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Maciel L, Ferraz MVF, Oliveira AA, Lins RD, dos Anjos J, Guido RVC, Soares TA. Inhibition of 3-Hydroxykynurenine Transaminase from Aedes aegypti and Anopheles gambiae: A Mosquito-Specific Target to Combat the Transmission of Arboviruses. ACS BIO & MED CHEM AU 2023; 3:211-222. [PMID: 37101811 PMCID: PMC10125267 DOI: 10.1021/acsbiomedchemau.2c00080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/07/2023] [Accepted: 02/07/2023] [Indexed: 04/28/2023]
Abstract
Arboviral infections such as Zika, chikungunya, dengue, and yellow fever pose significant health problems globally. The population at risk is expanding with the geographical distribution of the main transmission vector of these viruses, the Aedes aegypti mosquito. The global spreading of this mosquito is driven by human migration, urbanization, climate change, and the ecological plasticity of the species. Currently, there are no specific treatments for Aedes-borne infections. One strategy to combat different mosquito-borne arboviruses is to design molecules that can specifically inhibit a critical host protein. We obtained the crystal structure of 3-hydroxykynurenine transaminase (AeHKT) from A. aegypti, an essential detoxification enzyme of the tryptophan metabolism pathway. Since AeHKT is found exclusively in mosquitoes, it provides the ideal molecular target for the development of inhibitors. Therefore, we determined and compared the free binding energy of the inhibitors 4-(2-aminophenyl)-4-oxobutyric acid (4OB) and sodium 4-(3-phenyl-1,2,4-oxadiazol-5-yl)butanoate (OXA) to AeHKT and AgHKT from Anopheles gambiae, the only crystal structure of this enzyme previously known. The cocrystallized inhibitor 4OB binds to AgHKT with K i of 300 μM. We showed that OXA binds to both AeHKT and AgHKT enzymes with binding energies 2-fold more favorable than the crystallographic inhibitor 4OB and displayed a 2-fold greater residence time τ upon binding to AeHKT than 4OB. These findings indicate that the 1,2,4-oxadiazole derivatives are inhibitors of the HKT enzyme not only from A. aegypti but also from A. gambiae.
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Affiliation(s)
- Larissa
G. Maciel
- Department
of Fundamental Chemistry, Federal University
of Pernambuco, 50740-560 Recife, Brazil
| | - Matheus V. F. Ferraz
- Department
of Fundamental Chemistry, Federal University
of Pernambuco, 50740-560 Recife, Brazil
- Aggeu
Magalhães Institute, Oswaldo Cruz
Foundation, 50740-465 Recife, Brazil
| | - Andrew A. Oliveira
- São
Carlos Institute of Physics, University
of São Paulo, 13563-120 São Carlos, Brazil
| | - Roberto D. Lins
- Aggeu
Magalhães Institute, Oswaldo Cruz
Foundation, 50740-465 Recife, Brazil
| | - Janaína
V. dos Anjos
- Department
of Fundamental Chemistry, Federal University
of Pernambuco, 50740-560 Recife, Brazil
| | - Rafael V. C. Guido
- São
Carlos Institute of Physics, University
of São Paulo, 13563-120 São Carlos, Brazil
| | - Thereza A. Soares
- Department
of Chemistry, University of São Paulo, 055508-090 Ribeirão
Preto, Brazil
- Hylleraas
Centre for Quantum Molecular Sciences, University
of Oslo, 0315 Oslo, Norway
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Chen H, Bhowmick B, Tang Y, Lozano-Fernandez J, Han Q. Biochemical Evolution of a Potent Target of Mosquito Larvicide, 3-Hydroxykynurenine Transaminase. Molecules 2022; 27:molecules27154929. [PMID: 35956879 PMCID: PMC9369995 DOI: 10.3390/molecules27154929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 07/26/2022] [Accepted: 07/29/2022] [Indexed: 11/16/2022] Open
Abstract
A specific mosquito enzyme, 3-hydroxykynurenine transaminase (HKT), is involved in the processing of toxic metabolic intermediates of the tryptophan metabolic pathway. The HKT enzymatic product, xanthurenic acid, is required for Plasmodium spp. development in the mosquito vectors. Therefore, an inhibitor of HKT may not only be a mosquitocide but also a malaria-transmission blocker. In this work, we present a study investigating the evolution of HKT, which is a lineage-specific duplication of an alanine glyoxylate aminotransferases (AGT) in mosquitoes. Synteny analyses, together with the phylogenetic history of the AGT family, suggests that HKT and the mosquito AGTs are paralogous that were formed via a duplication event in their common ancestor. Furthermore, 41 amino acid sites with significant evidence of positive selection were identified, which could be responsible for biochemical and functional evolution and the stability of conformational stabilization. To get a deeper understanding of the evolution of ligands’ capacity and the ligand-binding mechanism of HKT, the sequence and the 3D homology model of the common ancestor of HKT and AGT in mosquitoes, ancestral mosquito AGT (AncMosqAGT), were inferred and built. The homology model along with 3-hydroxykynurenine, kynurenine, and alanine were used in docking experiments to predict the binding capacity and ligand-binding mode of the new substrates related to toxic metabolites detoxification. Our study provides evidence for the dramatic biochemical evolution of the key detoxifying enzyme and provides potential sites that could hinder the detoxification function, which may be used in mosquito larvicide and design.
