1
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Rajan KS, Madmoni H, Bashan A, Taoka M, Aryal S, Nobe Y, Doniger T, Galili Kostin B, Blumberg A, Cohen-Chalamish S, Schwartz S, Rivalta A, Zimmerman E, Unger R, Isobe T, Yonath A, Michaeli S. A single pseudouridine on rRNA regulates ribosome structure and function in the mammalian parasite Trypanosoma brucei. Nat Commun 2023; 14:7462. [PMID: 37985661 PMCID: PMC10662448 DOI: 10.1038/s41467-023-43263-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 11/05/2023] [Indexed: 11/22/2023] Open
Abstract
Trypanosomes are protozoan parasites that cycle between insect and mammalian hosts and are the causative agent of sleeping sickness. Here, we describe the changes of pseudouridine (Ψ) modification on rRNA in the two life stages of the parasite using four different genome-wide approaches. CRISPR-Cas9 knock-outs of all four snoRNAs guiding Ψ on helix 69 (H69) of the large rRNA subunit were lethal. A single knock-out of a snoRNA guiding Ψ530 on H69 altered the composition of the 80S monosome. These changes specifically affected the translation of only a subset of proteins. This study correlates a single site Ψ modification with changes in ribosomal protein stoichiometry, supported by a high-resolution cryo-EM structure. We propose that alteration in rRNA modifications could generate ribosomes preferentially translating state-beneficial proteins.
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Affiliation(s)
- K Shanmugha Rajan
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Hava Madmoni
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Anat Bashan
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Masato Taoka
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Saurav Aryal
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Yuko Nobe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Tirza Doniger
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Beathrice Galili Kostin
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Amit Blumberg
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Smadar Cohen-Chalamish
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Schraga Schwartz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Andre Rivalta
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Ella Zimmerman
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Ron Unger
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Toshiaki Isobe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Ada Yonath
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Shulamit Michaeli
- The Mina and Everard Goodman Faculty of Life Sciences and Advanced and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
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2
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Kramer S, Karolak NK, Odenwald J, Gabiatti B, Castañeda Londoño P, Zavřelová A, Freire E, Almeida K, Braune S, Moreira C, Eder A, Goos C, Field M, Carrington M, Holetz F, Górna M, Zoltner M. A unique mRNA decapping complex in trypanosomes. Nucleic Acids Res 2023; 51:7520-7540. [PMID: 37309887 PMCID: PMC10415143 DOI: 10.1093/nar/gkad497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 05/18/2023] [Accepted: 06/06/2023] [Indexed: 06/14/2023] Open
Abstract
Removal of the mRNA 5' cap primes transcripts for degradation and is central for regulating gene expression in eukaryotes. The canonical decapping enzyme Dcp2 is stringently controlled by assembly into a dynamic multi-protein complex together with the 5'-3'exoribonuclease Xrn1. Kinetoplastida lack Dcp2 orthologues but instead rely on the ApaH-like phosphatase ALPH1 for decapping. ALPH1 is composed of a catalytic domain flanked by C- and N-terminal extensions. We show that T. brucei ALPH1 is dimeric in vitro and functions within a complex composed of the trypanosome Xrn1 ortholog XRNA and four proteins unique to Kinetoplastida, including two RNA-binding proteins and a CMGC-family protein kinase. All ALPH1-associated proteins share a unique and dynamic localization to a structure at the posterior pole of the cell, anterior to the microtubule plus ends. XRNA affinity capture in T. cruzi recapitulates this interaction network. The ALPH1 N-terminus is not required for viability in culture, but essential for posterior pole localization. The C-terminus, in contrast, is required for localization to all RNA granule types, as well as for dimerization and interactions with XRNA and the CMGC kinase, suggesting possible regulatory mechanisms. Most significantly, the trypanosome decapping complex has a unique composition, differentiating the process from opisthokonts.
