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Rolemberg Santana Travaglini Berti de Correia C, Torres C, Gomes E, Maffei Rodriguez G, Klaysson Pereira Regatieri W, Takamiya NT, Aparecida Rogerio L, Malavazi I, Damário Gomes M, Dener Damasceno J, Luiz da Silva V, Antonio Fernandes de Oliveira M, Santos da Silva M, Silva Nascimento A, Cappellazzo Coelho A, Regina Maruyama S, Teixeira FR. Functional characterization of Cullin-1-RING ubiquitin ligase (CRL1) complex in Leishmania infantum. PLoS Pathog 2024; 20:e1012336. [PMID: 39018347 DOI: 10.1371/journal.ppat.1012336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 06/10/2024] [Indexed: 07/19/2024] Open
Abstract
Cullin-1-RING ubiquitin ligases (CRL1) or SCF1 (SKP1-CUL1-RBX1) E3 ubiquitin ligases are the largest and most extensively investigated class of E3 ligases in mammals that regulate fundamental processes, such as the cell cycle and proliferation. These enzymes are multiprotein complexes comprising SKP1, CUL1, RBX1, and an F-box protein that acts as a specificity factor by interacting with SKP1 through its F-box domain and recruiting substrates via other domains. E3 ligases are important players in the ubiquitination process, recognizing and transferring ubiquitin to substrates destined for degradation by proteasomes or processing by deubiquitinating enzymes. The ubiquitin-proteasome system (UPS) is the main regulator of intracellular proteolysis in eukaryotes and is required for parasites to alternate hosts in their life cycles, resulting in successful parasitism. Leishmania UPS is poorly investigated, and CRL1 in L. infantum, the causative agent of visceral leishmaniasis in Latin America, is yet to be described. Here, we show that the L. infantum genes LINF_110018100 (SKP1-like protein), LINF_240029100 (cullin-like protein-like protein), and LINF_210005300 (ring-box protein 1 -putative) form a LinfCRL1 complex structurally similar to the H. sapiens CRL1. Mass spectrometry analysis of the LinfSkp1 and LinfCul1 interactomes revealed proteins involved in several intracellular processes, including six F-box proteins known as F-box-like proteins (Flp) (data are available via ProteomeXchange with identifier PXD051961). The interaction of LinfFlp 1-6 with LinfSkp1 was confirmed, and using in vitro ubiquitination assays, we demonstrated the function of the LinfCRL1(Flp1) complex to transfer ubiquitin. We also found that LinfSKP1 and LinfRBX1 knockouts resulted in nonviable L. infantum lineages, whereas LinfCUL1 was involved in parasite growth and rosette formation. Finally, our results suggest that LinfCul1 regulates the S phase progression and possibly the transition between the late S to G2 phase in L. infantum. Thus, a new class of E3 ubiquitin ligases has been described in L. infantum with functions related to various parasitic processes that may serve as prospective targets for leishmaniasis treatment.
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Affiliation(s)
- Camila Rolemberg Santana Travaglini Berti de Correia
- Department of Genetics and Evolution, Federal University of São Carlos, São Carlos, Brazil
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Caroline Torres
- Department of Genetics and Evolution, Federal University of São Carlos, São Carlos, Brazil
| | - Ellen Gomes
- Department of Genetics and Evolution, Federal University of São Carlos, São Carlos, Brazil
| | | | | | - Nayore Tamie Takamiya
- Department of Genetics and Evolution, Federal University of São Carlos, São Carlos, Brazil
| | | | - Iran Malavazi
- Department of Genetics and Evolution, Federal University of São Carlos, São Carlos, Brazil
| | - Marcelo Damário Gomes
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Jeziel Dener Damasceno
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Vitor Luiz da Silva
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
- Department of Chemical and Biological Sciences, Biosciences Institute, São Paulo State University (UNESP), Botucatu, Brazil
| | | | - Marcelo Santos da Silva
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | | | | | - Sandra Regina Maruyama
- Department of Genetics and Evolution, Federal University of São Carlos, São Carlos, Brazil
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Abstract
Targeted protein degradation is an invaluable tool in studying the function of proteins. Such a tool was not available in Trypanosoma brucei, an evolutionarily divergent eukaryote that causes human African trypanosomiasis. Here, we have adapted deGradFP (degrade green fluorescent protein [GFP]), a protein degradation system based on the SCF E3 ubiquitin ligase complex and anti-GFP nanobody, in T. brucei. As a proof of principle, we targeted a kinetoplastid kinetochore protein (KKT3) that constitutively localizes at kinetochores in the nucleus. Induction of deGradFP in a cell line that had both alleles of KKT3 tagged with yellow fluorescent protein (YFP) caused a more severe growth defect than RNAi in procyclic (insect form) cells. deGradFP also worked on a cytoplasmic protein (COPII subunit, SEC31). Given the ease in making GFP fusion cell lines in T. brucei, deGradFP can serve as a powerful tool to rapidly deplete proteins of interest, especially those with low turnover rates.
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Affiliation(s)
- Midori Ishii
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
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Genome-scale RNA interference profiling of Trypanosoma brucei cell cycle progression defects. Nat Commun 2022; 13:5326. [PMID: 36088375 PMCID: PMC9464253 DOI: 10.1038/s41467-022-33109-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 08/31/2022] [Indexed: 11/21/2022] Open
Abstract
Trypanosomatids, which include major pathogens of humans and livestock, are flagellated protozoa for which cell cycle controls and the underlying mechanisms are not completely understood. Here, we describe a genome-wide RNA-interference library screen for cell cycle defects in Trypanosoma brucei. We induced massive parallel knockdown, sorted the perturbed population using high-throughput flow cytometry, deep-sequenced RNAi-targets from each stage and digitally reconstructed cell cycle profiles at a genomic scale; also enabling data visualisation using an online tool ( https://tryp-cycle.pages.dev/ ). Analysis of several hundred genes that impact cell cycle progression reveals >100 flagellar component knockdowns linked to genome endoreduplication, evidence for metabolic control of the G1-S transition, surface antigen regulatory mRNA-binding protein knockdowns linked to G2M accumulation, and a putative nucleoredoxin required for both mitochondrial genome segregation and for mitosis. The outputs provide comprehensive functional genomic evidence for the known and novel machineries, pathways and regulators that coordinate trypanosome cell cycle progression.