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Affiliation(s)
- Huaqing Chen
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life Sciences, Hainan University, Haikou 570228, China; (H.C.); (B.B.); (Y.T.)
- One Health Institute, Hainan University, Haikou 570228, China
| | - Biswajit Bhowmick
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life Sciences, Hainan University, Haikou 570228, China; (H.C.); (B.B.); (Y.T.)
- One Health Institute, Hainan University, Haikou 570228, China
| | - Yu Tang
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life Sciences, Hainan University, Haikou 570228, China; (H.C.); (B.B.); (Y.T.)
- One Health Institute, Hainan University, Haikou 570228, China
| | - Jesus Lozano-Fernandez
- Department of Genetics, Microbiology and Statistics, Biodiversity Research Institute (IRBio), University of Barcelona, Avd. Diagonal 643, 08028 Barcelona, Spain;
| | - Qian Han
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life Sciences, Hainan University, Haikou 570228, China; (H.C.); (B.B.); (Y.T.)
- One Health Institute, Hainan University, Haikou 570228, China
- Correspondence:
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Souza D, Christensen SA, Wu K, Buss L, Kleckner K, Darrisaw C, Shirk PD, Siegfried BD. RNAi-induced knockdown of white gene in the southern green stink bug (Nezara viridula L.). Sci Rep 2022; 12:10396. [PMID: 35729244 PMCID: PMC9213411 DOI: 10.1038/s41598-022-14620-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 06/09/2022] [Indexed: 12/01/2022] Open
Abstract
The southern green stink bug (SGSB) Nezara viridula L. is one of the most common stink bug species in the United States and can cause significant yield loss in a variety of crops. A suitable marker for the assessment of gene-editing tools in SGSB has yet to be characterized. The white gene, first documented in Drosophila, has been a useful target to assess the efficiency of introduced mutations in many species as it controls pigmentation processes and mutants display readily identifiable phenotypes. In this study we used the RNAi technique to investigate functions and phenotypes associated with the white ortholog in the SGSB and to validate white as a marker for genetic transformation in this species. This study revealed that white may be a suitable marker for germline transformation in the SGSB as white transcript knockdown was not lethal, did not impair embryo development and provided a distinguishable phenotype. Our results demonstrated that the white ortholog in SGSB is involved in the pathway for ommochrome synthesis and suggested additional functions of this gene such as in the integument composition, management of hemolymph compounds and riboflavin mobilization.
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Affiliation(s)
- Dariane Souza
- Entomology and Nematology Department, University of Florida, Gainesville, 32611, USA. .,Syngenta Crop Protection AG, WST-540.1.17 Schaffhauserstrasse, 4332, Stein, Switzerland.
