that codon choice directs the levels of constitutively expressed mRNAs. First, a novel codon usage metric, the gene expression codon adaptation index (geCAI), was developed that maximised the relationship between codon choice and the measured abundance for a transcriptome. Second, geCAI predictions of mRNA levels were tested using differently coded GFP transgenes and were successful over a 25-fold range, similar to the variation in endogenous mRNAs. Third, translation was necessary for the accelerated mRNA turnover resulting from codon choice. Thus, in trypanosomes, the information determining the levels of most mRNAs resides in the open reading frame and translation is required to access this information.
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Affiliation(s)
| | - Steven Kelly
- Department of Plant SciencesUniversity of OxfordOxfordUnited Kingdom
| | - Jack Sunter
- Department of BiochemistryUniversity of CambridgeCambridgeUnited Kingdom
| | - Mark Carrington
- Department of BiochemistryUniversity of CambridgeCambridgeUnited Kingdom
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19
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Freire ER, Moura DMN, Bezerra MJR, Xavier CC, Morais-Sobral MC, Vashisht AA, Rezende AM, Wohlschlegel JA, Sturm NR, de Melo Neto OP, Campbell DA. Trypanosoma brucei EIF4E2 cap-binding protein binds a homolog of the histone-mRNA stem-loop-binding protein. Curr Genet 2017; 64:821-839. [DOI: 10.1007/s00294-017-0795-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 12/01/2017] [Accepted: 12/08/2017] [Indexed: 12/12/2022]
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20
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Expression of the RNA-binding protein RBP10 promotes the bloodstream-form differentiation state in Trypanosoma brucei. PLoS Pathog 2017; 13:e1006560. [PMID: 28800584 PMCID: PMC5568443 DOI: 10.1371/journal.ppat.1006560] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 08/23/2017] [Accepted: 07/29/2017] [Indexed: 01/06/2023] Open
Abstract
In nearly all eukaryotes, cellular differentiation is governed by changes in transcription, and stabilized by chromatin and DNA modification. Gene expression control in the pathogen Trypanosoma brucei, in contrast, relies almost exclusively on post-transcriptional mechanisms, so RNA binding proteins must assume the burden that is usually borne by transcription factors. T. brucei multiply in the blood of mammals as bloodstream forms, and in the midgut of Tsetse flies as procyclic forms. We show here that a single RNA-binding protein, RBP10, promotes the bloodstream-form trypanosome differentiation state. Depletion of RBP10 from bloodstream-form trypanosomes gives cells that can grow only as procyclic forms; conversely, expression of RBP10 in procyclic forms converts them to bloodstream forms. RBP10 binds to procyclic-specific mRNAs containing an UAUUUUUU motif, targeting them for translation repression and destruction. Products of RBP10 target mRNAs include not only the major procyclic surface protein and enzymes of energy metabolism, but also protein kinases and stage-specific RNA-binding proteins: this suggests that alterations in RBP10 trigger a regulatory cascade.
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21
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De Pablos LM, Kelly S, de Freitas Nascimento J, Sunter J, Carrington M. Characterization of RBP9 and RBP10, two developmentally regulated RNA-binding proteins in Trypanosoma brucei. Open Biol 2017; 7:rsob.160159. [PMID: 28381627 PMCID: PMC5413900 DOI: 10.1098/rsob.160159] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 03/08/2017] [Indexed: 12/19/2022] Open
Abstract
The fate of an mRNA is determined by its interaction with proteins and small RNAs within dynamic complexes called ribonucleoprotein complexes (mRNPs). In Trypanosoma brucei and related kinetoplastids, responses to internal and external signals are mainly mediated by post-transcriptional processes. Here, we used proximity-dependent biotin identification (BioID) combined with RNA-seq to investigate the changes resulting from ectopic expression of RBP10 and RBP9, two developmentally regulated RNA-binding proteins (RBPs). Both RBPs have reduced expression in insect procyclic forms (PCFs) compared with bloodstream forms (BSFs). Upon overexpression in PCFs, both proteins were recruited to cytoplasmic foci, co-localizing with the processing body marker SCD6. Further, both RBPs altered the transcriptome from a PCF- to a BSF-like pattern. Notably, upon expression of BirA*-RBP9 and BirA*-RBP10, BioID yielded more than 200 high confidence protein interactors (more than 10-fold enriched); 45 (RBP9) and 31 (RBP10) were directly related to mRNA metabolism. This study validates the use of BioID for investigating mRNP components but also illustrates the complexity of mRNP function.
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Affiliation(s)
- Luis Miguel De Pablos
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.,Centre for Immunology and Infection (CII). Biology Dept., University of York, York YO10 5DD, UK
| | - Steve Kelly
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | | | - Jack Sunter
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
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22
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Rico E, Ivens A, Glover L, Horn D, Matthews KR. Genome-wide RNAi selection identifies a regulator of transmission stage-enriched gene families and cell-type differentiation in Trypanosoma brucei. PLoS Pathog 2017; 13:e1006279. [PMID: 28334017 PMCID: PMC5380359 DOI: 10.1371/journal.ppat.1006279] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 04/04/2017] [Accepted: 03/08/2017] [Indexed: 01/07/2023] Open
Abstract
Trypanosoma brucei, causing African sleeping-sickness, exploits quorum-sensing (QS) to generate the ‘stumpy forms’ necessary for the parasite’s transmission to tsetse-flies. These quiescent cells are generated by differentiation in the bloodstream from proliferative slender forms. Using genome-wide RNAi selection we screened for repressors of transmission stage-enriched mRNAs in slender forms, using the stumpy-elevated ESAG9 transcript as a model. This identified REG9.1, whose RNAi-silencing alleviated ESAG9 repression in slender forms and tsetse-midgut procyclic forms. Interestingly, trypanosome surface protein Family 5 and Family 7 mRNAs were also elevated, which, like ESAG9, are T. brucei specific and stumpy-enriched. We suggest these contribute to the distinct transmission biology and vector tropism of T. brucei from other African trypanosome species. As well as surface family regulation, REG9.1-depletion generated QS-independent development to stumpy forms in vivo, whereas REG9.1 overexpression in bloodstream forms potentiated spontaneous differentiation to procyclic forms in the absence of an external signal. Combined, this identifies REG9.1 as a regulator of developmental cell fate, controlling the expression of Trypanosoma brucei-specific molecules elevated during transmission. African trypanosomes cause important disease of humans and livestock in sub Saharan Africa and are transmitted by tsetse flies. In preparation for transmission, Trypanosoma brucei uses quorum sensing to generate ‘stumpy forms’ that are arrested and express a distinct subset of genes to the ‘slender forms’ that proliferate to establish the parasitaemia in the bloodstream. This necessitates that stumpy-enriched transcripts are repressed in slender forms, although the molecular control of this is unknown. Here, we have developed a genome-wide selectional strategy to isolate repressors of stumpy-enriched genes, and successfully identified a novel regulatory molecule, termed REG9.1. Silencing of REG9.1 alleviates the repression of the previously characterised stumpy-enriched ESAG9 gene family, and also two novel predicted surface protein families that are specific to Trypansoma brucei but absent from other African trypanosome species. REG9.1 silencing also drives density-independent differentiation to stumpy forms, whereas its ectopic expression in bloodstream forms potentiates differentiation to tsetse midgut procyclic forms in the absence of an external signal. REG9.1 is therefore identified as a novel developmental regulator whose action may contribute to the species-specific transmission biology of Trypanosoma brucei, which differs from that of either Trypanosoma congolense or Trypanosoma vivax.
