1
|
Pasquarelli RR, Quan JJ, Cheng ES, Yang V, Britton TA, Sha J, Wohlschlegel JA, Bradley PJ. Characterization and functional analysis of Toxoplasma Golgi-associated proteins identified by proximity labelling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.02.578703. [PMID: 38352341 PMCID: PMC10862792 DOI: 10.1101/2024.02.02.578703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Toxoplasma gondii possesses a highly polarized secretory pathway that contains both broadly conserved eukaryotic organelles and unique apicomplexan organelles which play essential roles in the parasite's lytic cycle. As in other eukaryotes, the T. gondii Golgi apparatus sorts and modifies proteins prior to their distribution to downstream organelles. Many of the typical trafficking factors found involved in these processes are missing from apicomplexan genomes, suggesting that these parasites have evolved unique proteins to fill these roles. Here we identify a novel Golgi-localizing protein (ULP1) which contains structural homology to the eukaryotic trafficking factor p115/Uso1. We demonstrate that depletion of ULP1 leads to a dramatic reduction in parasite fitness and replicative ability. Using ULP1 as bait for TurboID proximity labelling and immunoprecipitation, we identify eleven more novel Golgi-associated proteins and demonstrate that ULP1 interacts with the T. gondii COG complex. These proteins include both conserved trafficking factors and parasite-specific proteins. Using a conditional knockdown approach, we assess the effect of each of these eleven proteins on parasite fitness. Together, this work reveals a diverse set of novel T. gondii Golgi-associated proteins that play distinct roles in the secretory pathway. As several of these proteins are absent outside of the Apicomplexa, they represent potential targets for the development of novel therapeutics against these parasites. Importance Apicomplexan parasites such as Toxoplasma gondii infect a large percentage of the world's population and cause substantial human disease. These widespread pathogens use specialized secretory organelles to infect their host cells, modulate host cell functions, and cause disease. While the functions of the secretory organelles are now better understood, the Golgi apparatus of the parasite remains largely unexplored, particularly regarding parasite-specific innovations that may help direct traffic intracellularly. In this work, we characterize ULP1, a protein that is unique to parasites but shares structural similarity to the eukaryotic trafficking factor p115/Uso1. We show that ULP1 plays an important role in parasite replication and demonstrate that it interacts with the conserved oligomeric Golgi (COG) complex. We then use ULP1 proximity labelling to identify eleven additional Golgi-associated proteins which we functionally analyze via conditional knockdown. This work expands our knowledge of the Toxoplasma Golgi apparatus and identifies potential targets for therapeutic intervention.
Collapse
|
2
|
Filho CSMB, de Menezes RRPPB, Magalhães EP, Castillo YP, Martins AMC, de Sousa DP. Piplartine-Inspired 3,4,5-Trimethoxycinnamates: Trypanocidal, Mechanism of Action, and In Silico Evaluation. Molecules 2023; 28:molecules28114512. [PMID: 37298988 DOI: 10.3390/molecules28114512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 05/25/2023] [Accepted: 05/29/2023] [Indexed: 06/12/2023] Open
Abstract
Chagas disease (CD) is one of the main neglected tropical diseases that promote relevant socioeconomic impacts in several countries. The therapeutic options for the treatment of CD are limited, and parasite resistance has been reported. Piplartine is a phenylpropanoid imide that has diverse biological activities, including trypanocidal action. Thus, the objective of the present work was to prepare a collection of thirteen esters analogous to piplartine (1-13) and evaluate their trypanocidal activity against Trypanosoma cruzi. Of the tested analogues, compound 11 ((E)-furan-2-ylmethyl 3-(3,4,5-trimethoxyphenyl)acrylate) showed good activity with IC50 values = 28.21 ± 5.34 μM and 47.02 ± 8.70 μM, against the epimastigote and trypomastigote forms, respectively. In addition, it showed a high rate of selectivity to the parasite. The trypanocidal mechanism of action occurs through the induction of oxidative stress and mitochondrial damage. In addition, scanning electron microscopy showed the formation of pores and leakage of cytoplasmic content. Molecular docking indicated that 11 probably produces a trypanocidal effect through a multi-target mechanism, including affinity with proteins CRK1, MPK13, GSK3B, AKR, UCE-1, and UCE-2, which are important for the survival of the parasite. Therefore, the results suggest chemical characteristics that can serve for the development of new trypanocidal prototypes for researching drugs against Chagas disease.