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Affiliation(s)
| | - Natalia Katarzyna Karolak
- Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, Warsaw, Poland
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | | | - Bernardo Gabiatti
- Biocenter, University of Würzburg, Würzburg, Germany
- Carlos Chagas Institute (ICC), FIOCRUZ/PR, Curitiba, Brazil
| | | | - Anna Zavřelová
- Department of Parasitology, Faculty of Science, Charles University in Prague, Biocev, Vestec, Czech Republic
| | | | | | - Silke Braune
- Biocenter, University of Würzburg, Würzburg, Germany
| | - Claudia Moreira
- Biocenter, University of Würzburg, Würzburg, Germany
- Carlos Chagas Institute (ICC), FIOCRUZ/PR, Curitiba, Brazil
| | - Amelie Eder
- Biocenter, University of Würzburg, Würzburg, Germany
| | - Carina Goos
- Biocenter, University of Würzburg, Würzburg, Germany
| | - Mark Field
- School of Life Sciences, University of Dundee, Dundee, UK
- Biology Centre, Czech Academy of Sciences, Institute of Parasitology, České Budějovice, Czech Republic
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Fabiola Holetz
- Carlos Chagas Institute (ICC), FIOCRUZ/PR, Curitiba, Brazil
| | - Maria Wiktoria Górna
- Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, Warsaw, Poland
| | - Martin Zoltner
- Department of Parasitology, Faculty of Science, Charles University in Prague, Biocev, Vestec, Czech Republic
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3
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Macleod OJS, Cook AD, Webb H, Crow M, Burns R, Redpath M, Seisenberger S, Trevor CE, Peacock L, Schwede A, Kimblin N, Francisco AF, Pepperl J, Rust S, Voorheis P, Gibson W, Taylor MC, Higgins MK, Carrington M. Invariant surface glycoprotein 65 of Trypanosoma brucei is a complement C3 receptor. Nat Commun 2022; 13:5085. [PMID: 36038546 PMCID: PMC9424271 DOI: 10.1038/s41467-022-32728-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 08/10/2022] [Indexed: 11/16/2022] Open
Abstract
African trypanosomes are extracellular pathogens of mammals and are exposed to the adaptive and innate immune systems. Trypanosomes evade the adaptive immune response through antigenic variation, but little is known about how they interact with components of the innate immune response, including complement. Here we demonstrate that an invariant surface glycoprotein, ISG65, is a receptor for complement component 3 (C3). We show how ISG65 binds to the thioester domain of C3b. We also show that C3 contributes to control of trypanosomes during early infection in a mouse model and provide evidence that ISG65 is involved in reducing trypanosome susceptibility to C3-mediated clearance. Deposition of C3b on pathogen surfaces, such as trypanosomes, is a central point in activation of the complement system. In ISG65, trypanosomes have evolved a C3 receptor which diminishes the downstream effects of C3 deposition on the control of infection. Trypanosomes evade the immune response through antigenic variation of a surface coat containing variant surface glycoproteins (VSG). They also express invariant surface glycoproteins (ISGs), which are less well understood. Here, Macleod et al. show that ISG65 of T. brucei is a receptor for complement component 3. They provide the crystal structure of T. brucei ISG65 in complex with complement C3d and show evidence that ISG65 is involved in reducing trypanosome susceptibility to C3-mediated clearance in vivo.
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Affiliation(s)
- Olivia J S Macleod
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Alexander D Cook
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.,Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin Building, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Helena Webb
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Mandy Crow
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Roisin Burns
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Maria Redpath
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Stefanie Seisenberger
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Camilla E Trevor
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Lori Peacock
- Bristol Veterinary School and School of Biological Sciences, University of Bristol, Bristol, UK
| | - Angela Schwede
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Nicola Kimblin
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Amanda F Francisco
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Julia Pepperl
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Steve Rust
- Antibody Discovery and Protein Engineering, Biopharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Paul Voorheis
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Wendy Gibson
- Bristol Veterinary School and School of Biological Sciences, University of Bristol, Bristol, UK
| | - Martin C Taylor
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Matthew K Higgins
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK. .,Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin Building, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK.
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4
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Castañeda Londoño PA, Banholzer N, Bannermann B, Kramer S. Is mRNA decapping by ApaH like phosphatases present in eukaryotes beyond the Kinetoplastida? BMC Ecol Evol 2021; 21:131. [PMID: 34162332 PMCID: PMC8220851 DOI: 10.1186/s12862-021-01858-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 06/10/2021] [Indexed: 11/20/2022] Open
Abstract
Background ApaH like phosphatases (ALPHs) originate from the bacterial ApaH protein and have been identified in all eukaryotic super-groups. Only two of these proteins have been functionally characterised. We have shown that the ApaH like phosphatase ALPH1 from the Kinetoplastid Trypanosoma brucei is the mRNA decapping enzyme of the parasite. In eukaryotes, Dcp2 is the major mRNA decapping enzyme and mRNA decapping by ALPHs is unprecedented, but the bacterial ApaH protein was recently found decapping non-conventional caps of bacterial mRNAs. These findings prompted us to explore whether mRNA decapping by ALPHs is restricted to Kinetoplastida or could be more widespread among eukaryotes. Results We screened 827 eukaryotic proteomes with a newly developed Python-based algorithm for the presence of ALPHs and used the data to characterize the phylogenetic distribution, conserved features, additional domains and predicted intracellular localisation of this protein family. For most organisms, we found ALPH proteins to be either absent (495/827 organisms) or to have non-cytoplasmic localisation predictions (73% of all ALPHs), excluding a function in mRNA decapping. Although, non-cytoplasmic ALPH proteins had in vitro mRNA decapping activity. Only 71 non-Kinetoplastida have ALPH proteins with predicted cytoplasmic localisations. However, in contrast to Kinetoplastida, these organisms also possess a homologue of Dcp2 and in contrast to ALPH1 of Kinetoplastida, these ALPH proteins are very short and consist of the catalytic domain only. Conclusions ALPH was present in the last common ancestor of eukaryotes, but most eukaryotes have either lost the enzyme, or use it exclusively outside the cytoplasm. The acceptance of mRNA as a substrate indicates that ALPHs, like bacterial ApaH, have a wide substrate range: the need to protect mRNAs from unregulated degradation is one possible explanation for the selection against the presence of cytoplasmic ALPH proteins in most eukaryotes. Kinetoplastida succeeded to exploit ALPH as their only or major mRNA decapping enzyme. 71 eukaryotic organisms outside the Kinetoplastid lineage have short ALPH proteins with cytoplasmic localisation predictions: whether these proteins are used as decapping enzymes in addition to Dcp2 or else have adapted to not accept mRNAs as a substrate, remains to be explored. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01858-x.
