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Nakamura Y, Itagaki H, Tuji A, Shimode S, Yamaguchi A, Hidaka K, Ogiso-Tanaka E. DNA metabarcoding focused on difficult-to-culture protists: An effective approach to clarify biological interactions. Environ Microbiol 2023; 25:3630-3638. [PMID: 37853476 DOI: 10.1111/1462-2920.16524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 10/04/2023] [Indexed: 10/20/2023]
Abstract
DNA metabarcoding on a single organism is a promising approach to clarify the biological interactions (e.g., predator-prey relationships and symbiosis, including parasitism) of difficult-to-culture protists. To evaluate the effectiveness of this method, Radiolaria and Phaeodaria, which are ecologically important protistan groups, were chosen as target taxa. DNA metabarcoding on a single organism focused on the V9 region of the 18S rRNA gene revealed potential symbionts, parasites and food sources of Radiolaria and Phaeodaria. Previously reported hosts and symbionts (parasites) were detected, and newly recognized combinations were also identified. The contained organisms largely differed between Radiolaria and Phaeodaria. In Radiolaria, members of the same order tended to contain similar organisms, and the taxonomic composition of possible symbionts, parasites, and food sources was fixed at the species level. Members of the same phaeodarian family, however, did not contain similar organisms, and body part (i.e., the central capsule or the phaeodium) was the most important factor that divided the taxonomic composition of detected organisms, implying that the selection of appropriate body part is important when trying to ascertain contained organisms, even for unicellular zooplankton. Our results show that DNA metabarcoding on a single organism is effective in revealing the biological interactions of difficult-to-culture protists.
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Affiliation(s)
- Yasuhide Nakamura
- Estuary Research Center, Shimane University, Matsue, Japan
- Department of Botany, National Museum of Nature and Science, Tsukuba, Japan
| | - Hiryori Itagaki
- Department of Biological Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Akihiro Tuji
- Department of Botany, National Museum of Nature and Science, Tsukuba, Japan
| | - Shinji Shimode
- Manazuru Marine Center for Environmental Research and Education, Yokohama National University, Manazuru, Japan
| | | | - Kiyotaka Hidaka
- Fisheries Resources Institute, Fisheries Research and Education Agency, Yokohama, Japan
| | - Eri Ogiso-Tanaka
- Center for Molecular Biodiversity Research, National Museum of Nature and Science, Tsukuba, Japan
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2
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Targeting trypanosomes: how chemogenomics and artificial intelligence can guide drug discovery. Biochem Soc Trans 2023; 51:195-206. [PMID: 36606702 DOI: 10.1042/bst20220618] [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: 10/20/2022] [Revised: 12/01/2022] [Accepted: 12/05/2022] [Indexed: 01/07/2023]
Abstract
Trypanosomatids are protozoan parasites that cause human and animal neglected diseases. Despite global efforts, effective treatments are still much needed. Phenotypic screens have provided several chemical leads for drug discovery, but the mechanism of action for many of these chemicals is currently unknown. Recently, chemogenomic screens assessing the susceptibility or resistance of parasites carrying genome-wide modifications started to define the mechanism of action of drugs at large scale. In this review, we discuss how genomics is being used for drug discovery in trypanosomatids, how integration of chemical and genomics data from these and other organisms has guided prioritisations of candidate therapeutic targets and additional chemical starting points, and how these data can fuel the expansion of drug discovery pipelines into the era of artificial intelligence.
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Carnes J, McDermott SM, Lewis I, Tracy M, Stuart K. Domain function and predicted structure of three heterodimeric endonuclease subunits of RNA editing catalytic complexes in Trypanosoma brucei. Nucleic Acids Res 2022; 50:10123-10139. [PMID: 36095119 PMCID: PMC9508840 DOI: 10.1093/nar/gkac753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 08/18/2022] [Accepted: 08/24/2022] [Indexed: 11/13/2022] Open
Abstract
Each of the three similar RNA Editing Catalytic Complexes (RECCs) that perform gRNA-directed uridine insertion and deletion during Trypanosoma brucei mitochondrial (mt) mRNA editing has a distinct endonuclease activity that requires two related RNase III proteins, with only one competent for catalysis. We identified multiple loss-of-function mutations in the RNase III and other motifs of the non-catalytic KREPB6, KREPB7, and KREPB8 components by random mutagenesis and screening. These mutations had various effects on growth, editing, and both the abundances and RECC associations of these RNase III protein pairs in bloodstream form (BF) and procyclic form (PF) cells. Protein structure modelling predicted that the Zinc Finger (ZnF) of each paired RNase III protein contacts RNA positioned at the heterodimeric active site which is flanked by helices of a novel RNase III-Associated Motif (RAM). The results indicate that the protein domains of the non-catalytic subunits function together in RECC integrity, substrate binding, and editing site recognition during the multistep RNA editing process. Additionally, several mutants display distinct functional consequences in different life cycle stages. These results highlight the complementary roles of protein pairs and three RECCs within the complicated T. brucei mRNA editing machinery that matures mt mRNAs differentially between developmental stages.
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Affiliation(s)
- Jason Carnes
- Seattle Children's Research Institute, Seattle, WA, USA
| | - Suzanne M McDermott
- Seattle Children's Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, USA
| | - Isaac Lewis
- Seattle Children's Research Institute, Seattle, WA, USA
| | - Maxwell Tracy
- Seattle Children's Research Institute, Seattle, WA, USA
| | - Kenneth Stuart
- Seattle Children's Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, USA
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Morea EGO, Vasconcelos EJR, Alves CDS, Giorgio S, Myler PJ, Langoni H, Azzalin CM, Cano MIN. Exploring TERRA during Leishmania major developmental cycle and continuous in vitro passages. Int J Biol Macromol 2021; 174:573-586. [PMID: 33548324 DOI: 10.1016/j.ijbiomac.2021.01.192] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 01/25/2021] [Accepted: 01/28/2021] [Indexed: 12/22/2022]
Abstract
Telomeres from different eukaryotes, including trypanosomatids, are transcribed into TERRA noncoding RNAs, crucial in regulating chromatin deposition and telomere length. TERRA is transcribed from the C-rich subtelomeric strand towards the 3'-ends of the telomeric array. Using bioinformatics, we confirmed the presence of subtelomeric splice acceptor sites at all L. major chromosome ends. Splice leader sequences positioned 5' upstream of L. major chromosomes subtelomeres were then mapped using SL-RNA-Seq libraries constructed from three independent parasite life stages and helped confirm TERRA expression from several chromosomes ends. Northern blots and RT-qPCR validated the results showing that L. major TERRA is processed by trans-splicing and polyadenylation coupled reactions. The number of transcripts varied with the parasite's life stage and continuous passages, being more abundant in the infective forms. However, no putative subtelomeric promoters involved in TERRA's transcriptional regulation were detected. In contrast, the observed changes in parasite's telomere length during development, suggest that differences in telomeric base J levels may control TERRA transcription in L. major. Also, TERRA-R loops' detection, mainly in the infective forms, was suggestive of TERRA's involvement in telomere protection. Therefore, Leishmania TERRA shares conserved features with other eukaryotes and advances new telomere specific functions in a Public Health-impacting parasite.
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Affiliation(s)
- Edna Gicela Ortiz Morea
- Department of Chemical and Biological Sciences, Biosciences Institute, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil
| | | | - Cristiane de Santis Alves
- Department of Chemical and Biological Sciences, Biosciences Institute, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil
| | - Selma Giorgio
- Department of Animal Biology, Biology Institute, State University of Campinas, UNICAMP, Brazil
| | - Peter J Myler
- Department of Global Health and Department of Biomedical Informatics & Medical Education, University of Washington, Seattle, WA, United States of America
| | - Helio Langoni
- Department of Public Health, Veterinary Medical School, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil
| | | | - Maria Isabel Nogueira Cano
- Department of Chemical and Biological Sciences, Biosciences Institute, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil.