Collapse
Affiliation(s)
- Carlos S M B Filho
- Department of Pharmaceutical Sciences, Federal University of Paraíba, João Pessoa 58051-900, PB, Brazil
| | - Ramon R P P B de Menezes
- Department of Clinical and Toxicological Analysis, Federal University of Ceará, Fortaleza 60020-181, CE, Brazil
| | - Emanuel P Magalhães
- Department of Clinical and Toxicological Analysis, Federal University of Ceará, Fortaleza 60020-181, CE, Brazil
| | - Yunierkis P Castillo
- Escuela de Ciencias Físicas y Matemáticas, Universidad de Las Américas, Quito 170125, Ecuador
| | - Alice M C Martins
- Department of Clinical and Toxicological Analysis, Federal University of Ceará, Fortaleza 60020-181, CE, Brazil
| | - Damião P de Sousa
- Department of Pharmaceutical Sciences, Federal University of Paraíba, João Pessoa 58051-900, PB, Brazil
| |
Collapse
|
3
|
Faktorová D, Záhonová K, Benz C, Dacks JB, Field MC, Lukeš J. Functional differentiation of Sec13 paralogues in the euglenozoan protists. Open Biol 2023; 13:220364. [PMID: 37311539 DOI: 10.1098/rsob.220364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 05/23/2023] [Indexed: 06/15/2023] Open
Abstract
The β-propeller protein Sec13 plays roles in at least three distinct processes by virtue of being a component of the COPII endoplasmic reticulum export vesicle coat, the nuclear pore complex (NPC) and the Seh1-associated (SEA)/GATOR nutrient-sensing complex. This suggests that regulatory mechanisms coordinating these cellular activities may operate via Sec13. The NPC, COPII and SEA/GATOR are all ancient features of eukaryotic cells, and in the vast majority of eukaryotes, a single Sec13 gene is present. Here we report that the Euglenozoa, a lineage encompassing the diplonemid, kinetoplastid and euglenid protists, possess two Sec13 paralogues. Furthermore, based on protein interactions and localization studies we show that in diplonemids Sec13 functions are divided between the Sec13a and Sec13b paralogues. Specifically, Sec13a interacts with COPII and the NPC, while Sec13b interacts with Sec16 and components of the SEA/GATOR complex. We infer that euglenozoan Sec13a is responsible for NPC functions and canonical anterograde transport activities while Sec13b acts within nutrient and autophagy-related pathways, indicating a fundamentally distinct organization of coatomer complexes in euglenozoan flagellates.
Collapse
Affiliation(s)
- Drahomíra Faktorová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Sciences, University of South Bohemia, České Budějovice, Czech Republic
| | - Kristína Záhonová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
- Life Science Research Centre, Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
- Division of Infectious Diseases, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Corinna Benz
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Joel B Dacks
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Division of Infectious Diseases, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution, and Environment, University College London, London, UK
| | - Mark C Field
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- School of Life Sciences, University of Dundee, Dundee, UK
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Sciences, University of South Bohemia, České Budějovice, Czech Republic
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Thakur AK, Luthra-Guptasarma M. Differences in Cellular Clearing Mechanisms of Aggregates of Two Subtypes of HLA-B27. Front Immunol 2022; 12:795053. [PMID: 35082784 PMCID: PMC8785436 DOI: 10.3389/fimmu.2021.795053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/10/2021] [Indexed: 01/08/2023] Open
Abstract
Ankylosing spondylitis (AS) belongs to a group of diseases, called spondyloarthropathies (SpA), that are strongly associated with the genetic marker HLA-B27. AS is characterized by inflammation of joints and primarily affects the spine. Over 160 subtypes of HLA-B27 are known, owing to high polymorphism. Some are strongly associated with disease (e.g., B*2704), whereas others are not (e.g., B*2709). Misfolding of HLA-B27 molecules [as dimers, or as high-molecular-weight (HMW) oligomers] is one of several hypotheses proposed to explain the link between HLA-B27 and AS. Our group has previously established the existence of HMW species of HLA-B27 in AS patients. Still, very little is known about the mechanisms underlying differences in pathogenic outcomes of different HLA-B27 subtypes. We conducted a proteomics-based evaluation of the differential disease association of HLA B*2704 and B*2709, using stable transfectants of genes encoding the two proteins. A clear difference was observed in protein clearance mechanisms: whereas unfolded protein response (UPR), autophagy, and aggresomes were involved in the degradation of B*2704, the endosome–lysosome machinery was primarily involved in B*2709 degradation. These differences offer insights into the differential disease association of B*2704 and B*2709.
Collapse
Affiliation(s)
- Amit Kumar Thakur
- Department of Immunopathology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Manni Luthra-Guptasarma
- Department of Immunopathology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| |
Collapse
|
7
|
Assis LA, Santos Filho MVC, da Cruz Silva JR, Bezerra MJR, de Aquino IRPUC, Merlo KC, Holetz FB, Probst CM, Rezende AM, Papadopoulou B, da Costa Lima TDC, de Melo Neto OP. Identification of novel proteins and mRNAs differentially bound to the Leishmania Poly(A) Binding Proteins reveals a direct association between PABP1, the RNA-binding protein RBP23 and mRNAs encoding ribosomal proteins. PLoS Negl Trop Dis 2021; 15:e0009899. [PMID: 34705820 PMCID: PMC8575317 DOI: 10.1371/journal.pntd.0009899] [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: 07/06/2021] [Revised: 11/08/2021] [Accepted: 10/11/2021] [Indexed: 12/13/2022] Open
Abstract
Poly(A) Binding Proteins (PABPs) are major eukaryotic RNA-binding proteins (RBPs) with multiple roles associated with mRNA stability and translation and characterized mainly from multicellular organisms and yeasts. A variable number of PABP homologues are seen in different organisms however the biological reasons for multiple PABPs are generally not well understood. In the unicellular Leishmania, dependent on post-transcriptional mechanisms for the control of its gene expression, three distinct PABPs are found, with yet undefined functional distinctions. Here, using RNA-immunoprecipitation sequencing analysis we show that the Leishmania PABP1 preferentially associates with mRNAs encoding ribosomal proteins, while PABP2 and PABP3 bind to an overlapping set of mRNAs distinct to those enriched in PABP1. Immunoprecipitation studies combined to mass-spectrometry analysis identified RBPs differentially associated with PABP1 or PABP2, including RBP23 and DRBD2, respectively, that were investigated further. Both RBP23 and DRBD2 bind directly to the three PABPs in vitro, but reciprocal experiments confirmed preferential co-immunoprecipitation of PABP1, as well as the EIF4E4/EIF4G3 based translation initiation complex, with RBP23. Other RBP23 binding partners also imply a direct role in translation. DRBD2, in contrast, co-immunoprecipitated with PABP2, PABP3 and with RBPs unrelated to translation. Over 90% of the RBP23-bound mRNAs code for ribosomal proteins, mainly absent from the transcripts co-precipitated with DRBD2. These experiments suggest a novel and specific route for translation of the ribosomal protein mRNAs, mediated by RBP23, PABP1 and the associated EIF4E4/EIF4G3 complex. They also highlight the unique roles that different PABP homologues may have in eukaryotic cells associated with mRNA translation.