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Ishii M, Akiyoshi B. Targeted protein degradation using deGradFP in Trypanosoma brucei. Wellcome Open Res 2022; 7:175. [PMID: 35865221 PMCID: PMC9277568 DOI: 10.12688/wellcomeopenres.17964.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2022] [Indexed: 11/09/2023] Open
Abstract
Targeted protein degradation is an invaluable tool in studying the function of proteins. Such a tool was not available in Trypanosoma brucei, an evolutionarily divergent eukaryote that causes human African trypanosomiasis. Here, we have adapted deGradFP (degrade green fluorescent protein [GFP]), a protein degradation system based on the SCF E3 ubiquitin ligase complex and anti-GFP nanobody, in T. brucei. As a proof of principle, we targeted a kinetoplastid kinetochore protein (KKT3) that constitutively localizes at kinetochores in the nucleus. Induction of deGradFP in a cell line that had both alleles of KKT3 tagged with yellow fluorescent protein (YFP) caused a more severe growth defect than RNAi in procyclic (insect form) cells. deGradFP also worked on a cytoplasmic protein (COPII subunit, SEC31). Given the ease in making GFP fusion cell lines in T. brucei, deGradFP can serve as a powerful tool to rapidly deplete proteins of interest, especially those with low turnover rates.
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Affiliation(s)
- Midori Ishii
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
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Bravo Ruiz G, Tinti M, Ridgway M, Horn D. Control of Variant Surface Glycoprotein Expression by CFB2 in Trypanosoma brucei and Quantitative Proteomic Connections to Translation and Cytokinesis. mSphere 2022; 7:e0006922. [PMID: 35306877 PMCID: PMC9044945 DOI: 10.1128/msphere.00069-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 02/23/2022] [Indexed: 01/17/2023] Open
Abstract
Variant surface glycoproteins (VSGs) coat parasitic African trypanosomes and underpin antigenic variation and immune evasion. These VSGs are superabundant virulence factors that are subject to posttranscriptional gene expression controls mediated via the VSG 3' untranslated region (UTR). To identify positive VSG regulators in bloodstream-form Trypanosoma brucei, we used genome-scale screening data to prioritize mRNA binding protein (mRBP) knockdowns that phenocopy VSG mRNA knockdown, displaying loss of fitness and precytokinesis accumulation. The top three candidates were CFB2 (cyclin F-box protein 2) (Tb927.1.4650), MKT1 (Tb927.6.4770), and PBP1 (polyadenylate binding protein 1) (Tb927.8.4540). Notably, CFB2 was recently found to regulate VSG transcript stability, and all three proteins were found to associate. We used data-independent acquisition for accurate label-free quantification and deep proteome coverage to quantify the expression profiles following the depletion of each mRBP. Only CFB2 knockdown significantly reduced VSG expression and the expression of a reporter under the control of the VSG 3' UTR. CFB2 knockdown also triggered the depletion of cytoplasmic ribosomal proteins, consistent with translation arrest observed when VSG synthesis is blocked. In contrast, PBP1 knockdown triggered the depletion of CFB2, MKT1, and other components of the PBP1 complex. Finally, all three knockdowns triggered the depletion of cytokinesis initiation factors, consistent with a cytokinesis defect, which was confirmed here for all three knockdowns. Thus, genome-scale knockdown data sets facilitate the triage and prioritization of candidate regulators. Quantitative proteomic analysis confirms the 3'-UTR-dependent positive control of VSG expression by CFB2 and interactions with additional mRBPs. Our results also reveal new insights into the connections between VSG expression control by CFB2, ribosomal protein expression, and cytokinesis. IMPORTANCE VSG expression represents a key parasite virulence mechanism and an example of extreme biology. Posttranscriptional gene expression controls in trypanosomatids also continue to be the subject of substantial research interest. We have identified three candidate VSG regulators and used knockdown and quantitative proteomics, in combination with other approaches, to assess their function. CFB2 is found to control VSG expression via the VSG 3' untranslated region, while other data support the view that MKT1 and PBP1 also form part of a CFB2 mRNA binding complex. Remarkably, we also find the depletion of cytoplasmic ribosomal proteins upon CFB2 knockdown, consistent with translation arrest observed when VSG synthesis is blocked. Proteomic profiles following knockdown further yield insights into cytokinesis defects. Taken together, our findings confirm and elaborate the role of CFB2 in controlling VSG expression and reveal new insights into connectivity with translation and cytokinesis controls.
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Affiliation(s)
- Gustavo Bravo Ruiz
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Michele Tinti
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Melanie Ridgway
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - David Horn
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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Mulindwa J, Ssentamu G, Matovu E, Kamanyi Marucha K, Aresta-Branco F, Helbig C, Clayton C. In vitro culture of freshly isolated Trypanosoma brucei brucei bloodstream forms results in gene copy-number changes. PLoS Negl Trop Dis 2021; 15:e0009738. [PMID: 34516555 PMCID: PMC8459984 DOI: 10.1371/journal.pntd.0009738] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/23/2021] [Accepted: 08/17/2021] [Indexed: 11/19/2022] Open
Abstract
Most researchers who study unicellular eukaryotes work with an extremely limited number of laboratory-adapted isolates that were obtained from the field decades ago, but the effects of passage in laboratory rodents, and adaptation to in vitro culture, have been little studied. For example, the vast majority of studies of Trypanosoma brucei biology have concentrated on just two strains, Lister 427 and EATRO1125, which were taken from the field over half a century ago and have since have undergone innumerable passages in rodents and culture. We here describe two new Trypanosoma brucei brucei strains. MAK65 and MAK98, which have undergone only 3 rodent passages since isolation from Ugandan cattle. High-coverage sequencing revealed that adaptation of the parasites to culture was accompanied by changes in gene copy numbers. T. brucei has so far been considered to be uniformly diploid, but we also found trisomy of chromosome 5 not only in one Lister 427 culture, but also in the MAK98 field isolate. Trisomy of chromosome 6, and increased copies of other chromosome segments, were also seen in established cultured lines. The two new T. brucei strains should be useful to researchers interested in trypanosome differentiation and pathogenicity. Initial results suggested that the two strains have differing infection patterns in rodents. MAK65 is uniformly diploid and grew more reproducibly in bloodstream-form culture than MAK98.
