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Krakovka S, Ranjbarian F, Luján LA, Saura A, Larsen NB, Jiménez-González A, Reggenti A, Luján HD, Svärd SG, Hofer A. Giardia intestinalis thymidine kinase is a high-affinity enzyme crucial for DNA synthesis and an exploitable target for drug discovery. J Biol Chem 2022; 298:102028. [PMID: 35568200 PMCID: PMC9190010 DOI: 10.1016/j.jbc.2022.102028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/06/2022] [Accepted: 05/07/2022] [Indexed: 11/18/2022] Open
Abstract
Giardiasis is a diarrheal disease caused by the unicellular parasite Giardia intestinalis, for which metronidazole is the main treatment option. The parasite is dependent on exogenous deoxyribonucleosides for DNA replication and thus is also potentially vulnerable to deoxyribonucleoside analogs. Here, we characterized the G. intestinalis thymidine kinase, a divergent member of the thymidine kinase 1 family that consists of two weakly homologous parts within one polypeptide. We found that the recombinantly expressed enzyme is monomeric, with 100-fold higher catalytic efficiency for thymidine compared to its second-best substrate, deoxyuridine, and is furthermore subject to feedback inhibition by dTTP. This efficient substrate discrimination is in line with the lack of thymidylate synthase and dUTPase in the parasite, which makes deoxy-UMP a dead-end product that is potentially harmful if converted to deoxy-UTP. We also found that the antiretroviral drug azidothymidine (AZT) was an equally good substrate as thymidine and was active against WT as well as metronidazole-resistant G. intestinalis trophozoites. This drug inhibited DNA synthesis in the parasite and efficiently decreased cyst production in vitro, which suggests that it could reduce infectivity. AZT also showed a good effect in G. intestinalis–infected gerbils, reducing both the number of trophozoites in the small intestine and the number of viable cysts in the stool. Taken together, these results suggest that the absolute dependency of the parasite on thymidine kinase for its DNA synthesis can be exploited by AZT, which has promise as a future medication effective against metronidazole-refractory giardiasis.
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Affiliation(s)
- Sascha Krakovka
- Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden
| | - Farahnaz Ranjbarian
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Lucas A Luján
- Centro de Investigación y Desarrollo en Immunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), Cordoba, Argentina
| | - Alicia Saura
- Centro de Investigación y Desarrollo en Immunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), Cordoba, Argentina
| | | | | | - Anna Reggenti
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Hugo D Luján
- Centro de Investigación y Desarrollo en Immunología y Enfermedades Infecciosas (CIDIE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Católica de Córdoba (UCC), Cordoba, Argentina
| | - Staffan G Svärd
- Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden.
| | - Anders Hofer
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden.
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Abstract
BACKGROUND Polo-like kinases (PLKs) are conserved serine/threonine kinases that regulate the cell cycle. To date, the role of Giardia lamblia PLK (GlPLK) in cells has not been studied. Here, we report our investigation on the function of GlPLK to provide insight into the role of this PKL in Giardia cell division, especially during cytokinesis and flagella formation. METHODS To assess the function of GIPLK, Giardia trophozoites were treated with the PLK-specific inhibitor GW843286X (GW). Using a putative open reading frame for the PLK identified in the Giardia genomic database, we generated a transgenic Giardia expressing hemagglutinin (HA)-tagged GlPLK and used this transgenic for immunofluorescence assays (IFAs). GlPLK expression was knocked down using an anti-glplk morpholino to observe its effect on the number of nuclei number and length of flagella. Giardia cells ectopically expressing truncated GlPLKs, kinase domain + linker (GlPLK-KDL) or polo-box domains (GlPLK-PBD) were constructed for IFAs. Mutant GlPLKs at Lys51, Thr179 and Thr183 were generated by site-directed mutagenesis and then used for the kinase assay. To elucidate the role of phosphorylated GlPLK, the phosphorylation residues were mutated and expressed in Giardia trophozoites RESULTS: After incubating trophozoites with 5 μM GW, the percentage of cells with > 4 nuclei and longer caudal and anterior flagella increased. IFAs indicated that GlPLK was localized to basal bodies and flagella and was present at mitotic spindles in dividing cells. Morpholino-mediated GlPLK knockdown resulted in the same phenotypes as those observed in GW-treated cells. In contrast to Giardia expressing GlPLK-PBD, Giardia expressing GlPLK-KDL was defective in terms of GIPLK localization to mitotic spindles and had altered localization of the basal bodies in dividing cells. Kinase assays using mutant recombinant GlPLKs indicated that mutation at Lys51 or at both Thr179 and Thr183 resulted in loss of kinase activity. Giardia expressing these mutant GlPLKs also demonstrated defects in cell growth, cytokinesis and flagella formation. CONCLUSIONS These data indicate that GlPLK plays a role in Giardia cell division, especially during cytokinesis, and that it is also involved in flagella formation.
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Affiliation(s)
- Eun-Ah Park
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul, 03722, South Korea
| | - Juri Kim
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul, 03722, South Korea
| | - Mee Young Shin
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul, 03722, South Korea
| | - Soon-Jung Park
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul, 03722, South Korea.
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Hernández-Ochoa B, Gómez-Manzo S, Sánchez-Carrillo A, Marcial-Quino J, Rocha-Ramírez LM, Santos-Segura A, Ramírez-Nava EJ, Arreguin-Espinosa R, Cuevas-Cruz M, Méndez-Tenorio A, Calderón-Jaimes E. Enhanced Antigiardial Effect of Omeprazole Analog Benzimidazole Compounds. Molecules 2020; 25:molecules25173979. [PMID: 32882836 PMCID: PMC7504735 DOI: 10.3390/molecules25173979] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 08/25/2020] [Accepted: 08/28/2020] [Indexed: 11/22/2022] Open
Abstract
Giardiasis is a diarrheal disease that is highly prevalent in developing countries. Several drugs are available for the treatment of this parasitosis; however, failures in drug therapy are common, and have adverse effects and increased resistance of the parasite to the drug, generating the need to find new alternative treatments. In this study, we synthesized a series of 2-mercaptobenzimidazoles that are derivatives of omeprazole, and the chemical structures were confirmed through mass, 1H NMR, and 13C NMR techniques. The in vitro efficacy compounds against Giardia, as well as its effect on the inhibition of triosephosphate isomerase (TPI) recombinant, were investigated, the inactivation assays were performed with 0.2 mg/mL of the enzyme incubating for 2 h at 37 °C in TE buffer, pH 7.4 with increasing concentrations of the compounds. Among the target compounds, H-BZM2, O2N-BZM7, and O2N-BZM9 had greater antigiardial activity (IC50: 36, 14, and 17 µM on trophozoites), and inhibited the TPI enzyme (K2: 2.3, 3.2, and 2.8 M−1 s−1) respectively, loading alterations on the secondary structure, global stability, and tertiary structure of the TPI protein. Finally, we demonstrated that it had low toxicity on Caco-2 and HT29 cells. This finding makes it an attractive potential starting point for new antigiardial drugs.
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Affiliation(s)
- Beatriz Hernández-Ochoa
- Laboratorio de Inmunoquímica, Hospital Infantil de México Federico Gómez, Secretaría de Salud, Ciudad de Mexico 06720, Mexico; (A.S.-C.); (A.S.-S.)
- Correspondence: (B.H.-O.); (E.C.-J.); Tel.: +52-5228917 (ext. 2000) (B.H.-O.)
| | - Saúl Gómez-Manzo
- Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico; (S.G.-M.); (E.J.R.-N.)
| | - Adrián Sánchez-Carrillo
- Laboratorio de Inmunoquímica, Hospital Infantil de México Federico Gómez, Secretaría de Salud, Ciudad de Mexico 06720, Mexico; (A.S.-C.); (A.S.-S.)
| | - Jaime Marcial-Quino
- Consejo Nacional de Ciencia y Tecnología (CONACYT), Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de Mexico 04530, Mexico;
| | - Luz María Rocha-Ramírez
- Unidad de Investigación en Enfermedades Infecciosas, Hospital Infantil de México Federico Gómez, Secretaría de Salud Dr. Márquez No. 162, Col Doctores, Delegación Cuauhtémoc, Ciudad de México 06720, Mexico;
| | - Araceli Santos-Segura
- Laboratorio de Inmunoquímica, Hospital Infantil de México Federico Gómez, Secretaría de Salud, Ciudad de Mexico 06720, Mexico; (A.S.-C.); (A.S.-S.)
| | - Edson Jiovany Ramírez-Nava
- Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico; (S.G.-M.); (E.J.R.-N.)
| | - Roberto Arreguin-Espinosa
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de Mexico, Ciudad de Mexico 04510, Mexico; (R.A.-E.); (M.C.-C.)
| | - Miguel Cuevas-Cruz
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de Mexico, Ciudad de Mexico 04510, Mexico; (R.A.-E.); (M.C.-C.)
| | - Alfonso Méndez-Tenorio
- Laboratorio de Biotecnología y Bioinformática Genómica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México 11340, Mexico;
| | - Ernesto Calderón-Jaimes
- Laboratorio de Inmunoquímica, Hospital Infantil de México Federico Gómez, Secretaría de Salud, Ciudad de Mexico 06720, Mexico; (A.S.-C.); (A.S.-S.)
- Correspondence: (B.H.-O.); (E.C.-J.); Tel.: +52-5228917 (ext. 2000) (B.H.-O.)
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Morales-Luna L, González-Valdez A, Sixto-López Y, Correa-Basurto J, Hernández-Ochoa B, Cárdenas-Rodríguez N, Castillo-Rodríguez RA, Ortega-Cuellar D, Arreguin-Espinosa R, Pérez de la Cruz V, Serrano-Posada H, Centeno-Leija S, Rocha-Ramírez LM, Sierra-Palacios E, Montiel-González AM, Rufino-González Y, Marcial-Quino J, Gómez-Manzo S. Identification of the NADP + Structural Binding Site and Coenzyme Effect on the Fused G6PD::6PGL Protein from Giardia lamblia. Biomolecules 2019; 10:biom10010046. [PMID: 31892224 PMCID: PMC7022596 DOI: 10.3390/biom10010046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/24/2019] [Accepted: 12/24/2019] [Indexed: 11/29/2022] Open
Abstract
Giardia lambia is a flagellated protozoan parasite that lives in the small intestine and is the causal agent of giardiasis. It has been reported that G. lamblia exhibits glucose-6-phosphate dehydrogenase (G6PD), the first enzyme in the pentose phosphate pathway (PPP). Our group work demonstrated that the g6pd and 6pgl genes are present in the open frame that gives rise to the fused G6PD::6PGL protein; where the G6PD region is similar to the 3D structure of G6PD in Homo sapiens. The objective of the present work was to show the presence of the structural NADP+ binding site on the fused G6PD::6PGL protein and evaluate the effect of the NADP+ molecule on protein stability using biochemical and computational analysis. A protective effect was observed on the thermal inactivation, thermal stability, and trypsin digestions assays when the protein was incubated with NADP+. By molecular docking, we determined the possible structural-NADP+ binding site, which is located between the Rossmann fold of G6PD and 6PGL. Finally, molecular dynamic (MD) simulation was used to test the stability of this complex; it was determined that the presence of both NADP+ structural and cofactor increased the stability of the enzyme, which is in agreement with our experimental results.
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Affiliation(s)
- Laura Morales-Luna
- Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico;
| | - Abigail González-Valdez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico;
| | - Yudibeth Sixto-López
- Laboratorio de Modelado Molecular, Bioinformática y Diseño de Fármacos, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Ciudad de México 06720, Mexico; (Y.S.-L.); (J.C.-B.)
| | - José Correa-Basurto
- Laboratorio de Modelado Molecular, Bioinformática y Diseño de Fármacos, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Ciudad de México 06720, Mexico; (Y.S.-L.); (J.C.-B.)
| | - Beatriz Hernández-Ochoa
- Laboratorio de Inmunoquímica, Hospital Infantil de México Federico Gómez, Secretaría de Salud, Ciudad de México 06720, Mexico;
| | - Noemí Cárdenas-Rodríguez
- Laboratorio de Neurociencias, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico;
| | - Rosa Angélica Castillo-Rodríguez
- Consejo Nacional de Ciencia y Tecnología (CONACYT), Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico;
| | - Daniel Ortega-Cuellar
- Laboratorio de Nutrición Experimental, Instituto Nacional de Pediatría, Secretaría de Salud 04530, Mexico;
| | - Roberto Arreguin-Espinosa
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico;
| | - Verónica Pérez de la Cruz
- Departamento de Neuroquímica, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez, S.S.A., Ciudad de México 14269, Mexico;
| | - Hugo Serrano-Posada
- Consejo Nacional de Ciencia y Tecnología (CONACYT), Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera los Limones-Loma de Juárez, Colima 28629, Mexico; (H.S.-P.); (S.C.-L.)
| | - Sara Centeno-Leija
- Consejo Nacional de Ciencia y Tecnología (CONACYT), Laboratorio de Agrobiotecnología, Tecnoparque CLQ, Universidad de Colima, Carretera los Limones-Loma de Juárez, Colima 28629, Mexico; (H.S.-P.); (S.C.-L.)
| | - Luz María Rocha-Ramírez
- Departamento de Infectología, Hospital Infantil de México Federico Gómez, Dr. Márquez No. 162, Col Doctores, Delegación Cuauhtémoc 06720, Mexico;
| | - Edgar Sierra-Palacios
- Colegio de Ciencias y Humanidades, Plantel Casa Libertad, Universidad Autónoma de la Ciudad de México, Ciudad de México 09620, Mexico;
| | - Alba Mónica Montiel-González
- Centro de Investigación en Genética y Ambiente, Universidad Autónoma de Tlaxcala, Aut. San Martín Texmelucan-Tlaxcala Km 10.5, San Felipe Ixtlacuixtla, 90120 Tlaxcala, Mexico;
- México de Ciencias y Humanidades, Plantel Casa Libertad, Universidad Autónoma de la Ciudad de México, Ciudad de México 09620, Mexico
| | - Yadira Rufino-González
- Laboratorio de Parasitología Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico;
| | - Jaime Marcial-Quino
- Consejo Nacional de Ciencia y Tecnología (CONACYT), Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico;
- Correspondence: (J.M.-Q.); (S.G.-M.); Tel.: +52-55-1084-0900 (ext. 1442) (J.M.-Q. & S.G.-M.)
| | - Saúl Gómez-Manzo
- Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico;
- Correspondence: (J.M.-Q.); (S.G.-M.); Tel.: +52-55-1084-0900 (ext. 1442) (J.M.-Q. & S.G.-M.)