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Affiliation(s)
| | - Nicole Banholzer
- Zell- Und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany
| | | | - Susanne Kramer
- Zell- Und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany.
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5
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A rapid approach for in locus overexpression of Trypanosoma brucei proteins. Mol Biochem Parasitol 2020; 239:111300. [PMID: 32682799 DOI: 10.1016/j.molbiopara.2020.111300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 07/11/2020] [Accepted: 07/13/2020] [Indexed: 11/23/2022]
Abstract
Altering amounts of a protein in a cell has become a crucial tool for understanding its function. In many organisms, including the protozoan parasite Trypanosoma brucei, protein overexpression has been achieved by inserting a protein-coding sequence into an overexpression vector. Here, we have adapted the PCR only based system for tagging trypanosome proteins at their endogenous loci such that it in addition enables a tetracycline-inducible T7 RNA polymerase-mediated protein overexpression. Hence, this approach bypasses the need for molecular cloning, making it rapid and cost effective. We validated the approach for ten flagellum-associated proteins with molecular weights ranging from 40 to over 500 kDa. For a majority of the recombinant proteins a significant (3-50 fold) increase in the cellular amount was achieved upon induction of overexpression. Two of the largest proteins studied, the dynein heavy chains, were significantly overexpressed, while two were not. Our data suggest that this may reflect the extent of the T7 RNA polymerase processivity on the trypanosome genomic DNA. We further show that the overexpression is informative as to cellular functions of the studied proteins, and that these cultures can serve as an excellent source for purification of the overexpressed proteins. We believe that this rapid in locus overexpression system will become a valuable tool to interrogate cellular functions and biochemical activities of trypanosome proteins.
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6
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Goos C, Dejung M, Wehman AM, M-Natus E, Schmidt J, Sunter J, Engstler M, Butter F, Kramer S. Trypanosomes can initiate nuclear export co-transcriptionally. Nucleic Acids Res 2019; 47:266-282. [PMID: 30418648 PMCID: PMC6326799 DOI: 10.1093/nar/gky1136] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/25/2018] [Indexed: 02/03/2023] Open
Abstract
The nuclear envelope serves as important messenger RNA (mRNA) surveillance system. In yeast and human, several control systems act in parallel to prevent nuclear export of unprocessed mRNAs. Trypanosomes lack homologues to most of the involved proteins and their nuclear mRNA metabolism is non-conventional exemplified by polycistronic transcription and mRNA processing by trans-splicing. We here visualized nuclear export in trypanosomes by intra- and intermolecular multi-colour single molecule FISH. We found that, in striking contrast to other eukaryotes, the initiation of nuclear export requires neither the completion of transcription nor splicing. Nevertheless, we show that unspliced mRNAs are mostly prevented from reaching the nucleus-distant cytoplasm and instead accumulate at the nuclear periphery in cytoplasmic nuclear periphery granules (NPGs). Further characterization of NPGs by electron microscopy and proteomics revealed that the granules are located at the cytoplasmic site of the nuclear pores and contain most cytoplasmic RNA-binding proteins but none of the major translation initiation factors, consistent with a function in preventing faulty mRNAs from reaching translation. Our data indicate that trypanosomes regulate the completion of nuclear export, rather than the initiation. Nuclear export control remains poorly understood, in any organism, and the described way of control may not be restricted to trypanosomes.
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Affiliation(s)
- Carina Goos
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Mario Dejung
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Ann M Wehman
- Rudolf Virchow Center, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany
| | - Elisabeth M-Natus
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Johannes Schmidt
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jack Sunter
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Markus Engstler
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Falk Butter
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Susanne Kramer
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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7
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Niemirowicz GT, Cazzulo JJ, Álvarez VE, Bouvier LA. Simplified inducible system for Trypanosoma brucei. PLoS One 2018; 13:e0205527. [PMID: 30308039 PMCID: PMC6181392 DOI: 10.1371/journal.pone.0205527] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 09/26/2018] [Indexed: 11/18/2022] Open
Abstract
Nowadays, most reverse genetics approaches in Trypanosoma brucei, a protozoan parasite of medical and veterinary importance, rely on pre-established cell lines. Consequently, inducible experimentation is reduced to a few laboratory strains. Here we described a new transgene expression system based exclusively on endogenous transcription activities and a minimum set of regulatory components that can easily been adapted to different strains. The pTbFIX vectors are designed to contain the sequence of interest under the control of an inducible rRNA promoter along with a constitutive dicistronic unit encoding a nucleus targeted tetracycline repressor and puromycin resistance genes in a tandem “head-to-tail” configuration. Upon doxycycline induction, the system supports regulatable GFP expression (170 to 400 fold) in both bloodstream and procyclic T. brucei forms. Furthermore we have adapted the pTbFIX plasmid to perform RNAi experimentation. Lethal phenotypes, including α-tubulin and those corresponding to the enolase and clathrin heavy chain genes, were successfully recapitulated in procyclic and bloodstream parasites thus showing the versatility of this new tool.