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Affiliation(s)
- Eva Rico
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Alasdair Ivens
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Lucy Glover
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - David Horn
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Keith R. Matthews
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland, United Kingdom
- * E-mail:
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23
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Untranslated regions of mRNA and their role in regulation of gene expression in protozoan parasites. J Biosci 2017; 42:189-207. [PMID: 28229978 DOI: 10.1007/s12038-016-9660-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Protozoan parasites are one of the oldest living entities in this world that throughout their existence have shown excellent resilience to the odds of survival and have adapted beautifully to ever changing rigors of the environment. In view of the dynamic environment encountered by them throughout their life cycle, and in establishing pathogenesis, it is unsurprising that modulation of gene expression plays a fundamental role in their survival. In higher eukaryotes, untranslated regions (UTRs) of transcripts are one of the crucial regulators of gene expression (influencing mRNA stability and translation efficiency). Parasitic protozoan genome studies have led to the characterization (in silico, in vitro and in vivo) of a large number of their genes. Comparison of higher eukaryotic UTRs with parasitic protozoan UTRs reveals the existence of several similar and dissimilar facets of the UTRs. This review focuses on the elements of UTRs of medically important protozoan parasites and their regulatory role in gene expression. Such information may be useful to researchers in designing gene targeting strategies linked with perturbation of host-parasite relationships leading to control of specific parasites.
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24
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Developmental differentiation in Leishmania lifecycle progression: post-transcriptional control conducts the orchestra. Curr Opin Microbiol 2016; 34:82-89. [PMID: 27565628 DOI: 10.1016/j.mib.2016.08.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 12/30/2022]
Abstract
The successful progression of Leishmania spp. through their lifecycle entails a series of differentiation processes; the proliferative procyclic promastigote forms become quiescent, human-infective metacyclic promastigotes during metacyclogenesis in the sandfly vector, which then differentiate into amastigotes during amastigogenesis in the mammalian host. The progression to these infective forms requires two components: environmental cues and a coordinated cellular response. Recent studies have shown that the Leishmania cellular transformation into mammalian-infective stages is triggered by broad changes in the absolute and relative RNA and protein levels. In this review, we will discuss the implications of Leishmania transcriptomic and proteomic fluctuations, which adapt the parasitic cell for survival.
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25
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Capewell P, Cren-Travaillé C, Marchesi F, Johnston P, Clucas C, Benson RA, Gorman TA, Calvo-Alvarez E, Crouzols A, Jouvion G, Jamonneau V, Weir W, Stevenson ML, O'Neill K, Cooper A, Swar NRK, Bucheton B, Ngoyi DM, Garside P, Rotureau B, MacLeod A. The skin is a significant but overlooked anatomical reservoir for vector-borne African trypanosomes. eLife 2016; 5. [PMID: 27653219 PMCID: PMC5065312 DOI: 10.7554/elife.17716] [Citation(s) in RCA: 189] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 09/12/2016] [Indexed: 12/16/2022] Open
Abstract
The role of mammalian skin in harbouring and transmitting arthropod-borne protozoan parasites has been overlooked for decades as these pathogens have been regarded primarily as blood-dwelling organisms. Intriguingly, infections with low or undetected blood parasites are common, particularly in the case of Human African Trypanosomiasis caused by Trypanosoma brucei gambiense. We hypothesise, therefore, the skin represents an anatomic reservoir of infection. Here we definitively show that substantial quantities of trypanosomes exist within the skin following experimental infection, which can be transmitted to the tsetse vector, even in the absence of detectable parasitaemia. Importantly, we demonstrate the presence of extravascular parasites in human skin biopsies from undiagnosed individuals. The identification of this novel reservoir requires a re-evaluation of current diagnostic methods and control policies. More broadly, our results indicate that transmission is a key evolutionary force driving parasite extravasation that could further result in tissue invasion-dependent pathology. DOI:http://dx.doi.org/10.7554/eLife.17716.001
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Affiliation(s)
- Paul Capewell
- Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow, United Kingdom.,College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.,Henry Wellcome Building for Comparative Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Christelle Cren-Travaillé
- Trypanosome Transmission Group, Trypanosome Cell Biology Unit, INSERM U1201, Paris, France.,Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
| | - Francesco Marchesi
- Veterinary Diagnostic Services, Veterinary School, University of Glasgow, Glasgow, United Kingdom
| | - Pamela Johnston
- Veterinary Diagnostic Services, Veterinary School, University of Glasgow, Glasgow, United Kingdom
| | - Caroline Clucas
- Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow, United Kingdom.,College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.,Henry Wellcome Building for Comparative Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Robert A Benson
- College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.,Institute of Infection, Immunology and Inflammation, University of Glasgow, Glasgow, United Kingdom.,Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - Taylor-Anne Gorman
- Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow, United Kingdom.,College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.,Henry Wellcome Building for Comparative Medical Sciences, University of Glasgow, Glasgow, United Kingdom.,Institute of Infection, Immunology and Inflammation, University of Glasgow, Glasgow, United Kingdom.,Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - Estefania Calvo-Alvarez
- Trypanosome Transmission Group, Trypanosome Cell Biology Unit, INSERM U1201, Paris, France.,Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
| | - Aline Crouzols
- Trypanosome Transmission Group, Trypanosome Cell Biology Unit, INSERM U1201, Paris, France.,Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
| | - Grégory Jouvion
- Human Histopathology and Animal Models Unit, Institut Pasteur, Paris, France
| | - Vincent Jamonneau
- Institut de Recherche pour le Développement, Unité Mixte de Recherche IRD-CIRAD 177, Campus International de Baillarguet, Montpellier, France
| | - William Weir
- Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow, United Kingdom.,College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.,Henry Wellcome Building for Comparative Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - M Lynn Stevenson
- Veterinary Diagnostic Services, Veterinary School, University of Glasgow, Glasgow, United Kingdom
| | - Kerry O'Neill
- Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow, United Kingdom.,College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.,Henry Wellcome Building for Comparative Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Anneli Cooper
- Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow, United Kingdom.,College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.,Henry Wellcome Building for Comparative Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | | | - Bruno Bucheton
- Institut de Recherche pour le Développement, Unité Mixte de Recherche IRD-CIRAD 177, Campus International de Baillarguet, Montpellier, France