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Affiliation(s)
- Julius Mulindwa
- Department of Biochemistry and Sports Science, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Geofrey Ssentamu
- School of Biosecurity, Biotechnical and Laboratory Sciences, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Enock Matovu
- School of Biosecurity, Biotechnical and Laboratory Sciences, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | | | | | - Claudia Helbig
- Heidelberg University Centre for Molecular Biology (ZMBH), Heidelberg, Germany
| | - Christine Clayton
- Heidelberg University Centre for Molecular Biology (ZMBH), Heidelberg, Germany
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Melo do Nascimento L, Egler F, Arnold K, Papavasiliou N, Clayton C, Erben E. Functional insights from a surface antigen mRNA-bound proteome. eLife 2021; 10:e68136. [PMID: 33783358 PMCID: PMC8051951 DOI: 10.7554/elife.68136] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 03/18/2021] [Indexed: 01/13/2023] Open
Abstract
Trypanosoma brucei is the causative agent of human sleeping sickness. The parasites' variant surface glycoprotein (VSG) enables them to evade adaptive immunity via antigenic variation. VSG comprises 10% of total cell protein and the high stability of VSG mRNA is essential for trypanosome survival. To determine how VSG mRNA stability is maintained, we used mRNA affinity purification to identify all its associated proteins. CFB2 (cyclin F-box protein 2), an unconventional RNA-binding protein with an F-box domain, was specifically enriched with VSG mRNA. We demonstrate that CFB2 is essential for VSG mRNA stability, describe cis acting elements within the VSG 3'-untranslated region that regulate the interaction, identify trans-acting factors that are present in the VSG messenger ribonucleoprotein particle, and mechanistically explain how CFB2 stabilizes the mRNA of this key pathogenicity factor. Beyond T. brucei, the mRNP purification approach has the potential to supply detailed biological insight into metabolism of relatively abundant mRNAs in any eukaryote.
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Affiliation(s)
| | - Franziska Egler
- Centre for Molecular Biology of Heidelberg University (ZMBH)HeidelbergGermany
| | - Katharina Arnold
- Centre for Molecular Biology of Heidelberg University (ZMBH)HeidelbergGermany
| | - Nina Papavasiliou
- Division of Immune Diversity, Deutsche Krebsforschungszentrum (DKFZ)HeidelbergGermany
| | - Christine Clayton
- Centre for Molecular Biology of Heidelberg University (ZMBH)HeidelbergGermany
| | - Esteban Erben
- Centre for Molecular Biology of Heidelberg University (ZMBH)HeidelbergGermany
- Division of Immune Diversity, Deutsche Krebsforschungszentrum (DKFZ)HeidelbergGermany
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Melo do Nascimento L, Terrao M, Marucha KK, Liu B, Egler F, Clayton C. The RNA-associated proteins MKT1 and MKT1L form alternative PBP1-containing complexes in Trypanosoma brucei. J Biol Chem 2020; 295:10940-10955. [PMID: 32532821 DOI: 10.1074/jbc.ra120.013306] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 06/03/2020] [Indexed: 01/20/2023] Open
Abstract
Control of gene expression in kinetoplastids such as trypanosomes depends heavily on RNA-binding proteins that influence mRNA decay and translation. We previously showed that the trypanosome protein MKT1 forms a multicomponent protein complex: MKT1 interacts with PBP1, which in turn recruits LSM12 and poly(A)-binding protein. MKT1 is recruited to mRNAs by sequence-specific RNA-binding proteins, resulting in stabilization of the bound mRNA. We here show that PBP1, LSM12, and a 117-residue protein, XAC1 (Tb927.7.2780), are present in complexes that contain either MKT1 or an MKT1-like protein, MKT1L (Tb927.10.1490). All five proteins are present predominantly in the complexes, and we found evidence for a minor subset of complexes containing both MKT1 and MKT1L. XAC1-containing complexes reproducibly contained RNA-binding proteins that were previously found associated with MKT1. Moreover, XAC1- or MKT1-containing complexes specifically recruited one of the two poly(A)-binding proteins, PABP2, and one of the six cap-binding translation initiation complexes, EIF4E6-EIF4G5. Yeast two-hybrid assay results indicated that MKT1 directly interacts with EIF4G5. MKT1-PBP1 complexes can therefore interact with mRNAs via their poly(A) tails and caps, as well as through sequence-specific RNA-binding proteins. Correspondingly, MKT1 is associated with many mRNAs, although not with those encoding ribosomal proteins. Meanwhile, MKT1L resembles MKT1 at the C terminus but additionally features an N-terminal extension with low-complexity regions. Although MKT1L depletion inhibited cell proliferation, we found no evidence that it specifically interacts with RNA-binding proteins or mRNA. We speculate that MKT1L may compete with MKT1 for PBP1 binding and thereby modulate the function of MKT1-containing complexes.