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McDermott SM, Carnes J, Stuart K. Editosome RNase III domain interactions are essential for editing and differ between life cycle stages in Trypanosoma brucei. RNA (NEW YORK, N.Y.) 2019; 25:1150-1163. [PMID: 31171708 PMCID: PMC6800513 DOI: 10.1261/rna.071258.119] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/05/2019] [Indexed: 06/04/2023]
Abstract
Multiprotein editosomes catalyze gRNA-specified insertion and deletion of uridines to create functional mitochondrial mRNAs in Trypanosoma brucei Three functionally distinct editosomes are distinguished by their single KREN1, KREN2, or KREN3 RNase III endonuclease and, respectively, KREPB8, KREPB7, and KREPB6 partner proteins. These endonucleases perform the first catalytic step of editing, cleaving mRNA in diverse mRNA/gRNA heteroduplex substrates. We identified divergent and likely noncatalytic RNase III domains in KREPB4, KREPB5, KREPB6, KREPB7, KREPB8, KREPB9, and KREPB10 editosome proteins. Because known RNase III endonuclease functional domains are dimeric, the editing endonucleases may form heterodimers with one or more of these divergent RNase III proteins. We show here using conditional null cell lines that KREPB6, KREPB7, and KREPB8 are essential in both procyclic form (PF) and bloodstream (BF) cells. Loss of these proteins results in growth defects and loss of editing in vivo, as does mutation of their RNase III domain that is predicted to prevent dimerization. Loss of KREPB6, KREPB7, or KREPB8 also dramatically reduces cognate endonuclease abundance, as does the RNase III mutation, indicating that RNase III interactions with their partner proteins stabilize the endonucleases. The phenotypic consequences of repression are more severe in BF than in PF, indicating differences in endonuclease function between developmental stages that could impact regulation of editing. These results suggest that KREPB6, KREPB7, and KREPB8 form heterodimers with their respective endonucleases to perform mRNA cleavage. We also present a model wherein editosome proteins with divergent RNase III domains function in substrate selection via enzyme-pseudoenzyme interactions.
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Affiliation(s)
- Suzanne M McDermott
- Seattle Children's Research Institute (formerly Center for Infectious Disease Research), Seattle, Washington 98109, USA
| | - Jason Carnes
- Seattle Children's Research Institute (formerly Center for Infectious Disease Research), Seattle, Washington 98109, USA
| | - Kenneth Stuart
- Seattle Children's Research Institute (formerly Center for Infectious Disease Research), Seattle, Washington 98109, USA
- Department of Global Health, University of Washington, Seattle, Washington 98195, USA
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Mudogo CN, Werner SF, Mogk S, Betzel C, Duszenko M. The conserved hypothetical protein Tb427.10.13790 is required for cytokinesis in Trypanosoma brucei. Acta Trop 2018; 188:34-40. [PMID: 30153427 DOI: 10.1016/j.actatropica.2018.08.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 08/22/2018] [Accepted: 08/24/2018] [Indexed: 11/17/2022]
Abstract
Trypanosoma brucei, a flagellated protozoan causing the deadly tropical disease Human African Trypanosomiasis (HAT), affects people in sub-Saharan Africa. HAT therapy relies upon drugs which use is limited by toxicity and rigorous treatment regimes, while development of vaccines remains elusive, due to the effectiveness of the parasite´s antigenic variation. Here, we evaluate a hypothetical protein Tb427.10.13790, as a potential drug target. This protein is conserved among all kinetoplastids, but lacks homologs in all other pro- and eukaryotes. Knockdown of Tb427.10.13790 resulted in appearance of monster cells containing multiple nuclei and multiple flagella, a considerable enlargement of the flagellar pocket and eventually a lethal phenotype. Furthermore, analysis of kinetoplast and nucleus division in the knockdown cell line revealed a partial cell cycle arrest and failure to initiate cytokinesis. Likewise, overexpression of the respective protein fused with enhanced green fluorescent protein was also lethal for T. brucei. In these cells, the labelled protein appeared as a single dot near kinetoplast and flagellar pocket. Our results reveal that Tb427.10.13790 is essential for the parasite´s viability and may be a suitable new anti-trypanosomatid drug target candidate. Furthermore, we suggest that it might be worthwhile to investigate also other of the many so far just annotated trypanosome genes as a considerable number of them to lack human homologs but may be of critical importance for the kinetoplastid parasites.
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Affiliation(s)
- Celestin Nzanzu Mudogo
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany; Institute of Biochemistry and Molecular Biology, University of Hamburg, Laboratory for Structural Biology of Infection and Inflammation, Hamburg, Germany; Department of Basic Sciences, School of Medicine, University of Kinshasa, Democratic Republic of Congo.
| | | | - Stefan Mogk
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.
| | - Christian Betzel
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Laboratory for Structural Biology of Infection and Inflammation, Hamburg, Germany.
| | - Michael Duszenko
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany; School of Medicine, Tongji University, Shanghai, China.
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7
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Martínez-Calvillo S, Romero-Meza G, Vizuet-de-Rueda JC, Florencio-Martínez LE, Manning-Cela R, Nepomuceno-Mejía T. Epigenetic Regulation of Transcription in Trypanosomatid Protozoa. Curr Genomics 2018; 19:140-149. [PMID: 29491742 PMCID: PMC5814962 DOI: 10.2174/1389202918666170911163517] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 02/13/2017] [Accepted: 04/18/2017] [Indexed: 12/15/2022] Open
Abstract
The Trypanosomatid family includes flagellated parasites that cause fatal human diseases. Remarkably, protein-coding genes in these organisms are positioned in long tandem arrays that are transcribed polycistronically. However, the knowledge about regulation of transcription initiation and termination in trypanosomatids is scarce. The importance of epigenetic regulation in these processes has become evident in the last years, as distinctive histone modifications and histone variants have been found in transcription initiation and termination regions. Moreover, multiple chromatin-related proteins have been identified and characterized in trypanosomatids, including histone-modifying enzymes, effector complexes, chromatin-remodelling enzymes and histone chaperones. Notably, base J, a modified thymine residue present in the nuclear DNA of trypanosomatids, has been implicated in transcriptional regulation. Here we review the current knowledge on epigenetic control of transcription by all three RNA polymerases in this group of early-diverged eukaryotes.
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Affiliation(s)
- Santiago Martínez-Calvillo
- Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México. Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Edo. de México, CP 54090, México
| | - Gabriela Romero-Meza
- Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México. Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Edo. de México, CP 54090, México
| | - Juan C. Vizuet-de-Rueda
- Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México. Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Edo. de México, CP 54090, México
| | - Luis E. Florencio-Martínez
- Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México. Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Edo. de México, CP 54090, México
| | - Rebeca Manning-Cela
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Av. IPN 2508, México, D.F., CP 07360, México
| | - Tomás Nepomuceno-Mejía
- Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México. Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Edo. de México, CP 54090, México
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8
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Mensah GA, Burns KM, Peprah EK, Sampson UKA, Engelgau MM. Opportunities and challenges in chronic Chagas cardiomyopathy. Glob Heart 2016; 10:203-7. [PMID: 26407517 DOI: 10.1016/j.gheart.2015.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- George A Mensah
- Center for Translation Research and Implementation Science, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Kristin M Burns
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Emmanuel K Peprah
- Center for Translation Research and Implementation Science, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Uchechukwu K A Sampson
- Center for Translation Research and Implementation Science, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Michael M Engelgau
- Center for Translation Research and Implementation Science, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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McDermott SM, Guo X, Carnes J, Stuart K. Differential Editosome Protein Function between Life Cycle Stages of Trypanosoma brucei. J Biol Chem 2015; 290:24914-31. [PMID: 26304125 DOI: 10.1074/jbc.m115.669432] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Indexed: 11/06/2022] Open
Abstract
Uridine insertion and deletion RNA editing generates functional mitochondrial mRNAs in Trypanosoma brucei. The mRNAs are differentially edited in bloodstream form (BF) and procyclic form (PF) life cycle stages, and this correlates with the differential utilization of glycolysis and oxidative phosphorylation between the stages. The mechanism that controls this differential editing is unknown. Editing is catalyzed by multiprotein ∼20S editosomes that contain endonuclease, 3'-terminal uridylyltransferase, exonuclease, and ligase activities. These editosomes also contain KREPB5 and KREPA3 proteins, which have no functional catalytic motifs, but they are essential for parasite viability, editing, and editosome integrity in BF cells. We show here that repression of KREPB5 or KREPA3 is also lethal in PF, but the effects on editosome structure differ from those in BF. In addition, we found that point mutations in KREPB5 or KREPA3 differentially affect cell growth, editosome integrity, and RNA editing between BF and PF stages. These results indicate that the functions of KREPB5 and KREPA3 editosome proteins are adjusted between the life cycle stages. This implies that these proteins are involved in the processes that control differential editing and that the 20S editosomes differ between the life cycle stages.