| | - Dieudonné Mumba Ngoyi
- Department of Parasitology, National Institute of Biomedical Research, Kinshasa, Democratic Republic of the Congo
| | - Paul Garside
- College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.,Institute of Infection, Immunology and Inflammation, University of Glasgow, Glasgow, United Kingdom.,Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - Brice Rotureau
- Trypanosome Transmission Group, Trypanosome Cell Biology Unit, INSERM U1201, Paris, France.,Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
| | - Annette MacLeod
- Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow, United Kingdom.,College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.,Henry Wellcome Building for Comparative Medical Sciences, University of Glasgow, Glasgow, United Kingdom
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26
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Moura DMN, Reis CRS, Xavier CC, da Costa Lima TD, Lima RP, Carrington M, de Melo Neto OP. Two related trypanosomatid eIF4G homologues have functional differences compatible with distinct roles during translation initiation. RNA Biol 2015; 12:305-19. [PMID: 25826663 DOI: 10.1080/15476286.2015.1017233] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
In higher eukaryotes, eIF4A, eIF4E and eIF4G homologues interact to enable mRNA recruitment to the ribosome. eIF4G acts as a scaffold for these interactions and also interacts with other proteins of the translational machinery. Trypanosomatid protozoa have multiple homologues of eIF4E and eIF4G and the precise function of each remains unclear. Here, 2 previously described eIF4G homologues, EIF4G3 and EIF4G4, were further investigated. In vitro, both homologues bound EIF4AI, but with different interaction properties. Binding to distinct eIF4Es was also confirmed; EIF4G3 bound EIF4E4 while EIF4G4 bound EIF4E3, both these interactions required similar binding motifs. EIF4G3, but not EIF4G4, interacted with PABP1, a poly-A binding protein homolog. Work in vivo with Trypanosoma brucei showed that both EIF4G3 and EIF4G4 are cytoplasmic and essential for viability. Depletion of EIF4G3 caused a rapid reduction in total translation while EIF4G4 depletion led to changes in morphology but no substantial inhibition of translation. Site-directed mutagenesis was used to disrupt interactions of the eIF4Gs with either eIF4E or eIF4A, causing different levels of growth inhibition. Overall the results show that only EIF4G3, with its cap binding partner EIF4E4, plays a major role in translational initiation.
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Affiliation(s)
- Danielle M N Moura
- a Centro de Pesquisas Aggeu Magalhães; Fundação Oswaldo Cruz ; Campus UFPE; Recife , PE , Brazil
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27
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Schulz D, Mugnier MR, Paulsen EM, Kim HS, Chung CWW, Tough DF, Rioja I, Prinjha RK, Papavasiliou FN, Debler EW. Bromodomain Proteins Contribute to Maintenance of Bloodstream Form Stage Identity in the African Trypanosome. PLoS Biol 2015; 13:e1002316. [PMID: 26646171 PMCID: PMC4672894 DOI: 10.1371/journal.pbio.1002316] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 10/30/2015] [Indexed: 01/01/2023] Open
Abstract
Trypanosoma brucei, the causative agent of African sleeping sickness, is transmitted to its mammalian host by the tsetse. In the fly, the parasite's surface is covered with invariant procyclin, while in the mammal it resides extracellularly in its bloodstream form (BF) and is densely covered with highly immunogenic Variant Surface Glycoprotein (VSG). In the BF, the parasite varies this highly immunogenic surface VSG using a repertoire of ~2500 distinct VSG genes. Recent reports in mammalian systems point to a role for histone acetyl-lysine recognizing bromodomain proteins in the maintenance of stem cell fate, leading us to hypothesize that bromodomain proteins may maintain the BF cell fate in trypanosomes. Using small-molecule inhibitors and genetic mutants for individual bromodomain proteins, we performed RNA-seq experiments that revealed changes in the transcriptome similar to those seen in cells differentiating from the BF to the insect stage. This was recapitulated at the protein level by the appearance of insect-stage proteins on the cell surface. Furthermore, bromodomain inhibition disrupts two major BF-specific immune evasion mechanisms that trypanosomes harness to evade mammalian host antibody responses. First, monoallelic expression of the antigenically varied VSG is disrupted. Second, rapid internalization of antibodies bound to VSG on the surface of the trypanosome is blocked. Thus, our studies reveal a role for trypanosome bromodomain proteins in maintaining bloodstream stage identity and immune evasion. Importantly, bromodomain inhibition leads to a decrease in virulence in a mouse model of infection, establishing these proteins as potential therapeutic drug targets for trypanosomiasis. Our 1.25Å resolution crystal structure of a trypanosome bromodomain in complex with I-BET151 reveals a novel binding mode of the inhibitor, which serves as a promising starting point for rational drug design.
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Affiliation(s)
- Danae Schulz
- Laboratory of Lymphocyte Biology, The Rockefeller University, New York, New York, United States of America
| | - Monica R. Mugnier
- Laboratory of Lymphocyte Biology, The Rockefeller University, New York, New York, United States of America
| | - Eda-Margaret Paulsen
- Laboratory of Cell Biology, The Rockefeller University, New York, New York, United States of America
| | - Hee-Sook Kim
- Laboratory of Lymphocyte Biology, The Rockefeller University, New York, New York, United States of America
| | - Chun-wa W. Chung
- Computational and Structural Chemistry, GlaxoSmithKline R&D, Medicines Research Centre, Stevenage, United Kingdom
| | - David F. Tough
- Epinova DPU, Immuno-Inflammation Therapy Area, GlaxoSmithKline, Medicines Research Centre, Stevenage, United Kingdom
| | - Inmaculada Rioja
- Epinova DPU, Immuno-Inflammation Therapy Area, GlaxoSmithKline, Medicines Research Centre, Stevenage, United Kingdom
| | - Rab K. Prinjha
- Epinova DPU, Immuno-Inflammation Therapy Area, GlaxoSmithKline, Medicines Research Centre, Stevenage, United Kingdom
| | - F. Nina Papavasiliou
- Laboratory of Lymphocyte Biology, The Rockefeller University, New York, New York, United States of America
- * E-mail:
| | - Erik W. Debler
- Laboratory of Cell Biology, The Rockefeller University, New York, New York, United States of America
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28
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Gazestani VH, Salavati R. Deciphering RNA Regulatory Elements Involved in the Developmental and Environmental Gene Regulation of Trypanosoma brucei. PLoS One 2015; 10:e0142342. [PMID: 26529602 PMCID: PMC4631447 DOI: 10.1371/journal.pone.0142342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 10/20/2015] [Indexed: 11/17/2022] Open
Abstract
Trypanosoma brucei is a vector-borne parasite with intricate life cycle that can cause serious diseases in humans and animals. This pathogen relies on fine regulation of gene expression to respond and adapt to variable environments, with implications in transmission and infectivity. However, the involved regulatory elements and their mechanisms of actions are largely unknown. Here, benefiting from a new graph-based approach for finding functional regulatory elements in RNA (GRAFFER), we have predicted 88 new RNA regulatory elements that are potentially involved in the gene regulatory network of T. brucei. We show that many of these newly predicted elements are responsive to both transcriptomic and proteomic changes during the life cycle of the parasite. Moreover, we found that 11 of predicted elements strikingly resemble previously identified regulatory elements for the parasite. Additionally, comparison with previously predicted motifs on T. brucei suggested the superior performance of our approach based on the current limited knowledge of regulatory elements in T. brucei.