Collapse
Affiliation(s)
- Ludmila A. Assis
- Department of Microbiology, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil
- Department of Genetics, Federal University of Pernambuco, Recife, Pernambuco, Brazil
| | - Moezio V. C. Santos Filho
- Department of Microbiology, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil
- Department of Genetics, Federal University of Pernambuco, Recife, Pernambuco, Brazil
| | - Joao R. da Cruz Silva
- Department of Microbiology, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil
| | - Maria J. R. Bezerra
- Department of Microbiology, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil
| | | | - Kleison C. Merlo
- Department of Microbiology, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil
| | - Fabiola B. Holetz
- Laboratory of Gene Expression Regulation, Carlos Chagas Institute, Oswaldo Cruz Foundation, Curitiba, Paraná, Brazil
| | - Christian M. Probst
- Laboratory of Gene Expression Regulation, Carlos Chagas Institute, Oswaldo Cruz Foundation, Curitiba, Paraná, Brazil
| | - Antonio M. Rezende
- Department of Microbiology, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil
| | - Barbara Papadopoulou
- CHU de Quebec Research Center and Department of Microbiology-Infectious Disease and Immunology, Laval University, Quebec, Quebec, Canada
| | | | - Osvaldo P. de Melo Neto
- Department of Microbiology, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil
| |
Collapse
|
8
|
Bisnett BJ, Condon BM, Linhart NA, Lamb CH, Huynh DT, Bai J, Smith TJ, Hu J, Georgiou GR, Boyce M. Evidence for nutrient-dependent regulation of the COPII coat by O-GlcNAcylation. Glycobiology 2021; 31:1102-1120. [PMID: 34142147 PMCID: PMC8457363 DOI: 10.1093/glycob/cwab055] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 06/01/2021] [Accepted: 06/03/2021] [Indexed: 12/18/2022] Open
Abstract
O-linked β-N-acetylglucosamine (O-GlcNAc) is a dynamic form of intracellular glycosylation common in animals, plants and other organisms. O-GlcNAcylation is essential in mammalian cells and is dysregulated in myriad human diseases, such as cancer, neurodegeneration and metabolic syndrome. Despite this pathophysiological significance, key aspects of O-GlcNAc signaling remain incompletely understood, including its impact on fundamental cell biological processes. Here, we investigate the role of O-GlcNAcylation in the coat protein II complex (COPII), a system universally conserved in eukaryotes that mediates anterograde vesicle trafficking from the endoplasmic reticulum. We identify new O-GlcNAcylation sites on Sec24C, Sec24D and Sec31A, core components of the COPII system, and provide evidence for potential nutrient-sensitive pathway regulation through site-specific glycosylation. Our work suggests a new connection between metabolism and trafficking through the conduit of COPII protein O-GlcNAcylation.
Collapse
Affiliation(s)
- Brittany J Bisnett
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Brett M Condon
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Noah A Linhart
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Caitlin H Lamb
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Duc T Huynh
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Jingyi Bai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Timothy J Smith
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Jimin Hu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - George R Georgiou
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Michael Boyce
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| |
Collapse
|
9
|
Overexpression of ERAP2N in Human Trophoblast Cells Promotes Cell Death. Int J Mol Sci 2021; 22:ijms22168585. [PMID: 34445292 PMCID: PMC8395336 DOI: 10.3390/ijms22168585] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/19/2021] [Accepted: 07/22/2021] [Indexed: 12/13/2022] Open
Abstract
The genes involved in implantation and placentation are tightly regulated to ensure a healthy pregnancy. The endoplasmic reticulum aminopeptidase 2 (ERAP2) gene is associated with preeclampsia (PE). Our studies have determined that an isoform of ERAP2-arginine (N), expressed in trophoblast cells (TC), significantly activates immune cells, and ERAP2N-expressing TCs are preferentially killed by both cytotoxic T lymphocytes (CTLs) and Natural Killer cells (NKCs). To understand the cause of this phenomenon, we surveyed differentially expressed genes (DEGs) between ERAP2N expressing and non-expressing TCs. Our RNAseq data revealed 581 total DEGs between the two groups. 289 genes were up-regulated, and 292 genes were down-regulated. Interestingly, most of the down-regulated genes of significance were pro-survival genes that play a crucial role in cell survival (LDHA, EGLN1, HLA-C, ITGB5, WNT7A, FN1). However, the down-regulation of these genes in ERAP2N-expressing TCs translates into a propensity for cell death. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that 64 DEGs were significantly enriched in nine pathways, including “Protein processing in endoplasmic reticulum” and “Antigen processing and presentation”, suggesting that the genes may be associated with peptide processes involved in immune recognition during the reproductive cycle.