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Muthmann N, Guez T, Vasseur JJ, Jaffrey SR, Debart F, Rentmeister A. Combining Chemical Synthesis and Enzymatic Methylation to Access Short RNAs with Various 5' Caps. Chembiochem 2019; 20:1693-1700. [PMID: 30768827 PMCID: PMC6755138 DOI: 10.1002/cbic.201900037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Indexed: 12/31/2022]
Abstract
Eukaryotic RNAs are heavily processed, including co- and post-transcriptional formation of various 5' caps. In small nuclear RNAs (snRNAs) or small nucleolar RNAs (snoRNAs), the canonical 7m G cap is hypermethylated at the N2 -position, whereas in higher eukaryotes and viruses 2'-O-methylation of the first transcribed nucleotide yields the cap1 structure. The function and potential dynamics of several RNA cap modifications have not been fully elucidated, which necessitates preparative access to these caps. However, the introduction of these modifications during chemical solid-phase synthesis is challenging and enzymatic production of defined short and uniform RNAs also faces difficulties. In this work, the chemical synthesis of RNA is combined with site-specific enzymatic methylation by using the methyltransferases human trimethylguanosine synthase 1 (hTgs1), trimethylguanosine synthase from Giardia lamblia (GlaTgs2), and cap methyltransferase 1 (CMTR1). It is shown that RNAs with di-and trimethylated caps, as well as RNAs with caps methylated at the 2'-O-position of the first transcribed nucleotide, can be conveniently prepared. These highly modified RNAs, with a defined and uniform sequence, are hard to access by in vitro transcription or chemical synthesis alone.
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Affiliation(s)
- Nils Muthmann
- Department of Chemistry and Pharmacy, Institute for Biochemistry, University of Münster, Wilhelm-Klemm-Strasse 2, 48149, Münster, Germany
| | - Théo Guez
- Institut des Biomolécules Max Mousseron (IBMM), Université de Montpellier, CNRS, ENSCM, Campus Triolet UM, Place Eugène Bataillon, 34095, Montpellier, France
| | - Jean-Jacques Vasseur
- Institut des Biomolécules Max Mousseron (IBMM), Université de Montpellier, CNRS, ENSCM, Campus Triolet UM, Place Eugène Bataillon, 34095, Montpellier, France
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, 1300 York Avenue, Box 70, New York, NY, 10065, USA
| | - Françoise Debart
- Institut des Biomolécules Max Mousseron (IBMM), Université de Montpellier, CNRS, ENSCM, Campus Triolet UM, Place Eugène Bataillon, 34095, Montpellier, France
| | - Andrea Rentmeister
- Department of Chemistry and Pharmacy, Institute for Biochemistry, University of Münster, Wilhelm-Klemm-Strasse 2, 48149, Münster, Germany
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Hennessey KM, Smith TR, Xu JW, Alas GCM, Ojo KK, Merritt EA, Paredez AR. Identification and Validation of Small-Gatekeeper Kinases as Drug Targets in Giardia lamblia. PLoS Negl Trop Dis 2016; 10:e0005107. [PMID: 27806042 PMCID: PMC5091913 DOI: 10.1371/journal.pntd.0005107] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 10/12/2016] [Indexed: 12/18/2022] Open
Abstract
Giardiasis is widely acknowledged to be a neglected disease in need of new therapeutics to address toxicity and resistance issues associated with the limited available treatment options. We examined seven protein kinases in the Giardia lamblia genome that are predicted to share an unusual structural feature in their active site. This feature, an expanded active site pocket resulting from an atypically small gatekeeper residue, confers sensitivity to "bumped" kinase inhibitors (BKIs), a class of compounds that has previously shown good pharmacological properties and minimal toxicity. An initial phenotypic screen for biological activity using a subset of an in-house BKI library found that 5 of the 36 compounds tested reduced trophozoite growth by at least 50% at a concentration of 5 μM. The cellular localization and the relative expression levels of the seven protein kinases of interest were determined after endogenously tagging the kinases. Essentiality of these kinases for parasite growth and infectivity were evaluated genetically using morpholino knockdown of protein expression to establish those that could be attractive targets for drug design. Two of the kinases were critical for trophozoite growth and attachment. Therefore, recombinant enzymes were expressed, purified and screened against a BKI library of >400 compounds in thermal stability assays in order to identify high affinity compounds. Compounds with substantial thermal stabilization effects on recombinant protein were shown to have good inhibition of cell growth in wild-type G. lamblia and metronidazole-resistant strains of G. lamblia. Our data suggest that BKIs are a promising starting point for the development of new anti-giardiasis therapeutics that do not overlap in mechanism with current drugs.
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Affiliation(s)
- Kelly M. Hennessey
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Tess R. Smith
- Division of Allergy and Infectious Diseases, Center for Emerging and Re-emerging Infectious Disease (CERID), University of Washington, Seattle, Washington, United States of America
| | - Jennifer W. Xu
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Germain C. M. Alas
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Kayode K. Ojo
- Division of Allergy and Infectious Diseases, Center for Emerging and Re-emerging Infectious Disease (CERID), University of Washington, Seattle, Washington, United States of America
| | - Ethan A. Merritt
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
- * E-mail: (ARP); (EAM)
| | - Alexander R. Paredez
- Department of Biology, University of Washington, Seattle, Washington, United States of America
- * E-mail: (ARP); (EAM)
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Bhargava A, Cotton JA, Dixon BR, Gedamu L, Yates RM, Buret AG. Giardia duodenalis Surface Cysteine Proteases Induce Cleavage of the Intestinal Epithelial Cytoskeletal Protein Villin via Myosin Light Chain Kinase. PLoS One 2015; 10:e0136102. [PMID: 26334299 PMCID: PMC4559405 DOI: 10.1371/journal.pone.0136102] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 07/29/2015] [Indexed: 01/13/2023] Open
Abstract
Giardia duodenalis infections are among the most common causes of waterborne diarrhoeal disease worldwide. At the height of infection, G. duodenalis trophozoites induce multiple pathophysiological processes within intestinal epithelial cells that contribute to the development of diarrhoeal disease. To date, our understanding of pathophysiological processes in giardiasis remains incompletely understood. The present study reveals a previously unappreciated role for G. duodenalis cathepsin cysteine proteases in intestinal epithelial pathophysiological processes that occur during giardiasis. Experiments first established that Giardia trophozoites indeed produce cathepsin B and L in strain-dependent fashion. Co-incubation of G. duodenalis with human enterocytes enhanced cathepsin production by Assemblage A (NF and S2 isolates) trophozoites, but not when epithelial cells were exposed to Assemblage B (GSM isolate) trophozoites. Direct contact between G. duodenalis parasites and human intestinal epithelial monolayers resulted in the degradation and redistribution of the intestinal epithelial cytoskeletal protein villin; these effects were abolished when parasite cathepsin cysteine proteases were inhibited. Interestingly, inhibition of parasite proteases did not prevent degradation of the intestinal tight junction-associated protein zonula occludens 1 (ZO-1), suggesting that G. duodenalis induces multiple pathophysiological processes within intestinal epithelial cells. Finally, this study demonstrates that G. duodenalis-mediated disruption of villin is, at least, in part dependent on activation of myosin light chain kinase (MLCK). Taken together, this study indicates a novel role for parasite cathepsin cysteine proteases in the pathophysiology of G. duodenalis infections.
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Affiliation(s)
- Amol Bhargava
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
- Inflammation Research Network, University of Calgary, Calgary, Alberta, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, Alberta, Canada
| | - James A. Cotton
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
- Inflammation Research Network, University of Calgary, Calgary, Alberta, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, Alberta, Canada
| | - Brent R. Dixon
- Bureau of Microbial Hazards, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada
| | - Lashitew Gedamu
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, Alberta, Canada
| | - Robin M. Yates
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
| | - Andre G. Buret
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
- Inflammation Research Network, University of Calgary, Calgary, Alberta, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
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8
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Kurnosova OP, Odoevskaya IM, Krasavchenko KS. [DETERMINATION OF GIARDIA DUODENALIS GENOTYPES IN LAMBLIA-INFESTED PEOPLE IN THE CITY OF MOSCOW]. Med Parazitol (Mosk) 2015:21-24. [PMID: 26720965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Our first experience in genotyping Giardia from Moscow residents, has shown that 4 and 2 of seven samples belong to G. duodenalis genotype A and genotype B, respectively; one sample was negative during amplification with two types of primers. Genotyping was Carried out using the specific primers TPIA and TPIB to the gene encoding for the enzyme triosephosphate isomerase from the parasite. Thus, further such investigations using a larger number of samples will be able to complement the epidemiology of Lamblia infection in Moscow residents.
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Abendroth J, Choi R, Wall A, Clifton MC, Lukacs CM, Staker BL, Van Voorhis W, Myler P, Lorimer DD, Edwards TE. Structures of aspartate aminotransferases from Trypanosoma brucei, Leishmania major and Giardia lamblia. Acta Crystallogr F Struct Biol Commun 2015; 71:566-71. [PMID: 25945710 PMCID: PMC4427166 DOI: 10.1107/s2053230x15001831] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/27/2015] [Indexed: 11/10/2022] Open
Abstract
The structures of three aspartate aminotransferases (AATs) from eukaryotic pathogens were solved within the Seattle Structural Genomics Center for Infectious Disease (SSGCID). Both the open and closed conformations of AAT were observed. Pyridoxal phosphate was bound to the active site via a Schiff base to a conserved lysine. An active-site mutant showed that Trypanosoma brucei AAT still binds pyridoxal phosphate even in the absence of the tethering lysine. The structures highlight the challenges for the structure-based design of inhibitors targeting the active site, while showing options for inhibitor design targeting the N-terminal arm.