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Affiliation(s)
| | - Monica Terrao
- Heidelberg University Centre for Molecular Biology (ZMBH), Heidelberg, Germany
| | | | - Bin Liu
- Heidelberg University Centre for Molecular Biology (ZMBH), Heidelberg, Germany
| | - Franziska Egler
- Heidelberg University Centre for Molecular Biology (ZMBH), Heidelberg, Germany
| | - Christine Clayton
- Heidelberg University Centre for Molecular Biology (ZMBH), Heidelberg, Germany
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Hammarton TC. Who Needs a Contractile Actomyosin Ring? The Plethora of Alternative Ways to Divide a Protozoan Parasite. Front Cell Infect Microbiol 2019; 9:397. [PMID: 31824870 PMCID: PMC6881465 DOI: 10.3389/fcimb.2019.00397] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/06/2019] [Indexed: 01/21/2023] Open
Abstract
Cytokinesis, or the division of the cytoplasm, following the end of mitosis or meiosis, is accomplished in animal cells, fungi, and amoebae, by the constriction of an actomyosin contractile ring, comprising filamentous actin, myosin II, and associated proteins. However, despite this being the best-studied mode of cytokinesis, it is restricted to the Opisthokonta and Amoebozoa, since members of other evolutionary supergroups lack myosin II and must, therefore, employ different mechanisms. In particular, parasitic protozoa, many of which cause significant morbidity and mortality in humans and animals as well as considerable economic losses, employ a wide diversity of mechanisms to divide, few, if any, of which involve myosin II. In some cases, cell division is not only myosin II-independent, but actin-independent too. Mechanisms employed range from primitive mechanical cell rupture (cytofission), to motility- and/or microtubule remodeling-dependent mechanisms, to budding involving the constriction of divergent contractile rings, to hijacking host cell division machinery, with some species able to utilize multiple mechanisms. Here, I review current knowledge of cytokinesis mechanisms and their molecular control in mammalian-infective parasitic protozoa from the Excavata, Alveolata, and Amoebozoa supergroups, highlighting their often-underappreciated diversity and complexity. Billions of people and animals across the world are at risk from these pathogens, for which vaccines and/or optimal treatments are often not available. Exploiting the divergent cell division machinery in these parasites may provide new avenues for the treatment of protozoal disease.
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Affiliation(s)
- Tansy C Hammarton
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
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Hu H, Majneri P, Li D, Kurasawa Y, An T, Dong G, Li Z. Functional analyses of the CIF1-CIF2 complex in trypanosomes identify the structural motifs required for cytokinesis. J Cell Sci 2017; 130:4108-4119. [PMID: 29074577 DOI: 10.1242/jcs.207134] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/10/2017] [Indexed: 12/28/2022] Open
Abstract
Cytokinesis in trypanosomes occurs uni-directionally along the longitudinal axis from the cell anterior towards the cell posterior and requires a trypanosome-specific CIF1-CIF2 protein complex. However, little is known about the contribution of the structural motifs in CIF1 and CIF2 to complex assembly and cytokinesis. Here, we demonstrate that the two zinc-finger motifs but not the coiled-coil motif in CIF1 are required for interaction with the EF-hand motifs in CIF2. We further show that localization of CIF1 depends on the coiled-coil motif and the first zinc-finger motif and that localization of CIF2 depends on the EF-hand motifs. Deletion of the coiled-coil motif and mutation of either zinc-finger motif in CIF1 disrupts cytokinesis. Furthermore, mutation of either zinc-finger motif in CIF1 mislocalizes CIF2 to the cytosol and destabilizes CIF2, whereas deletion of the coiled-coil motif in CIF1 spreads CIF2 over to the new flagellum attachment zone and stabilizes CIF2. Together, these results uncover the requirement of the coiled-coil and zinc-finger motifs for CIF1 function in cytokinesis and for CIF2 localization and stability, providing structural insights into the functional interplay between the two cytokinesis regulators.
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Affiliation(s)
- Huiqing Hu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Paul Majneri
- Max F. Perutz Laboratories, Vienna Bio-center, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Dielan Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Yasuhiro Kurasawa
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Tai An
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Gang Dong
- Max F. Perutz Laboratories, Vienna Bio-center, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
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Rojas F, Koszela J, Búa J, Llorente B, Burchmore R, Auer M, Mottram JC, Téllez-Iñón MT. The ubiquitin-conjugating enzyme CDC34 is essential for cytokinesis in contrast to putative subunits of a SCF complex in Trypanosoma brucei. PLoS Negl Trop Dis 2017; 11:e0005626. [PMID: 28609481 PMCID: PMC5507466 DOI: 10.1371/journal.pntd.0005626] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 07/11/2017] [Accepted: 05/06/2017] [Indexed: 12/31/2022] Open
Abstract
The ubiquitin-proteasome system is a post-translational regulatory pathway for controlling protein stability and activity that underlies many fundamental cellular processes, including cell cycle progression. Target proteins are tagged with ubiquitin molecules through the action of an enzymatic cascade composed of E1 ubiquitin activating enzymes, E2 ubiquitin conjugating enzymes, and E3 ubiquitin ligases. One of the E3 ligases known to be responsible for the ubiquitination of cell cycle regulators in eukaryotes is the SKP1-CUL1-F-box complex (SCFC). In this work, we identified and studied the function of homologue proteins of the SCFC in the life cycle of Trypanosoma brucei, the causal agent of the African sleeping sickness. Depletion of trypanosomal SCFC components TbRBX1, TbSKP1, and TbCDC34 by RNAi resulted in decreased growth rate and contrasting cell cycle abnormalities for both procyclic (PCF) and bloodstream (BSF) forms. Depletion of TbRBX1 in PCF cells interfered with kinetoplast replication, whilst depletion of TbSKP1 arrested PCF and BSF cells in the G1/S transition. Silencing of TbCDC34 in BSF cells resulted in a block in cytokinesis and caused rapid clearance of parasites from infected mice. We also show that TbCDC34 is able to conjugate ubiquitin in vitro and in vivo, and that its activity is necessary for T. brucei infection progression in mice. This study reveals that different components of a putative SCFC have contrasting phenotypes once depleted from the cells, and that TbCDC34 is essential for trypanosome replication, making it a potential target for therapeutic intervention. African sleeping sickness is a neglected tropical disease caused by infection with the protozoan parasite Trypanosoma brucei, which is transmitted to humans by tsetse flies (Glossina genus). Treatment of the disease is complex and relies on limited pharmaceutical options. Understanding how T. brucei regulates cell cycle progression at a molecular level when alternating between the mammalian host and the insect vector could lead to better therapies. In this study, we examined different T. brucei proteins with homology to components of the SKP1-CUL1-F-box ubiquitin ligase complex (SCFC), previously characterized in other eukaryotes as a regulator of cell cycle progression. We found that depletion of the homologues of a putative SCFC cause T. brucei to develop abnormally, generating different phenotypes of the mammalian and insect stages. Interestingly, depletion of the ubiquitin conjugating enzyme TbCDC34 arrest cells in a pre-cytokinesis stage, indicating that this protein is essential for cytokinesis. In addition to improving our fundamental understanding of the molecular regulation underlying the sophisticated life cycle of T. brucei, this work pinpoints a potential target for drug development against trypanosomiasis.