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Affiliation(s)
- Gabriela T. Niemirowicz
- Instituto de Investigaciones Biotecnológicas (IIB) Dr. Rodolfo A. Ugalde, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
| | - Juan J. Cazzulo
- Instituto de Investigaciones Biotecnológicas (IIB) Dr. Rodolfo A. Ugalde, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
| | - Vanina E. Álvarez
- Instituto de Investigaciones Biotecnológicas (IIB) Dr. Rodolfo A. Ugalde, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
| | - León A. Bouvier
- Instituto de Investigaciones Biotecnológicas (IIB) Dr. Rodolfo A. Ugalde, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
- * E-mail:
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8
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Kramer S. Simultaneous detection of mRNA transcription and decay intermediates by dual colour single mRNA FISH on subcellular resolution. Nucleic Acids Res 2017; 45:e49. [PMID: 27940558 PMCID: PMC5397161 DOI: 10.1093/nar/gkw1245] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 11/28/2016] [Indexed: 02/06/2023] Open
Abstract
The detection of mRNAs undergoing transcription or decay is challenging, because both processes are fast. However, the relative proportion of an mRNA in synthesis or decay increases with mRNA size and decreases with mRNA half-life. Based on this rationale, I have exploited a 22 200 nucleotide-long, short-lived endogenous mRNA as a reporter for mRNA metabolism in trypanosomes. The extreme 5΄ and 3΄ ends were labeled with red- and green-fluorescent Affymetrix® single mRNA FISH probes, respectively. In the resulting fluorescence images, yellow spots represent intact mRNAs; red spots are mRNAs in transcription or 3΄-5΄ decay, and green spots are mRNAs in 5΄-3΄ degradation. Most red spots were nuclear and insensitive to transcriptional inhibition and thus likely transcription intermediates. Most green spots were cytoplasmic, confirming that the majority of cytoplasmic decay in trypanosomes is 5΄-3΄. The system showed the expected changes at inhibition of transcription or translation and RNAi depletion of the trypanosome homologue to the 5΄-3΄ exoribonuclease Xrn1. The method allows to monitor changes in mRNA metabolism both on cellular and on population/tissue wide levels, but also to study the subcellular localization of mRNA transcription and decay pathways. I show that the system is applicable to mammalian cells.
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Affiliation(s)
- Susanne Kramer
- Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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9
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Abstract
5’-3’ decay is the major mRNA decay pathway in many eukaryotes, including trypanosomes. After deadenylation, mRNAs are decapped by the nudix hydrolase DCP2 of the decapping complex and finally degraded by the 5’-3’ exoribonuclease. Uniquely, trypanosomes lack homologues to all subunits of the decapping complex, while deadenylation and 5’-3’ degradation are conserved. Here, I show that the parasites use an ApaH-like phosphatase (ALPH1) as their major mRNA decapping enzyme. The protein was recently identified as a novel trypanosome stress granule protein and as involved in mRNA binding. A fraction of ALPH1 co-localises exclusively with the trypanosome 5’-3’ exoribonuclease XRNA to a special granule at the posterior pole of the cell, indicating a connection between the two enzymes. RNAi depletion of ALPH1 is lethal and causes a massive increase in total mRNAs that are deadenylated, but have not yet started 5’-3’ decay. These data suggest that ALPH1 acts downstream of deadenylation and upstream of mRNA degradation, consistent with a function in mRNA decapping. In vitro experiments show that recombinant, N-terminally truncated ALHP1 protein, but not a catalytically inactive mutant, sensitises the capped trypanosome spliced leader RNA to yeast Xrn1, but only if an RNA 5’ polyphosphatase is included. This indicates that the decapping mechanism of ALPH1 differs from the decapping mechanism of Dcp2 by leaving more than one phosphate group at the mRNA’s 5’ end. This is the first reported function of a eukaryotic ApaH-like phosphatase, a bacterial-derived class of enzymes present in all phylogenetic super-groups of the eukaryotic kingdom. The substrates of eukaryotic ApaH-like phosphatases are unknown. However, the substrate of the related bacterial enzyme ApaH, diadenosine tetraphosphate, is highly reminiscent of a eukaryotic mRNA cap. Eukaryotic mRNAs are stabilised by a 5’ cap and one important step in mRNA decay is the removal of this cap by the nudix domain protein Dcp2 of the decapping complex. The decapping complex is highly conserved throughout eukaryotes, with the exception of trypanosomes that lack the entire complex. Here, I show that trypanosomes have evolved to use an ApaH-like phosphatase instead of a nudix domain protein as their major decapping enzyme. This work closes an important gap in the knowledge of trypanosome mRNA metabolism. Moreover, this is the first reported function of an ApaH-like phosphatase, a bacterial derived class of enzymes that are widespread throughout eukaryotes.