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Affiliation(s)
- Jan Abendroth
- Seattle Structural Genomics Center for Infectious Disease, http://www.ssgcid.org, USA
- Beryllium Inc., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Ryan Choi
- Seattle Structural Genomics Center for Infectious Disease, http://www.ssgcid.org, USA
- Department of Medicine, Division of Allergy and Infectious Diseases, School of Medicine, University of Washington, Box 356423, Seattle, WA 98195, USA
| | - Abigail Wall
- Seattle Structural Genomics Center for Infectious Disease, http://www.ssgcid.org, USA
- Beryllium Inc., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Matthew C. Clifton
- Seattle Structural Genomics Center for Infectious Disease, http://www.ssgcid.org, USA
- Beryllium Inc., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Christine M. Lukacs
- Seattle Structural Genomics Center for Infectious Disease, http://www.ssgcid.org, USA
- Beryllium Inc., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Bart L. Staker
- Seattle Structural Genomics Center for Infectious Disease, http://www.ssgcid.org, USA
- Seattle BioMed, 307 Westlake Avenure North, Seattle, WA 98109, USA
| | - Wesley Van Voorhis
- Seattle Structural Genomics Center for Infectious Disease, http://www.ssgcid.org, USA
- Department of Medicine, Division of Allergy and Infectious Diseases, School of Medicine, University of Washington, Box 356423, Seattle, WA 98195, USA
| | - Peter Myler
- Seattle Structural Genomics Center for Infectious Disease, http://www.ssgcid.org, USA
- Seattle BioMed, 307 Westlake Avenure North, Seattle, WA 98109, USA
| | - Don D. Lorimer
- Seattle Structural Genomics Center for Infectious Disease, http://www.ssgcid.org, USA
- Beryllium Inc., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Thomas E. Edwards
- Seattle Structural Genomics Center for Infectious Disease, http://www.ssgcid.org, USA
- Beryllium Inc., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
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10
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Merino MC, Zamponi N, Vranych CV, Touz MC, Rópolo AS. Identification of Giardia lamblia DHHC proteins and the role of protein S-palmitoylation in the encystation process. PLoS Negl Trop Dis 2014; 8:e2997. [PMID: 25058047 PMCID: PMC4109852 DOI: 10.1371/journal.pntd.0002997] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 05/23/2014] [Indexed: 12/17/2022] Open
Abstract
Protein S-palmitoylation, a hydrophobic post-translational modification, is performed by protein acyltransferases that have a common DHHC Cys-rich domain (DHHC proteins), and provides a regulatory switch for protein membrane association. In this work, we analyzed the presence of DHHC proteins in the protozoa parasite Giardia lamblia and the function of the reversible S-palmitoylation of proteins during parasite differentiation into cyst. Two specific events were observed: encysting cells displayed a larger amount of palmitoylated proteins, and parasites treated with palmitoylation inhibitors produced a reduced number of mature cysts. With bioinformatics tools, we found nine DHHC proteins, potential protein acyltransferases, in the Giardia proteome. These proteins displayed a conserved structure when compared to different organisms and are distributed in different monophyletic clades. Although all Giardia DHHC proteins were found to be present in trophozoites and encysting cells, these proteins showed a different intracellular localization in trophozoites and seemed to be differently involved in the encystation process when they were overexpressed. dhhc transgenic parasites showed a different pattern of cyst wall protein expression and yielded different amounts of mature cysts when they were induced to encyst. Our findings disclosed some important issues regarding the role of DHHC proteins and palmitoylation during Giardia encystation. Giardiasis is a major cause of non-viral/non-bacterial diarrheal disease worldwide and has been included within the WHO Neglected Disease Initiative since 2004. Infection begins with the ingestion of Giardia lamblia in cyst form, which, after exposure to gastric acid in the host stomach and proteases in the duodenum, gives rise to trophozoites. The inverse process is called encystation and begins when the trophozoites migrate to the lower part of the small intestine where they receive signals that trigger synthesis of the components of the cyst wall. The cyst form enables the parasite to survive in the environment, infect a new host and evade the immune response. In this work, we explored the role of protein S-palmitoylation, a unique reversible post-translational modification, during Giardia encystation, because de novo generation of endomembrane compartments, protein sorting and vesicle fusion occur in this process. Our findings may contribute to the design of therapeutic agents against this important human pathogen.
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Affiliation(s)
- María C. Merino
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
- * E-mail:
| | - Nahuel Zamponi
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Cecilia V. Vranych
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María C. Touz
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Andrea S. Rópolo
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
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11
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Mastronicola D, Falabella M, Testa F, Pucillo LP, Teixeira M, Sarti P, Saraiva LM, Giuffrè A. Functional characterization of peroxiredoxins from the human protozoan parasite Giardia intestinalis. PLoS Negl Trop Dis 2014; 8:e2631. [PMID: 24416465 PMCID: PMC3886907 DOI: 10.1371/journal.pntd.0002631] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 11/26/2013] [Indexed: 01/03/2023] Open
Abstract
The microaerophilic protozoan parasite Giardia intestinalis, causative of one of the most common human intestinal diseases worldwide, infects the mucosa of the proximal small intestine, where it has to cope with O2 and nitric oxide (NO). Elucidating the antioxidant defense system of this pathogen lacking catalase and other conventional antioxidant enzymes is thus important to unveil novel potential drug targets. Enzymes metabolizing O2, NO and superoxide anion (O2−•) have been recently reported for Giardia, but it is yet unknown how the parasite copes with H2O2 and peroxynitrite (ONOO−). Giardia encodes two yet uncharacterized 2-cys peroxiredoxins (Prxs), GiPrx1a and GiPrx1b. Peroxiredoxins are peroxidases implicated in virulence and drug resistance in several parasitic protozoa, able to protect from nitroxidative stress and repair oxidatively damaged molecules. GiPrx1a and a truncated form of GiPrx1b (deltaGiPrx1b) were expressed in Escherichia coli, purified and functionally characterized. Both Prxs effectively metabolize H2O2 and alkyl-hydroperoxides (cumyl- and tert-butyl-hydroperoxide) in the presence of NADPH and E. coli thioredoxin reductase/thioredoxin as the reducing system. Stopped-flow experiments show that both proteins in the reduced state react with ONOO− rapidly (k = 4×105 M−1 s−1 and 2×105 M−1 s−1 at 4°C, for GiPrx1a and deltaGiPrx1b, respectively). Consistent with a protective role against oxidative stress, expression of GiPrx1a (but not deltaGiPrx1b) is induced in parasitic cells exposed to air O2 for 24 h. Based on these results, GiPrx1a and deltaGiPrx1b are suggested to play an important role in the antioxidant defense of Giardia, possibly contributing to pathogenesis. Giardia intestinalis causes one of the most common human intestinal diseases worldwide, called giardiasis. This microorganism infects the small intestine where it has to cope with O2, nitric oxide (NO) and related reactive species that are toxic for Giardia as it lacks most of the conventional antioxidant enzymes. Understanding how this pathogen survives oxidative stress is thus important because it may help to identify novel drug targets to combat giardiasis. Some enzymes playing a role in the antioxidant defense of Giardia have been recently reported, but it is yet unknown how the parasite copes with two well-known oxidants, hydrogen peroxide (H2O2) and peroxynitrite (ONOO−). In this study, the Authors show that Giardia expresses two enzymes (called peroxiredoxins), yet uncharacterized, that are able not only to degrade both H2O2 and ONOO−, but also to repair damaged molecules (called hydroperoxides) that accumulate in the cell under oxidative stress conditions. These results are totally unprecedented because no enzymes with these types of functions have been reported for Giardia to date. If these two enzymes will prove to be essential for Giardia virulence in future studies, a new way will be paved towards the discovery of novel drugs to treat giardiasis.
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Affiliation(s)
| | - Micol Falabella
- Department of Biochemical Sciences and Istituto Pasteur – Fondazione Cenci Bolognetti, Sapienza University of Rome, Italy
| | - Fabrizio Testa
- Department of Biochemical Sciences and Istituto Pasteur – Fondazione Cenci Bolognetti, Sapienza University of Rome, Italy
| | | | - Miguel Teixeira
- Instituto de Tecnologia Quimica e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Paolo Sarti
- CNR Institute of Molecular Biology and Pathology, Rome, Italy
- Department of Biochemical Sciences and Istituto Pasteur – Fondazione Cenci Bolognetti, Sapienza University of Rome, Italy
| | - Lígia M. Saraiva
- Instituto de Tecnologia Quimica e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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12
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Feng X, Yang C, Zheng W, Wen J. Structural and evolutionary characteristics of pyruvate phosphate dikinase in Giardia lamblia and other amitochondriate protozoa. Chin Med J (Engl) 2014; 127:4097-4103. [PMID: 25430456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023] Open
Abstract
BACKGROUND Pyruvate phosphate dikinase (PPDK) reversibly catalyzes the interconversion of phosphoenolpyruvate (PEP) and pyruvic acid, leading to catabolism and adenosine triphosphate (ATP) synthesis or gluconeogenesis and ATP consumption. Molecular modeling of PPDKs from divergent organisms demonstrates that the orientation of the phosphorylatable histidine residue within the central domain of PPDK determines whether this enzyme promotes catabolism or gluconeogenesis. The goal of this study was to determine whether PDDK from Giardia underwent adaptive evolution in order to produce more energy under anaerobic conditions. METHODS A total of 123 PPDK sequences from protozoans, proteobacteria, plants, and algae were selected, based upon sequence similarities to Giardia lamblia PPDK and Zea mays PPDK. Three-dimensional (3-D) models were generated for PPDKs from divergent organisms and were used to compare the orientation of the phosphorylatable histidine residue within the central domain of PPDKs. These PPDKs were compared using a maximum-likelihood tree. RESULTS For PPDK from Giardia, as well as from other anaerobic protozoans, the central domain tilted toward the N-terminal nucleotide-binding domain, indicating that this enzyme catalyzed ATP synthesis. Furthermore, the orientation of this central domain was determined by interactions between the N- and C-terminal domains. Phylogenetic analysis of the N- and C-terminal sequences of PPDKs from different species suggested that PPDK has likely undergone adaptive evolution in response to differences in environmental and metabolic conditions. CONCLUSION These results suggested that PPDK in anaerobic organisms is functionally adapted to generate energy more efficiently in an anaerobic environment.
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Affiliation(s)
- Xianmin Feng
- The School of Laboratory Medicine, Jilin Medical College, Jilin, Jilin 132013, China
| | - Chunlin Yang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
| | - Wenyu Zheng
- The Department of Hand Microsurgery, Central Hospital of Jilin City, Jilin, Jilin 132000, China
| | - Jianfan Wen
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China.
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13
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Buchko GW, Hewitt SN, Van Voorhis WC, Myler PJ. Solution structure of a putative FKBP-type peptidyl-propyl cis-trans isomerase from Giardia lamblia. J Biomol NMR 2013; 57:369-374. [PMID: 24293257 PMCID: PMC3903135 DOI: 10.1007/s10858-013-9797-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 11/19/2013] [Indexed: 06/02/2023]
Affiliation(s)
- Garry W Buchko
- Seattle Structural Genomics Center for Infectious Disease, Seattle, WA, USA,
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14
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Hernández-Alcántara G, Torres-Larios A, Enríquez-Flores S, García-Torres I, Castillo-Villanueva A, Méndez ST, de la Mora-de la Mora I, Gómez-Manzo S, Torres-Arroyo A, López-Velázquez G, Reyes-Vivas H, Oria-Hernández J. Structural and functional perturbation of Giardia lamblia triosephosphate isomerase by modification of a non-catalytic, non-conserved region. PLoS One 2013; 8:e69031. [PMID: 23894402 PMCID: PMC3718800 DOI: 10.1371/journal.pone.0069031] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 06/04/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND We have previously proposed triosephosphate isomerase of Giardia lamblia (GlTIM) as a target for rational drug design against giardiasis, one of the most common parasitic infections in humans. Since the enzyme exists in the parasite and the host, selective inhibition is a major challenge because essential regions that could be considered molecular targets are highly conserved. Previous biochemical evidence showed that chemical modification of the non-conserved non-catalytic cysteine 222 (C222) inactivates specifically GlTIM. The inactivation correlates with the physicochemical properties of the modifying agent: addition of a non-polar, small chemical group at C222 reduces the enzyme activity by one half, whereas negatively charged, large chemical groups cause full inactivation. RESULTS In this work we used mutagenesis to extend our understanding of the functional and structural effects triggered by modification of C222. To this end, six GlTIM C222 mutants with side chains having diverse physicochemical characteristics were characterized. We found that the polarity, charge and volume of the side chain in the mutant amino acid differentially alter the activity, the affinity, the stability and the structure of the enzyme. The data show that mutagenesis of C222 mimics the effects of chemical modification. The crystallographic structure of C222D GlTIM shows the disruptive effects of introducing a negative charge at position 222: the mutation perturbs loop 7, a region of the enzyme whose interactions with the catalytic loop 6 are essential for TIM stability, ligand binding and catalysis. The amino acid sequence of TIM in phylogenetic diverse groups indicates that C222 and its surrounding residues are poorly conserved, supporting the proposal that this region is a good target for specific drug design. CONCLUSIONS The results demonstrate that it is possible to inhibit species-specifically a ubiquitous, structurally highly conserved enzyme by modification of a non-conserved, non-catalytic residue through long-range perturbation of essential regions.
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Affiliation(s)
- Gloria Hernández-Alcántara
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
| | - Alfredo Torres-Larios
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Sergio Enríquez-Flores
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
| | - Itzhel García-Torres
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
| | - Adriana Castillo-Villanueva
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
| | - Sara T. Méndez
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
| | | | - Saúl Gómez-Manzo
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
| | - Angélica Torres-Arroyo
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
| | - Gabriel López-Velázquez
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
| | - Horacio Reyes-Vivas
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
- * E-mail: (JOH); (HRV)
| | - Jesús Oria-Hernández
- Laboratorio de Bioquímica-Genética, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City, Mexico
- * E-mail: (JOH); (HRV)
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15
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Banik S, Renner Viveros P, Seeber F, Klotz C, Ignatius R, Aebischer T. Giardia duodenalis arginine deiminase modulates the phenotype and cytokine secretion of human dendritic cells by depletion of arginine and formation of ammonia. Infect Immun 2013; 81:2309-17. [PMID: 23589577 PMCID: PMC3697621 DOI: 10.1128/iai.00004-13] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 04/06/2013] [Indexed: 12/22/2022] Open
Abstract
Depletion of arginine is a recognized strategy that pathogens use to evade immune effector mechanisms. Depletion depends on microbial enzymes such as arginases, which are considered virulence factors. The effect is mostly interpreted as being a consequence of successful competition with host enzymes for the substrate. However, both arginases and arginine deiminases (ADI) have been associated with pathogen virulence. Both deplete arginine, but their reaction products differ. An ADI has been implicated in the virulence of Giardia duodenalis, an intestinal parasite that infects humans and animals, causing significant morbidity. Dendritic cells (DC) play a critical role in host defense and also in a murine G. duodenalis infection model. The functional properties of these innate immune cells depend on the milieu in which they are activated. Here, the dependence of the response of these cells on arginine was studied by using Giardia ADI and lipopolysaccharide-stimulated human monocyte-derived DC. Arginine depletion by ADI significantly increased tumor necrosis factor alpha and decreased interleukin-10 (IL-10) and IL-12p40 secretion. It also reduced the upregulation of surface CD83 and CD86 molecules, which are involved in cell-cell interactions. Arginine depletion also reduced the phosphorylation of S6 kinase in DC, suggesting the involvement of the mammalian target of rapamycin signaling pathway. The changes were due to arginine depletion and the formation of reaction products, in particular, ammonium ions. Comparison of NH(4)(+) and urea revealed distinct immunomodulatory activities of these products of deiminases and arginases, respectively. The data suggest that a better understanding of the role of arginine-depleting pathogen enzymes for immune evasion will have to take enzyme class and reaction products into consideration.