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Affiliation(s)
- Suzanne M McDermott
- From the Center for Infectious Disease Research, formerly known as Seattle Biomedical Research Institute, Seattle, Washington 98109
| | - Xuemin Guo
- From the Center for Infectious Disease Research, formerly known as Seattle Biomedical Research Institute, Seattle, Washington 98109
| | - Jason Carnes
- From the Center for Infectious Disease Research, formerly known as Seattle Biomedical Research Institute, Seattle, Washington 98109
| | - Kenneth Stuart
- From the Center for Infectious Disease Research, formerly known as Seattle Biomedical Research Institute, Seattle, Washington 98109
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Parasite aquaporins: Current developments in drug facilitation and resistance. Biochim Biophys Acta Gen Subj 2014; 1840:1566-73. [DOI: 10.1016/j.bbagen.2013.10.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 10/02/2013] [Accepted: 10/06/2013] [Indexed: 01/15/2023]
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12
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da Silva MS, Monteiro JP, Nunes VS, Vasconcelos EJ, Perez AM, Freitas-Júnior LDH, Elias MC, Cano MIN. Leishmania amazonensis promastigotes present two distinct modes of nucleus and kinetoplast segregation during cell cycle. PLoS One 2013; 8:e81397. [PMID: 24278433 PMCID: PMC3836779 DOI: 10.1371/journal.pone.0081397] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 10/11/2013] [Indexed: 11/18/2022] Open
Abstract
Here, we show the morphological events associated with organelle segregation and their timing in the cell cycle of a reference strain of Leishmania (L.) amazonensis promastigotes, the main causative agent of Tegumentary leishmaniasis in the Americas. We show evidences that during the cell cycle, L. amazonensis promastigotes present two distinct modes of nucleus and kinetoplast segregation, which occur in different temporal order in different proportions of cells. We used DAPI-staining and EdU-labeling to monitor the segregation of DNA-containing organelles and DNA replication in wild-type parasites. The emergence of a new flagellum was observed using a specific monoclonal antibody. The results show that L. amazonensis cell cycle division is peculiar, with 65% of the dividing cells duplicating the kinetoplast before the nucleus, and the remaining 35% doing the opposite or duplicating both organelles concomitantly. In both cases, the new flagellum appeared during S to G2 phase in 1N1K cells and thus before the segregation of both DNA-containing organelles; however, we could not determine the exact timing of flagellar synthesis. Most of these results were confirmed by the synchronization of parasites using hydroxyurea. Altogether, our data show that during the cell cycle of L. amazonensis promastigotes, similarly to L. donovani, the segregation of nucleus and kinetoplast do not follow a specific order, especially when compared to other trypanosomatids, reinforcing the idea that this characteristic seems to be species-specific and may represent differences in cellular biology among members of the Leishmania genus.
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Affiliation(s)
- Marcelo Santos da Silva
- Departamento de Genética, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Botucatu, São Paulo, Brazil
- Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Jomar Patrício Monteiro
- Empresa Brasileira de Pesquisa Agropecuária (Embrapa) Caprinos e Ovinos, Sobral, Ceará, Brazil
| | - Vinícius Santana Nunes
- Departamento de Genética, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Botucatu, São Paulo, Brazil
| | | | - Arina Marina Perez
- Departamento de Genética, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Botucatu, São Paulo, Brazil
| | - Lúcio de Holanda Freitas-Júnior
- Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Maria Carolina Elias
- Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, São Paulo, Brazil
| | - Maria Isabel Nogueira Cano
- Departamento de Genética, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Botucatu, São Paulo, Brazil
- * E-mail:
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13
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Maity AK, Saha P. The histone acetyl transferase LdHAT1 fromLeishmania donovaniis regulated by S-phase cell cycle kinase. FEMS Microbiol Lett 2012; 336:57-63. [DOI: 10.1111/j.1574-6968.2012.02656.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 07/25/2012] [Accepted: 08/03/2012] [Indexed: 11/29/2022] Open
Affiliation(s)
- Anup Kumar Maity
- Crystallography and Molecular Biology Division; Saha Institute of Nuclear Physics; Kolkata; India
| | - Partha Saha
- Crystallography and Molecular Biology Division; Saha Institute of Nuclear Physics; Kolkata; India
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14
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Beitz E. Aquaporins from pathogenic protozoan parasites: structure, function and potential for chemotherapy. Biol Cell 2012; 97:373-83. [PMID: 15901246 DOI: 10.1042/bc20040095] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Infectious diseases, caused by protozoa, such as malaria, sleeping sickness, Chagas' disease or leishmaniasis, are a global threat. The increase in the number of affected individuals and the rapid spread of drug-resistant strains call for specific novel strategies to combat human pathogenic parasites. In the search for novel drug targets, transport proteins for nutrients and metabolites of the parasite-host interface are getting into focus. The present review summarizes and discusses the currently available results on protozoan aquaporins. Various genes coding for aquaporin water and solute channels have been identified in the protozoan genomes and they are probable elements of the parasite's cell membrane. Phylogenetic analysis reveals that individual aquaporin genes are of bacterial or plant origin. So far, six protozoan aquaporins have been cloned and functionally characterized. Typically, these are bifunctional channels and pass water at intermediate to high rates as well as uncharged solutes. In the present review, amino acid compositions of the individual pore entries are compared and permeability properties are attributed to specific protein features. Furthermore, possible physiological roles in osmotic protection and metabolism are discussed. Finally, the potential of protozoan aquaporins for use as a target or entry pathway for chemotherapeutic compounds is reviewed.
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Affiliation(s)
- Eric Beitz
- Department of Pharmaceutical Chemistry, University of Tübingen, Morgenstelle 8, D-72076 Tübingen, Germany.
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15
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Speijer D. Does constructive neutral evolution play an important role in the origin of cellular complexity? Making sense of the origins and uses of biological complexity. Bioessays 2011; 33:344-9. [PMID: 21381061 DOI: 10.1002/bies.201100010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Recently, constructive neutral evolution has been touted as an important concept for the understanding of the emergence of cellular complexity. It has been invoked to help explain the development and retention of, amongst others, RNA splicing, RNA editing and ribosomal and mitochondrial respiratory chain complexity. The theory originated as a welcome explanation of isolated small scale cellular idiosyncrasies and as a reaction to 'overselectionism'. Here I contend, that in its extended form, it has major conceptual problems, can not explain observed patterns of complex processes, is too easily dismissive of alternative selectionist models, underestimates the creative force of complexity as such, and--if seen as a major evolutionary mechanism for all organisms--could stifle further thought regarding the evolution of highly complex biological processes.
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Affiliation(s)
- Dave Speijer
- Academic Medical Center (AMC), Department of Medical Biochemistry, University of Amsterdam, Amsterdam, The Netherlands.