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Affiliation(s)
- Susanne Kramer
- Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- * E-mail:
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10
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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: 1.7] [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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11
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Manna PT, Obado SO, Boehm C, Gadelha C, Sali A, Chait BT, Rout MP, Field MC. Lineage-specific proteins essential for endocytosis in trypanosomes. J Cell Sci 2017; 130:1379-1392. [PMID: 28232524 PMCID: PMC5399782 DOI: 10.1242/jcs.191478] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 02/13/2017] [Indexed: 01/05/2023] Open
Abstract
Clathrin-mediated endocytosis (CME) is the most evolutionarily ancient endocytic mechanism known, and in many lineages the sole mechanism for internalisation. Significantly, in mammalian cells CME is responsible for the vast bulk of endocytic flux and has likely undergone multiple adaptations to accommodate specific requirements by individual species. In African trypanosomes, we previously demonstrated that CME is independent of the AP-2 adaptor protein complex, that orthologues to many of the animal and fungal CME protein cohort are absent, and that a novel, trypanosome-restricted protein cohort interacts with clathrin and drives CME. Here, we used a novel cryomilling affinity isolation strategy to preserve transient low-affinity interactions, giving the most comprehensive trypanosome clathrin interactome to date. We identified the trypanosome AP-1 complex, Trypanosoma brucei (Tb)EpsinR, several endosomal SNAREs plus orthologues of SMAP and the AP-2 associated kinase AAK1 as interacting with clathrin. Novel lineage-specific proteins were identified, which we designate TbCAP80 and TbCAP141. Their depletion produced extensive defects in endocytosis and endomembrane system organisation, revealing a novel molecular pathway subtending an early-branching and highly divergent form of CME, which is conserved and likely functionally important across the kinetoplastid parasites. Summary: Endocytosis is a vital process in most cells, and here we identify important proteins required for this process in trypanosomes. Significantly, these are unique and not present in animals, fungi or plants.
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Affiliation(s)
- Paul T Manna
- School of Life Sciences, University of Dundee, Dundee, Scotland DD1 5EH, UK
| | - Samson O Obado
- The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
| | - Cordula Boehm
- School of Life Sciences, University of Dundee, Dundee, Scotland DD1 5EH, UK
| | - Catarina Gadelha
- School of Life Sciences, University of Nottingham, Nottingham NG2 7UH, UK
| | - Andrej Sali
- California Institute for Quantitative Biosciences, University of California, San Francisco, CA 94158, USA
| | - Brian T Chait
- The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
| | - Michael P Rout
- The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
| | - Mark C Field
- School of Life Sciences, University of Dundee, Dundee, Scotland DD1 5EH, UK
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12
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McAllaster MR, Sinclair-Davis AN, Hilton NA, de Graffenried CL. A unified approach towards Trypanosoma brucei functional genomics using Gibson assembly. Mol Biochem Parasitol 2016; 210:13-21. [PMID: 27496178 DOI: 10.1016/j.molbiopara.2016.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/28/2016] [Accepted: 08/02/2016] [Indexed: 12/27/2022]
Abstract
Trypanosoma brucei is the causative agent of human African trypanosomiasis and nagana in cattle. Recent advances in high throughput phenotypic and interaction screens have identified a wealth of novel candidate proteins for diverse functions such as drug resistance, life cycle progression, and cytoskeletal biogenesis. Characterization of these proteins will allow a more mechanistic understanding of the biology of this important pathogen and could identify novel drug targets. However, methods for rapidly validating and prioritizing these potential targets are still being developed. While gene tagging via homologous recombination and RNA interference are available in T. brucei, a general strategy for creating the most effective constructs for these approaches is lacking. Here, we adapt Gibson assembly, a one-step isothermal process that rapidly assembles multiple DNA segments in a single reaction, to create endogenous tagging, overexpression, and long hairpin RNAi constructs that are compatible with well-established T. brucei vectors. The generality of the Gibson approach has several advantages over current methodologies and substantially increases the speed and ease with which these constructs can be assembled.
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Affiliation(s)
- Michael R McAllaster
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912, United States
| | - Amy N Sinclair-Davis
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912, United States
| | - Nicholas A Hilton
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912, United States
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13
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Sanchez MA, Tran KD, Valli J, Hobbs S, Johnson E, Gluenz E, Landfear SM. KHARON Is an Essential Cytoskeletal Protein Involved in the Trafficking of Flagellar Membrane Proteins and Cell Division in African Trypanosomes. J Biol Chem 2016; 291:19760-73. [PMID: 27489106 DOI: 10.1074/jbc.m116.739235] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 11/06/2022] Open
Abstract
African trypanosomes and related kinetoplastid parasites selectively traffic specific membrane proteins to the flagellar membrane, but the mechanisms for this trafficking are poorly understood. We show here that KHARON, a protein originally identified in Leishmania parasites, interacts with a putative trypanosome calcium channel and is required for its targeting to the flagellar membrane. KHARON is located at the base of the flagellar axoneme, where it likely mediates targeting of flagellar membrane proteins, but is also on the subpellicular microtubules and the mitotic spindle. Hence, KHARON is probably a multifunctional protein that associates with several components of the trypanosome cytoskeleton. RNA interference-mediated knockdown of KHARON mRNA results in failure of the calcium channel to enter the flagellar membrane, detachment of the flagellum from the cell body, and disruption of mitotic spindles. Furthermore, knockdown of KHARON mRNA induces a lethal failure of cytokinesis in both bloodstream (mammalian host) and procyclic (insect vector) life cycle stages, and KHARON is thus critical for parasite viability.