| | - Shawn A Christensen
- USDA-ARS Center for Medical, Agricultural and Veterinary Entomology, Gainesville, 32608, USA
| | - Ke Wu
- Entomology and Nematology Department, University of Florida, Gainesville, 32611, USA
| | - Lyle Buss
- Entomology and Nematology Department, University of Florida, Gainesville, 32611, USA
| | - Kaylin Kleckner
- Entomology and Nematology Department, University of Florida, Gainesville, 32611, USA
| | - Constance Darrisaw
- Entomology and Nematology Department, University of Florida, Gainesville, 32611, USA
| | - Paul D Shirk
- USDA-ARS Center for Medical, Agricultural and Veterinary Entomology, Gainesville, 32608, USA
| | - Blair D Siegfried
- Entomology and Nematology Department, University of Florida, Gainesville, 32611, USA
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Maciel LG, Barbosa ADS, de Alencar-Filho EB, Soares TA, Dos Anjos JV. A second generation of 1,2,4-oxadiazole derivatives with enhanced solubility for inhibition of 3-hydroxykynurenine transaminase (HKT) from Aedes aegypti. RSC Med Chem 2020; 12:222-236. [PMID: 34046611 DOI: 10.1039/d0md00305k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/17/2020] [Indexed: 12/30/2022] Open
Abstract
The most widely used method for the control of the Aedes aegypti mosquito population is the chemical control method. It represents a time- and cost-effective way to curb several diseases (e.g. dengue, Zika, chikungunya, yellow fever) through vector control. For this reason, the discovery of new compounds with a distinct mode of action from the available ones is essential in order to minimize the rise of insecticide resistance. Detoxification enzymes are an attractive target for the discovery of new insecticides. The kynurenine pathway is an important metabolic pathway, and it leads to the chemically stable xanthurenic acid, biosynthesized from 3-hydroxykynurenine, a precursor of reactive oxygen and nitrogen species, by the enzyme 3-hydroxykynurenine transaminase (HKT). Previously, we have reported the effectiveness of 1,2,4-oxadiazole derivatives acting as larvicides for A. aegypti and AeHKT inhibitors from in vitro and in silico studies. Here, we report the synthesis of new sodium 4-[3-(aryl)-1,2,4-oxadiazol-5-yl] propanoates and the cognate HKT-inhibitory activity. These new derivatives act as competitive inhibitors with IC50 values in the range of 42 to 339 μM. We further performed molecular docking simulations and QSAR analysis for the previously synthesized sodium 4-[3-(aryl)-1,2,4-oxadiazol-5-yl] butanoates reported earlier by our group and the data produced herein. Most of the 1,2,4-oxadiazole derivatives, including the canonical compounds for both series, showed a similar binding mode with HKT. The binding occurs similarly to the co-crystallized inhibitor via anchoring to Arg356 and positioning of the aromatic ring and its substituents outwards at the entry of the active site. QSAR analysis was performed in search of more than 770 molecular descriptors to establish a relationship between the lowest energy conformations and the IC50 values. The five best descriptors were selected to create and validate the model, which exhibited parameters that attested to its robustness and predictability. In summary, we observed that compounds with a para substitution and heavier groups (i.e. CF3 and NO2 substituents) had an enhanced HKT-inhibition profile. These compounds comprise a series described as AeHKT inhibitors via enzymatic inhibition experiments, opening the way to further the development of new substances with higher potency against HKT from Aedes aegypti.
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Affiliation(s)
- Larissa G Maciel
- Department of Fundamental Chemistry, Federal University of Pernambuco (UFPE) Recife - PE Brazil
| | - Andrey da S Barbosa
- Department of Fundamental Chemistry, Federal University of Pernambuco (UFPE) Recife - PE Brazil
| | | | - Thereza A Soares
- Department of Fundamental Chemistry, Federal University of Pernambuco (UFPE) Recife - PE Brazil
| | - Janaína V Dos Anjos
- Department of Fundamental Chemistry, Federal University of Pernambuco (UFPE) Recife - PE Brazil
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Combined metabolome and transcriptome analysis reveals key components of complete desiccation tolerance in an anhydrobiotic insect. Proc Natl Acad Sci U S A 2020; 117:19209-19220. [PMID: 32723826 PMCID: PMC7431039 DOI: 10.1073/pnas.2003650117] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Anhydrobiosis is a reversible ametabolic state that occurs in response to severe desiccation. The largest anhydrobiotic animal known is the larva of the African chironomid Polypedilum vanderplanki. Here, we investigated how the metabolism of larvae changes during the desiccation–rehydration cycle and how simple biochemical processes determine viability of the chironomid. Major findings suggest that, in addition to its known anhydroprotectant role, trehalose acts as a major source of energy for rehydration. Citrate and adenosine monophosphate, accumulated in the dry state, allow rapid resumption of metabolism during the recovery phase. Finally, metabolic waste is stored as stable or nontoxic compounds such as allantoin, xanthurenic acid, or ophthalmic acid that may also act as antioxidants. Some organisms have evolved a survival strategy to withstand severe dehydration in an ametabolic state, called anhydrobiosis. The only known example of anhydrobiosis among insects is observed in larvae of the chironomid Polypedilum vanderplanki. Recent studies have led to a better understanding of the molecular mechanisms underlying anhydrobiosis and the action of specific protective proteins. However, gene regulation alone cannot explain the rapid biochemical reactions and independent metabolic changes that are expected to sustain anhydrobiosis. For this reason, we conducted a comprehensive comparative metabolome–transcriptome analysis in the larvae. We showed that anhydrobiotic larvae adopt a unique metabolic strategy to cope with complete desiccation and, in particular, to allow recovery after rehydration. We argue that trehalose, previously known for its anhydroprotective properties, plays additional vital roles, providing both the principal source of energy and also the restoration of antioxidant potential via the pentose phosphate pathway during the early stages of rehydration. Thus, larval viability might be directly dependent on the total amount of carbohydrate (glycogen and trehalose). Furthermore, in the anhydrobiotic state, energy is stored as accumulated citrate and adenosine monophosphate, allowing rapid reactivation of the citric acid cycle and mitochondrial activity immediately after rehydration, before glycolysis is fully functional. Other specific adaptations to desiccation include potential antioxidants (e.g., ophthalmic acid) and measures to avoid the accumulation of toxic waste metabolites by converting these to stable and inert counterparts (e.g., xanthurenic acid and allantoin). Finally, we confirmed that these metabolic adaptations correlate with unique organization and expression of the corresponding enzyme genes.