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Affiliation(s)
- Vahid H Gazestani
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Ste. Anne de Bellevue, Montreal, Quebec, Canada
| | - Reza Salavati
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Ste. Anne de Bellevue, Montreal, Quebec, Canada; McGill Centre for Bioinformatics, McGill University, 3649 Promenade Sir William Osler, Montreal, Quebec, Canada; Department of Biochemistry, McGill University, McIntyre Medical Building, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada
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29
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Bühlmann M, Walrad P, Rico E, Ivens A, Capewell P, Naguleswaran A, Roditi I, Matthews KR. NMD3 regulates both mRNA and rRNA nuclear export in African trypanosomes via an XPOI-linked pathway. Nucleic Acids Res 2015; 43:4491-504. [PMID: 25873624 PMCID: PMC4482084 DOI: 10.1093/nar/gkv330] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 03/30/2015] [Accepted: 03/31/2015] [Indexed: 02/03/2023] Open
Abstract
Trypanosomes mostly regulate gene expression through post-transcriptional mechanisms, particularly mRNA stability. However, much mRNA degradation is cytoplasmic such that mRNA nuclear export must represent an important level of regulation. Ribosomal RNAs must also be exported from the nucleus and the trypanosome orthologue of NMD3 has been confirmed to be involved in rRNA processing and export, matching its function in other organisms. Surprisingly, we found that TbNMD3 depletion also generates mRNA accumulation of procyclin-associated genes (PAGs), these being co-transcribed by RNA polymerase I with the procyclin surface antigen genes expressed on trypanosome insect forms. By whole transcriptome RNA-seq analysis of TbNMD3-depleted cells we confirm the regulation of the PAG transcripts by TbNMD3 and using reporter constructs reveal that PAG1 regulation is mediated by its 5'UTR. Dissection of the mechanism of regulation demonstrates that it is not dependent upon translational inhibition mediated by TbNMD3 depletion nor enhanced transcription. However, depletion of the nuclear export factors XPO1 or MEX67 recapitulates the effects of TbNMD3 depletion on PAG mRNAs and mRNAs accumulated in the nucleus of TbNMD3-depleted cells. These results invoke a novel RNA regulatory mechanism involving the NMD3-dependent nuclear export of mRNA cargos, suggesting a shared platform for mRNA and rRNA export.
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Affiliation(s)
- Melanie Bühlmann
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
| | - Pegine Walrad
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK Centre for Immunology and Infection, Department of Biology, University of York, YO10 5DD, UK
| | - Eva Rico
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
| | - Alasdair Ivens
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
| | - Paul Capewell
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
| | | | - Isabel Roditi
- Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
| | - Keith R Matthews
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
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30
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Lambertz U, Oviedo Ovando ME, Vasconcelos EJR, Unrau PJ, Myler PJ, Reiner NE. Small RNAs derived from tRNAs and rRNAs are highly enriched in exosomes from both old and new world Leishmania providing evidence for conserved exosomal RNA Packaging. BMC Genomics 2015; 16:151. [PMID: 25764986 PMCID: PMC4352550 DOI: 10.1186/s12864-015-1260-7] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 01/21/2015] [Indexed: 01/09/2023] Open
Abstract
Background Leishmania use exosomes to communicate with their mammalian hosts and these secreted vesicles appear to contribute to pathogenesis by delivering protein virulence factors to macrophages. In other eukaryotes, exosomes were found to carry RNA cargo, such as mRNAs and small non-coding RNAs, capable of altering recipient cell phenotype. Whether leishmania exosomes also contain RNAs which they are able to deliver to bystander cells is not known. Here, we show that leishmania exosomes indeed contain RNAs and compare and contrast the RNA content of exosomes released by Leishmania donovani and Leishmania braziliensis. Results We purified RNA from exosomes collected from axenic amastigote culture supernatant and found that when compared with total leishmania RNA, exosomes mainly contained short RNA sequences. Exosomes with intact membranes were capable of protecting their RNA cargo from degradation by RNase. Moreover, exosome RNA cargo was delivered to host cell cytoplasm in vitro. Sequencing of exosomal RNA indicated that the majority of cargo sequences were derived from non-coding RNA species such as rRNA and tRNA. In depth analysis revealed the presence of tRNA-derived small RNAs, a novel RNA type with suspected regulatory functions. Northern blotting confirmed the specific and selective enrichment of tRNA-derived small RNAs in exosomes. We also identified a number of novel transcripts, which appeared to be specifically enriched in exosomes compared to total cell RNA. In addition, we observed the presence of sequences mapping to siRNA-coding regions in L. braziliensis , but not in L. donovani exosomes. Conclusions These results show that leishmania exosomes are selectively and specifically enriched in small RNAs derived almost exclusively from non-coding RNAs. These exosomes are competent to deliver their cargo of novel, potential small regulatory RNAs to macrophages where they may influence parasite-host cell interactions. The remarkably high degree of congruence in exosomal RNA content between L. donovani and L. braziliensis, argues for the presence of a conserved mechanism for exosomal RNA packaging in leishmania. These findings open up a new avenue of research on non-canonical, small RNA pathways in this trypanosomatid, which may elucidate pathogenesis and identify novel therapeutic approaches. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1260-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ulrike Lambertz
- Departments of Medicine, Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada.
| | - Mariana E Oviedo Ovando
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.
| | | | - Peter J Unrau
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.
| | - Peter J Myler
- Seattle Biomedical Research Institute, Seattle, WA, USA. .,Departments of Global Health and Biomedical Informatics & Medical Education, University of Washington, Washington, WA, USA.
| | - Neil E Reiner
- Departments of Medicine, Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada.