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Affiliation(s)
- Marco A Sanchez
- From the Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, Oregon 97239 and
| | - Khoa D Tran
- From the Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, Oregon 97239 and
| | - Jessica Valli
- the Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Sam Hobbs
- From the Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, Oregon 97239 and
| | - Errin Johnson
- the Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Eva Gluenz
- the Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Scott M Landfear
- From the Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, Oregon 97239 and
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14
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Sunter JD. A vanillic acid inducible expression system for Trypanosoma brucei. Mol Biochem Parasitol 2016; 207:45-8. [PMID: 27063979 PMCID: PMC4920640 DOI: 10.1016/j.molbiopara.2016.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 03/31/2016] [Accepted: 04/01/2016] [Indexed: 01/30/2023]
Abstract
Inducible gene expression system for Trypanosoma brucei. Addition of vanillic acid results in gene expression. Tetracycline and vanillic acid inducible systems are independent of each other. Tetracycline and vanillic acid inducible systems can be used simultaneously.
Reverse genetics in Trypanosoma brucei is dependent on the tetracycline inducible system for the precise control over the expression of both genes and dsRNA. Another independent inducible system for trypanosomes would enable the control of the activities of two different genes in the same cell, providing greater experimental sophistication. Here, I describe the development of the vanillic acid based inducible expression system for T. brucei, which operates independently of, and can be used in parallel with the tetracycline inducible system.
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Affiliation(s)
- Jack D Sunter
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE, UK.
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15
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Kramer S, Piper S, Estevez A, Carrington M. Polycistronic trypanosome mRNAs are a target for the exosome. Mol Biochem Parasitol 2016; 205:1-5. [PMID: 26946399 PMCID: PMC4850246 DOI: 10.1016/j.molbiopara.2016.02.009] [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: 02/03/2016] [Revised: 02/26/2016] [Accepted: 02/29/2016] [Indexed: 11/02/2022]
Abstract
Eukaryotic cells have several mRNA quality control checkpoints to avoid the production of aberrant proteins. Intron-containing mRNAs are actively degraded by the nuclear exosome, prevented from nuclear exit and, if these systems fail, degraded by the cytoplasmic NMD machinery. Trypanosomes have only two introns. However, they process mRNAs from long polycistronic precursors by trans-splicing and polycistronic mRNA molecules frequently arise from any missed splice site. Here, we show that RNAi depletion of the trypanosome exosome, but not of the cytoplasmic 5'-3' exoribonuclease XRNA or the NMD helicase UPF1, causes accumulation of oligocistronic mRNAs. We have also revisited the localization of the trypanosome exosome by expressing eYFP-fusion proteins of the exosome subunits RRP44 and RRP6. Both proteins are significantly enriched in the nucleus. Together with published data, our data suggest a major nuclear function of the trypanosome exosome in rRNA, snoRNA and mRNA quality control.
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Affiliation(s)
- Susanne Kramer
- Biozentrum, Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg, Germany; Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK.
| | - Sophie Piper
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Antonio Estevez
- Instituto de Parasitología y Biomedicina "López-Neyra", IPBL N-CSIC, Parque Tecnológico de Ciencias de la Salud, Avda. del Conocimiento, s/n.18100 Armilla, Granada, Spain
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
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16
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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: 2.9] [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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17
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Sunter JD, Varga V, Dean S, Gull K. A dynamic coordination of flagellum and cytoplasmic cytoskeleton assembly specifies cell morphogenesis in trypanosomes. J Cell Sci 2015; 128:1580-94. [PMID: 25736289 PMCID: PMC4406125 DOI: 10.1242/jcs.166447] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 02/22/2015] [Indexed: 01/26/2023] Open
Abstract
Plasma membrane-to-plasma membrane connections are common features of eukaryotic cells, with cytoskeletal frameworks below the respective membranes underpinning these connections. A defining feature of Trypanosoma brucei is the lateral attachment of its single flagellum to the cell body, which is mediated by a cytoskeletal structure called the flagellum attachment zone (FAZ). The FAZ is a key morphogenetic structure. Disruption of FAZ assembly can lead to flagellum detachment and dramatic changes in cell shape. To understand this complex structure, the identity of more of its constituent proteins is required. Here, we have used both proteomics and bioinformatics to identify eight new FAZ proteins. Using inducible expression of FAZ proteins tagged with eYFP we demonstrate that the site of FAZ assembly is close to the flagellar pocket at the proximal end of the FAZ. This contrasts with the flagellum, which is assembled at its distal end; hence, these two interconnected cytoskeletal structures have distinct spatially separated assembly sites. This challenging result has many implications for understanding the process of cell morphogenesis and interpreting mutant phenotypes.