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Maciel LG, Oliveira AA, Romão TP, Leal LLL, Guido RVC, Silva-Filha MHNL, Dos Anjos JV, Soares TA. Discovery of 1,2,4-oxadiazole derivatives as a novel class of noncompetitive inhibitors of 3-hydroxykynurenine transaminase (HKT) from Aedes aegypti. Bioorg Med Chem 2019; 28:115252. [PMID: 31864777 DOI: 10.1016/j.bmc.2019.115252] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 12/05/2019] [Accepted: 12/05/2019] [Indexed: 12/14/2022]
Abstract
The mosquito Aedes aegypti is the vector of arboviruses such as Zika, Chikungunya, dengue and yellow fever. These infectious diseases have a major impact on public health. The unavailability of effective vaccines or drugs to prevent or treat most of these diseases makes vector control the main form of prevention. One strategy to promote mosquito population control is the use of synthetic insecticides to inhibit key enzymes in the metabolic pathway of these insects, particularly during larval stages. One of the main targets of the kynurenine detoxification pathway in mosquitoes is the enzyme 3-hydroxykynurenine transaminase (HKT), which catalyzes the conversion of 3-hydroxykynurenine (3-HK) into xanthurenic acid (XA). In this work, we report eleven newly synthesized oxadiazole derivatives and demonstrate that these compounds are potent noncompetitive inhibitors of HKT from Ae. aegypti. The present data provide direct evidence that HKT can be explored as a molecular target for the discovery of novel larvicides against Ae. aegypti. More importantly, it ensures that structural information derived from the HKT 3D-structure can be used to guide the development of more potent inhibitors.
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Affiliation(s)
- Larissa G Maciel
- Department of Fundamental Chemistry - Federal University of Pernambuco, Av. Jornalista Aníbal Fernandes, s/n°Cidade Universitária - Recife, PE 50740-560, Brazil
| | - Andrew A Oliveira
- Sao Carlos Institute of Physics - University of São Paulo, Av. Joao Dagnone, 1100 Jardim Santa Angelina, São Carlos, SP 13563-120, Brazil
| | - Tatiany P Romão
- Institute Aggeu Magalhães (IAM) - FIOCRUZ, Av. Professor Moraes Rego s/n°, Recife, PE 50740-560 Brazil
| | - Laylla L L Leal
- Department of Fundamental Chemistry - Federal University of Pernambuco, Av. Jornalista Aníbal Fernandes, s/n°Cidade Universitária - Recife, PE 50740-560, Brazil
| | - Rafael V C Guido
- Sao Carlos Institute of Physics - University of São Paulo, Av. Joao Dagnone, 1100 Jardim Santa Angelina, São Carlos, SP 13563-120, Brazil
| | | | - Janaína V Dos Anjos
- Department of Fundamental Chemistry - Federal University of Pernambuco, Av. Jornalista Aníbal Fernandes, s/n°Cidade Universitária - Recife, PE 50740-560, Brazil.
| | - Thereza A Soares
- Department of Fundamental Chemistry - Federal University of Pernambuco, Av. Jornalista Aníbal Fernandes, s/n°Cidade Universitária - Recife, PE 50740-560, Brazil.