Collapse
|
10
|
Nihei CI, Nakanishi M. Cargo selection in the early secretory pathway of African trypanosomes. Parasitol Int 2021; 84:102379. [PMID: 34000424 DOI: 10.1016/j.parint.2021.102379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/30/2021] [Accepted: 05/06/2021] [Indexed: 11/25/2022]
Abstract
Membrane and secretory proteins are synthesized by ribosomes and then enter the endoplasmic reticulum (ER) where they undergo glycosylation and quality control for proper folding. Subsequently, proteins are transported to the Golgi apparatus and then sorted to the plasma membrane or intracellular organelles. Transport vesicles are formed at ER-exit sites (ERES) on the ER with several coat protein complexes. Cargo proteins loaded into the vesicles are selected by specific interactions with cargo receptors and/or adaptors during vesicle formation. p24 family and intracellular lectin ERGIC-53-membrane proteins are the known cargo receptors acting in the early secretory pathway (ER-Golgi). Oligomerization of the cargo receptors have been suggested to play an important role in cargo selection and sorting via posttranslational modifications in fungi and metazoans. On the other hand, the mechanisms involved in the early secretory pathway in protozoa remain unclear. In this review, we focus on Trypanosoma brucei as a representative of protozoan and discuss differences and commonalities in the molecular mechanisms of its early secretory pathway compared with other organisms.
Collapse
Affiliation(s)
- Coh-Ichi Nihei
- Institute of Microbial Chemistry, Microbial Chemistry Research Foundation (BIKAKEN), 3-14-23, Kamiosaki, Shinagawa-ku, Tokyo 141-0023, Japan.
| | - Masayuki Nakanishi
- Laboratory of Biochemistry, College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan.
| |
Collapse
|
11
|
de Lima GB, de Lima Cavalcanti TYV, de Brito ANALM, de Assis LA, Andrade-Vieira RP, Freire ER, da Silva Assunção TR, de Souza Reis CR, Zanchin NIT, Guimarães BG, de-Melo-Neto OP. The translation initiation factor EIF4E5 from Leishmania: crystal structure and interacting partners. RNA Biol 2021; 18:2433-2449. [PMID: 33945405 DOI: 10.1080/15476286.2021.1918919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The mRNA cap-binding protein, eIF4E, mediates the recognition of the mRNA 5' end and, as part of the heterotrimeric eIF4F complex, facilitates the recruitment of the ribosomal subunits to initiate eukaryotic translation. Various regulatory events involving eIF4E and a second eIF4F subunit, eIF4G, are required for proper control of translation initiation. In pathogenic trypanosomatids, six eIF4Es and five eIF4Gs have been described, several forming different eIF4F-like complexes with yet unresolved roles. EIF4E5 is one of the least known of the trypanosomatid eIF4Es and has not been characterized in Leishmania species. Here, we used immunoprecipitation assays, combined with mass-spectrometry, to identify major EIF4E5 interacting proteins in L. infantum. A constitutively expressed, HA-tagged, EIF4E5 co-precipitated mainly with EIF4G1 and binding partners previously described in Trypanosoma brucei, EIF4G1-IP, RBP43 and the 14-3-3 proteins. In contrast, no clear co-precipitation with EIF4G2, also previously reported, was observed. EIF4E5 also co-precipitated with protein kinases, possibly associated with cell-cycle regulation, selected RNA binding proteins and histones. Phosphorylated residues were identified and mapped to the Leishmania-specific C-terminal end. Mutagenesis of the tryptophan residue (W53) postulated to mediate interactions with protein partners or of a neighbouring tryptophan conserved in Leishmania (W45) did not substantially impair the identified interactions. Finally, the crystal structure of Leishmania EIF4E5 evidences remarkable differences in the eIF4G interfacing region, when compared with human eIF4E-1 and with its Trypanosoma orthologue. Mapping of its C-terminal end near the cap-binding site also imply relevant differences in cap-binding function and/or regulation.
Collapse
Affiliation(s)
- Gustavo Barbosa de Lima
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil
| | - Thaíse Yasmine Vasconcelos de Lima Cavalcanti
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil.,Programa de Pós-Graduação em Genética, Universidade Federal de Pernambuco, Recife-PE, Brazil
| | - Adriana Neuman Albuquerque Lins Moura de Brito
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil.,Programa de Pós-Graduação em Genética, Universidade Federal de Pernambuco, Recife-PE, Brazil
| | - Ludmilla Arruda de Assis
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil
| | | | - Eden Ribeiro Freire
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil.,Laboratório de Biologia Estrutural e Engenharia de Proteínas, Instituto Carlos Chagas, FIOCRUZ-PR, Curitiba-PR, Brazil
| | | | | | - Nilson Ivo Tonin Zanchin
- Laboratório de Biologia Estrutural e Engenharia de Proteínas, Instituto Carlos Chagas, FIOCRUZ-PR, Curitiba-PR, Brazil
| | - Beatriz Gomes Guimarães
- Laboratório de Biologia Estrutural e Engenharia de Proteínas, Instituto Carlos Chagas, FIOCRUZ-PR, Curitiba-PR, Brazil
| | | |
Collapse
|
12
|
Lee KJ, Li Z. The CRK2-CYC13 complex functions as an S-phase cyclin-dependent kinase to promote DNA replication in Trypanosoma brucei. BMC Biol 2021; 19:29. [PMID: 33568178 PMCID: PMC7876812 DOI: 10.1186/s12915-021-00961-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 01/15/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Faithful DNA replication is essential to maintain genomic stability in all living organisms, and the regulatory pathway for DNA replication initiation is conserved from yeast to humans. The evolutionarily ancient human parasite Trypanosoma brucei, however, lacks many of the conserved DNA replication factors and may employ unusual mechanisms for DNA replication. Neither the S-phase cyclin-dependent kinase (CDK) nor the regulatory pathway governing DNA replication has been previously identified in T. brucei. RESULTS Here we report that CRK2 (Cdc2-related kinase 2) complexes with CYC13 (Cyclin13) and functions as an S-phase CDK to promote DNA replication in T. brucei. We further show that CRK2 phosphorylates Mcm3, a subunit of the Mcm2-7 sub-complex of the Cdc45-Mcm2-7-GINS complex, and demonstrate that Mcm3 phosphorylation by CRK2 facilitates interaction with Sld5, a subunit of the GINS sub-complex of the Cdc45-Mcm2-7-GINS complex. CONCLUSIONS These results identify the CRK2-CYC13 complex as an S-phase regulator in T. brucei and reveal its role in regulating DNA replication through promoting the assembly of the Cdc45-Mcm2-7-GINS complex.