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Affiliation(s)
- Federico Rojas
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Buenos Aires, Argentina
- * E-mail:
| | - Joanna Koszela
- Institute of Quantitative Biology Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh, King’s Buildings, Edinburgh, United Kingdom
| | - Jacqueline Búa
- Instituto Nacional de Parasitología ‘Dr. M. Fatala Chabén’, A.N.L.I.S., ‘Dr. Carlos G. Malbrán’, Buenos Aires, Argentina
| | - Briardo Llorente
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Buenos Aires, Argentina
| | - Richard Burchmore
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Manfred Auer
- Institute of Quantitative Biology Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh, King’s Buildings, Edinburgh, United Kingdom
| | - Jeremy C. Mottram
- Centre for Immunology and Infection, Department of Biology, University of York, York, United Kingdom
| | - María Teresa Téllez-Iñón
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Buenos Aires, Argentina
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Lueong S, Merce C, Fischer B, Hoheisel JD, Erben ED. Gene expression regulatory networks in Trypanosoma brucei: insights into the role of the mRNA-binding proteome. Mol Microbiol 2016; 100:457-71. [PMID: 26784394 DOI: 10.1111/mmi.13328] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2016] [Indexed: 12/11/2022]
Abstract
Control of gene expression at the post-transcriptional level is essential in all organisms, and RNA-binding proteins play critical roles from mRNA synthesis to decay. To fully understand this process, it is necessary to identify the complete set of RNA-binding proteins and the functional consequences of the protein-mRNA interactions. Here, we provide an overview of the proteins that bind to mRNAs and their functions in the pathogenic bloodstream form of Trypanosoma brucei. We describe the production of a small collection of open-reading frames encoding proteins potentially involved in mRNA metabolism. With this ORFeome collection, we used tethering to screen for proteins that play a role in post-transcriptional control. A yeast two-hybrid screen showed that several of the discovered repressors interact with components of the CAF1/NOT1 deadenylation complex. To identify the RNA-binding proteins, we obtained the mRNA-bound proteome. We identified 155 high-confidence candidates, including many not previously annotated as RNA-binding proteins. Twenty seven of these proteins affected reporter expression in the tethering screen. Our study provides novel insights into the potential trypanosome mRNPs composition, architecture and function.
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Affiliation(s)
- Smiths Lueong
- Functional Genome Analysis, Deutsche Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
| | - Clementine Merce
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282
| | - Bernd Fischer
- Computational Genome Biology, Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 580, 69120 Heidelberg
| | - Jörg D Hoheisel
- Functional Genome Analysis, Deutsche Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
| | - Esteban D Erben
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282
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Singh A, Minia I, Droll D, Fadda A, Clayton C, Erben E. Trypanosome MKT1 and the RNA-binding protein ZC3H11: interactions and potential roles in post-transcriptional regulatory networks. Nucleic Acids Res 2014; 42:4652-68. [PMID: 24470144 PMCID: PMC3985637 DOI: 10.1093/nar/gkt1416] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The trypanosome zinc finger protein ZC3H11 binds to AU-rich elements in mRNAs. It is essential for survival of the mammalian-infective bloodstream form, where it stabilizes several mRNAs including some encoding chaperones, and is also required for stabilization of chaperone mRNAs during the heat-shock response in the vector-infective procyclic form. When ZC3H11 was artificially 'tethered' to a reporter mRNA in bloodstream forms it increased reporter expression. We here show that ZC3H11 interacts with trypanosome MKT1 and PBP1, and that domains required for both interactions are necessary for function in the bloodstream-form tethering assay. PBP1 interacts with MKT1, LSM12 and poly(A) binding protein, and localizes to granules during parasite starvation. All of these proteins are essential for bloodstream-form trypanosome survival and increase gene expression in the tethering assay. MKT1 is cytosolic and polysome associated. Using a yeast two-hybrid screen and tandem affinity purification we found that trypanosome MKT1 interacts with multiple RNA-binding proteins and other potential RNA regulators, placing it at the centre of a post-transcriptional regulatory network. A consensus interaction sequence, H(E/D/N/Q)PY, was identified. Recruitment of MKT1-containing regulatory complexes to mRNAs via sequence-specific mRNA-binding proteins could thus control several different post-transcriptional regulons.
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Affiliation(s)
- Aditi Singh
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D69120 Heidelberg, Germany
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Zhou Q, Hu H, Li Z. New insights into the molecular mechanisms of mitosis and cytokinesis in trypanosomes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 308:127-66. [PMID: 24411171 DOI: 10.1016/b978-0-12-800097-7.00004-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Trypanosoma brucei, a unicellular eukaryote and the causative agent of human sleeping sickness, possesses multiple single-copy organelles that all need to be duplicated and segregated during cell division. Trypanosomes undergo a closed mitosis in which the mitotic spindle is anchored on the nuclear envelope and connects the kinetochores made of novel protein components. Cytokinesis in trypanosomes is initiated from the anterior tip of the new flagellum attachment zone, and proceeds along the longitudinal axis without the involvement of the actomyosin contractile ring, the well-recognized cytokinesis machinery conserved from yeast to humans. Trypanosome appears to employ both evolutionarily conserved and trypanosome-specific proteins to regulate its cell cycle, and has evolved certain cell cycle regulatory pathways that are either distinct between its life cycle stages or different from its human host. Understanding the mechanisms of mitosis and cytokinesis in trypanosomes not only would shed novel light on the evolution of cell cycle control, but also could provide new drug targets for chemotherapy.
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Affiliation(s)
- Qing Zhou
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Huiqing Hu
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas, USA.