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Affiliation(s)
- Jack D Sunter
- Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE, UK
| | - Vladimir Varga
- Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE, UK
| | - Samuel Dean
- Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE, UK
| | - Keith Gull
- Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE, UK
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18
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A new strategy of RNA interference that targets heterologous sequences reveals CITFA1 as an essential component of class I transcription factor A in Trypanosoma brucei. EUKARYOTIC CELL 2014; 13:785-95. [PMID: 24728195 DOI: 10.1128/ec.00014-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Conditional gene silencing by RNA interference in Trypanosoma brucei can be inconclusive if knockdowns are inefficient or have off-target effects. To enable efficient, specific silencing of single-copy genes in mammalian-infective, bloodstream form trypanosomes, we developed a system that targets the heterologous and functional Trypanosoma cruzi U2AF35 3' untranslated region (UTR) (Tc3) or, alternatively, the sequence of the PTP tag, which can be fused to any mRNA of interest. Two cell lines were created, single-marker Tc3 (smTc3) and smPTP, which conditionally express Tc3 and PTP double-stranded RNA (dsRNA), respectively. The system depends on manipulating both alleles of the gene of interest so that cells exclusively express the target mRNA as a fusion to one of these heterologous sequences. We generated allele integration vectors in which the C-terminal part of a gene's coding sequence can be fused to either heterologous sequence in a single cloning step. We first tested this system with CITFA7, which encodes a well-characterized subunit of the class I transcription factor A (CITFA), an essential factor for transcription initiation by RNA polymerase I. Targeting either Tc3 or PTP fused to the CITFA7 mRNA resulted in gene knockdowns that were as efficient and specific as targeting the endogenous CITFA7 mRNA. Moreover, application of this system to CITFA1, which could not be silenced by established methods, demonstrated that the gene encodes an essential CITFA subunit that mediates binding of the transcription factor complex to RNA polymerase I promoters.
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19
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Kramer S, Carrington M. An AU-rich instability element in the 3'UTR mediates an increase in mRNA stability in response to expression of a dhh1 ATPase mutant. ACTA ACUST UNITED AC 2014; 2:e28587. [PMID: 26779405 PMCID: PMC4705827 DOI: 10.4161/trla.28587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 03/10/2014] [Accepted: 03/18/2014] [Indexed: 12/11/2022]
Abstract
The DEAD box RNA helicase DHH1 acts as a general repressor of translation and activator of decapping but can also act specifically on individual mRNAs. In trypanosomes, DHH1 overexpression or expression of a dhh1 ATPase mutant, dhh1 DEAD:DQAD, resulted in increased or decreased stability of a small group of mRNAs, mainly encoding developmentally regulated genes. Here, four of the mRNAs affected by dhh1 DEAD:DQAD expression have been analyzed to identify cis-elements involved in dhh1 DEAD:DQAD action. For three mRNAs, the 3′ UTR mediated the change in mRNA level and, in one case, both the 5′ and the 3′ UTR contributed. No responsive elements were detected in the protein coding sequences. One mRNA stabilized by dhh1 DEAD:DQAD expression was analyzed in more detail: deletion or mutation of an AU-rich element in the 3′ UTR resulted in mRNA stabilization in the absence of dhh1 DEAD:DQAD and completely abolished the response to dhh1 DEAD:DQAD. While AU-rich instability elements have been previously shown to mediate mRNA decrease or translational exit by recruitment of DHH1, this is, to our knowledge, the first report of an AU-rich instability element that is responsible for a DHH1 mediated increase in mRNA stability. We suggest a novel model for the selective action of dhh1 on individual mRNAs that is based on the change in the turnover rate of stabilizing or destabilizing RNA binding proteins.
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Affiliation(s)
- Susanne Kramer
- Department of Biochemistry; University of Cambridge; Cambridge, UK
| | - Mark Carrington
- Department of Biochemistry; University of Cambridge; Cambridge, UK
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20
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Krüger T, Hofweber M, Kramer S. SCD6 induces ribonucleoprotein granule formation in trypanosomes in a translation-independent manner, regulated by its Lsm and RGG domains. Mol Biol Cell 2013; 24:2098-111. [PMID: 23676662 PMCID: PMC3694794 DOI: 10.1091/mbc.e13-01-0068] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Trypanosomes lack many core components of ribonucleoprotein (RNP) granules identified in yeast and humans (e.g., DCP1/2). This study provides evidence for SCD6 being the core RNP granule component in trypanosomes: overexpression induces granules independent of translation, and even when SCD6 is targeted to the nucleus. Granule type and granule number are dependent on the RGG domain. Ribonucleoprotein (RNP) granules are cytoplasmic, microscopically visible structures composed of RNA and protein with proposed functions in mRNA decay and storage. Trypanosomes have several types of RNP granules, but lack most of the granule core components identified in yeast and humans. The exception is SCD6/Rap55, which is essential for processing body (P-body) formation. In this study, we analyzed the role of trypanosome SCD6 in RNP granule formation. Upon overexpression, the majority of SCD6 aggregates to multiple granules enriched at the nuclear periphery that recruit both P-body and stress granule proteins, as well as mRNAs. Granule protein composition depends on granule distance to the nucleus. In contrast to findings in yeast and humans, granule formation does not correlate with translational repression and can also take place in the nucleus after nuclear targeting of SCD6. While the SCD6 Lsm domain alone is both necessary and sufficient for granule induction, the RGG motif determines granule type and number: the absence of an intact RGG motif results in the formation of fewer granules that resemble P-bodies. The differences in granule number remain after nuclear targeting, indicating translation-independent functions of the RGG domain. We propose that, in trypanosomes, a local increase in SCD6 concentration may be sufficient to induce granules by recruiting mRNA. Proteins that bind selectively to the RGG and/or Lsm domain of SCD6 could be responsible for regulating granule type and number.