Collapse
Affiliation(s)
- Kyu Joon Lee
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA.
| |
Collapse
|
13
|
Bisnett BJ, Condon BM, Lamb CH, Georgiou GR, Boyce M. Export Control: Post-transcriptional Regulation of the COPII Trafficking Pathway. Front Cell Dev Biol 2021; 8:618652. [PMID: 33511128 PMCID: PMC7835409 DOI: 10.3389/fcell.2020.618652] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 12/14/2020] [Indexed: 11/13/2022] Open
Abstract
The coat protein complex II (COPII) mediates forward trafficking of protein and lipid cargoes from the endoplasmic reticulum. COPII is an ancient and essential pathway in all eukaryotes and COPII dysfunction underlies a range of human diseases. Despite this broad significance, major aspects of COPII trafficking remain incompletely understood. For example, while the biochemical features of COPII vesicle formation are relatively well characterized, much less is known about how the COPII system dynamically adjusts its activity to changing physiologic cues or stresses. Recently, post-transcriptional mechanisms have emerged as a major mode of COPII regulation. Here, we review the current literature on how post-transcriptional events, and especially post-translational modifications, govern the COPII pathway.
Collapse
Affiliation(s)
- Brittany J Bisnett
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
| | - Brett M Condon
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
| | - Caitlin H Lamb
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
| | - George R Georgiou
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
| | - Michael Boyce
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
| |
Collapse
|
14
|
Gosavi U, Srivastava A, Badjatia N, Günzl A. Rapid block of pre-mRNA splicing by chemical inhibition of analog-sensitive CRK9 in Trypanosoma brucei. Mol Microbiol 2020; 113:1225-1239. [PMID: 32068297 PMCID: PMC7299817 DOI: 10.1111/mmi.14489] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 02/13/2020] [Accepted: 02/14/2020] [Indexed: 12/24/2022]
Abstract
Trypanosoma brucei CRK9 is an essential cyclin-dependent kinase for the parasite-specific mode of pre-mRNA processing. In trypanosomes, protein coding genes are arranged in directional arrays that are transcribed polycistronically, and individual mRNAs are generated by spliced leader trans-splicing and polyadenylation, processes that are functionally linked. Since CRK9 silencing caused a decline of mRNAs, a concomitant increase of unspliced pre-mRNAs and the disappearance of the trans-splicing Y structure intermediate, CRK9 is essential for the first step of splicing. CRK9 depletion also caused a loss of phosphorylation in RPB1, the largest subunit of RNA polymerase (pol) II. Here, we established cell lines that exclusively express analog-sensitive CRK9 (CRK9AS ). Inhibition of CRK9AS in these cells by the ATP-competitive inhibitor 1-NM-PP1 reproduced the splicing defects and proved that it is the CKR9 kinase activity that is required for pre-mRNA processing. Since defective trans-splicing was detected as early as 5 min after inhibitor addition, CRK9 presumably carries out reversible phosphorylation on the pre-mRNA processing machinery. Loss of RPB1 phosphorylation, however, took 12-24 hr. Surprisingly, RNA pol II-mediated RNA synthesis in 24 hr-treated cells was upregulated, indicating that, in contrast to other eukaryotes, RPB1 phosphorylation is not a prerequisite for transcription in trypanosomes.