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Hall M, Misra S, Chaudhuri M, Chaudhuri G. Peptide aptamer mimicking RAD51-binding domain of BRCA2 inhibits DNA damage repair and survival in Trypanosoma brucei. Microb Pathog 2011; 50:252-62. [PMID: 21296653 DOI: 10.1016/j.micpath.2010.11.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Revised: 11/26/2010] [Accepted: 11/30/2010] [Indexed: 10/18/2022]
Abstract
The eukaryotic DNA recombination repair protein BRCA2 is functional in the parasitic protozoan Trypanosoma brucei. The mechanism of the involvement of BRCA2 in homologous recombination includes its interaction with the DNA recombinase proteins of the RAD51 family. BRCA2 is known to interact with RAD51 through its unique and essential BRC sequence motifs. T. brucei BRCA2 homolog (TbBRCA2) has fifteen repeating BRC motifs as compared to mammalian BRCA2 that has only eight. We report here our yeast 2-hybrid analysis studies on the interactions of TbBRCA2 BRC motifs with five different RAD51 paralogues of T. brucei. Our study revealed that a single BRC motif is sufficient to bind to these RAD51 paralogues. To test the possibility whether a single 44 amino acid long repeating unit of the TbBRCA2 BRC motif may be exploited as an inhibitor of T. brucei growth, we ectopically expressed this peptide segment in the procyclic form of the parasite and evaluated its effects on cell survival as well as the sensitivity of these cells to the DNA damaging agent methyl methane sulfonate (MMS). Expression of a single BRC motif led to MMS sensitivity and inhibited cellular proliferation in T. brucei.
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Affiliation(s)
- Mack Hall
- Department of Microbiology and Immunology, Meharry Medical College, Nashville, TN 37208, USA
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17
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de Jesus TCL, Tonelli RR, Nardelli SC, da Silva Augusto L, Motta MCM, Girard-Dias W, Miranda K, Ulrich P, Jimenez V, Barquilla A, Navarro M, Docampo R, Schenkman S. Target of rapamycin (TOR)-like 1 kinase is involved in the control of polyphosphate levels and acidocalcisome maintenance in Trypanosoma brucei. J Biol Chem 2010; 285:24131-40. [PMID: 20495004 DOI: 10.1074/jbc.m110.120212] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Target of rapamycin (TOR) kinases are highly conserved protein kinases that integrate signals from nutrients and growth factors to coordinate cell growth and cell cycle progression. It has been previously described that two TOR kinases control cell growth in the protozoan parasite Trypanosoma brucei, the causative agent of African trypanosomiasis. Here we studied an unusual TOR-like protein named TbTOR-like 1 containing a PDZ domain and found exclusively in kinetoplastids. TbTOR-like 1 localizes to unique cytosolic granules. After hyperosmotic stress, the localization of the protein shifts to the cell periphery, different from other organelle markers. Ablation of TbTOR-like 1 causes a progressive inhibition of cell proliferation, producing parasites accumulating in the S/G(2) phase of the cell cycle. TbTOR-like 1 knocked down cells have an increased area occupied by acidic vacuoles, known as acidocalcisomes, and are enriched in polyphosphate and pyrophosphate. These results suggest that TbTOR-like 1 might be involved in the control of acidocalcisome and polyphosphate metabolism in T. brucei.
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18
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Fadiel A, Isokpehi RD, Stambouli N, Hamza A, Benammar-Elgaaied A, Scalise TJ. Protozoan parasite aquaporins. Expert Rev Proteomics 2009; 6:199-211. [PMID: 19385945 DOI: 10.1586/epr.09.10] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Protozoan parasites are a major threat to human health with millions of fatalities worldwide, especially in nonindustrialized countries. Currently, there is no cure for many of these parasitic diseases. Consequently, there is an imperative to find treatment targets and develop novel drugs based on the proteins encoded in the genomes of these parasites. Aquaporins, members of membrane proteins discovered and characterized within the past 20 years, are the mechanism through which water is transported through living membranes. The presence of aquaporins explains disease etiology related to water physiology and presents new pharmacogenomic targets. In this article, we review the literature on aquaporins found in Apicomplexan, Kinetoplastida and Microsporidia parasites as potential drug targets. Furthermore, by analyzing protein motion dynamics, we identify impediments that need to be surmounted for developing effective drugs targeting the aquaglyceroporin of Plasmodium falciparum, the causative agent of the most fatal form of human malaria.
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Affiliation(s)
- Ahmed Fadiel
- Department of OBGYN, New York University School of Medicine, Bellevue Hospital Center, New York, NY 10016, USA.
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19
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Bornens M, Azimzadeh J. Origin and evolution of the centrosome. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 607:119-29. [PMID: 17977464 DOI: 10.1007/978-0-387-74021-8_10] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
In this brief account we specifically address the question of how the plasma membrane-associated basal body/axoneme of the unicellular ancestor of eukaryotes has evolved into the centrosome organelle through the several attempts to multicellularity. We propose that the connection between the flagellar apparatus and the nucleus has been a critical feature for leading to the centriole-based centrosome of metazoa, the Spindle Pole Body of fungi, or to the absence of any centrosome in seed plants. We further suggest that the evolution of this connection could be reflected in the evolution of the centrin proteins. We then review evidence showing that the evolution of the centrosome-based tubulin network has been correlated with the evolution of the cortical actin-based cleavage apparatus. Finally we argue that this coevolution had a major impact on the cell individuation process and on the evolution of multicellular organisms. We conclude that only the metazoan lineage evolved multicellularity without loosing the ancestral association of three basic cellular functions of the basal body/axoneme or the derived centrosome organelle, namely sensation, motion and division.
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20
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Biogenesis of the trypanosome endo-exocytotic organelle is cytoskeleton mediated. PLoS Biol 2008; 6:e105. [PMID: 18462016 PMCID: PMC2365980 DOI: 10.1371/journal.pbio.0060105] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Accepted: 03/17/2008] [Indexed: 12/31/2022] Open
Abstract
Trypanosoma brucei is a protozoan parasite that is used as a model organism to study such biological phenomena as gene expression, protein trafficking, and cytoskeletal biogenesis. In T. brucei, endocytosis and exocytosis occur exclusively through a sequestered organelle called the flagellar pocket (FP), an invagination of the pellicular membrane. The pocket is the sole site for specific receptors thus maintaining them inaccessible to components of the innate immune system of the mammalian host. The FP is also responsible for the sorting of protective parasite glycoproteins targeted to, or recycling from, the pellicular membrane, and for the removal of host antibodies from the cell surface. Here, we describe the first characterisation of a flagellar pocket cytoskeletal protein, BILBO1. BILBO1 functions to form a cytoskeleton framework upon which the FP is made and which is also required and essential for FP biogenesis and cell survival. Remarkably, RNA interference (RNAi)-mediated ablation of BILBO1 in insect procyclic-form parasites prevents FP biogenesis and induces vesicle accumulation, Golgi swelling, the aberrant repositioning of the new flagellum, and cell death. Cultured bloodstream-form parasites are also nonviable when subjected to BILBO1 RNAi. These results provide the first molecular evidence for cytoskeletally mediated FP biogenesis. Trypanosomes are ubiquitous unicellular parasites that infect humans, animals, insects, and plants. African, Asian, and some South American trypanosomes have evolved the amazing ability to change their surface coat proteins, an essential strategy for their survival. The surface coat proteins are recycled and targeted to the surface of the parasite via an endocytic and exocytotic organelle called the flagellar pocket, which is sequestered in the trypanosome cell's cytoplasm. The flagellar pocket is also used to remove host-derived antibodies that are bound to the surface of the parasite, making this organelle critical for the parasite's evasion of the host immune system. We describe a novel protein, “BILBO1,” which was identified from the insect-form parasite of the African trypanosome Trypanosoma brucei. We show that BILBO1 is part of a ring or horseshoe-like cytoskeletal structure that is located in a region of the flagellar pocket called the collar. When BILBO1 transcripts were knocked down with inducible RNA interference, trypanosome cells became arrested in a post-mitotic cell-cycle stage. Induced cells lost the normal flagellum-to-cell-body attachment, were unable to regulate endocytosis and exocytosis, and most importantly, were unable to construct a new flagellar pocket. These results provide molecular evidence for the idea that flagellar pocket biogenesis is cytoskeletally mediated. RNAi of the parasite protein BILBO1 prevents the biogenesis of the endocytic and exocytotic organelle in Trypanosoma brucei, kills the parasite, and reveals novel insights into how this pathogen organizes and uses one of its distinctive organelles.