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31
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Matthews KR. 25 years of African trypanosome research: From description to molecular dissection and new drug discovery. Mol Biochem Parasitol 2015; 200:30-40. [PMID: 25736427 PMCID: PMC4509711 DOI: 10.1016/j.molbiopara.2015.01.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 01/09/2015] [Accepted: 01/13/2015] [Indexed: 01/27/2023]
Abstract
The Molecular Parasitology conference was first held at the Marine Biological laboratory, Woods Hole, USA 25 years ago. Since that first meeting, the conference has evolved and expanded but has remained the showcase for the latest research developments in molecular parasitology. In this perspective, I reflect on the scientific discoveries focussed on African trypanosomes (Trypanosoma brucei spp.) that have occurred since the inaugural MPM meeting and discuss the current and future status of research on these parasites.
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Affiliation(s)
- Keith R Matthews
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK.
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32
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Clayton CE. Networks of gene expression regulation in Trypanosoma brucei. Mol Biochem Parasitol 2014; 195:96-106. [PMID: 24995711 DOI: 10.1016/j.molbiopara.2014.06.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 06/19/2014] [Accepted: 06/23/2014] [Indexed: 10/25/2022]
Abstract
Regulation of gene expression in Kinetoplastids relies mainly on post-transcriptional mechanisms. Recent high-throughput analyses, combined with mathematical modelling, have demonstrated possibilities for transcript-specific regulation at every stage: trans splicing, polyadenylation, translation, and degradation of both the precursor and the mature mRNA. Different mRNA degradation pathways result in different types of degradation kinetics. The original idea that the fate of an mRNA - or even just its degradation kinetics - can be defined by a single "regulatory element" is an over-simplification. It is now clear that every mRNA can bind many different proteins, some of which may compete with each other. Superimposed upon this complexity are the interactions of those proteins with effectors of gene expression. The amount of protein that is made from a gene is therefore determined by a complex network of interactions.
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Affiliation(s)
- C E Clayton
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
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33
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Panunzi LG, Agüero F. A genome-wide analysis of genetic diversity in Trypanosoma cruzi intergenic regions. PLoS Negl Trop Dis 2014; 8:e2839. [PMID: 24784238 PMCID: PMC4006747 DOI: 10.1371/journal.pntd.0002839] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 03/20/2014] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Trypanosoma cruzi is the causal agent of Chagas Disease. Recently, the genomes of representative strains from two major evolutionary lineages were sequenced, allowing the construction of a detailed genetic diversity map for this important parasite. However this map is focused on coding regions of the genome, leaving a vast space of regulatory regions uncharacterized in terms of their evolutionary conservation and/or divergence. METHODOLOGY Using data from the hybrid CL Brener and Sylvio X10 genomes (from the TcVI and TcI Discrete Typing Units, respectively), we identified intergenic regions that share a common evolutionary ancestry, and are present in both CL Brener haplotypes (TcII-like and TcIII-like) and in the TcI genome; as well as intergenic regions that were conserved in only two of the three genomes/haplotypes analyzed. The genetic diversity in these regions was characterized in terms of the accumulation of indels and nucleotide changes. PRINCIPAL FINDINGS Based on this analysis we have identified i) a core of highly conserved intergenic regions, which remained essentially unchanged in independently evolving lineages; ii) intergenic regions that show high diversity in spite of still retaining their corresponding upstream and downstream coding sequences; iii) a number of defined sequence motifs that are shared by a number of unrelated intergenic regions. A fraction of indels explains the diversification of some intergenic regions by the expansion/contraction of microsatellite-like repeats.
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Affiliation(s)
- Leonardo G. Panunzi
- Instituto de Investigaciones Biotecnológicas – Instituto Tecnológico de Chascomús, Universidad de San Martín – CONICET, Sede San Marítn, Buenos Aires, Argentina
| | - Fernán Agüero
- Instituto de Investigaciones Biotecnológicas – Instituto Tecnológico de Chascomús, Universidad de San Martín – CONICET, Sede San Marítn, Buenos Aires, Argentina
- * E-mail: ;
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34
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Holden JM, Koreny L, Obado S, Ratushny AV, Chen WM, Chiang JH, Kelly S, Chait BT, Aitchison JD, Rout MP, Field MC. Nuclear pore complex evolution: a trypanosome Mlp analogue functions in chromosomal segregation but lacks transcriptional barrier activity. Mol Biol Cell 2014; 25:1421-36. [PMID: 24600046 PMCID: PMC4004592 DOI: 10.1091/mbc.e13-12-0750] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The nuclear face of the nuclear pore complex (NPC) interfaces with chromatin, transcription, and transport intermediates. A novel architecture for the nuclear face of the trypanosome NPC provides insights into NPC function and evolution. The nuclear pore complex (NPC) has dual roles in nucleocytoplasmic transport and chromatin organization. In many eukaryotes the coiled-coil Mlp/Tpr proteins of the NPC nuclear basket have specific functions in interactions with chromatin and defining specialized regions of active transcription, whereas Mlp2 associates with the mitotic spindle/NPC in a cell cycle–dependent manner. We previously identified two putative Mlp-related proteins in African trypanosomes, TbNup110 and TbNup92, the latter of which associates with the spindle. We now provide evidence for independent ancestry for TbNup92/TbNup110 and Mlp/Tpr proteins. However, TbNup92 is required for correct chromosome segregation, with knockout cells exhibiting microaneuploidy and lowered fidelity of telomere segregation. Further, TbNup92 is intimately associated with the mitotic spindle and spindle anchor site but apparently has minimal roles in control of gene transcription, indicating that TbNup92 lacks major barrier activity. TbNup92 therefore acts as a functional analogue of Mlp/Tpr proteins, and, together with the lamina analogue NUP-1, represents a cohort of novel proteins operating at the nuclear periphery of trypanosomes, uncovering complex evolutionary trajectories for the NPC and nuclear lamina.