Collapse
Affiliation(s)
- Ujwala Gosavi
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
| | - Ankita Srivastava
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
| | - Nitika Badjatia
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
- Current address: Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Arthur Günzl
- Department of Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403, USA
| |
Collapse
|
15
|
Edouarzin E, Horn C, Paudyal A, Zhang C, Lu J, Tong Z, Giaever G, Nislow C, Veerapandian R, Hua DH, Vediyappan G. Broad-spectrum antifungal activities and mechanism of drimane sesquiterpenoids. MICROBIAL CELL 2020; 7:146-159. [PMID: 32548177 PMCID: PMC7278516 DOI: 10.15698/mic2020.06.719] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Eight drimane sesquiterpenoids including (-)-drimenol and (+)-albicanol were synthesized from (+)-sclareolide and evaluated for their antifungal activities. Three compounds, (-)-drimenol, (+)-albicanol, and (1R,2R,4aS,8aS)-2-hydroxy-2,5,5,8a-tetramethyl-decahydronaphthalene-1-carbaldehyde (4) showed strong activity against C. albicans. (-)-Drimenol, the strongest inhibitor of the three, (at concentrations of 8 – 64 µg/ml, causing 100% death of various fungi), acts not only against C. albicans in a fungicidal manner, but also inhibits other fungi such as Aspergillus, Cryptococcus, Pneumocystis, Blastomyces, Saksenaea and fluconazole resistant strains of C. albicans, C. glabrata, C. krusei, C. parapsilosis and C. auris. These observations suggest that drimenol is a broad-spectrum antifungal agent. At a high concentration (100 μg/ml) drimenol caused rupture of the fungal cell wall/membrane. In a nematode model of C. albicans infection, drimenol rescued the worms from C. albicans-mediated death, indicating drimenol is tolerable and bioactive in metazoans. Genome-wide fitness profiling assays of both S. cerevisiae (nonessential homozygous and essential heterozygous) and C. albicans (Tn-insertion mutants) collections revealed putative genes and pathways affected by drimenol. Using a C. albicans mutant spot assay, the Crk1 kinase associated gene products, Ret2, Cdc37, and orf19.759, orf19.1672, and orf19.4382 were revealed to be involved in drimenol's mechanism of action. The three orfs identified in this study are novel and appear to be linked with Crk1 function. Further, computational modeling results suggest possible modifications of the structure of drimenol, including the A ring, for improving the antifungal activity.
Collapse
Affiliation(s)
- Edruce Edouarzin
- Department of Chemistry, 1212 Mid Campus Drive North, Kansas State University, Manhattan, KS 66506 USA
| | - Connor Horn
- Division of Biology, 1717 Claflin Road, Kansas State University, Manhattan, KS 66506 USA
| | - Anuja Paudyal
- Division of Biology, 1717 Claflin Road, Kansas State University, Manhattan, KS 66506 USA
| | - Cunli Zhang
- Department of Chemistry, 1212 Mid Campus Drive North, Kansas State University, Manhattan, KS 66506 USA
| | - Jianyu Lu
- Department of Chemistry, 1212 Mid Campus Drive North, Kansas State University, Manhattan, KS 66506 USA
| | - Zongbo Tong
- Department of Chemistry, 1212 Mid Campus Drive North, Kansas State University, Manhattan, KS 66506 USA
| | - Guri Giaever
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC Canada V6T 1Z3
| | - Corey Nislow
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC Canada V6T 1Z3
| | - Raja Veerapandian
- Division of Biology, 1717 Claflin Road, Kansas State University, Manhattan, KS 66506 USA
| | - Duy H Hua
- Department of Chemistry, 1212 Mid Campus Drive North, Kansas State University, Manhattan, KS 66506 USA
| | - Govindsamy Vediyappan
- Division of Biology, 1717 Claflin Road, Kansas State University, Manhattan, KS 66506 USA
| |
Collapse
|
16
|
An T, Liu Y, Gourguechon S, Wang CC, Li Z. CDK Phosphorylation of Translation Initiation Factors Couples Protein Translation with Cell-Cycle Transition. Cell Rep 2019; 25:3204-3214.e5. [PMID: 30540951 PMCID: PMC6350937 DOI: 10.1016/j.celrep.2018.11.063] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/18/2018] [Accepted: 11/15/2018] [Indexed: 01/17/2023] Open
Abstract
Protein translation in eukaryotes is cell-cycle dependent, with translation rates more robust in G1 phase of the cell cycle than in mitosis. However, whether the fundamental cell-cycle control machinery directly activates protein translation during the G1/S cell-cycle transition remains unknown. Using the early divergent eukaryote Trypanosoma brucei as a model organism, we report that the G1 cyclin-dependent kinase CRK1 phosphorylates two translation initiation factors, eIF4E4 and PABP1, to promote the G1/S cell-cycle transition and global protein translation. Phosphorylation of eIF4E4 by CRK1 enhances binding to the m7G cap structure and interaction with eIF4E4 and eIF4G3, and phosphorylation of PABP1 by CRK1 promotes association with the poly(A) sequence, self-interaction, and interaction with eIF4E4. These findings demonstrate that cyclin-dependent kinase-mediated regulation of translation initiation factors couples global protein translation with the G1/S cell-cycle transition. Protein translation is cell-cycle dependent, with more robust translation rates in the G1 phase of the cell cycle than in mitosis. An et al. show that the G1 cyclin-dependent kinase CRK1 phosphorylates translation initiation factors eIF4E4 and PABP1 to couple protein translation initiation with the G1/S cell-cycle transition.