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21
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Histone H1 of Trypanosoma cruzi is concentrated in the nucleolus region and disperses upon phosphorylation during progression to mitosis. EUKARYOTIC CELL 2008; 7:560-8. [PMID: 18281601 DOI: 10.1128/ec.00460-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Phosphorylation of histone H1 is intimately related to the cell cycle progression in higher eukaryotes, reaching maximum levels during mitosis. We have previously shown that in the flagellated protozoan Trypanosoma cruzi, which does not condense chromatin during mitosis, histone H1 is phosphorylated at a single cyclin-dependent kinase site. By using an antibody that recognizes specifically the phosphorylated T. cruzi histone H1 site, we have now confirmed that T. cruzi histone H1 is also phosphorylated in a cell cycle-dependent manner. Differently from core histones, the bulk of nonphosphorylated histone H1 in G(1) and S phases of the cell cycle is concentrated in the central regions of the nucleus, which contains the nucleolus and less densely packed chromatin. When cells pass G(2), histone H1 becomes phosphorylated and starts to diffuse. At the onset of mitosis, histone H1 phosphorylation is maximal and found in the entire nuclear space. As permeabilized parasites preferentially lose phosphorylated histone H1, we conclude that this modification promotes its release from less condensed and nucleolar chromatin after G(2).
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Banerjee S, Sen A, Das P, Saha P. Leishmania donovani cyclin 1 (LdCyc1) forms a complex with cell cycle kinase subunit CRK3 (LdCRK3) and is possibly involved in S-phase-related activities. FEMS Microbiol Lett 2007; 256:75-82. [PMID: 16487322 DOI: 10.1111/j.1574-6968.2006.00105.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Expression of Leishmania donovani cyclin 1 (LdCyc1) mRNA during the cell cycle of promastigotes is S-phase specific. Here, we show that the LdCyc1 protein is periodically expressed and the activity of its associated kinase varies during the cell cycle in line with its expression pattern. In addition, we have shown that LdCRK3, homologous to CRK3 from L. mexicana, is the cognate Cdk partner of LdCyc1 and that the activity of the complex is inhibited specifically by heat stable factor(s) from the parasite.
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Affiliation(s)
- Sampali Banerjee
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Kolkata, India
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23
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Brandão A. The untranslated regions of genes from Trypanosoma cruzi: perspectives for functional characterization of strains and isolates. Mem Inst Oswaldo Cruz 2007; 101:775-7. [PMID: 17160286 DOI: 10.1590/s0074-02762006000700011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Accepted: 08/15/2006] [Indexed: 11/21/2022] Open
Abstract
The sequencing of Trypanosoma cruzi genome has been completed and a great deal of information is now available. However, the organization of protozoa genomes is somewhat elusive and much effort must be applied to reveal all the information coded in the nucleotide sequences. Among the DNA segments that needs further investigation are the untranslated regions of genes. Many of the T. cruzi genes that were revealed by the genome sequencing lack information about the untranslated regions. In this paper, some features of these untranslated segments as well as their applications in T. cruzi populations are discussed.
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Affiliation(s)
- Adeilton Brandão
- Departamento de Medicina Tropical, Instituto Oswaldo Cruz-Fiocruz, 21045-900 Rio de Janeiro, RJ, Brazil.
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24
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Schneider A, Charrière F, Pusnik M, Horn EK. Isolation of mitochondria from procyclic Trypanosoma brucei. Methods Mol Biol 2007; 372:67-80. [PMID: 18314718 DOI: 10.1007/978-1-59745-365-3_5] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The mitochondrion of the parasitic protozoon Trypanosoma brucei shows a number of unique features, many of which represent highly interesting research topics. Studies of these subjects require the purification of mitochondrial fractions. Here, we describe and discuss the two most commonly used methods to isolate mitochondria from insect stage T. brucei. In the first protocol, the cells are lysed under hypotonic conditions, and mitoplast vesicles are isolated on Percoll gradients; in the second method, lysis occurs isotonically by N2 cavitation, and the mitochondrial vesicles are isolated by Nycodenz gradient centrifugation.
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25
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Barbosa JARG, Netto LES, Farah CS, Schenkman S, Meneghini R. The structural molecular biology network of the State of São Paulo, Brazil. AN ACAD BRAS CIENC 2006; 78:241-53. [PMID: 16710564 DOI: 10.1590/s0001-37652006000200006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This article describes the achievements of the Structural Molecular Biology Network (SMolBNet), a collaborative program of structural molecular biology, centered in the State of São Paulo, Brazil, and supported by São Paulo State Funding Agency (FAPESP). It gathers twenty scientific groups and is coordinated by the scientific staff of the Center of Structural Molecular Biology, at the National Laboratory of Synchrotron Light (LNLS), in Campinas. The SMolBNet program has been aimed at 1) solving the structure of proteins of interest related to the research projects of the groups. In some cases, the choice has been to select proteins of unknown function or of possible novel structure obtained from the sequenced genomes of the FAPESP genomic program; 2) providing the groups with training in all the steps of the protein structure determination: gene cloning, protein expression, protein purification, protein crystallization and structure determination. Having begun in 2001, the program has been successful in both aims. Here, four groups reveal their participation in the program and describe the structural aspects of the proteins they have selected to study.
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Affiliation(s)
- João A R G Barbosa
- Laboratório Nacional de Luz Síncrotron, Centro de Biologia Molecular Estrutural, 13084-971 Campinas, SP, Brazil
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26
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Mehta A, Shaha C. Mechanism of metalloid-induced death in Leishmania spp.: role of iron, reactive oxygen species, Ca2+, and glutathione. Free Radic Biol Med 2006; 40:1857-68. [PMID: 16678023 DOI: 10.1016/j.freeradbiomed.2006.01.024] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 01/20/2006] [Indexed: 01/24/2023]
Abstract
There is growing evidence that metalloid-induced cell death in protozoan parasites is due to oxidative injury; however, the biochemical changes related to this event are not fully understood. Leishmania spp. demonstrated cross-resistance to two related metalloids, arsenic and antimony, and both metalloids induced cell death accompanied by cell shrinkage and DNA fragmentation that was preceded by an increase in reactive oxygen species. Both drugs caused mitochondrial dysfunction in terms of loss of membrane potential and a drop in ATP levels. Arsenic treatment resulted in an elevation of intracellular Ca2+ levels that did not occur with antimony exposure. Cellular glutathione level was reduced after antimony treatment but arsenic did not affect glutathione. Inhibition of Ca2+ influx during arsenic treatment reduced cell death, whereas supplementation of glutathione during antimony treatment rescued cell loss. Under iron-depleted conditions, the cytotoxic effects of arsenic and antimony did not occur and cell survival increased; in contrast, the presence of excess iron resulted in higher cell death. Therefore, this study provides a new possibility that iron can potentiate parasite death induced by metalloids like arsenic and antimony. In addition, an important observation is that the two similar metalloids produce toxicity by very different mechanisms.
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Affiliation(s)
- Ashish Mehta
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India
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27
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Kissinger JC. A tale of three genomes: the kinetoplastids have arrived. Trends Parasitol 2006; 22:240-3. [PMID: 16635586 DOI: 10.1016/j.pt.2006.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Revised: 03/15/2006] [Accepted: 04/04/2006] [Indexed: 01/23/2023]
Abstract
July 2005 marked a milestone in kinetoplastid biology research. A tour de force effort led by the Tri-Trypanosomatidae "Tritryp" genome consortium yielded the publication of three prominent kinetoplastid parasite genome sequences: Trypanosoma brucei, Trypanosoma cruzi and Leishmania major. The individual and combined comparative analyses of these three genome sequences, combined with proteomic analyses, have yielded insights into topics ranging from genome evolution and horizontal gene transfer to potential new therapeutic and vaccine targets.