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Affiliation(s)
- Stefanie Banik
- Department of Parasitology/Mycology/Intracellular Pathogens (FG 16), Robert Koch Institute, Berlin, Germany
| | - Pablo Renner Viveros
- Institute of Tropical Medicine and International Health, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Frank Seeber
- Department of Parasitology/Mycology/Intracellular Pathogens (FG 16), Robert Koch Institute, Berlin, Germany
| | - Christian Klotz
- Department of Parasitology/Mycology/Intracellular Pathogens (FG 16), Robert Koch Institute, Berlin, Germany
| | - Ralf Ignatius
- Institute of Tropical Medicine and International Health, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Toni Aebischer
- Department of Parasitology/Mycology/Intracellular Pathogens (FG 16), Robert Koch Institute, Berlin, Germany
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Niño CA, Prucca CG, Chaparro J, Luján HD, Wasserman M. The ubiquitin-activating enzyme (E1) of the early-branching eukaryote Giardia intestinalis shows unusual proteolytic modifications and play important roles during encystation. Acta Trop 2012; 123:39-46. [PMID: 22498829 DOI: 10.1016/j.actatropica.2012.03.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 03/14/2012] [Accepted: 03/28/2012] [Indexed: 01/14/2023]
Abstract
Giardia intestinalis is considered an early-branching eukaryote and is therefore a valuable model for studying primordial cellular processes. This work reports the characterization of the ubiquitin-activating enzyme (E1) during growth and different stages of trophozoite differentiation into cysts. We found that in Giardia E1 expression (both at mRNA and protein levels) is regulated during encystation. The enzyme is proteolytically processed mainly into two fragments of 68kDa (N-terminal) and 47kDa (C-terminal). This phenomenon has not been described for any other E1. In trophozoites, this enzyme localized at spots within the cytoplasm as detected by using polyclonal antibodies against either E1 N- or C-terminal fragments. This pattern changed during encystation into a diffuse localization throughout the cytoplasm of encysting cells. E1 localizes in mature cysts at cytoplasmic spots and in the cyst wall. Our antisense silencing experiments suggested that E1 is an essential gene for parasite viability. On the other hand, E1 over-expression greatly increased the encystation rate, indicating a relationship between E1 and Giardia differentiation.
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Affiliation(s)
- Carlos A Niño
- Laboratory of Basic Research in Biochemistry - LIBBIQ, Departamento de Química, Universidad Nacional de Colombia, Bogotá, Colombia
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17
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Zhang W, Shen Y, Wang R, Liu A, Ling H, Li Y, Cao J, Zhang X, Shu J, Zhang L. Cryptosporidium cuniculus and Giardia duodenalis in rabbits: genetic diversity and possible zoonotic transmission. PLoS One 2012; 7:e31262. [PMID: 22363600 PMCID: PMC3281947 DOI: 10.1371/journal.pone.0031262] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 01/04/2012] [Indexed: 11/23/2022] Open
Abstract
Background Cryptosporidium and Giardia are the two important zoonotic pathogens causing diarrhea of humans and animals worldwide. Considering the human cryptosporidiosis outbreak and sporadic cases caused by C. cuniculus, the important public health significance of G. duodenalis and little obtained information regarding rabbit infected with Cryptosporidium and Giardia in China, the aim of this study is to determine the prevalence and molecularly characterize Cryptosporidium and Giardia in rabbits in Heilongjiang Province, China. Methodology/Principal Findings 378 fecal samples were obtained from rabbits in Heilongjiang Province. Cryptosporidium oocysts and Giardia cysts were detected using Sheather's sugar flotation technique and Lugol's iodine stain method, respectively. The infection rates of Cryptosporidium and Giardia were 2.38% (9/378) and 7.41% (28/378), respectively. Genotyping of Cryptosporidium spp. was done by DNA sequencing of the small subunit rRNA (SSU rRNA) gene and all the nine isolates were identified as Cryptosporidium cuniculus. The nine isolates were further subtyped using the 60-kDa glycoprotein (gp60) gene and two subtypes were detected, including VbA32 (n = 3) and a new subtype VbA21 (n = 6). G. duodenalis genotypes and subtypes were identified by sequence analysis of the triosephosphate isomerase (TPI) gene. The assemblage B (belonging to eight different subtypes B-I to B-VIII) was found in 28 G. duodenalis-positive samples. Conclusions/Significance The rabbits have been infected with Cryptosporidium and Giardia in Heilongjiang Province. The results show that the rabbits pose a threat to human health in the studied areas. Genotypes and subgenotypes of C. cuniculus and G. duodenalis in this study might present the endemic genetic characterization of population structure of the two parasites.
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Affiliation(s)
- Weizhe Zhang
- Department of Parasitology, Harbin Medical University, Harbin, Heilongjiang, China
| | - Yujuan Shen
- Key Laboratory of Parasite and Vector Biology, National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Ministry of Health, World Health Organization, Collaborating Centre for Malaria, Schistosomiasis and Filariasis, Shanghai, China
| | - Rongjun Wang
- College of Animal Science and Veterinary Medicine, Henan Agricultural University Zhengzhou, Henan, China
| | - Aiqin Liu
- Department of Parasitology, Harbin Medical University, Harbin, Heilongjiang, China
- * E-mail: (AL); (LZ)
| | - Hong Ling
- Department of Parasitology, Harbin Medical University, Harbin, Heilongjiang, China
| | - Yihong Li
- Department of Parasitology, Harbin Medical University, Harbin, Heilongjiang, China
| | - Jianping Cao
- Key Laboratory of Parasite and Vector Biology, National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Ministry of Health, World Health Organization, Collaborating Centre for Malaria, Schistosomiasis and Filariasis, Shanghai, China
| | - Xiaoyun Zhang
- Department of Parasitology, Harbin Medical University, Harbin, Heilongjiang, China
| | - Jing Shu
- Department of Parasitology, Harbin Medical University, Harbin, Heilongjiang, China
| | - Longxian Zhang
- Department of Parasitology, Harbin Medical University, Harbin, Heilongjiang, China
- Key Laboratory of Parasite and Vector Biology, National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Ministry of Health, World Health Organization, Collaborating Centre for Malaria, Schistosomiasis and Filariasis, Shanghai, China
- College of Animal Science and Veterinary Medicine, Henan Agricultural University Zhengzhou, Henan, China
- * E-mail: (AL); (LZ)
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Siripattanapipong S, Leelayoova S, Mungthin M, Thompson RCA, Boontanom P, Saksirisampant W, Tan-ariya P. Clonal diversity of the glutamate dehydrogenase gene in Giardia duodenalis from Thai isolates: evidence of genetic exchange or mixed infections? BMC Microbiol 2011; 11:206. [PMID: 21933419 PMCID: PMC3191338 DOI: 10.1186/1471-2180-11-206] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 09/20/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The glutamate dehydrogenase gene (gdh) is one of the most popular and useful genetic markers for the genotypic analysis of Giardia duodenalis (syn. G. lamblia, G. intestinalis), the protozoan that widely causes enteric disease in humans. To determine the distribution of genotypes of G. duodenalis in Thai populations and to investigate the extent of sequence variation at this locus, 42 fecal samples were collected from 3 regions of Thailand i.e., Central, Northern, and Eastern regions. All specimens were analyzed using PCR-based genotyping and recombinant subcloning methods. RESULTS The results showed that the prevalence of assemblages A and B among these populations was approximately equal, 20 (47.6%) and 22 (52.4%), respectively. Sequence analysis revealed that the nucleotide diversity of assemblage B was significantly greater than that in assemblage A. Among all assemblage B positive specimens, the allelic sequence divergence within isolates was detected. Nine isolates showed mixed alleles, ranged from three to nine distinct alleles per isolate. Statistical analysis demonstrated the occurrence of genetic recombination within subassemblages BIII and BIV was likely. CONCLUSION This study supports increasing evidence that G. duodenalis has the potential for genetic exchange.
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Affiliation(s)
- Suradej Siripattanapipong
- Department of Microbiology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok, 10400, Thailand
| | - Saovanee Leelayoova
- Department of Parasitology, Phramongkutklao College of Medicine, Rajawithi Rd., Bangkok, 10400, Thailand
| | - Mathirut Mungthin
- Department of Parasitology, Phramongkutklao College of Medicine, Rajawithi Rd., Bangkok, 10400, Thailand
| | - RC Andrew Thompson
- WHO Collaborating Centre for the Molecular Epidemiology of Parasitic Infections, School of Veterinary and Biomedical Sciences, Murdoch University, South Street, Murdoch, Western Australia, 6150, Australia
| | - Parima Boontanom
- Department of Parasitology, Phramongkutklao College of Medicine, Rajawithi Rd., Bangkok, 10400, Thailand
| | - Wilai Saksirisampant
- Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Rama IV Rd., Bangkok, 10330, Thailand
| | - Peerapan Tan-ariya
- Department of Microbiology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok, 10400, Thailand
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Leibly DJ, Newling PA, Abendroth J, Guo W, Kelley A, Stewart LJ, Van Voorhis W. Structure of a cyclin-dependent kinase from Giardia lamblia. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:1084-9. [PMID: 21904054 PMCID: PMC3169406 DOI: 10.1107/s1744309111018070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 05/12/2011] [Indexed: 11/10/2022]
Abstract
Giardia lamblia is the etiologic agent of giardiasis, a water-borne infection that is prevalent throughout the world. The need for new therapeutics for the treatment of giardiasis is of paramount importance. Owing to the ubiquitous nature of kinases and their vital importance in organisms, they are potential drug targets. In this paper, the first structure of a cyclin-dependent kinase (CDK) from G. lamblia (GlCDK; UniProt A8BZ95) is presented. CDKs are cell-cycle-associated kinases that are actively being pursued as targets for anticancer drugs as well as for antiparasitic chemotherapy. Generally, a CDK forms a complex with its associated cyclin. This CDK-cyclin complex is active and acts as a serine/threonine protein kinase. Typically, CDKs are responsible for the transition to the next phase of the cell cycle. Although the structure of GlCDK with its associated cyclin was not solved, the 1.85 Å resolution structure of apo GlCDK and a 2.0 Å resolution structure of GlCDK in complex with adenosine monophosphate are presented and the structural differences from the orthologous human CDK2 and CDK3 are discussed.
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Affiliation(s)
- David J. Leibly
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA
- Department of Medicine, Division of Allergy and Infectious Diseases, School of Medicine, University of Washington, Box 356423, Seattle, WA 98195-6423, USA
| | - Paul A. Newling
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA
- Department of Medicine, Division of Allergy and Infectious Diseases, School of Medicine, University of Washington, Box 356423, Seattle, WA 98195-6423, USA
| | - Jan Abendroth
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA
- Emerald BioStructures Inc., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Wenjin Guo
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA
- Seattle Biomed, 307 Westlake Avenue North, Suite 500, Seattle, WA 98109, USA
| | - Angela Kelley
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA
- Department of Medicine, Division of Allergy and Infectious Diseases, School of Medicine, University of Washington, Box 356423, Seattle, WA 98195-6423, USA
| | - Lance J. Stewart
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA
- Emerald BioStructures Inc., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Wesley Van Voorhis
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), USA
- Department of Medicine, Division of Allergy and Infectious Diseases, School of Medicine, University of Washington, Box 356423, Seattle, WA 98195-6423, USA
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20
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Ferrell M, Abendroth J, Zhang Y, Sankaran B, Edwards TE, Staker BL, Van Voorhis WC, Stewart LJ, Myler PJ. Structure of aldose reductase from Giardia lamblia. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:1113-7. [PMID: 21904059 PMCID: PMC3169411 DOI: 10.1107/s1744309111030879] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 08/01/2011] [Indexed: 12/02/2022]
Abstract
Giardia lamblia is an anaerobic aerotolerant eukaryotic parasite of the intestines. It is believed to have diverged early from eukarya during evolution and is thus lacking in many of the typical eukaryotic organelles and biochemical pathways. Most conspicuously, mitochondria and the associated machinery of oxidative phosphorylation are absent; instead, energy is derived from substrate-level phosphorylation. Here, the 1.75 Å resolution crystal structure of G. lamblia aldose reductase heterologously expressed in Escherichia coli is reported. As in other oxidoreductases, G. lamblia aldose reductase adopts a TIM-barrel conformation with the NADP(+)-binding site located within the eight β-strands of the interior.