Collapse
Affiliation(s)
- Tai An
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Yi Liu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Stéphane Gourguechon
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Ching C Wang
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
| |
Collapse
|
17
|
Zappa F, Wilson C, Di Tullio G, Santoro M, Pucci P, Monti M, D'Amico D, Pisonero‐Vaquero S, De Cegli R, Romano A, Saleem MA, Polishchuk E, Failli M, Giaquinto L, De Matteis MA. The TRAPP complex mediates secretion arrest induced by stress granule assembly. EMBO J 2019; 38:e101704. [PMID: 31429971 PMCID: PMC6769382 DOI: 10.15252/embj.2019101704] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 12/29/2022] Open
Abstract
The TRAnsport Protein Particle (TRAPP) complex controls multiple membrane trafficking steps and is strategically positioned to mediate cell adaptation to diverse environmental conditions, including acute stress. We have identified the TRAPP complex as a component of a branch of the integrated stress response that impinges on the early secretory pathway. The TRAPP complex associates with and drives the recruitment of the COPII coat to stress granules (SGs) leading to vesiculation of the Golgi complex and arrest of ER export. The relocation of the TRAPP complex and COPII to SGs only occurs in cycling cells and is CDK1/2-dependent, being driven by the interaction of TRAPP with hnRNPK, a CDK substrate that associates with SGs when phosphorylated. In addition, CDK1/2 inhibition impairs TRAPP complex/COPII relocation to SGs while stabilizing them at ER exit sites. Importantly, the TRAPP complex controls the maturation of SGs. SGs that assemble in TRAPP-depleted cells are smaller and are no longer able to recruit RACK1 and Raptor, two TRAPP-interactive signaling proteins, sensitizing cells to stress-induced apoptosis.
Collapse
Affiliation(s)
- Francesca Zappa
- Telethon Institute of Genetics and MedicinePozzuoli (Naples)Italy
| | - Cathal Wilson
- Telethon Institute of Genetics and MedicinePozzuoli (Naples)Italy
| | | | - Michele Santoro
- Telethon Institute of Genetics and MedicinePozzuoli (Naples)Italy
| | | | | | - Davide D'Amico
- Telethon Institute of Genetics and MedicinePozzuoli (Naples)Italy
| | | | | | - Alessia Romano
- Telethon Institute of Genetics and MedicinePozzuoli (Naples)Italy
| | - Moin A Saleem
- Bristol RenalBristol Medical SchoolUniversity of BristolBristolUK
| | - Elena Polishchuk
- Telethon Institute of Genetics and MedicinePozzuoli (Naples)Italy
| | - Mario Failli
- Telethon Institute of Genetics and MedicinePozzuoli (Naples)Italy
| | - Laura Giaquinto
- Telethon Institute of Genetics and MedicinePozzuoli (Naples)Italy
| | | |
Collapse
|
18
|
McCaughey J, Stephens DJ. COPII-dependent ER export in animal cells: adaptation and control for diverse cargo. Histochem Cell Biol 2018; 150:119-131. [PMID: 29916038 PMCID: PMC6096569 DOI: 10.1007/s00418-018-1689-2] [Citation(s) in RCA: 38] [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] [Accepted: 06/06/2018] [Indexed: 12/31/2022]
Abstract
The export of newly synthesized proteins from the endoplasmic reticulum is fundamental to the ongoing maintenance of cell and tissue structure and function. After co-translational translocation into the ER, proteins destined for downstream intracellular compartments or secretion from the cell are sorted and packaged into transport vesicles by the COPII coat protein complex. The fundamental discovery and characterization of the pathway has now been augmented by a greater understanding of the role of COPII in diverse aspects of cell function. We now have a deep understanding of how COPII contributes to the trafficking of diverse cargoes including extracellular matrix molecules, developmental signalling proteins, and key metabolic factors such as lipoproteins. Structural and functional studies have shown that the COPII coat is both highly flexible and subject to multiple modes of regulation. This has led to new discoveries defining roles of COPII in development, autophagy, and tissue organization. Many of these newly emerging features of the canonical COPII pathway are placed in a context of procollagen secretion because of the fundamental interest in how a coat complex that typically generates 80-nm transport vesicles can package a cargo reported to be over 300 nm. Here we review the current understanding of COPII and assess the current consensus on its role in packaging diverse cargo proteins.
Collapse
Affiliation(s)
- Janine McCaughey
- Cell Biology Laboratories, School of Biochemistry, University Walk, University of Bristol, Bristol, BS8 1TD, UK
| | - David J Stephens
- Cell Biology Laboratories, School of Biochemistry, University Walk, University of Bristol, Bristol, BS8 1TD, UK.
| |
Collapse
|
19
|
de Melo Neto OP, da Costa Lima TDC, Merlo KC, Romão TP, Rocha PO, Assis LA, Nascimento LM, Xavier CC, Rezende AM, Reis CRS, Papadopoulou B. Phosphorylation and interactions associated with the control of the Leishmania Poly-A Binding Protein 1 (PABP1) function during translation initiation. RNA Biol 2018; 15:739-755. [PMID: 29569995 DOI: 10.1080/15476286.2018.1445958] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Poly-A Binding Protein (PABP) is a conserved eukaryotic polypeptide involved in many aspects of mRNA metabolism. During translation initiation, PABP interacts with the translation initiation complex eIF4F and enhances the translation of polyadenylated mRNAs. Schematically, most PABPs can be divided into an N-terminal RNA-binding region, a non-conserved linker segment and the C-terminal MLLE domain. In pathogenic Leishmania protozoans, three PABP homologues have been identified, with the first one (PABP1) targeted by phosphorylation and shown to co-immunoprecipitate with an eIF4F-like complex (EIF4E4/EIF4G3) implicated in translation initiation. Here, PABP1 phosphorylation was shown to be linked to logarithmic cell growth, reminiscent of EIF4E4 phosphorylation, and coincides with polysomal association. Phosphorylation targets multiple serine-proline (SP) or threonine-proline (TP) residues within the PABP1 linker region. This is an essential protein, but phosphorylation is not needed for its association with polysomes or cell viability. Mutations which do impair PABP1 polysomal association and are required for viability do not prevent phosphorylation, although further mutations lead to a presumed inactive protein largely lacking phosphorylated isoforms. Co-immunoprecipitation experiments were carried out to investigate PABP1 function further, identifying several novel protein partners and the EIF4E4/EIF4G3 complex, but no other eIF4F-like complex or subunit. A novel, direct interaction between PABP1 and EIF4E4 was also investigated and found to be mediated by the PABP1 MLLE binding to PABP Interacting Motifs (PAM2) within the EIF4E4 N-terminus. The results shown here are consistent with phosphorylation of PABP1 being part of a novel pathway controlling its function and possibly translation in Leishmania.