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15
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Distinct roles of a mitogen-activated protein kinase in cytokinesis between different life cycle forms of Trypanosoma brucei. EUKARYOTIC CELL 2013; 13:110-8. [PMID: 24213350 DOI: 10.1128/ec.00258-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mitogen-activated protein kinase (MAPK) modules are evolutionarily conserved signaling cascades that function in response to the environment and play crucial roles in intracellular signal transduction in eukaryotes. The involvement of a MAP kinase in regulating cytokinesis in yeast, animals, and plants has been reported, but the requirement for a MAP kinase for cytokinesis in the early-branching protozoa is not documented. Here, we show that a MAP kinase homolog (TbMAPK6) from Trypanosoma brucei plays distinct roles in cytokinesis in two life cycle forms of T. brucei. TbMAPK6 is distributed throughout the cytosol in the procyclic form but is localized in both the cytosol and the nucleus in the bloodstream form. RNA interference (RNAi) of TbMAPK6 results in moderate growth inhibition in the procyclic form but severe growth defects and rapid cell death in the bloodstream form. Moreover, TbMAPK6 appears to be implicated in furrow ingression and cytokinesis completion in the procyclic form but is essential for cytokinesis initiation in the bloodstream form. Despite the distinct defects in cytokinesis in the two forms, RNAi of TbMAPK6 also caused defective basal body duplication/segregation in a small cell population in both life cycle forms. Altogether, our results demonstrate the involvement of the TbMAPK6-mediated pathway in regulating cytokinesis in trypanosomes and suggest distinct roles of TbMAPK6 in cytokinesis between different life cycle stages of T. brucei.
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16
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Zhang X, Shen Y, Ding G, Tian Y, Liu Z, Li B, Wang Y, Jiang C. TFPP: an SVM-based tool for recognizing flagellar proteins in Trypanosoma brucei. PLoS One 2013; 8:e54032. [PMID: 23349782 PMCID: PMC3547966 DOI: 10.1371/journal.pone.0054032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 12/07/2012] [Indexed: 11/18/2022] Open
Abstract
Trypanosoma brucei is a unicellular flagellated eukaryotic parasite that causes African trypanosomiasis in human and domestic animals with devastating health and economic consequences. Recent studies have revealed the important roles of the single flagellum of T. brucei in many aspects, especially that the flagellar motility is required for the viability of the bloodstream form T. brucei, suggesting that impairment of the flagellar function may provide a promising cure for African sleeping sickness. Knowing the flagellum proteome is crucial to study the molecular mechanism of the flagellar functions. Here we present a novel computational method for identifying flagellar proteins in T. brucei, called trypanosome flagellar protein predictor (TFPP). TFPP was developed based on a list of selected discriminating features derived from protein sequences, and could predict flagellar proteins with ∼92% specificity at a ∼84% sensitivity rate. Applied to the whole T. brucei proteome, TFPP reveals 811 more flagellar proteins with high confidence, suggesting that the flagellar proteome covers ∼10% of the whole proteome. Comparison of the expression profiles of the whole T. brucei proteome at three typical life cycle stages found that ∼45% of the flagellar proteins were significantly changed in expression levels between the three life cycle stages, indicating life cycle stage-specific regulation of flagellar functions in T. brucei. Overall, our study demonstrated that TFPP is highly effective in identifying flagellar proteins and could provide opportunities to study the trypanosome flagellar proteome systematically. Furthermore, the web server for TFPP can be freely accessed at http:/wukong.tongji.edu.cn/tfpp.
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Affiliation(s)
- Xiaobai Zhang
- Department of Bioinformatics, the School of Life Sciences and Technology, Tongji University, Shanghai, China
- * E-mail: (XZ); (CJ)
| | - Yuefeng Shen
- Department of Bioinformatics, the School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Guitao Ding
- Department of Bioinformatics, the School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yi Tian
- Department of Bioinformatics, the School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Zhenping Liu
- Department of Bioinformatics, the School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Bing Li
- Department of Bioinformatics, the School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yun Wang
- Department of Bioinformatics, the School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Cizhong Jiang
- Department of Bioinformatics, the School of Life Sciences and Technology, Tongji University, Shanghai, China
- * E-mail: (XZ); (CJ)
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Abstract
The cell division cycle is tightly regulated by the activation and inactivation of a series of proteins that control the replication and segregation of organelles to the daughter cells. During the past decade, we have witnessed significant advances in our understanding of the cell cycle in Trypanosoma brucei and how the cycle is regulated by various regulatory proteins. However, many other regulators, especially those unique to trypanosomes, remain to be identified, and we are just beginning to delineate the signaling pathways that drive the transitions through different cell cycle stages, such as the G(1)/S transition, G(2)/M transition, and mitosis-cytokinesis transition. Trypanosomes appear to employ both evolutionarily conserved and trypanosome-specific molecules to regulate the various stages of its cell cycle, including DNA replication initiation, spindle assembly, chromosome segregation, and cytokinesis initiation and completion. Strikingly, trypanosomes lack some crucial regulators that are well conserved across evolution, such as Cdc6 and Cdt1, which are involved in DNA replication licensing, the spindle motor kinesin-5, which is required for spindle assembly, the central spindlin complex, which has been implicated in cytokinesis initiation, and the actomyosin contractile ring, which is located at the cleavage furrow. Conversely, trypanosomes possess certain regulators, such as cyclins, cyclin-dependent kinases, and mitotic centromere-associated kinesins, that are greatly expanded and likely play diverse cellular functions. Overall, trypanosomes apparently have integrated unique regulators into the evolutionarily conserved pathways to compensate for the absence of those conserved molecules and, additionally, have evolved certain cell cycle regulatory pathways that are either different from its human host or distinct between its own life cycle forms.