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Affiliation(s)
- M Ferrell
- Seattle Structural Genomics Center for Infectious Disease, USA.
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21
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Li Z, Liu Z, Cho DW, Zou J, Gong M, Breece RM, Galkin A, Li L, Zhao H, Maestas GD, Tierney DL, Herzberg O, Dunaway-Mariano D, Mariano PS. Rational design, synthesis and evaluation of first generation inhibitors of the Giardia lamblia fructose-1,6-biphosphate aldolase. J Inorg Biochem 2011; 105:509-17. [PMID: 21333622 PMCID: PMC3071891 DOI: 10.1016/j.jinorgbio.2010.12.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2010] [Revised: 12/22/2010] [Accepted: 12/23/2010] [Indexed: 11/16/2022]
Abstract
Inhibitors of the Giardia lamblia fructose 1,6-bisphosphate aldolase (GlFBPA), which transforms fructose 1,6-bisphosphate (FBP) to dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, were designed based on 3-hydroxy-2-pyridone and 1,2-dihydroxypyridine scaffolds that position two negatively charged tetrahedral groups for interaction with substrate phosphate binding residues, a hydrogen bond donor to the catalytic Asp83, and a Zn(2+) binding group. The inhibition activities for the GlFBPA catalyzed reaction of FBP of the prepared alkyl phosphonate/phosphate substituted 3-hydroxy-2-pyridinones and a dihydroxypyridine were determined. The 3-hydroxy-2-pyridone inhibitor 8 was found to bind to GlFBPA with an affinity (K(i)=14μM) that is comparable to that of FBP (K(m)=2μM) or its inert analog TBP (K(i)=1μM). The X-ray structure of the GlFBPA-inhibitor 8 complex (2.3Å) shows that 8 binds to the active site in the manner predicted by in silico docking with the exception of coordination with Zn(2+). The observed distances and orientation of the pyridone ring O=C-C-OH relative to Zn(2+) are not consistent with a strong interaction. To determine if Zn(2+)coordination occurs in the GlFBPA-inhibitor 8 complex in solution, EXAFS spectra were measured. A four coordinate geometry comprised of the three enzyme histidine ligands and an oxygen atom from the pyridone ring O=C-C-OH was indicated. Analysis of the Zn(2+) coordination geometries in recently reported structures of class II FBPAs suggests that strong Zn(2+) coordination is reserved for the enediolate-like transition state, accounting for minimal contribution of Zn(2+) coordination to binding of 8 to GlFBPA.
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Affiliation(s)
- Zhimin Li
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | | | - Dae Won Cho
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Jiwen Zou
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Maozhen Gong
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Robert M. Breece
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056
| | - Andrey Galkin
- Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850
| | - Ling Li
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Hong Zhao
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Gabriel D. Maestas
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - David L. Tierney
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056
| | - Osnat Herzberg
- Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850
| | - Debra Dunaway-Mariano
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Patrick S. Mariano
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
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Davids BJ, Gilbert MA, Liu Q, Reiner DS, Smith AJ, Lauwaet T, Lee C, McArthur AG, Gillin FD. An atypical proprotein convertase in Giardia lamblia differentiation. Mol Biochem Parasitol 2010; 175:169-80. [PMID: 21075147 DOI: 10.1016/j.molbiopara.2010.11.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 10/29/2010] [Accepted: 11/05/2010] [Indexed: 01/24/2023]
Abstract
Proteolytic activity is important in the lifecycles of parasites and their interactions with hosts. Cysteine proteases have been best studied in Giardia, but other protease classes have been implicated in growth and/or differentiation. In this study, we employed bioinformatics to reveal the complete set of putative proteases in the Giardia genome. We identified 73 peptidase homologs distributed over 5 catalytic classes in the genome. Serial analysis of gene expression of the G. lamblia lifecycle found thirteen protease genes with significant transcriptional variation over the lifecycle, with only one serine protease transcript upregulated late in encystation. The translated gene sequence of this encystation-specific transcript was most similar to eukaryotic subtilisin-like proprotein convertases (SPC), although the typical catalytic triad was not identified. Epitope-tagged gSPC protein expressed in Giardia under its own promoter was upregulated during encystation with highest expression in cysts and it localized to encystation-specific secretory vesicles (ESV). Total gSPC from encysting cells produced proteolysis in gelatin gels that co-migrated with the epitope-tagged protease in immunoblots. Immuno-purified gSPC also had gelatinase activity. To test whether endogenous gSPC activity is involved in differentiation, trophozoites and cysts were exposed to the specific serine proteinase inhibitor 4-(2-aminoethyl)-benzenesulfonyl fluoride hydrochloride (AEBSF). After 21 h encystation, a significant decrease in ESV was observed with 1mM AEBSF and by 42 h the number of cysts was significantly reduced, but trophozoite growth was not inhibited. Concurrently, levels of cyst wall proteins 1 and 2, and AU1-tagged gSPC protein itself were decreased. Excystation of G. muris cysts was also significantly reduced in the presence of AEBSF. These results support the idea that serine protease activity is essential for Giardia encystation and excystation.
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Affiliation(s)
- B J Davids
- Department of Pathology, University of California, San Diego, CA 92103-8416, USA.
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Feng XM, Cao LJ, Wang FY, Zhang XC, Lu SQ. [Inhibition of pyruvate kinase mRNA expression in Giardia lamblia by specific hammerhead ribozyme]. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 2010; 28:257-260. [PMID: 21137307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
OBJECTIVE To inhibit the expression of pyruvate kinase (PK) mRNA in Giardia lamblia by specific hammerhead ribozyme. METHODS The constructed hammerhead-GCV vector (pGCV-PKH) which aims to PK mRNA was electroporated into G. lamnblia trophozoites (group A). Electroporated trophozoites (group B) and normal trophozoites (group C) served as control Trophozoites in each group were collected at 24, 48, 72 and 96 h post-electroporation, respectively. The concentrations of trophozoites were calculated and the growth curves were constructed. At 24, 48, 72 and 96 h post-electroporation, mRNA of each group was detected by RT-PCR and real-time PCR, respectively. The PK activity was tested by ultraviolet spectrophotometry. RESULTS The growth curve showed that the growth of trophozoites was considerably depressed after 96 h post-electroporation. RT-PCR result displayed that the specific ribozyme mRNA was detected in group A from 24 h to 96 h post-electroporation. At 24 and 48 h after transfection, the PK mRNA level of group A decreased to 5% (5 +/- 0.17) and 8% (8 +/- 0.19) of the level in group C, respectively; and the PK activity of group A decreased to 32% (32 +/- 0.64) and 38% (38 +/- 0.65) of the level in group C. CONCLUSION PK mRNA expression in G. lamblia has been inhibited by specific hammerhead ribozyme.
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Affiliation(s)
- Xian-min Feng
- Department of Pathogen Biology, Jilin Medical College, Jiln 132013, China
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24
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Cao LJ, Feng XM, Wei CJ, Wang FY, Zang XC, Lu SQ. [Construction of GCV-specific hammerhead ribozyme recombinant vector of pyruvate kinase in Giardia lamblia]. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 2010; 28:98-138. [PMID: 20666309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
OBJECTIVE To construct a recombinant vector of Giardia canis virus (GCV)-specific hammerhead ribozyme of pyruvate kinase (PK) in Giardia lamblia. METHODS Using RNA draw software, the secondary structure of PK gene in Giardia was predicted and the cleavage site of ribozyme was selected. The antisense-specific hammerhead ribozyme (PKH) targeting this site was designed. The DNA encoding the ribozyme was synthesized and the recombinant vector pGCV-PKH was constructed. The extracellular and intracellular cleavage of PK mRNA was carried out with the linear recombinant vector. Trophozoites in each group were observed with fluorescent microscopy at 24th hour after transfection. Real-time PCR was used for relative quantitative analysis of cleavage products. RESULTS The recombinant vector of GCV-specific hammerhead ribozyme of pyruvate kinase in Giardia lamblia (pGCV-PKH) was constructed. Intracellular cleavage assays showed that the green fluorescence could only be seen in pGCV-GFP transfected trophozoites. The relative content of PK mRNA in pGCV-PKH transfected group was 33.14% of that in normal control group. It could cleave PK mRNA extracellularly and the efficiency was 58.5%. CONCLUSION The recombinant vector can transfect Giardia trophozoites, and cleave mRNA of PK intracellularly and extracellularly.
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Affiliation(s)
- Li-jing Cao
- Pediatric Intensive Care Unit, Hebei Children's Hospital, Shjiiazhuang 050031, China
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Galkin A, Kulakova L, Wu R, Nash TE, Dunaway-Mariano D, Herzberg O. X-ray structure and characterization of carbamate kinase from the human parasite Giardia lamblia. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:386-90. [PMID: 20383005 PMCID: PMC2852327 DOI: 10.1107/s1744309110004665] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 02/05/2010] [Indexed: 11/10/2022]
Abstract
Carbamate kinase catalyzes the reversible conversion of carbamoyl phosphate and ADP to ATP and ammonium carbamate, which is hydrolyzed to ammonia and carbonate. The three-dimensional structure of carbamate kinase from the human parasite Giardia lamblia (glCK) has been determined at 3 A resolution. The crystals belonged to the monoclinic space group P2(1), with unit-cell parameters a = 69.77, b = 85.41, c = 102.1 A, beta = 106.8 degrees . The structure was refined to a final R factor of 0.227. The essentiality of glCK together with its absence in humans makes the enzyme an attractive candidate for anti-Giardia drug development. Steady-state kinetic rate constants have been determined. The k(cat) for ATP formation is 319 +/- 9 s(-1). The K(m) values for carbamoyl phosphate and ADP are 85 +/- 6 and 70 +/- 5 microM, respectively. The structure suggests that three invariant lysine residues (Lys131, Lys216 and Lys278) may be involved in the binding of substrates and phosphoryl transfer. The structure of glCK reveals that a glycerol molecule binds in the likely carbamoyl phosphate-binding site.
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Affiliation(s)
- Andrey Galkin
- W. M. Keck Laboratory for Structural Biology, Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland, USA
| | - Liudmila Kulakova
- W. M. Keck Laboratory for Structural Biology, Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland, USA
| | - Rui Wu
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Theodore E. Nash
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Debra Dunaway-Mariano
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Osnat Herzberg
- W. M. Keck Laboratory for Structural Biology, Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland, USA
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Benarroch D, Jankowska-Anyszka M, Stepinski J, Darzynkiewicz E, Shuman S. Cap analog substrates reveal three clades of cap guanine-N2 methyltransferases with distinct methyl acceptor specificities. RNA 2010; 16:211-20. [PMID: 19926722 PMCID: PMC2802030 DOI: 10.1261/rna.1872110] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The Tgs proteins are structurally homologous AdoMet-dependent eukaryal enzymes that methylate the N2 atom of 7-methyl guanosine nucleotides. They have an imputed role in the synthesis of the 2,2,7-trimethylguanosine (TMG) RNA cap. Here we exploit a collection of cap-like substrates to probe the repertoire of three exemplary Tgs enzymes, from mammalian, protozoan, and viral sources, respectively. We find that human Tgs (hTgs1) is a bona fide TMG synthase adept at two separable transmethylation steps: (1) conversion of m(7)G to m(2,7)G, and (2) conversion of m(2,7)G to m(2,2,7)G. hTgs1 is unable to methylate G or m(2)G, signifying that both steps require an m(7)G cap. hTgs1 utilizes a broad range of m(7)G nucleotides, including mono-, di-, tri-, and tetraphosphate derivatives as well as cap dinucleotides with triphosphate or tetraphosphate bridges. In contrast, Giardia lamblia Tgs (GlaTgs2) exemplifies a different clade of guanine-N2 methyltransferase that synthesizes only a dimethylguanosine (DMG) cap structure and cannot per se convert DMG to TMG under any conditions tested. Methylation of benzyl(7)G and ethyl(7)G nucleotides by hTgs1 and GlaTgs2 underscored the importance of guanine N7 alkylation in providing a key pi-cation interaction in the methyl acceptor site. Mimivirus Tgs (MimiTgs) shares with the Giardia homolog the ability to catalyze only a single round of methyl addition at guanine-N2, but is distinguished by its capacity for guanine-N2 methylation in the absence of prior N7 methylation. The relaxed cap specificity of MimiTgs is revealed at alkaline pH. Our findings highlight both stark and subtle differences in acceptor specificity and reaction outcomes among Tgs family members.