Collapse
Affiliation(s)
| | | | - Kleison C Merlo
- a Instituto Aggeu Magalhães - FIOCRUZ , Recife , PE , Brazil
| | - Tatiany P Romão
- a Instituto Aggeu Magalhães - FIOCRUZ , Recife , PE , Brazil
| | | | - Ludmila A Assis
- a Instituto Aggeu Magalhães - FIOCRUZ , Recife , PE , Brazil
| | | | - Camila C Xavier
- a Instituto Aggeu Magalhães - FIOCRUZ , Recife , PE , Brazil
| | | | | | - Barbara Papadopoulou
- c CHU de Quebec Research Center and Department of Microbiology-Infectious Disease and Immunology , Laval University , Quebec , QC , Canada
| |
Collapse
|
20
|
The Role of Cytoplasmic mRNA Cap-Binding Protein Complexes in Trypanosoma brucei and Other Trypanosomatids. Pathogens 2017; 6:pathogens6040055. [PMID: 29077018 PMCID: PMC5750579 DOI: 10.3390/pathogens6040055] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 10/21/2017] [Accepted: 10/22/2017] [Indexed: 11/16/2022] Open
Abstract
Trypanosomatid protozoa are unusual eukaryotes that are well known for having unusual ways of controlling their gene expression. The lack of a refined mode of transcriptional control in these organisms is compensated by several post-transcriptional control mechanisms, such as control of mRNA turnover and selection of mRNA for translation, that may modulate protein synthesis in response to several environmental conditions found in different hosts. In other eukaryotes, selection of mRNA for translation is mediated by the complex eIF4F, a heterotrimeric protein complex composed by the subunits eIF4E, eIF4G, and eIF4A, where the eIF4E binds to the 5'-cap structure of mature mRNAs. In this review, we present and discuss the characteristics of six trypanosomatid eIF4E homologs and their associated proteins that form multiple eIF4F complexes. The existence of multiple eIF4F complexes in trypanosomatids evokes exquisite mechanisms for differential mRNA recognition for translation.
Collapse
|
21
|
da Silva MS, Muñoz PAM, Armelin HA, Elias MC. Differences in the Detection of BrdU/EdU Incorporation Assays Alter the Calculation for G1, S, and G2 Phases of the Cell Cycle in Trypanosomatids. J Eukaryot Microbiol 2017; 64:756-770. [PMID: 28258618 DOI: 10.1111/jeu.12408] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 02/17/2017] [Accepted: 02/23/2017] [Indexed: 01/22/2023]
Abstract
Trypanosomatids are the etiologic agents of various infectious diseases in humans. They diverged early during eukaryotic evolution and have attracted attention as peculiar models for evolutionary and comparative studies. Here, we show a meticulous study comparing the incorporation and detection of the thymidine analogs BrdU and EdU in Leishmania amazonensis, Trypanosoma brucei, and Trypanosoma cruzi to monitor their DNA replication. We used BrdU- and EdU-incorporated parasites with the respective standard detection approaches: indirect immunofluorescence to detect BrdU after standard denaturation (2 M HCl) and "click" chemistry to detect EdU. We found a discrepancy between these two thymidine analogs due to the poor detection of BrdU, which is reflected on the estimative of the duration of the cell cycle phases G1, S, and G2. To solve this discrepancy, we increase the exposure of incorporated BrdU using different concentrations of HCl. Using a new value for HCl concentration, we re-estimated the phases G1, S, G2 + M, and cytokinesis durations, confirming the values found by this approach using EdU. In conclusion, we suggest that the studies using BrdU with standard detection approach, not only in trypanosomatids but also in others cell types, should be reviewed to ensure an accurate estimation of DNA replication monitoring.
Collapse
Affiliation(s)
- Marcelo Santos da Silva
- Laboratório Especial de Ciclo Celular, Center of Toxins, Immune Response and Cell Signaling (CeTICS), Butantan Institute, 1500, Vital Brasil Avenue, 05503-900, São Paulo, Brazil
| | - Paula Andrea Marin Muñoz
- Laboratório Especial de Ciclo Celular, Center of Toxins, Immune Response and Cell Signaling (CeTICS), Butantan Institute, 1500, Vital Brasil Avenue, 05503-900, São Paulo, Brazil
| | - Hugo Aguirre Armelin
- Laboratório Especial de Ciclo Celular, Center of Toxins, Immune Response and Cell Signaling (CeTICS), Butantan Institute, 1500, Vital Brasil Avenue, 05503-900, São Paulo, Brazil
| | - Maria Carolina Elias
- Laboratório Especial de Ciclo Celular, Center of Toxins, Immune Response and Cell Signaling (CeTICS), Butantan Institute, 1500, Vital Brasil Avenue, 05503-900, São Paulo, Brazil
| |
Collapse
|