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Affiliation(s)
- Timothy Krüger
- Lehrstuhl für Zell- und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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21
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Sanchez MA. Molecular identification and characterization of an essential pyruvate transporter from Trypanosoma brucei. J Biol Chem 2013; 288:14428-14437. [PMID: 23569205 DOI: 10.1074/jbc.m113.473157] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pyruvate export is an essential physiological process for the bloodstream form of Trypanosoma brucei as the parasite would otherwise accumulate this end product of glucose metabolism to toxic levels. In the studies reported here, genetic complementation in Saccharomyces cerevisiae has been employed to identify a gene (TbPT0) that encodes this vital pyruvate transporter from T. brucei. Expression of TbPT0 in S. cerevisiae reveals that TbPT0 is a high affinity pyruvate transporter. TbPT0 belongs to a clustered multigene family consisting of five members, whose expression is up-regulated in the bloodstream form. Interestingly, TbPT family permeases are related to polytopic proteins from plants but not to characterized monocarboxylate transporters from mammals. Remarkably, inhibition of the TbPT gene family expression in bloodstream parasites by RNAi is lethal, confirming the physiological relevance of these transporters. The discovery of TbPT0 reveals for the first time the identity of the essential pyruvate transporter and provides a potential drug target against the mammalian life cycle stage of T. brucei.
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Affiliation(s)
- Marco A Sanchez
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon 97239.
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22
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Kramer S, Bannerman-Chukualim B, Ellis L, Boulden EA, Kelly S, Field MC, Carrington M. Differential localization of the two T. brucei poly(A) binding proteins to the nucleus and RNP granules suggests binding to distinct mRNA pools. PLoS One 2013; 8:e54004. [PMID: 23382864 PMCID: PMC3559699 DOI: 10.1371/journal.pone.0054004] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 12/06/2012] [Indexed: 12/30/2022] Open
Abstract
The number of paralogs of proteins involved in translation initiation is larger in trypanosomes than in yeasts or many metazoan and includes two poly(A) binding proteins, PABP1 and PABP2, and four eIF4E variants. In many cases, the paralogs are individually essential and are thus unlikely to have redundant functions although, as yet, distinct functions of different isoforms have not been determined. Here, trypanosome PABP1 and PABP2 have been further characterised. PABP1 and PABP2 diverged subsequent to the differentiation of the Kinetoplastae lineage, supporting the existence of specific aspects of translation initiation regulation. PABP1 and PABP2 exhibit major differences in intracellular localization and distribution on polysome fractionation under various conditions that interfere with mRNA metabolism. Most striking are differences in localization to the four known types of inducible RNP granules. Moreover, only PABP2 but not PABP1 can accumulate in the nucleus. Taken together, these observations indicate that PABP1 and PABP2 likely associate with distinct populations of mRNAs. The differences in localization to inducible RNP granules also apply to paralogs of components of the eIF4F complex: eIF4E1 showed similar localization pattern to PABP2, whereas the localisation of eIF4E4 and eIF4G3 resembled that of PABP1. The grouping of translation initiation as either colocalizing with PABP1 or with PABP2 can be used to complement interaction studies to further define the translation initiation complexes in kinetoplastids.
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Affiliation(s)
- Susanne Kramer
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Louise Ellis
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Steve Kelly
- Department of Plant Sciences, University of Oxford, and Oxford Centre for Integrative Systems Biology, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Mark C. Field
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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23
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Kramer S, Marnef A, Standart N, Carrington M. Inhibition of mRNA maturation in trypanosomes causes the formation of novel foci at the nuclear periphery containing cytoplasmic regulators of mRNA fate. J Cell Sci 2012; 125:2896-909. [PMID: 22366449 PMCID: PMC3434824 DOI: 10.1242/jcs.099275] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Maturation of all cytoplasmic mRNAs in trypanosomes involves trans-splicing of a short exon at the 5′ end. Inhibition of trans-splicing results in an accumulation of partially processed oligocistronic mRNAs. Here, we show that the accumulation of newly synthesised partially processed mRNAs results in the formation of foci around the periphery of the nucleus. These nuclear periphery granules (NPGs) contain the full complement of P-body proteins identified in trypanosomes to date, as well as poly(A)-binding protein 2 and the trypanosome homologue of the RNA helicase VASA. NPGs resemble perinuclear germ granules from metazoa more than P-bodies because they: (1) are localised around the nuclear periphery; (2) are dependent on active transcription; (3) are not dissipated by cycloheximide; (4) contain VASA; and (5) depend on nuclear integrity. In addition, NPGs can be induced in cells depleted of the P-body core component SCD6. The description of NPGs in trypanosomes provides evidence that there is a perinuclear compartment that can determine the fate of newly transcribed mRNAs and that germ granules could be a specialised derivative.
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Affiliation(s)
- Susanne Kramer
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
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