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Affiliation(s)
- Jessica C Kissinger
- Department of Genetics and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30606, USA.
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28
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Misra S, Bennett J, Friew YN, Abdulghani J, Irvin-Wilson CV, Tripathi MK, Williams S, Chaudhuri M, Chaudhuri G. A type II ribonuclease H from Leishmania mitochondria: an enzyme essential for the growth of the parasite. Mol Biochem Parasitol 2006; 143:135-45. [PMID: 15978682 PMCID: PMC3089020 DOI: 10.1016/j.molbiopara.2005.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2004] [Revised: 05/18/2005] [Accepted: 05/25/2005] [Indexed: 10/25/2022]
Abstract
Replication of kDNA in the mitochondrion of the kinetoplastid protozoan is an essential process. One of the proteins that may be required for the kDNA replication is the ribonuclease H (RNase H; EC 3.1.26.4). We have identified four distinct ribonuclease H genes in Leishmania, one type I (LRNase HI) and three type II (LRNase HIIA, LRNase HIIB and LRNase HIIC). We detail here molecular characterization of LRNase HIIC. The coding sequence of LRNase HIIC is 1425 bp in length encoding a 474-amino acid protein with a calculated molecular mass of approximately 53 kDa. While LRNase HIIC shares several conserved domains with mitochondrial RNase H from other organisms, it has three extra patches of amino acid sequences unique to this enzyme. Functional identity of this protein as an RNase H was verified by genetic complementation in RNase H-deficient Escherichia coli. The precursor protein may be enzymatically inactive as it failed to complement the E. coli mutant. The mitochondrial localization signal in LRNase HIIC is within the first 40 amino acid residues at the N-terminus. In vitro import of the protein by the mitochondrial vesicles showed that the precursor protein is processed to a 49-kDa protein. Antisense ablation of LRNase HIIC gene expression is lethal to the parasite cells both in vitro and in vivo. This study not only reveals the significance of the LRNase HIIC in the kinetoplast biology but also identifies a potential molecular target for antileishmanial chemotherapy.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Gautam Chaudhuri
- Corresponding author. Tel.: +1 615 327 6499; fax: +1 615 327 5559. (G. Chaudhuri)
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29
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De Lima AR, Medina R, Uzcanga GL, Noris Suárez K, Contreras VT, Navarro MC, Arteaga R, Bubis J. Tight binding between a pool of the heterodimeric α/β tubulin and a protein kinase CK2 inTrypanosoma cruziepimastigotes. Parasitology 2005; 132:511-23. [PMID: 16332290 DOI: 10.1017/s0031182005009352] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Revised: 09/28/2005] [Accepted: 09/28/2005] [Indexed: 01/23/2023]
Abstract
Tubulin is the predominant phosphoprotein inTrypanosoma cruziepimastigotes and is phosphorylated by a protein kinase CK2. Interestingly, the presence or absence of divalent cations affected the solubilization of a pool of the parasite tubulin and the CK2 responsible for its phosphorylation. This fraction of tubulin and its kinase co-eluted using phosphocellulose, DEAE-Sepharose and Sephacryl S-300 chromatographies. Anti-α tubulin antibodies co-immunoprecipitated both tubulin and the CK2 responsible for its phosphorylation, and anti-CK2 α-subunit antibodies immunoprecipitated radioactively labelled α and β tubulin from phosphorylated epimastigote homogenates. Additionally, native polyacrylamide gel electrophoresis of the purified and radioactively labelled fraction containing tubulin and its kinase demonstrated the phosphorylation of a unique band that reacted with both anti-CK2 α-subunit and anti-tubulin antibodies. Together, these results establish a strong interaction between a pool of the heterodimeric α/β tubulin and a CK2 in this parasite. Hydrodynamic measurements indicated that theT. cruzitubulin-CK2 complex is globular with an estimated size of 145·4–147·5 kDa.
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Affiliation(s)
- A R De Lima
- Departamento de Biología Celular, Universidad Simón Bolívar, Apartado 89.000, Valle de Sartenejas, Caracas 1081-A, Venezuela
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30
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Coppel RL, Black CG. Parasite genomes. Int J Parasitol 2005; 35:465-79. [PMID: 15826640 DOI: 10.1016/j.ijpara.2005.01.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Revised: 02/24/2005] [Accepted: 02/24/2005] [Indexed: 01/01/2023]
Abstract
The availability of genome sequences and the associated transcriptome and proteome mapping projects has revolutionised research in the field of parasitology. As more parasite species are sequenced, comparative and phylogenetic comparisons are improving the quality of gene prediction and annotation. Genome sequences of parasites are also providing important data sets for understanding parasite biology and identifying new vaccine candidates and drug targets. We review some of the preliminary conclusions from examination of parasite genome sequences and discuss some of the bioinformatics approaches taken in this analysis.
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Affiliation(s)
- Ross L Coppel
- Department of Microbiology and the Victorian Bioinformatics Consortium, Monash University, Melbourne, Vic. 3800, Australia.
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31
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Jayanarayan KG, Dey CS. Altered tubulin dynamics, localization and post-translational modifications in sodium arsenite resistant Leishmania donovani in response to paclitaxel, trifluralin and a combination of both and induction of apoptosis-like cell death. Parasitology 2005; 131:215-30. [PMID: 16145938 DOI: 10.1017/s0031182005007687] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this study the anti-leishmanial activity and anti-microtubule effects of paclitaxel, trifluralin and a combination of paclitaxel and trifluralin have been tested in a wild type and sodium arsenite-resistant strain of Leishmania donovani. Both paclitaxel and trifluralin have been shown to be effective in limiting parasite growth. Specific alterations in morphology, tubulin polymerization dynamics, post-translational modifications and cellular distribution of the tubulins have been confirmed to be a part of the intracellular anti-microtubule-events that occur in arsenite-resistant L. donovani in response to these agents, ultimately leading to death of the parasite. DNA analyses of the drug-treated wild type and arsenite-resistant strains revealed an apoptosis-like death in response to paclitaxel and the combination but not to trifluralin. Data provide valuable information for further development of chemotherapeutic strategies based on anti-microtubule agents against drug resistant Leishmania parasites.
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Affiliation(s)
- K G Jayanarayan
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.4S IVAGAR, Punjab 160062, India
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32
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Abstract
The mitochondrial DNA of Trypanosoma brucei, termed kinetoplast DNA or kDNA, consists of thousands of minicircles and a small number of maxicircles catenated into a single network organized as a nucleoprotein disk at the base of the flagellum. Minicircles are replicated free of the network but still contain nicks and gaps after rejoining to the network. Covalent closure of remaining discontinuities in newly replicated minicircles after their rejoining to the network is delayed until all minicircles have been replicated. The DNA ligase involved in this terminal step in minicircle replication has not been identified. A search of kinetoplastid genome databases has identified two putative DNA ligase genes in tandem. These genes (LIG k alpha and LIG k beta) are highly diverged from mitochondrial and nuclear DNA ligase genes of higher eukaryotes. Expression of epitope-tagged versions of these genes shows that both LIG k alpha and LIG k beta are mitochondrial DNA ligases. Epitope-tagged LIG k alpha localizes throughout the kDNA, whereas LIG k beta shows an antipodal localization close to, but not overlapping, that of topoisomerase II, suggesting that these proteins may be contained in distinct structures or protein complexes. Knockdown of the LIG k alpha mRNA by RNA interference led to a cessation of the release of minicircles from the network and resulted in a reduction in size of the kDNA networks and rapid loss of the kDNA from the cell. Closely related pairs of mitochondrial DNA ligase genes were also identified in Leishmania major and Crithidia fasciculata.