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Affiliation(s)
- Delphine Benarroch
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
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27
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Niño CA, Wasserman M. Synthesis of pyruvate: ferredoxin oxidoreductase and alcohol dehydrogenase E enzymes during Giardia intestinalis excystation. Biomedica 2010; 30:32-38. [PMID: 20890547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Accepted: 07/29/2009] [Indexed: 05/29/2023]
Abstract
INTRODUCTION Giardia intestinalis is a unicellular parasite of worldwide distribution. It causes an intestinal illness known as giardiasis, and it is probably the earliest diverging eukaryotic microorganism. Previously, changes have been reported in the expression of mRNAs at several stages of the life cycle; however specific enzymatic activity changes have not been explored. OBJECTIVE The expression of pyruvate ferredoxin oxidoreductase (PFOR) and alcohol dehydrogenase E (ADHE) enzymes was measured in cyst and trophozoite stages, and during the excystation process. MATERIALS AND METHODS Recombinant proteins were generated for PFOR and ADHE to be used as antigens in the production of polyclonal antibodies for the detection of native proteins by Western Blot. The enzymatic activity of ADHE and glutamate dehydrogenase (GDH) was evaluated by spectrophotometric assays. RESULTS PFOR (139 kDa) and ADHE (97 kDa) proteins were detected in trophozoites, but not in cysts. During excystation, ADHE protein was detected after the first phase of induction, but the PFOR protein appeared only after the second phase. This indicated that both proteins were synthesized during excystation, although at different times. ADHE enzymatic activity was present only in trophozoites and not in cysts whereas GDH activity was detected in both stages. CONCLUSION These results conclusively showed that PFOR and ADHE enzymes were translated during the excystation process and is strong evidence that active protein synthesis was occurring during excystation.
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Affiliation(s)
- Carlos Alberto Niño
- Laboratorio de investigaciones Básicas en Bioquímica, Departamento de Química, Universidad Nacional de Colombia, Bogotá, DC, Colombia
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Enriquez-Flores S, Rodriguez-Romero A, Hernandez-Alcantara G, De la Mora-De la Mora I, Gutierrez-Castrellon P, Carvajal K, Lopez-Velazquez G, Reyes-Vivas H. Species-specific inhibition of Giardia lamblia triosephosphate isomerase by localized perturbation of the homodimer. Mol Biochem Parasitol 2007; 157:179-86. [PMID: 18077010 DOI: 10.1016/j.molbiopara.2007.10.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Revised: 10/05/2007] [Accepted: 10/30/2007] [Indexed: 11/18/2022]
Abstract
Giardia lamblia depends on glycolysis to obtain ATP, highlighting the suitability of glycolytic enzymes as targets for drug design. We studied triosephosphate isomerase from G. lamblia (GlTIM) as a potential species-specific drug target. Cysteine-reactive agents were used as probes, in order to test those regions near to cysteine residues as targets to perturb enzyme structure and activity. Methyl methanethiosulfonate (MMTS) derivatized three of the five Cys per subunit of dimeric GlTIM and induced 50% of inactivation. The 2-carboxyethyl methanethiosulfonate (MTSCE) modified four Cys and induced 97% of inactivation. Inactivation by MMTS or MTSCE did not affect secondary structure, nor induce dimer dissociation; however, Cys modification decreased thermal stability of enzyme. Inactivation and dissociation of the dimer to stable monomers were reached when four Cys were derivatized by 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB). The effects of DTNB were completely abolished when GlTIM was first treated with MMTS. The effect of thiol reagents on human TIM was also assayed; it is 180-fold less sensitive than GlTIM. Collectively, the data illustrate GlTIM as a good target for drug design.
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Affiliation(s)
- Sergio Enriquez-Flores
- Laboratorio de Bioquímica-Genética y Dirección de Investigación, Instituto Nacional de Pediatría, 04530 México, DF, Mexico
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Harris KM, Goldberg B, Biagini GA, Lloyd D. Trichomonas vaginalis and Giardia intestinalis produce nitric oxide and display NO-synthase activity. J Eukaryot Microbiol 2007; 53 Suppl 1:S182-3. [PMID: 17169054 DOI: 10.1111/j.1550-7408.2006.00224.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hernandez Y, Zamora G, Ray S, Chapoy J, Chavez E, Valvarde R, Williams E, Aley SB, Das S. Transcriptional analysis of three major putative phosphatidylinositol kinase genes in a parasitic protozoan, Giardia lamblia. J Eukaryot Microbiol 2007; 54:29-32. [PMID: 17300515 PMCID: PMC3124632 DOI: 10.1111/j.1550-7408.2006.00142.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The current investigation evaluates the expression of phosphatidylinositol kinase (PIK) genes in the parasitic protozoan, Giardia lamblia. The G. lamblia Genome Database revealed the presence of two putative phosphatidylinositol-3-kinase (gPI3K) and one phosphatidylinositol-4-kinase (gPI4K) genes resembling the catalytic subunit of eukaryotic PIKs. Primers, designed to amplify mRNA of these three genes, were used to measure transcription by quantitative reverse-transcriptase polymerase chain reactions. Results suggest that all three PIK genes are expressed in non-encysting and encysting trophozoites. The relative levels of the mRNA were highest in parasites cultured in pre-encysting medium that contained no bile. Two inhibitors of PI3K, LY 294002 and wortmannin were found to inhibit the growth of the trophozoite in culture. However, wortmannin was more effective than LY294002. Altogether, the present study indicates that Giardia is capable of expressing PIKs that are necessary for the growth and differentiation of this pathogen.
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Affiliation(s)
- Yunuen Hernandez
- Infectious Diseases and Immunology Unit, The Border Biomedical Research Center (BBRC), and Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas 79968-0519, USA
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31
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Souza SLP, Gennari SM, Richtzenhain LJ, Pena HFJ, Funada MR, Cortez A, Gregori F, Soares RM. Molecular identification of Giardia duodenalis isolates from humans, dogs, cats and cattle from the state of São Paulo, Brazil, by sequence analysis of fragments of glutamate dehydrogenase (gdh) coding gene. Vet Parasitol 2007; 149:258-64. [PMID: 17900812 DOI: 10.1016/j.vetpar.2007.08.019] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 08/07/2007] [Accepted: 08/14/2007] [Indexed: 11/29/2022]
Abstract
The nucleotide sequence of glutamate dehydrogenase (gdh) coding genes were obtained from cysts of Giardia duodenalis isolated from feces of naturally infected cats (n=19), dogs (n=27), humans (n=37) and cattle (n=5). The samples were from several municipalities within the state of São Paulo, Brazil and were collected from January 2004 to August 2006. Sequences analysis of the 37 specimens recovered from humans revealed 29 G. duodenalis assemblage AII and 8 G. duodenalis assemblage B. Among samples from cats, 11 were classified into assemblage F and 8 into assemblage AI. Only the host-adapted assemblages C and D were detected in samples from dogs (7 and 20, respectively). Among the samples from cattle, the genotype livestock was found in four samples and the assemblage AI was detected in one sample. The molecular identification of assemblages of G. duodenalis isolates from different hosts reveals that genetic diversity of this protozoon in Brazil is similar to that of Giardias from other parts of the world.
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Affiliation(s)
- Sílvio L P Souza
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Dr. Orlando Marques de Paiva 87, CEP 05508-900, São Paulo, SP, Brazil
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32
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Lopez AB, Sener K, Trosien J, Jarroll EL, van Keulen H. UDP-N-acetylglucosamine 4'-epimerase from the intestinal protozoan Giardia intestinalis lacks UDP-glucose 4'-epimerase activity. J Eukaryot Microbiol 2007; 54:154-60. [PMID: 17403156 DOI: 10.1111/j.1550-7408.2007.00246.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The protozoan parasite Giardia intestinalis has a simple life cycle consisting of an intestinal trophozoite stage and an environmentally resistant cyst stage. The cyst is formed when a trophozoite encases itself within an external filamentous covering, the cyst wall, which is crucial to the cyst's survival outside of the host. The filaments in the cyst wall consist mainly of a beta (1-3) polymer of N-acetylgalactosamine. Its precursor, UDP-N-acetylgalactosamine, is synthesized from fructose 6-phosphate by a pathway of five inducible enzymes. The fifth, UDP-N-acetylglucosamine 4'-epimerase, epimerizes UDP-N-acetylglucosamine to UDP-N-acetylgalactosamine reversibly. The epimerase of G. intestinalis lacks UDP-glucose/UDP-galactose 4'-epimerase activity and shows characteristic amino acyl residues to allow binding of only the larger UDP-N-acetylhexosamines. While the Giardia epimerase catalyzes the reversible epimerization of UDP-N-acetylglucosamine to UDP-N-acetylgalactosamine, the reverse reaction apparently is favored. The enzyme has a higher Vmax and a smaller Km in this direction. Therefore, an excess of UDP-N-acetylglucosamine is required to drive the reaction towards the synthesis of UDP-N-acetylgalactosamine, when it is needed for cyst wall formation. This forms the ultimate regulatory step in cyst wall biosynthesis.
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Affiliation(s)
- Alex B Lopez
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, Ohio 44115, USA
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33
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MacRae IJ, Zhou K, Doudna JA. Structural determinants of RNA recognition and cleavage by Dicer. Nat Struct Mol Biol 2007; 14:934-40. [PMID: 17873886 DOI: 10.1038/nsmb1293] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 07/24/2007] [Indexed: 01/06/2023]
Abstract
A hallmark of RNA interference is the production of short double-stranded RNA (dsRNA) molecules 21-28 nucleotides in length by the specialized RNase III protein Dicer. Dicer enzymes uniquely generate RNA products of specific lengths by mechanisms that have not been fully elucidated. Here we show that the PAZ domain responsible for dsRNA end recognition confers this measuring ability through both its structural position and RNA-binding specificity. Point mutations define the dsRNA-binding surface and reveal a protein loop important for cleavage of substrates containing perfect or imperfect base pairing. On the basis of these results, we reengineered Dicer with a U1A RNA-binding domain in place of the PAZ domain to create an enzyme with altered end-recognition specificity and RNA product length. These results explain how Dicer functions as a molecular ruler and provide a structural basis for modifying its activity in cells.
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Affiliation(s)
- Ian J MacRae
- Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA
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34
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MacRae IJ, Doudna JA. An unusual case of pseudo-merohedral twinning in orthorhombic crystals of Dicer. Acta Crystallogr D Biol Crystallogr 2007; 63:993-9. [PMID: 17704568 DOI: 10.1107/s0907444907036128] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Accepted: 07/23/2007] [Indexed: 11/10/2022]
Abstract
The crystal structure of the enzyme Dicer from Giardia intestinalis was solved to 3.3 A resolution by MAD using crystals belonging to space group P2(1)2(1)2 [Macrae et al. (2006), Science, 311, 195-198]. These crystals were derived from crystals that diffracted X-rays to 3.0 A resolution but were refractory to structure determination because they were twinned. It is shown here that the original Dicer crystals represent an unusual case of perfect pseudo-merohedral twinning of orthorhombic crystals. Before the twinning problem was overcome, it was possible to calculate a low-resolution electron-density map in space group P4(1) that was used to build a partial molecular model. Experimental phases were sufficient to identify heavy-atom sites that indicated space-group inconsistency, leading to identification of the true space group. This information guided the search for different crystallization conditions that yielded untwinned crystals and ultimately a fully interpretable electron-density map.
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Affiliation(s)
- Ian J MacRae
- Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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35
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Abstract
Dicer is a specialized ribonuclease that processes double-stranded RNA (dsRNA) into small RNA fragments about 25 nucleotides in length during the initiation phase of RNA interference (RNAi). We previously determined the crystal structure of a Dicer enzyme from the diplomonad Giardia intestinalis and proposed a structural model for dsRNA processing. Here, we provide evidence that Dicer is composed of three structurally rigid regions connected by flexible hinges and propose that conformational flexibility facilitates dsRNA binding and processing. We also examine the role of the accessory domains found in Dicers of higher eukaryotes but absent in Giardia Dicer. Finally, we combine the structure of Dicer with published biochemical data to propose a model for the architecture of the RNA-induced silencing complex (RISC)-loading complex.