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Cytokinesis in bloodstream stage Trypanosoma brucei requires a family of katanins and spastin. PLoS One 2012; 7:e30367. [PMID: 22279588 PMCID: PMC3261199 DOI: 10.1371/journal.pone.0030367] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 12/19/2011] [Indexed: 11/19/2022] Open
Abstract
Microtubule severing enzymes regulate microtubule dynamics in a wide range of organisms and are implicated in important cell cycle processes such as mitotic spindle assembly and disassembly, chromosome movement and cytokinesis. Here we explore the function of several microtubule severing enzyme homologues, the katanins (KAT80, KAT60a, KAT60b and KAT60c), spastin (SPA) and fidgetin (FID) in the bloodstream stage of the African trypanosome parasite, Trypanosoma brucei. The trypanosome cytoskeleton is microtubule based and remains assembled throughout the cell cycle, necessitating its remodelling during cytokinesis. Using RNA interference to deplete individual proteins, we show that the trypanosome katanin and spastin homologues are non-redundant and essential for bloodstream form proliferation. Further, cell cycle analysis revealed that these proteins play essential but discrete roles in cytokinesis. The KAT60 proteins each appear to be important during the early stages of cytokinesis, while downregulation of KAT80 specifically inhibited furrow ingression and SPA depletion prevented completion of abscission. In contrast, RNA interference of FID did not result in any discernible effects. We propose that the stable microtubule cytoskeleton of T. brucei necessitates the coordinated action of a family of katanins and spastin to bring about the cytoskeletal remodelling necessary to complete cell division.
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Listovsky T, Brandeis M, Zilberstein D. Leishmania express a functional Cdc20 homologue. Biochem Biophys Res Commun 2011; 408:71-7. [PMID: 21458414 DOI: 10.1016/j.bbrc.2011.03.118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 03/26/2011] [Indexed: 11/15/2022]
Abstract
Our knowledge concerning the mechanisms of cell cycle regulation in organisms belonging to the Trypanosometidae family is limited. Leishmania donovani are parasitic protozoa that cause kala azar, a fatal form of visceral leishmaniasis in humans. Here we provide evidence that the L. donovani genome contains a Cdc20 homologue. Cdc20 is a regulator of the Anaphase Promoting Complex/Cyclosome (APC/C) that mediates ubiquitin-dependent proteasomal degradation of key cell cycle regulators in eukaryotes. We show that L. donovani Cdc20 protein (LdCdc20p) can complement a lack of yeast Cdc20 protein in Saccharomyces cerevisiae cells, validating the functionality of LdCdc20p. Furthermore, we demonstrate cyclic expression of LdCdc20p and that it contains an active RXXL destruction motif, a distinctive feature of proteins targeted for proteasomal degradation by APC/C. Finally, in line with the proteasome mediating LdCdc20p degradation, promastigotes exposed to proteasome inhibitor display elevated LdCdc20p levels. Taken together our data indicate that Leishmania regulate their cell cycle by ubiquitin-dependent proteasomal degradation mediated by the APC/C.
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Affiliation(s)
- Tamar Listovsky
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
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20
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Ma J, Benz C, Grimaldi R, Stockdale C, Wyatt P, Frearson J, Hammarton TC. Nuclear DBF-2-related kinases are essential regulators of cytokinesis in bloodstream stage Trypanosoma brucei. J Biol Chem 2010; 285:15356-15368. [PMID: 20231285 PMCID: PMC2865264 DOI: 10.1074/jbc.m109.074591] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Nuclear DBF-2-related (NDR) kinases are essential regulators of cell cycle progression, growth, and development in many organisms and are activated by the binding of an Mps One Binder (MOB) protein partner, autophosphorylation, and phosphorylation by an upstream STE20 family kinase. In the protozoan parasite, Trypanosoma brucei, the causative agent of human African trypanosomiasis, the NDR kinase, PK50, is expressed in proliferative life cycle stages and was shown to complement a yeast NDR kinase mutant cell line. However, the function of PK50 and a second NDR kinase, PK53, in T. brucei has not been determined to date, although trypanosome MOB1 is known to be essential for cytokinesis, suggesting the NDR kinases may also be involved in this process. Here, we show that specific depletion of PK50 or PK53 from bloodstream stage trypanosomes resulted in the rapid accumulation of cells with two nuclei and two kinetoplasts, indicating that cytokinesis was specifically inhibited. This led to a deregulation of the cell cycle and cell death and provides genetic validation of these kinases as potential novel drug targets for human African trypanosomiasis. Recombinant active PK50 and PK53 were produced and biochemically characterized. Both enzymes autophosphorylated, were able to trans-phosphorylate generic kinase substrates in vitro, and were active in the absence of phosphorylation by an upstream kinase. Additionally, both enzymes were active in the absence of MOB1 binding, which was also demonstrated to likely be a feature of the kinases in vivo. Biochemical characterization of recombinant PK50 and PK53 has revealed key kinetic differences between them, and the identification of in vitro peptide substrates in this study paves the way for high throughput inhibitor screening of these kinases.
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Affiliation(s)
- Jiangtao Ma
- Division of Infection & Immunity, Faculty of Biomedical and Life Sciences and Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow G12 8QQ
| | - Corinna Benz
- Division of Infection & Immunity, Faculty of Biomedical and Life Sciences and Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow G12 8QQ
| | - Raffaella Grimaldi
- Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, James Black Centre, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Christopher Stockdale
- Division of Infection & Immunity, Faculty of Biomedical and Life Sciences and Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow G12 8QQ
| | - Paul Wyatt
- Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, James Black Centre, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Julie Frearson
- Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, James Black Centre, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Tansy C Hammarton
- Division of Infection & Immunity, Faculty of Biomedical and Life Sciences and Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow G12 8QQ.
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Smith TK, Vasileva N, Gluenz E, Terry S, Portman N, Kramer S, Carrington M, Michaeli S, Gull K, Rudenko G. Blocking variant surface glycoprotein synthesis in Trypanosoma brucei triggers a general arrest in translation initiation. PLoS One 2009; 4:e7532. [PMID: 19855834 PMCID: PMC2762041 DOI: 10.1371/journal.pone.0007532] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Accepted: 09/22/2009] [Indexed: 01/22/2023] Open
Abstract
Background The African trypanosome Trypanosoma brucei is covered with a dense layer of Variant Surface Glycoprotein (VSG), which protects it from lysis by host complement via the alternative pathway in the mammalian bloodstream. Blocking VSG synthesis by the induction of VSG RNAi triggers an unusually precise precytokinesis cell-cycle arrest. Methodology/Principal Findings Here, we characterise the cells arrested after the induction of VSG RNAi. We were able to rescue the VSG221 RNAi induced cell-cycle arrest through expression of a second different VSG (VSG117 which is not recognised by the VSG221 RNAi) from the VSG221 expression site. Metabolic labeling of the arrested cells showed that blocking VSG synthesis triggered a global translation arrest, with total protein synthesis reduced to less than 1–4% normal levels within 24 hours of induction of VSG RNAi. Analysis by electron microscopy showed that the translation arrest was coupled with rapid disassociation of ribosomes from the endoplasmic reticulum. Polysome analysis showed a drastic decrease in polysomes in the arrested cells. No major changes were found in levels of transcription, total RNA transcript levels or global amino acid concentrations in the arrested cells. Conclusions The cell-cycle arrest phenotype triggered by the induction of VSG221 RNAi is not caused by siRNA toxicity, as this arrest can be alleviated if a second different VSG is inserted downstream of the active VSG221 expression site promoter. Analysis of polysomes in the stalled cells showed that the translation arrest is mediated at the level of translation initiation rather than elongation. The cell-cycle arrest induced in the presence of a VSG synthesis block is reversible, suggesting that VSG synthesis and/or trafficking to the cell surface could be monitored during the cell-cycle as part of a specific cell-cycle checkpoint.