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Affiliation(s)
- Jennifer M Holden
- Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom Division of Biological Chemistry and Drug Discovery, University of Dundee, Dundee DD1 5EH, United Kingdom The Rockefeller University, New York, NY 10021 Seattle Biomedical Research Institute and Institute for Systems Biology, Seattle, WA 98109 Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan City 701, Taiwan Department of Plant Sciences, University of Oxford, Oxford OX1 4JP, United Kingdom
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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: 131] [Impact Index Per Article: 11.9] [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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Rico E, Rojas F, Mony BM, Szoor B, Macgregor P, Matthews KR. Bloodstream form pre-adaptation to the tsetse fly in Trypanosoma brucei. Front Cell Infect Microbiol 2013; 3:78. [PMID: 24294594 PMCID: PMC3827541 DOI: 10.3389/fcimb.2013.00078] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 10/24/2013] [Indexed: 12/04/2022] Open
Abstract
African trypanosomes are sustained in the bloodstream of their mammalian hosts by their extreme capacity for antigenic variation. However, for life cycle progression, trypanosomes also must generate transmission stages called stumpy forms that are pre-adapted to survive when taken up during the bloodmeal of the disease vector, tsetse flies. These stumpy forms are rather different to the proliferative slender forms that maintain the bloodstream parasitaemia. Firstly, they are non proliferative and morphologically distinct, secondly, they show particular sensitivity to environmental cues that signal entry to the tsetse fly and, thirdly, they are relatively robust such that they survive the changes in temperature, pH and proteolytic environment encountered within the tsetse midgut. These characteristics require regulated changes in gene expression to pre-adapt the parasite and the use of environmental sensing mechanisms, both of which allow the rapid initiation of differentiation to tsetse midgut procyclic forms upon transmission. Interestingly, the generation of stumpy forms is also regulated and periodic in the mammalian blood, this being governed by a density-sensing mechanism whereby a parasite-derived signal drives cell cycle arrest and cellular development both to optimize transmission and to prevent uncontrolled parasite multiplication overwhelming the host. In this review we detail recent developments in our understanding of the molecular mechanisms that underpin the production of stumpy forms in the mammalian bloodstream and their signal perception pathways both in the mammalian bloodstream and upon entry into the tsetse fly. These discoveries are discussed in the context of conserved eukaryotic signaling and differentiation mechanisms. Further, their potential to act as targets for therapeutic strategies that disrupt parasite development either in the mammalian bloodstream or upon their transmission to tsetse flies is also discussed.
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Affiliation(s)
- Eva Rico
- Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh Edinburgh, UK
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Affiliation(s)
- Christine Clayton
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- * E-mail:
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Adenosine-uridine-rich element is one of the required cis-elements for epimastigote form stage-specific gene expression of the congolense epimastigote specific protein. Mol Biochem Parasitol 2013; 191:36-43. [PMID: 24041588 DOI: 10.1016/j.molbiopara.2013.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 09/04/2013] [Accepted: 09/04/2013] [Indexed: 11/23/2022]
Abstract
It is known that gene expression in kinetoplastida is regulated post-transcriptionally. Several previous studies have shown that stage-specific gene expression in trypanosomes is regulated by cis-elements located in the 3' untranslated region (UTR) of each mRNA and also by RNA binding proteins. Our previous study revealed that gene expression of congolense epimastigote specific protein (cesp) was regulated by cis-elements located in the 3'UTR. In the present study, we identified the adenosine and uridine rich region in the cesp 3'UTR. Using transgenic trypanosome cell lines with different egfp expression cassettes, we showed that this adenosine and uridine rich region is one of the regulatory elements for epimastigote form (EMF) stage-specific gene expression via the regulatory cis-element of the eukaryotic AU rich element (ARE). Therefore this required element within the cesp 3'UTR was designated as T. congolense ARE. This required cis-element might selectively stabilize mRNA in the EMF stage and destabilize mRNA in other stages. By RNA electro mobility shift assay, unknown stage-specific RNA binding proteins (RBPs) whose sequences specifically interacted with the required cis-element were found. These results indicate that EMF stage specific cis-element and RBP complexes might specifically stabilize cesp mRNA in EMF.
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Gupta SK, Kosti I, Plaut G, Pivko A, Tkacz ID, Cohen-Chalamish S, Biswas DK, Wachtel C, Waldman Ben-Asher H, Carmi S, Glaser F, Mandel-Gutfreund Y, Michaeli S. The hnRNP F/H homologue of Trypanosoma brucei is differentially expressed in the two life cycle stages of the parasite and regulates splicing and mRNA stability. Nucleic Acids Res 2013; 41:6577-94. [PMID: 23666624 PMCID: PMC3711420 DOI: 10.1093/nar/gkt369] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Trypanosomes are protozoan parasites that cycle between a mammalian host (bloodstream form) and an insect host, the Tsetse fly (procyclic stage). In trypanosomes, all mRNAs are trans-spliced as part of their maturation. Genome-wide analysis of trans-splicing indicates the existence of alternative trans-splicing, but little is known regarding RNA-binding proteins that participate in such regulation. In this study, we performed functional analysis of the Trypanosoma brucei heterogeneous nuclear ribonucleoproteins (hnRNP) F/H homologue, a protein known to regulate alternative splicing in metazoa. The hnRNP F/H is highly expressed in the bloodstream form of the parasite, but is also functional in the procyclic form. Transcriptome analyses of RNAi-silenced cells were used to deduce the RNA motif recognized by this protein. A purine rich motif, AAGAA, was enriched in both the regulatory regions flanking the 3′ splice site and poly (A) sites of the regulated genes. The motif was further validated using mini-genes carrying wild-type and mutated sequences in the 3′ and 5′ UTRs, demonstrating the role of hnRNP F/H in mRNA stability and splicing. Biochemical studies confirmed the binding of the protein to this proposed site. The differential expression of the protein and its inverse effects on mRNA level in the two lifecycle stages demonstrate the role of hnRNP F/H in developmental regulation.
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Affiliation(s)
- Sachin Kumar Gupta
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
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Xiao Y, Nguyen S, Kim SH, Volkov OA, Tu BP, Phillips MA. Product feedback regulation implicated in translational control of the Trypanosoma brucei S-adenosylmethionine decarboxylase regulatory subunit prozyme. Mol Microbiol 2013; 88:846-61. [PMID: 23634831 DOI: 10.1111/mmi.12226] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2013] [Indexed: 12/12/2022]
Abstract
Human African sleeping sickness (HAT) is caused by the parasitic protozoan Trypanosoma brucei. Polyamine biosynthesis is an important drug target in the treatment of HAT. Previously we showed that trypanosomatid S-adenosylmethionine decarboxylase (AdoMetDC), a key enzyme for biosynthesis of the polyamine spermidine, is activated by heterodimer formation with an inactive paralogue termed prozyme. Furthermore, prozyme protein levels were regulated in response to reduced AdoMetDC activity. Herein we show that T. brucei encodes three prozyme transcripts. The 3'UTRs of these transcripts were mapped and chloramphenicol acetyltransferase (CAT) reporter constructs were used to identify a 1.2 kb region that contained a 3'UTR prozyme regulatory element sufficient to upregulate CAT protein levels (but not RNA) upon AdoMetDC inhibition, supporting the hypothesis that prozyme expression is regulated translationally. To gain insight into trans-acting factors, genetic rescue of AdoMetDC RNAi knock-down lines with human AdoMetDC was performed leading to rescue of the cell growth block, and restoration of prozyme protein to wild-type levels. Metabolite analysis showed that prozyme protein levels were inversely proportional to intracellular levels of decarboxylated AdoMet (dcAdoMet). These data suggest that prozyme translation may be regulated by dcAdoMet, a metabolite not previously identified to play a regulatory role.