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Affiliation(s)
- I J Macrae
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA
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36
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Müller J, Wastling J, Sanderson S, Müller N, Hemphill A. A novel Giardia lamblia nitroreductase, GlNR1, interacts with nitazoxanide and other thiazolides. Antimicrob Agents Chemother 2007; 51:1979-86. [PMID: 17438059 PMCID: PMC1891416 DOI: 10.1128/aac.01548-06] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The nitrothiazole analogue nitazoxanide [NTZ; 2-acetolyloxy-N-(5-nitro-2-thiazolyl)benzamide] represents the parent compound of a class of drugs referred to as thiazolides and exhibits a broad spectrum of activities against a wide variety of helminths, protozoa, and enteric bacteria infecting animals and humans. NTZ and other thiazolides are active against a wide range of other intracellular and extracellular protozoan parasites in vitro and in vivo, but their mode of action and respective subcellular target(s) have only recently been investigated. In order to identify potential targets of NTZ and other thiazolides in Giardia lamblia trophozoites, we have developed an affinity chromatography system using the deacetylated derivative of NTZ, tizoxanide (TIZ), as a ligand. Affinity chromatography on TIZ-agarose using cell extracts of G. lamblia trophozoites resulted in the isolation of an approximately 35-kDa polypeptide, which was identified by mass spectrometry as a nitroreductase (NR) homologue (EAA43030.1). NR was overexpressed as a six-histidine-tagged recombinant protein in Escherichia coli, purified, and then characterized using an assay for oxygen-insensitive NRs with dinitrotoluene as a substrate. This demonstrated that the NR was functionally active, and the protein was designated GlNR1. In this assay system, NR activity was severely inhibited by NTZ and other thiazolides, demonstrating that the antigiardial activity of these drugs could be, at least partially, mediated through inhibition of GlNR1.
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Affiliation(s)
- Joachim Müller
- Institute of Parasitology, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland.
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37
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Lauwaet T, Davids BJ, Torres‐Escobar A, Birkeland SR, Cipriano MJ, Preheim SP, Palm D, Svärd SG, McArthur AG, Gillin FD. Protein phosphatase 2A plays a crucial role in Giardia lamblia differentiation. Mol Biochem Parasitol 2007; 152:80-9. [PMID: 17204341 PMCID: PMC1964530 DOI: 10.1016/j.molbiopara.2006.12.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 12/05/2006] [Accepted: 12/06/2006] [Indexed: 01/24/2023]
Abstract
The ability of Giardia lamblia to undergo two distinct differentiations in response to physiologic stimuli is central to its pathogenesis. The giardial cytoskeleton changes drastically during encystation and excystation. However, the signal transduction pathways mediating these transformations are poorly understood. We tested the hypothesis that PP2A, a highly conserved serine/threonine protein phosphatase, might be important in giardial differentiation. We found that in vegetatively growing trophozoites, gPP2A-C protein localizes to basal bodies/centrosomes, and to cytoskeletal structures unique to Giardia: the ventral disk, and the dense rods of the anterior, posterior-lateral, and caudal flagella. During encystation, gPP2A-C protein disappears from only the anterior flagellar dense rods. During excystation, gPP2A-C localizes to the cyst wall in excysting cysts but is not found in the wall of cysts with emerging excyzoites. Transcriptome and immunoblot analyses indicated that gPP2A-C mRNA and protein are upregulated in mature cysts and during the early stage of excystation that models passage through the host stomach. Stable expression of gPP2A-C antisense RNA did not affect vegetative growth, but strongly inhibited the formation of encystation secretory vesicles (ESV) and water-resistant cysts. Moreover, the few cysts that formed were highly defective in excystation. Thus, gPP2A-C localizes to universal cytoskeletal structures and to structures unique to Giardia. It is also important for encystation and excystation, crucial giardial transformations that entail entry into and exit from dormancy.
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MESH Headings
- Adaptation, Physiological
- Amino Acid Sequence
- Animals
- Blotting, Western
- Centrosome/chemistry
- Cytoskeleton/chemistry
- DNA, Protozoan/chemistry
- DNA, Protozoan/genetics
- Flagella/chemistry
- Gene Expression Regulation, Developmental
- Giardia lamblia/enzymology
- Giardia lamblia/genetics
- Giardia lamblia/growth & development
- Immunohistochemistry
- Microscopy, Fluorescence
- Molecular Sequence Data
- Morphogenesis/genetics
- Phosphoprotein Phosphatases/biosynthesis
- Phosphoprotein Phosphatases/genetics
- Phosphoprotein Phosphatases/metabolism
- Protein Phosphatase 2
- Protozoan Proteins/analysis
- Protozoan Proteins/genetics
- RNA, Protozoan/analysis
- RNA, Protozoan/genetics
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
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Affiliation(s)
- Tineke Lauwaet
- Department of Pathology, Division of Infectious Diseases, University of California, San Diego, CA 92103‐8416, USA
| | - Barbara J. Davids
- Department of Pathology, Division of Infectious Diseases, University of California, San Diego, CA 92103‐8416, USA
| | - Ascención Torres‐Escobar
- Department of Pathology, Division of Infectious Diseases, University of California, San Diego, CA 92103‐8416, USA
| | | | | | | | - Daniel Palm
- Department of Cell and Molecular Biology, Uppsala University, SE‐751 24 Uppsala, Sweden
| | - Staffan G. Svärd
- Department of Cell and Molecular Biology, Uppsala University, SE‐751 24 Uppsala, Sweden
| | | | - Frances D. Gillin
- Department of Pathology, Division of Infectious Diseases, University of California, San Diego, CA 92103‐8416, USA
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38
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Hausmann S, Ramirez A, Schneider S, Schwer B, Shuman S. Biochemical and genetic analysis of RNA cap guanine-N2 methyltransferases from Giardia lamblia and Schizosaccharomyces pombe. Nucleic Acids Res 2007; 35:1411-20. [PMID: 17284461 PMCID: PMC1865056 DOI: 10.1093/nar/gkl1150] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
RNA cap guanine-N2 methyltransferases such as Schizosaccharomyces pombe Tgs1 and Giardia lamblia Tgs2 catalyze methylation of the exocyclic N2 amine of 7-methylguanosine. Here we performed a mutational analysis of Giardia Tgs2, entailing an alanine scan of 17 residues within the minimal active domain. Alanine substitutions at Phe18, Thr40, Asp76, Asn103 and Asp140 reduced methyltransferase specific activity to <3% of wild-type Tgs2, thereby defining these residues as essential. Alanines at Pro142, Tyr148 and Pro185 reduced activity to 7–12% of wild-type. Structure–activity relationships at Phe18, Thr40, Asp76, Asn103, Asp140 and Tyr148, and at three other essential residues defined previously (Asp68, Glu91 and Trp143) were gleaned by testing the effects of 18 conservative substitutions. Our results engender a provisional map of the Tgs2 active site, which we discuss in light of crystal structures of related methyltransferases. A genetic analysis of S. pombe Tgs1 showed that it is nonessential. An S. pombe tgs1Δ strain grows normally, notwithstanding the absence of 2,2,7-trimethylguanosine caps on its U1, U2, U4 and U5 snRNAs. However, we find that S. pombe requires cap guanine-N7 methylation catalyzed by the enzyme Pcm1. Deletion of the pcm1+ gene was lethal, as were missense mutations in the Pcm1 active site. Thus, whereas m7G caps are essential in both S. pombe and S. cerevisiae, m2,2,7G caps are not.
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Affiliation(s)
- Stéphane Hausmann
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA and Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, NY 10021, USA
| | - Alejandro Ramirez
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA and Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, NY 10021, USA
| | - Susanne Schneider
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA and Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, NY 10021, USA
| | - Beate Schwer
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA and Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, NY 10021, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA and Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, NY 10021, USA
- *To whom correspondence should be addressed.
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39
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Galkin A, Kulakova L, Melamud E, Li L, Wu C, Mariano P, Dunaway-Mariano D, Nash TE, Herzberg O. Characterization, kinetics, and crystal structures of fructose-1,6-bisphosphate aldolase from the human parasite, Giardia lamblia. J Biol Chem 2006; 282:4859-4867. [PMID: 17166851 DOI: 10.1074/jbc.m609534200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Class I and class II fructose-1,6-bisphosphate aldolases (FBPA), glycolytic pathway enzymes, exhibit no amino acid sequence homology and utilize two different catalytic mechanisms. The mammalian class I FBPA employs a Schiff base mechanism, whereas the human parasitic protozoan Giardia lamblia class II FBPA is a zinc-dependent enzyme. In this study, we have explored the potential exploitation of the Giardia FBPA as a drug target. First, synthesis of FBPA was demonstrated in Giardia trophozoites by using an antibody-based fluorescence assay. Second, inhibition of FBPA gene transcription in Giardia trophozoites suggested that the enzyme is necessary for the survival of the organism under optimal laboratory growth conditions. Third, two crystal structures of FBPA in complex with the transition state analog phosphoglycolohydroxamate (PGH) show that the enzyme is homodimeric and that its active site contains a zinc ion. In one crystal form, each subunit contains PGH, which is coordinated to the zinc ion through the hydroxamic acid hydroxyl and carbonyl oxygen atoms. The second crystal form contains PGH only in one subunit and the active site of the second subunit is unoccupied. Inspection of the two states of the enzyme revealed that it undergoes a conformational transition upon ligand binding. The enzyme cleaves d-fructose-1,6-bisphosphate but not d-tagatose-1,6-bisphosphate, which is a tight binding competitive inhibitor. The essential role of the active site residue Asp-83 in catalysis was demonstrated by amino acid replacement. Determinants of catalysis and substrate recognition, derived from comparison of the G. lamblia FBPA structure with Escherichia coli FBPA and with a closely related enzyme, E. coli tagatose-1,6-bisphosphate aldolase (TBPA), are described.
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Affiliation(s)
- Andrey Galkin
- Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850
| | - Liudmila Kulakova
- Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850
| | - Eugene Melamud
- Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850
| | - Ling Li
- Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, and
| | - Chun Wu
- Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, and
| | - Patrick Mariano
- Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, and
| | - Debra Dunaway-Mariano
- Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, and
| | - Theodore E Nash
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Osnat Herzberg
- Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850.
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40
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Reyes-Vivas H, Diaz A, Peon J, Mendoza-Hernandez G, Hernandez-Alcantara G, De la Mora-De la Mora I, Enriquez-Flores S, Dominguez-Ramirez L, Lopez-Velazquez G. Disulfide bridges in the mesophilic triosephosphate isomerase from Giardia lamblia are related to oligomerization and activity. J Mol Biol 2006; 365:752-63. [PMID: 17095008 DOI: 10.1016/j.jmb.2006.10.053] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 10/12/2006] [Accepted: 10/17/2006] [Indexed: 11/25/2022]
Abstract
Triosephosphate isomerase from the mesophile Giardia lamblia (GlTIM) is the only known TIM with natural disulfide bridges. We previously found that oxidized and reduced thiol states of GlTIM are involved in the interconversion between native dimers and higher oligomeric species, and in the regulation of enzymatic activity. Here, we found that trophozoites and cysts have different oligomeric species of GlTIM and complexes of GlTIM with other proteins. Our data indicate that the internal milieu of G. lamblia is favorable for the formation of disulfide bonds. Enzyme mutants of the three most solvent exposed Cys of GlTIM (C202A, C222A, and C228A) were prepared to ascertain their contribution to oligomerization and activity. The data show that the establishment of a disulfide bridge between two C202 of two dimeric GlTIMs accounts for multimerization. In addition, we found that the establishment of an intramonomeric disulfide bond between C222 and C228 abolishes catalysis. Multimerization and inactivation are both reversed by reducing conditions. The 3D structure of the C202A GlTIM was solved at 2.1 A resolution, showing that the environment of the C202 is prone to hydrophobic interactions. Molecular dynamics of an in silico model of GlTIM when the intramonomeric disulfide bond is formed, showed that S216 is displaced 4.6 A from its original position, causing loss of hydrogen bonds with residues of the active-site loop. This suggests that this change perturb the conformational state that aligns the catalytic center with the substrate, inducing enzyme inactivation.
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Affiliation(s)
- Horacio Reyes-Vivas
- Laboratorio de Bioquimica Genetica, Instituto Nacional de Pediatria, 04530 Mexico, D.F
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41
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Gibson C, Schanen B, Chakrabarti D, Chakrabarti R. Functional characterisation of the regulatory subunit of cyclic AMP-dependent protein kinase A homologue of Giardia lamblia: Differential expression of the regulatory and catalytic subunits during encystation. Int J Parasitol 2006; 36:791-9. [PMID: 16472811 DOI: 10.1016/j.ijpara.2005.11.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 11/19/2005] [Accepted: 11/25/2005] [Indexed: 10/25/2022]
Abstract
To understand the functional roles of protein kinase A (PKA) during vegetative and differentiating states of Giardia parasites, we studied the structural and functional characteristics of the regulatory subunit of PKA (gPKAr) and its involvement in the giardial encystment process. Molecular cloning and characterisation showed that gPKAr contains two tandem 3'5'-cyclic adenosine monphosphate (cyclic AMP) binding domains at the C-terminal end and the interaction domain for the catalytic subunit. A number of consensus residues including in vivo phosphorylation site for PKAc and dimerisation/docking domain are present in gPKAr. The regulatory subunit physically interacts with the catalytic subunit and inhibits its kinase activity in the absence of cyclic AMP, which could be partially restored upon addition of cyclic AMP. Western blot analysis showed a marked reduction in the endogenous gPKAr concentration during differentiation of Giardia into cysts. An increased activity of gPKAc was also detected during encystation without any significant change in the protein concentration. Distinct localisations of gPKAc to the anterior flagella, basal bodies and caudal flagella as noted in trophozoites were absent in encysting cells at later stages. Instead, PKAc staining was punctate and located mostly to the cell periphery. Our study indicates possible enrichment of the active gPKAc during late stages of encystation, which may have implications in completion of the encystment process or priming of cysts for efficient excystation.