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Affiliation(s)
- Terry K. Smith
- Centre for Biomolecular Sciences, University of St. Andrews, Fife, Scotland, United Kingdom
| | - Nadina Vasileva
- The Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
| | - Eva Gluenz
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Stephen Terry
- The Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
| | - Neil Portman
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Susanne Kramer
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Keith Gull
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Gloria Rudenko
- The Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
- * E-mail:
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Zhang L, Hou Y, Wang M, Wu B, Li N. A study on the functions of ubiquitin metabolic system related gene FBG2 in gastric cancer cell line. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2009; 28:78. [PMID: 19515249 PMCID: PMC2709112 DOI: 10.1186/1756-9966-28-78] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Accepted: 06/10/2009] [Indexed: 11/10/2022]
Abstract
Background FBG2 (F-BOX6) gene is an important member in ubiquitin metabolic system F-BOX family, and forms E3 complex with the other members in the family. But its role in gastric cancer is still not clear. In the present study, we intended to investigate the influence of FBG2 on the growth, proliferation, apoptosis, invasion and cell cycle of the gastric cancer line MKN45 and gastric cell line HFE145. Methods As a critical component of ubiquitin-protein ligase complex, FBG2 cDNA was subcloned into a constitutive vector PCDNA3.1 followed by transfection in MKN45 and HFE145 by using liposome. Then stable transfectants were selected and appraised. The apoptosis and cell cycles of these clones were analyzed by using flow cytometry. The growth and proliferation were analyzed by cell growth curves and colony-forming assay respectively. The invasion of these clones was tested by using cancer cell migration assay. The FBG2 stable expression clones(MKN-FBG2 and HFE-FBG2) and their control groups were detected and compared respectively. Results MKN-FBG2 grew faster than MKN45 and MKN-PC(MKN45 transfected with PCDNA3.1 vector). HFE-FBG2 grew faster than HFE145 and HFE-PC(HFE145 transfected with PCDNA3.1 vector). The cell counts of MKN-FBG2 in the forth, fifth, sixth and seventh days were significantly more than those of others (P < 0.05). Cell cycle analysis showed that MKN-FBG2 and HFE-FBG2 proliferated faster, proportions of cells in G2-M and S were different significantly with control groups (P < 0.05). Results of colony-forming assay showed that the colony formation rates of MKN-FBG2 and HFE-FBG2 were higher than those of control groups (P < 0.05). The results of cell migration assay were all negative. Conclusion FBG2 can promote the growth and proliferation of gastric cancer cells and normal gastric cells. It can help tumor cell maintain malignant phenotype too. But it can have a negative influence on the apoptosis or the ability of invasion of gastric cancer cells.
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Affiliation(s)
- Lin Zhang
- Department of Gastroenterology, Second Affiliated Hospital of General Hospital of PLA, Beijing, PR China.
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Wurst M, Robles A, Po J, Luu VD, Brems S, Marentije M, Stoitsova S, Quijada L, Hoheisel J, Stewart M, Hartmann C, Clayton C. An RNAi screen of the RRM-domain proteins of Trypanosoma brucei. Mol Biochem Parasitol 2009; 163:61-5. [DOI: 10.1016/j.molbiopara.2008.09.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 08/15/2008] [Accepted: 09/03/2008] [Indexed: 01/09/2023]
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Hartmann C, Benz C, Brems S, Ellis L, Luu VD, Stewart M, D'Orso I, Busold C, Fellenberg K, Frasch ACC, Carrington M, Hoheisel J, Clayton CE. Small trypanosome RNA-binding proteins TbUBP1 and TbUBP2 influence expression of F-box protein mRNAs in bloodstream trypanosomes. EUKARYOTIC CELL 2007; 6:1964-78. [PMID: 17873084 PMCID: PMC2168414 DOI: 10.1128/ec.00279-07] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the African trypanosome Trypanosoma brucei nearly all control of gene expression is posttranscriptional; sequences in the 3'-untranslated regions of mRNAs determine the steady-state mRNA levels by regulation of RNA turnover. Here we investigate the roles of two related proteins, TbUBP1 and TbUBP2, containing a single RNA recognition motif, in trypanosome gene expression. TbUBP1 and TbUBP2 are in the cytoplasm and nucleus, comprise ca. 0.1% of the total protein, and are not associated with polysomes or RNA degradation enzymes. Overexpression of TbUBP2 upregulated the levels of several mRNAs potentially involved in cell division, including the CFB1 mRNA, which encodes a protein with a cyclin F-box domain. CFB1 regulation was mediated by the 3'-untranslated region and involved stabilization of the mRNA. Depletion of TbUBP2 and TbUBP1 inhibited growth and downregulated expression of the cyclin F box protein gene CFB2; trans splicing was unaffected. The results of pull-down assays indicated that all tested mRNAs were bound to TbUBP2 or TbUBP1, with some preference for CFB1. We suggest that TbUBP1 and TbUBP2 may be relatively nonspecific RNA-binding proteins and that specific effects of overexpression or depletion could depend on competition between various different proteins for RNA binding.
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Affiliation(s)
- Claudia Hartmann
- Zentrum für Molekulare Biologie der Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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