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MESH Headings
- Amino Acid Sequence
- Animals
- Cloning, Molecular
- DNA Ligases/genetics
- DNA Ligases/metabolism
- DNA Topoisomerases, Type II/metabolism
- DNA, Kinetoplast/genetics
- DNA, Kinetoplast/metabolism
- DNA, Mitochondrial/genetics
- DNA, Protozoan/genetics
- Databases as Topic
- Genome
- Mitochondria/enzymology
- Molecular Sequence Data
- RNA Interference
- RNA, Messenger/antagonists & inhibitors
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Homology, Amino Acid
- Trypanosoma brucei brucei/enzymology
- Trypanosoma brucei brucei/genetics
- Trypanosoma brucei brucei/ultrastructure
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Affiliation(s)
- Nick Downey
- Molecular Biology Institute and Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90095-1570, USA
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33
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Dossin FDM, Schenkman S. Actively transcribing RNA polymerase II concentrates on spliced leader genes in the nucleus of Trypanosoma cruzi. EUKARYOTIC CELL 2005; 4:960-70. [PMID: 15879530 PMCID: PMC1140094 DOI: 10.1128/ec.4.5.960-970.2005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
RNA polymerase II of trypanosomes, early diverging eukaryotes, transcribes long polycistronic messages, which are not capped but are processed by trans-splicing and polyadenylation to form mature mRNAs. The same RNA polymerase II also transcribes the genes coding for the spliced leader RNA, which are capped, exported to the cytoplasm, processed, and reimported into the nucleus before they are used as splicing donors to form mRNAs from pre-mRNA polycistronic transcripts. As pre-mRNA and spliced leader transcription events appear to be uncoupled, we studied how the RNA polymerase II is distributed in the nucleus of Trypanosoma cruzi. Using specific antibodies to the T. cruzi RNA polymerase II unique carboxy-terminal domain, we demonstrated that large amounts of the enzyme are found concentrated in a domain close to the parasite nucleolus and containing the spliced leader genes. The remaining RNA polymerase II is diffusely distributed in the nucleoplasm. The spliced leader-associated RNA polymerase II localization is dependent on the cell transcriptional state. It disperses when transcription is blocked by alpha-amanitin and actinomycin D. Tubulin genes are excluded from this domain, suggesting that it may exclusively be the transcriptional site of spliced leader genes. Trypomastigote forms of the parasite, which have reduced spliced leader transcription, show less RNA polymerase II labeling, and the spliced leader genes are more dispersed in the nucleoplasm. These results provide strong evidences that transcription of spliced leader RNAs occurs in a particular domain in the T. cruzi nucleus.
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Affiliation(s)
- Fernando de Macedo Dossin
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, R. Botucatu 862 8 andar, 04023-062 São Paulo, Brazil.
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Jayanarayan KG, Dey CS. Altered expression, polymerisation and cellular distribution of alpha-/beta-tubulins and apoptosis-like cell death in arsenite resistant Leishmania donovani promastigotes. Int J Parasitol 2004; 34:915-25. [PMID: 15217730 DOI: 10.1016/j.ijpara.2004.03.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2004] [Revised: 03/24/2004] [Accepted: 03/25/2004] [Indexed: 10/26/2022]
Abstract
Studies in mammalian systems have shown specific affinity of arsenite for tubulin proteins. The sodium m-arsenite (NaAsO2) resistant Leishmania donovani used in this study is resistant to 20 microM NaAsO2, which is a 13-fold increase in resistance compared to the wild type. Data presented in this study shows decreased expression of alpha- and beta-tubulin in wild type L. donovani promastigotes on exposure to NaAsO2 from 0.0016 to 5.0 microM (IC50 in the wild type strain) in a dose-dependent manner. alpha- and beta-tubulins in the resistant strain show decreased expression levels only at 65.0 microM NaAsO2 (IC50 in the resistant strain). Treatment with respective IC50 concentrations of NaAsO2 caused alterations in tubulin polymerisation dynamics and deregulated the cellular distribution of the microtubules in wild type and resistant strains. The NaAsO2-induced cell death exhibited characteristics of apoptosis-like DNA laddering and fragmentation in both the affected wild type and resistant cells. However, poly(ADP-ribose)polymerase cleavage was evident in the wild type strain but not in the resistant strain.
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Affiliation(s)
- K G Jayanarayan
- Signal Transduction Research Laboratory, Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S Nagar, Punjab 160062, India
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35
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Unnikrishnan M, Burleigh BA. Inhibition of host connective tissue growth factor expression: a novel
Trypanosoma cruzi
‐mediated response. FASEB J 2004; 18:1625-35. [PMID: 15522908 DOI: 10.1096/fj.04-1554com] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Connective tissue growth factor (CTGF) is a secreted cytokine that plays a fundamental role in the development of tissue fibrosis by mediating many of the profibrotic effects of TGF-beta. We present the novel finding that the intracellular pathogen Trypanosoma cruzi elicits immediate and sustained repression of basal CTGF expression in dermal fibroblasts, followed by down-regulation of the extracellular matrix proteins, fibronectin, and collagen I alpha1. To address mechanisms underlying this response, the major CTGF-regulating pathways were investigated. We report that both T. cruzi trypomastigotes and secreted parasite factor(s) antagonize TGF-beta-dependent induction of CTGF in fibroblasts. Of the TGF-beta-dependent signaling pathways required for CTGF expression, we demonstrate that T. cruzi interferes with cellular Erk1/2 phosphorylation but not Smad3 signaling. While increased stimulation of Erk phosphorylation alone was insufficient to override the parasite-mediated repression of CTGF, stimulation of fibroblasts with increased concentrations of TGF-beta, which activates both Smad3 and Erk1/2, completely abrogated this inhibition. Together with the finding that T. cruzi-mediated down-regulation of CTGF expression requires de novo host cell protein synthesis, our data indicate that the unique ability of T. cruzi to interfere with the host fibrogenic response is a complex process requiring input from multiple host cell signaling pathways.
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Affiliation(s)
- Meera Unnikrishnan
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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36
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Peña-Diaz J, Akbari M, Sundheim O, Farez-Vidal ME, Andersen S, Sneve R, Gonzalez-Pacanowska D, Krokan HE, Slupphaug G. Trypanosoma cruzi contains a single detectable uracil-DNA glycosylase and repairs uracil exclusively via short patch base excision repair. J Mol Biol 2004; 342:787-99. [PMID: 15342237 DOI: 10.1016/j.jmb.2004.07.043] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2004] [Revised: 07/08/2004] [Accepted: 07/12/2004] [Indexed: 11/23/2022]
Abstract
Enzymes involved in genomic maintenance of human parasites are attractive targets for parasite-specific drugs. The parasitic protozoan Trypanosoma cruzi contains at least two enzymes involved in the protection against potentially mutagenic uracil, a deoxyuridine triphosphate nucleotidohydrolase (dUTPase) and a uracil-DNA glycosylase belonging to the highly conserved UNG-family. Uracil-DNA glycosylase activities excise uracil from DNA and initiate a multistep base-excision repair (BER) pathway to restore the correct nucleotide sequence. Here we report the biochemical characterisation of T.cruzi UNG (TcUNG) and its contribution to the total uracil repair activity in T.cruzi. TcUNG is shown to be the major uracil-DNA glycosylase in T.cruzi. The purified recombinant TcUNG exhibits substrate preference for removal of uracil in the order ssU>U:G>U:A, and has no associated thymine-DNA glycosylase activity. T.cruzi apparently repairs U:G DNA substrate exclusively via short-patch BER, but the DNA polymerase involved surprisingly displays a vertebrate POLdelta-like pattern of inhibition. Back-up UDG activities such as SMUG, TDG and MBD4 were not found, underlying the importance of the TcUNG enzyme in protection against uracil in DNA and as a potential target for drug therapy.