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Affiliation(s)
- Candace Gibson
- Department of Molecular Biology and Microbiology, University of Central Florida, 12722 Research Parkway, Orlando, FL 32826, USA
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42
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Cox SSE, van der Giezen M, Tarr SJ, Crompton MR, Tovar J. Evidence from bioinformatics, expression and inhibition studies of phosphoinositide-3 kinase signalling in Giardia intestinalis. BMC Microbiol 2006; 6:45. [PMID: 16707026 PMCID: PMC1483827 DOI: 10.1186/1471-2180-6-45] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Accepted: 05/18/2006] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Giardia intestinalis is a parasitic protozoan and major cause of diarrhoeal disease. Disease transmission is dependent on the ability of the parasite to differentiate back and forth between an intestine-colonising trophozoite and an environmentally-resistant infective cyst. Our current understanding of the intracellular signalling mechanisms that regulate parasite replication and differentiation is limited, yet such information could suggest new methods of disease control. Phosphoinositide-3 kinase (PI3K) signalling pathways have a central involvement in many vital eukaryotic processes, such as regulation of cell growth, intracellular membrane trafficking and cell motility. Here we present evidence for the existence of functional PI3K intracellular signalling pathways in G. intestinalis. RESULTS We have identified and characterised two genes, Gipi3k1 and Gipi3k2, which encode putative PI3Ks. Both genes are expressed in trophozoites and encysting cells, suggesting a possible role of GiPI3K1 and GiPI3K2 in regulating giardial growth and differentiation. Extensive nucleotide and amino acid sequence characterisation predicts that both encoded PI3Ks are functional as indicated by the presence of highly conserved structural domains and essential catalytic residues. The inhibitory effect of the PI3K inhibitor LY294002 on trophozoite proliferation also supports their functionality. Phylogenetic analysis supports the identity of GiPI3K1 as a Class I isoform and GiPI3K2 as a Class III isoform. In addition, giardial genes encoding putative homologues of phosphoinositide-metabolising enzymes such as PTEN, MTM, PIPkin and PI 5-phosphatase as well as downstream effectors with phosphoinositide-binding domains have been identified, placing GiPI3K1 and GiPI3K2 in a broader signalling context. Compared with twenty-six PI3Ks from other organisms, GiPI3K1 and GiPI3K2 are unique in that they contain large insertions within their highly conserved kinase domains. The function of these insertions is unknown; however we show here that they are not intron-derived and would probably not hinder substrate binding. These insertions may represent a plausible drug target. CONCLUSION G. intestinalis encodes and expresses two putative PI3Ks, at least one of which appears to be required during normal parasite proliferation. The identification of Class I and Class III but not Class II isoforms suggests that both extracellularly-initiated signalling (Class I-regulated) and intracellular vesicle trafficking (Class III-regulated) might be controlled by PI3Ks in G. intestinalis. The presence of genes encoding putative homologues of phosphoinositide-metabolising enzymes and downstream effectors in the G. intestinalis genome further suggests that the overall architecture of PI3K signalling may be comparable with pathways present in other better-studied organisms.
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Affiliation(s)
- Siân SE Cox
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, UK
| | - Mark van der Giezen
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London, UK
| | - Sarah J Tarr
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, UK
| | - Mark R Crompton
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, UK
| | - Jorge Tovar
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, UK
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Affiliation(s)
- Kelly N DuBois
- Department of Pathology and the Sandler Center for Basic Research in Parasitic Diseases, University of California, San Francisco, CA 94158-2550, USA.
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Abstract
The specialized ribonuclease Dicer initiates RNA interference by cleaving double-stranded RNA (dsRNA) substrates into small fragments about 25 nucleotides in length. In the crystal structure of an intact Dicer enzyme, the PAZ domain, a module that binds the end of dsRNA, is separated from the two catalytic ribonuclease III (RNase III) domains by a flat, positively charged surface. The 65 angstrom distance between the PAZ and RNase III domains matches the length spanned by 25 base pairs of RNA. Thus, Dicer itself is a molecular ruler that recognizes dsRNA and cleaves a specified distance from the helical end.
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Affiliation(s)
- Ian J Macrae
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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Itagaki T, Kinoshita S, Aoki M, Itoh N, Saeki H, Sato N, Uetsuki J, Izumiyama S, Yagita K, Endo T. Genotyping of Giardia intestinalis from domestic and wild animals in Japan using glutamete dehydrogenase gene sequencing. Vet Parasitol 2005; 133:283-7. [PMID: 16029929 DOI: 10.1016/j.vetpar.2005.05.061] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2005] [Revised: 05/19/2005] [Accepted: 05/28/2005] [Indexed: 10/25/2022]
Abstract
To determine the genotypes of Giardia intestinalis from domestic and wild animals in Japan, Giardia isolates obtained from feces of 24 dogs kept in households and breeding kennels, three companion cats, five dairy calves and three wild monkeys, Macaca fuscata, were genotyped using the 177 bp sequence of the glutamete dehydrogenase gene (gdh). The genotypes were assemblages A, C, D or A/D for dog isolates, Assemblage F for cat isolates, assemblages A or E for calf isolates and assemblage B for monkey isolates. This is the first report on the genotypes of Giardia isolates from cats, calves and wild monkeys in Japan.
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Affiliation(s)
- Tadashi Itagaki
- Laboratory of Veterinary Parasitology, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka 020-0105, Japan.
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Mok MTS, Edwards MR. Critical sources of error in colorimetric assay for UDP-N-acetylglucosamine pyrophosphorylase. Anal Biochem 2005; 343:341-3. [PMID: 15992757 DOI: 10.1016/j.ab.2005.05.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Revised: 04/27/2005] [Accepted: 05/16/2005] [Indexed: 10/25/2022]
Affiliation(s)
- Myth T S Mok
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia.
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Abstract
The intestinal protozoan parasite Giardia lamblia undergoes surface antigenic variation whereby one of a family of structurally related variant-specific surface proteins (VSPs) is replaced in a regulated process by another antigenically distinct VSP. All VSPs are type I membrane proteins that have a conserved hydrophobic sequence terminated by the invariant hydrophilic amino acids, CRGKA. Using transfected Giardia constitutively expressing HA-tagged VSPH7 and incubated with radioactive [3H]palmitate, we demonstrate that the palmitate is attached to the Cys in the conserved CRGKA tail. Surface location of mutant VSPs lacking either the CRGKA tail or its Cys is identical to that of wild-type VSPH7 but non-palmitoylated mutants fail to undergo complement-independent antibody specific cytotoxicity. In addition, membrane localization of non-palmitoylated mutant VSPH7 changes from a pattern similar to rafts to non-rafts. Palmitoyl transferases (PAT), responsible for protein palmitoylation in other organisms, often possess a cysteine-rich domain containing a conserved DHHC motif (DHHC-CRD). An open reading frame corresponding to a putative 50 kDa Giardia PAT (gPAT) containing a DHHC-CRD motif was found in the Giardia genome database. Expression of epitope-tagged gPAT using a tetracycline inducible vector localized gPAT to the plasma membrane, a pattern similar to that of VSPs. Transfection with gPAT antisense producing vectors inhibits gPAT expression and palmitoylation of VSPs in vitro confirming the function of gPAT. These results show that VSPs are palmitoylated at the cysteine within the conserved tail by gPAT and indicate an essential function of palmitoylation in control of VSP-mediated signalling and processing.
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Affiliation(s)
- María C Touz
- Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, MD 20892, USA
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Mok MTS, Edwards MR. Kinetic and physical characterization of the inducible UDP-N-acetylglucosamine pyrophosphorylase from Giardia intestinalis. J Biol Chem 2005; 280:39363-72. [PMID: 16169849 DOI: 10.1074/jbc.m509209200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The UDP-N-acetylglucosamine pyrophosphorylase in Giardia intestinalis (GiUAP) is one of the five inducible enzymes to synthesize UDP-GalNAc, which is an important precursor for cyst wall synthesis. The recombinant UDP-N-acetylglucosamine pyrophosphorylase (rGiUAP) and its mutants G108A and G210A were expressed and identified by SDS-PAGE, size-exclusion chromatography, Western hybridization, and MALDI mass spectrometry. Sequence comparison with other eukaryotic UAPs has identified three specific motifs. Within these motifs alanine substitution for Gly(108) or Gly(210) dramatically reduced the pyrophosphate synthesis, suggesting these amino acids are catalytic residues. Besides, the rGiUAP was found to have relaxed binding to other uridine-based nucleotides, suggesting the substrate binding pocket is specific to uridine rather than phosphate group(s). Moreover, thermal denaturation analysis showed a significant increase in T(m) for the rGiUAP and G108A upon binding of the substrate Mg-UTP. In contrast, G210A showed a decreased T(m) upon binding of Mg-UTP. These results showed that binding of Mg-UTP increases protein stability of the rGiUAP, and the catalytic residue Gly(210) plays a significant role in stabilizing the protein structure. Such stabilization effect induced by substrate binding might be physiologically important as it favors the production of UDP-GlcNAc and hence the downstream GalNAc, which is crucial to survival of Giardia. These results help to define the essential amino acids for catalysis in the GiUAP and reveal the role of Mg-UTP binding in regulation of protein stability.
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Affiliation(s)
- Myth T S Mok
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia.
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Mok MTS, Tay E, Sekyere E, Glenn WK, Bagnara AS, Edwards MR. Giardia intestinalis: Molecular characterization of UDP-N-acetylglucosamine pyrophosphorylase. Gene 2005; 357:73-82. [PMID: 15951138 DOI: 10.1016/j.gene.2005.05.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Revised: 04/25/2005] [Accepted: 05/10/2005] [Indexed: 01/18/2023]
Abstract
The flagellated protozoan Giardia intestinalis is one of the most prevalent human-infective parasites with a worldwide distribution. This parasite must encyst to complete the life cycle and N-acetylgalactosamine is produced from endogenous glucose for cyst wall synthesis during the transformation. UDP-N-acetylglucosamine pyrophosphorylase in G. intestinalis (GiUAP, EC 2.7.7.23) is the fourth enzyme in the inducible pathway of N-acetylgalactosamine biosynthesis, catalysing the conversion of N-acetylglucosamine-1-P to UDP-N-acetylglucosamine. In this study the gene GiUAP was cloned and sequenced from the Portland 1 strain using PCR techniques. It has an ORF of approximately 1.3 kb and contains no introns. BLAST and ClustalW analysis of the deduced amino acid sequence revealed significant similarities to other eukaryotic UAPs with putative active sites identified. Southern hybridization showed that GiUAP exists as a single-copy gene and it was shown to have two transcripts by RT-PCR and Northern hybridization. RLM-RACE identified both 5' and 3' untranslated regions and suggested the transcripts exist as a 5'-capped mRNA, with the use of two tandem polyadenylation sites to generate two unusually long giardial 3' untranslated regions of approximately 522 bp and approximately 3 kb. Moreover, a recombinant protein (rGiUAP) was expressed in E. coli and subjected to physical characterizations. Surprisingly the results obtained in this study were significantly different from those reported for the GiUAP in MR4 strain, suggesting this gene is under different transcription control in different strains of G. intestinalis. This report describes the molecular characterization of GiUAP and provides an opportunity to explore the control of gene expression during encystation of the parasite.
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Affiliation(s)
- Myth T S Mok
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia.
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He D, Wen JF, Chen WQ, Lu SQ, Xin DD. Identification, characteristic and phylogenetic analysis of type II DNA topoisomerase gene in Giardia lamblia. Cell Res 2005; 15:474-82. [PMID: 15987606 DOI: 10.1038/sj.cr.7290316] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The genes encoding type II DNA topoisomerases were investigated in Giardia lamblia genome, and a type IIA gene, GlTop 2 was identified. It is a single copy gene with a 4476 bp long ORF without intron. The deduced amino acid sequence shows strong homology to eukaryotic DNA Top 2. However, some distortions were found, such as six insertions in the ATPase domain and the central domain, a approximately 100 aa longer central domain; a approximately 200 aa shorter C-terminal domain containing rich charged residues. These features revealed by comparing with Top 2 of the host, human, might be helpful in exploiting drug selectivity for antigiardial therapy. Phylogenetic analysis of eukaryotic enzymes showed that kinetoplastids, plants, fungi, and animals were monophyletic groups, and the animal and fungi lineages shared a more recent common ancestor than either did with the plant lineage; microsporidia grouped with fungi. However, unlike many previous phylogenetic analyses, the "amitochondriate"G. lamblia was not the earliest branch but diverged after mitochondriate kinetoplastids in our trees. Both the finding of typical eukaryotic type IIA topoisomerase and the phylogenetic analysis suggest G. lamblia is not possibly as primitive as was regarded before and might diverge after the acquisition of mitochondria. This is consistent with the recent discovery of mitochondrial remnant organelles in G. lamblia.
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Affiliation(s)
- De He
- Key Laboratory of Cellular and Molecular Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.
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