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Affiliation(s)
- Yanjing Xiao
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA
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Schumann Burkard G, Käser S, de Araújo PR, Schimanski B, Naguleswaran A, Knüsel S, Heller M, Roditi I. Nucleolar proteins regulate stage-specific gene expression and ribosomal RNA maturation in Trypanosoma brucei. Mol Microbiol 2013; 88:827-40. [PMID: 23617823 DOI: 10.1111/mmi.12227] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2013] [Indexed: 12/20/2022]
Abstract
Different life-cycle stages of Trypanosoma brucei are characterized by stage-specific glycoprotein coats. GPEET procyclin, the major surface protein of early procyclic (insect midgut) forms, is transcribed in the nucleolus by RNA polymerase I as part of a polycistronic precursor that is processed to monocistronic mRNAs. In culture, when differentiation to late procyclic forms is triggered by removal of glycerol, the precursor is still transcribed, but accumulation of GPEET mRNA is prevented by a glycerol-responsive element in the 3' UTR. A genome-wide RNAi screen for persistent expression of GPEET in glycerol-free medium identified a novel protein, NRG1 (Nucleolar Regulator of GPEET 1), as a negative regulator. NRG1 associates with GPEET mRNA and with several nucleolar proteins. These include two PUF proteins, TbPUF7 and TbPUF10, and BOP1, a protein required for rRNA processing in other organisms. RNAi against each of these components prolonged or even increased GPEET expression in the absence of glycerol as well as causing a significant reduction in 5.8S rRNA and its immediate precursor. These results indicate that components of a complex used for rRNA maturation can have an additional role in regulating mRNAs that originate in the nucleolus.
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Dostalova A, Käser S, Cristodero M, Schimanski B. The nuclear mRNA export receptor Mex67-Mtr2 ofTrypanosoma bruceicontains a unique and essential zinc finger motif. Mol Microbiol 2013; 88:728-39. [DOI: 10.1111/mmi.12217] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2013] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | - Bernd Schimanski
- Institute of Cell Biology; University of Bern; Bern; Switzerland
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Droll D, Minia I, Fadda A, Singh A, Stewart M, Queiroz R, Clayton C. Post-transcriptional regulation of the trypanosome heat shock response by a zinc finger protein. PLoS Pathog 2013; 9:e1003286. [PMID: 23592996 PMCID: PMC3616968 DOI: 10.1371/journal.ppat.1003286] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 02/19/2013] [Indexed: 12/30/2022] Open
Abstract
In most organisms, the heat-shock response involves increased heat-shock gene transcription. In Kinetoplastid protists, however, virtually all control of gene expression is post-transcriptional. Correspondingly, Trypanosoma brucei heat-shock protein 70 (HSP70) synthesis after heat shock depends on regulation of HSP70 mRNA turnover. We here show that the T. brucei CCCH zinc finger protein ZC3H11 is a post-transcriptional regulator of trypanosome chaperone mRNAs. ZC3H11 is essential in bloodstream-form trypanosomes and for recovery of insect-form trypanosomes from heat shock. ZC3H11 binds to mRNAs encoding heat-shock protein homologues, with clear specificity for the subset of trypanosome chaperones that is required for protein refolding. In procyclic forms, ZC3H11 was required for stabilisation of target chaperone-encoding mRNAs after heat shock, and the HSP70 mRNA was also decreased upon ZC3H11 depletion in bloodstream forms. Many mRNAs bound to ZC3H11 have a consensus AUU repeat motif in the 3'-untranslated region. ZC3H11 bound preferentially to AUU repeats in vitro, and ZC3H11 regulation of HSP70 mRNA in bloodstream forms depended on its AUU repeat region. Tethering of ZC3H11 to a reporter mRNA increased reporter expression, showing that it is capable of actively stabilizing an mRNA. These results show that expression of trypanosome heat-shock genes is controlled by a specific RNA-protein interaction. They also show that heat-shock-induced chaperone expression in procyclic trypanosome enhances parasite survival at elevated temperatures.
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Affiliation(s)
- Dorothea Droll
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Igor Minia
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Abeer Fadda
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Aditi Singh
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Mhairi Stewart
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Rafael Queiroz
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Christine Clayton
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- * E-mail:
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Monk SL, Simmonds P, Matthews KR. A short bifunctional element operates to positively or negatively regulate ESAG9 expression in different developmental forms of Trypanosoma brucei. J Cell Sci 2013; 126:2294-304. [PMID: 23524999 DOI: 10.1242/jcs.126011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In their mammalian host trypanosomes generate 'stumpy' forms from proliferative 'slender' forms as an adaptation for transmission to their tsetse fly vector. This transition is characterised by the repression of many genes while quiescent stumpy forms accumulate during each wave of parasitaemia. However, a subset of genes are upregulated either as an adaptation for transmission or to sustain infection chronicity. Among this group are ESAG9 proteins, whose genes were originally identified as a component of some telomeric variant surface glycoprotein gene expression sites, although many members of this diverse family are also transcribed elsewhere in the genome. ESAG9 genes are among the most highly regulated genes in transmissible stumpy forms, encoding a group of secreted proteins of cryptic function. To understand their developmental silencing in slender forms and activation in stumpy forms, the post-transcriptional control signals for a well conserved ESAG9 gene have been mapped. This identified a precise RNA sequence element of 34 nucleotides that contributes to gene expression silencing in slender forms but also acts positively, activating gene expression in stumpy forms. We predict that this bifunctional RNA sequence element is targeted by competing negative and positive regulatory factors in distinct developmental forms of the parasite. Analysis of the 3'UTR regulatory regions flanking the highly diverse ESAG9 family reveals that the linear regulatory sequence is not highly conserved, suggesting that RNA structure is important for interactions with regulatory proteins.