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Affiliation(s)
- Javier Peña-Diaz
- Instituto de Parasitologia y Biomedicina "Lopez Neyra", Consejo Superior de Investigaciones Cientificas, C/Ventanilla 11, 18001 Granada, Spain
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37
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Halbig K, De Nova-Ocampo M, Cruz-Reyes J. Complete cycles of bloodstream trypanosome RNA editing in vitro. RNA (NEW YORK, N.Y.) 2004; 10:914-20. [PMID: 15146075 PMCID: PMC1370583 DOI: 10.1261/rna.5157704] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
RNA editing in kinetoplastid protists is required for the maturation of mitochondrial pre-mRNAs and occurs by protein-catalyzed cycles of uridylate insertion and deletion. During the complex life cycle of Trypanosoma brucei this process is differentially regulated in the mammalian bloodstream and insect procyclic stages. Complementary guide RNAs (gRNAs) direct editing, but the abundance of these transcripts is not developmentally controlled. The establishment of in vitro systems that recreate efficient RNA editing in bloodstream T. brucei would be valuable for mechanistic studies of regulation. Here we describe a robust in vitro system that reconstitutes full cycles of both U insertion and U deletion in bloodstream trypanosomes, and the first direct comparisons of the in vitro systems for strains of mammalian and insect stages.
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Affiliation(s)
- Kari Halbig
- Department of Biochemistry and Biophyisics, Texas A&M University, College Station, Texas 77843, USA
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38
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Doerig C. Protein kinases as targets for anti-parasitic chemotherapy. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2004; 1697:155-68. [PMID: 15023358 DOI: 10.1016/j.bbapap.2003.11.021] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2003] [Accepted: 11/12/2003] [Indexed: 11/19/2022]
Abstract
Parasitic protozoa infecting humans have a staggering impact on public health, especially in the developing world. Furthermore, several protozoan species are major pathogens of domestic animals and have a considerable impact on food production. In many instances, the parasites have developed resistance against available chemotherapeutic agents, making the search for alternative drugs a priority. In line with the current interest in protein kinases inhibitors as potential drugs against a variety of diseases, the possibility that protein kinases may represent targets for novel anti-parasitic agents is being explored. Research into parasite protein kinases has benefited greatly from genome and EST sequencing projects, with the genomes of a few species fully sequenced (notably that of the human malaria parasite Plasmodium falciparum) and several more under way. The overall picture that emerged from research in this area shows that the phylogenetic isolation of parasitic protozoa is reflected by atypical structural and functional properties of many of their protein kinase homologues. Likewise, evidence is emerging, which suggests that the organisation of some otherwise well-conserved signal transduction pathways is divergent in some parasitic species. The differences between protein kinases of a parasite and their homologues in its host cell suggest that specific inhibition of the former can be achieved. The development of anti-parasitic drugs based on protein kinase inhibition is being pursued following two avenues: one consists of screening chemical libraries on recombinant enzymes; several protein kinases from parasitic protozoa are now available for this approach. The second approach relies on the identification of the molecular targets of kinase inhibitors which display anti-parasitic properties. This has led to promising developments in a few instances, in particular regarding PKG as a drug target against Eimeria and Toxoplasma, and purvalanol B, a purine-based CDK inhibitor which appears to affect unexpected targets in several protozoan parasites. The recent resolution of the structure of a Plasmodium protein kinase complexed with small inhibitory molecules opens the way to a rational approach towards the design of anti-parasitic drugs based on kinase inhibition.
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Affiliation(s)
- Christian Doerig
- Wellcome Centre for Molecular Parasitology, University of Glasgow, INSERM, 56 Dumbarton Road, Glasgow G11 6NU, Scotland, UK.
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39
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Abstract
In common with all eukaryotic cells, trypanosomes must coordinate a complex series of morphogenetic events both temporally and spatially during the cell cycle. The structural and molecular cues that synchronise these events in trypanosomes have started to be elucidated, and intriguingly although similarities to cell cycle events in other eukaryotes can be identified, trypanosomes have also evolved novel solutions to the common challenges faced by dividing eukaryotic cells. Although cellular morphology is clearly pivotal for successful progression through the trypanosome cell cycle, most cytological studies to date have focused exclusively on procyclic form trypanosomes. These studies provide an excellent framework for understanding cell cycle events in trypanosomes, however recent data indicates that profound differences might exist between different life cycle stages in relation to the regulation of cell cycle and cytokinesis.
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Affiliation(s)
- Paul G McKean
- Department of Biological Sciences, The Lancaster Environment Centre, Lancaster University, Lancaster, Lancashire LA1 4YQ, UK.
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40
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Abstract
Microtubules are cytoskeletal polymers essential for the survival of all eukaryotes. These proteins are the proposed cellular targets of many anticancerous, antifungal and antihelminthic drugs. Sufficient differences exist between the microtubules of kinetoplastid parasites like Leishmania and humans to explore the selective targeting of these proteins for therapeutic purposes. This review describes the basic structure of microtubules and its dynamics in general, with specific insights into leishmanial microtubules, the salient features of microtubule-drug interactions including the specificity of certain drugs for parasitic microtubules. Chemotherapy against leishmanial parasites is failing because of the emergence of drug resistant strains. The possible mechanisms of resistance to antimicrotubule agents along with insights into the role of microtubules in mediating drug resistance in Leishmania are discussed.
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Affiliation(s)
- K G Jayanarayan
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER), Punjab, India
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41
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Casas B, Calabokis M, Kurz L, Galán-Caridad JM, Bubis J, Gonzatti MI. Trypanosoma cruzi: in vitro phosphorylation of tubulin by a protein kinase CK2-like enzyme. Exp Parasitol 2002; 101:129-37. [PMID: 12427467 DOI: 10.1016/s0014-4894(02)00110-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
One predominant 55-kDa polypeptide was phosphorylated in vitro in Trypanosoma cruzi homogenates prepared from three differentiation stages: epimastigotes, trypomastigotes, and spheromastigotes. Anti-alpha and anti-beta tubulin monoclonal antibodies immunoprecipitated the phosphorylated 55-kDa polypeptide from epimastigote extracts. Phosphoserine was the only residue phosphorylated in vitro in the 55-kDa polypeptide and in immunoprecipitated alpha tubulin. The phosphorylation of both the 55-kDa polypeptide and exogenously added casein was inhibited with GTP, heparin, and 2,3-bisphosphoglycerate in a dose-dependent manner, indicating the involvement of a CK2-like protein kinase. Moreover, when tubulin was isolated from an epimastigote homogenate by ultracentrifugation, followed by DEAE-Sephacel chromatography, a protein kinase that phosphorylated tubulin and casein co-purified with this cytoskeletal component. This result suggests an association between tubulin and its corresponding protein kinase in T. cruzi.
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Affiliation(s)
- Beatriz Casas
- Departamento de Biología Celular, Universidad Simón Bolívar, Apartado 89.000, Caracas, Venezuela
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Siman-Tov MM, Ivens AC, Jaffe CL. Identification and cloning of Lmairk, a member of the Aurora/Ipl1p protein kinase family, from the human protozoan parasite Leishmania. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1519:241-5. [PMID: 11418192 DOI: 10.1016/s0167-4781(01)00240-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Lmairk, a gene encoding a member of the Aurora/Ipl1p family of protein kinases (AIRK), was cloned from the protozoan parasite Leishmania major. Aurora kinases are key enzymes involved in the regulation of normal chromosome segregation during mitosis and cytokenesis of eukaryotic cells. This single-copy gene located on L. major chromosome 28 encodes a 301 amino acid polypeptide. All 11 conserved eukaryotic protein kinase catalytic subdomains are present and the proposed AIRK signature sequence was identified in the activation loop between subdomains VII and VIII. Lmairk is expressed, as an approximately 2.4 kb message, in at least three different species of Leishmania. This report represents the first identification of an AIRK from the trypanosomatid family of early divergent eukaryotes.
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Affiliation(s)
- M M Siman-Tov
- Department of Parasitology, Hebrew University, Hadassah Medical School, Jerusalem, Israel
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43
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Current Awareness on Comparative and Functional Genomics. Comp Funct Genomics 2001. [PMCID: PMC2447222 DOI: 10.1002/cfg.60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
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