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Affiliation(s)
- Stephanie L Monk
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3JT, UK
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Suganuma K, Yamasaki S, Asada M, Kawazu SI, Inoue N. The epimastigote stage-specific gene expression of CESP is tightly regulated by its 3′ UTR. Mol Biochem Parasitol 2012; 186:77-80. [DOI: 10.1016/j.molbiopara.2012.09.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 09/24/2012] [Accepted: 09/28/2012] [Indexed: 10/27/2022]
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Das A, Morales R, Banday M, Garcia S, Hao L, Cross GA, Estevez AM, Bellofatto V. The essential polysome-associated RNA-binding protein RBP42 targets mRNAs involved in Trypanosoma brucei energy metabolism. RNA (NEW YORK, N.Y.) 2012; 18:1968-1983. [PMID: 22966087 PMCID: PMC3479388 DOI: 10.1261/rna.033829.112] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 08/02/2012] [Indexed: 05/29/2023]
Abstract
RNA-binding proteins that target mRNA coding regions are emerging as regulators of post-transcriptional processes in eukaryotes. Here we describe a newly identified RNA-binding protein, RBP42, which targets the coding region of mRNAs in the insect form of the African trypanosome, Trypanosoma brucei. RBP42 is an essential protein and associates with polysome-bound mRNAs in the cytoplasm. A global survey of RBP42-bound mRNAs was performed by applying HITS-CLIP technology, which captures protein-RNA interactions in vivo using UV light. Specific RBP42-mRNA interactions, as well as mRNA interactions with a known RNA-binding protein, were purified using specific antibodies. Target RNA sequences were identified and quantified using high-throughput RNA sequencing. Analysis revealed that RBP42 bound mainly within the coding region of mRNAs that encode proteins involved in cellular energy metabolism. Although the mechanism of RBP42's function is unclear at present, we speculate that RBP42 plays a critical role in modulating T. brucei energy metabolism.
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Affiliation(s)
- Anish Das
- Department of Microbiology and Molecular Genetics, UMDNJ-NJ Medical School, Newark, New Jersey 07103, USA
| | - Rachel Morales
- Department of Microbiology and Molecular Genetics, UMDNJ-NJ Medical School, Newark, New Jersey 07103, USA
| | - Mahrukh Banday
- Department of Microbiology and Molecular Genetics, UMDNJ-NJ Medical School, Newark, New Jersey 07103, USA
| | - Stacey Garcia
- Department of Microbiology and Molecular Genetics, UMDNJ-NJ Medical School, Newark, New Jersey 07103, USA
| | - Li Hao
- Center for Genome Informatics, UMDNJ-NJ Medical School, Newark, New Jersey 07103, USA
| | | | - Antonio M. Estevez
- Instituto de Parasitologia y Biomedicina “Lopez-Neyra,” CSIC Avda. Del Comocimiento s/n. Armilla, 18100 Granada, Spain
| | - Vivian Bellofatto
- Department of Microbiology and Molecular Genetics, UMDNJ-NJ Medical School, Newark, New Jersey 07103, USA
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Mörking PA, Rampazzo RDCP, Walrad P, Probst CM, Soares MJ, Gradia DF, Pavoni DP, Krieger MA, Matthews K, Goldenberg S, Fragoso SP, Dallagiovanna B. The zinc finger protein TcZFP2 binds target mRNAs enriched during Trypanosoma cruzi metacyclogenesis. Mem Inst Oswaldo Cruz 2012; 107:790-9. [DOI: 10.1590/s0074-02762012000600014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 04/12/2012] [Indexed: 11/22/2022] Open
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Mahajan A, Bhogale S, Kang IH, Hannapel DJ, Banerjee AK. The mRNA of a Knotted1-like transcription factor of potato is phloem mobile. PLANT MOLECULAR BIOLOGY 2012; 79:595-608. [PMID: 22638904 DOI: 10.1007/s11103-012-9931-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Accepted: 05/16/2012] [Indexed: 05/18/2023]
Abstract
Potato Homeobox1 (POTH1) is a Knotted1-like transcription factor from the Three Amino Acid Loop Extension (TALE) superfamily that is involved in numerous aspects of development in potato (Solanum tuberosum L). POTH1 interacts with its protein partner, StBEL5, to facilitate binding to specific target genes to modulate hormone levels, mediate leaf architecture, and enhance tuber formation. In this study, promoter analyses show that the upstream sequence of POTH1 drives β-glucuronidase activity in response to light and in association with phloem cells in both petioles and stems. Because POTH1 transcripts have previously been detected in phloem cells, long-distance movement of its mRNA was tested. Using RT-PCR and transgenic potato lines over-expressing POTH1, in vitro micrografts demonstrated unilateral movement of POTH1 RNA in a rootward direction. Movement across a graft union into leaves from newly arising axillary shoots and roots of wild type stocks was verified using soil-grown tobacco heterografts. Leaves from the wild type stock containing the mobile POTH1 RNA exhibited a reduction in leaf size relative to leaves from wild type grafts. Both untranslated regions of POTH1 when fused to an expression marker β-glucuronidase, repressed its translation in tobacco protoplasts. RNA/protein binding assays demonstrated that the UTRs of POTH1 bind to two RNA-binding proteins, a polypyrimidine tract-binding protein and an alba-domain type. Conserved glycerol-responsive elements (GRE), specific to alba-domain interaction, are duplicated in both the 5' and 3' untranslated regions of POTH1. These results suggest that POTH1 functions as a mobile signal in regulating development.
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Affiliation(s)
- Ameya Mahajan
- Indian Institute of Science Education and Research, 900, NCL Innovation Park, Pune 411008, India
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Abstract
Trypanosomatids are protozoan micro-organisms that cause serious health problems in humans and domestic animals. In addition to their medical relevance, these pathogens have novel biological structures and processes. From nuclear DNA transcription to mRNA translation, trypanosomes use unusual mechanisms to control gene expression. For example, transcription by RNAPII (RNA polymerase II) is polycistronic, and only a few transcription initiation sites have been identified so far. The sequences present in the polycistronic units code for proteins having unrelated functions, that is, not involved in a similar metabolic pathway. Owing to these biological constraints, these micro-organisms regulate gene expression mostly by post-transcriptional events. Consequently, the function of proteins that recognize RNA elements preferentially at the 3' UTR (untranslated region) of transcripts is central. It was recently shown that mRNP (messenger ribonucleoprotein) complexes are organized within post-transcriptional operons to co-ordinately regulate gene expression of functionally linked transcripts. In the present chapter we will focus on particular characteristics of gene expression in the so-called TriTryp parasites: Trypanosoma cruzi, Trypanosoma brucei and Leishmania major.
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References. Parasitology 2012. [DOI: 10.1002/9781119968986.refs] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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