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Costa ÂCF, Cavalcanti SCH, Santana AS, Lima APS, Brito TB, Oliveira RRB, Macêdo NA, Cristaldo PF, Araújo APA, Bacci L. Insecticidal activity of indole derivatives against Plutella xylostella and selectivity to four non-target organisms. ECOTOXICOLOGY (LONDON, ENGLAND) 2019; 28:973-982. [PMID: 31420785 DOI: 10.1007/s10646-019-02095-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/31/2019] [Indexed: 06/10/2023]
Abstract
The diamondback moth Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae) is a destructive pest of brassica crops of economic importance that have resistance to a range of insecticides. Indole derivates can exert diverse biological activities, and different effects may be obtained from small differences in their molecular structures. Indole is the parent substance of a large number of synthetic and natural compounds, such as plant and animal hormones. In the present study, we evaluate the insecticidal activity of 20 new synthesized indole derivatives against P. xylostella, and the selectivity of these derivatives against non-target hymenopteran beneficial arthropods: the pollinator Apis mellifera (Linnaeus, 1758) (Hymenoptera: Apidae), and the predators Polybia scutellaris (White, 1841), Polybia sericea (Olivier, 1791) and Polybia rejecta (Fabricius, 1798) (Hymenoptera: Vespidae). Bioassays were performed in the laboratory to determine the lethal and sublethal effects of the compounds on P. xylostella and to examine their selectivity to non-target organisms by topical application and foliar contact. The treatments consisted of two synthesized derivatives (most and least toxic), the positive control (deltamethrin) and the negative control (solvent). The synthesized compound 4e [1-(1H-indol-3-yl)hexan-1-one] showed high toxicity (via topical application and ingestion) and decreased the leaf consumption by P. xylostella, displaying a higher efficiency than the pyrethroid deltamethrin, widely used to control this pest. In addition, the synthesized indole derivatives were selective to the pollinator A. mellifera and the predators P. scutellaris, P. sericea and P. rejecta, none of which were affected by deltamethrin. Our results highlight the promising potential of the synthesized indole derivatives for the generation of new chemical compounds for P. xylostella management.
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Affiliation(s)
- Ângela C F Costa
- Programa de Pós-Graduação em Agricultura e Biodiversidade, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | | | - Alisson S Santana
- Programa de Pós-Graduação em Agricultura e Biodiversidade, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | - Ana P S Lima
- Programa de Pós-Graduação em Agricultura e Biodiversidade, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | - Thaysnara B Brito
- Departamento de Farmácia, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | - Rafael R B Oliveira
- Departamento de Farmácia, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | - Nathália A Macêdo
- Departamento de Farmácia, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | - Paulo F Cristaldo
- Programa de Pós-Graduação em Entomologia Agrícola, Departamento de Agronomia, Universidade Federal Rural de Pernambuco, Recife, PE, Brazil
| | - Ana Paula A Araújo
- Departamento de Ecologia, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | - Leandro Bacci
- Programa de Pós-Graduação em Agricultura e Biodiversidade, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil.
- Departamento de Engenharia Agronômica, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil.
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Shu S, Xu Y, Xie L, Ouyang Y. The role of C/EBPβ phosphorylation in modulating membrane phospholipids repairing in LPS-induced human lung/bronchial epithelial cells. Gene 2017; 629:76-85. [PMID: 28760550 PMCID: PMC7125708 DOI: 10.1016/j.gene.2017.07.076] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 06/22/2017] [Accepted: 07/27/2017] [Indexed: 11/19/2022]
Abstract
Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a common critical emergency with high mortality in clinical practice. The key mechanism of ALI/ARDS is that the excessive inflammatory response damages the integrity of alveolar and bronchial cell membrane and thus affects their basic function. Phospholipids are the main component of cell membranes. Phospholipase A2 (PLA2), which catalyzes the cleavage of membrane phospholipids, is the most important inflammatory mediator of ALI. However, clara cell secretory protein 1 (CCSP1), an endogenous PLA2 inhibitor can increase the self-defense of membrane phospholipids. Thus, CCSP1 up-regulation and PLA2 inhibition constitutes an effective method for ensuring the stability of membrane phospholipids and for the treatment of ALI/ARDS. In the present study, we developed an in vitro model of ALI via lipopolysaccharide (LPS) stimulation of a human bronchial epithelial cell line, BEAS-2B, and assessed the mRNA and protein levels of CCSP1 and PLA2 in the model cells. The results demonstrated LPS induction inhibited the transcription and protein expression of CCSP1, but only the protein level of membrane associated PLA2 was increased, suggesting that in the in vitro ALI model, abnormally regulated CCSP1 transcription plays a crucial role in the damage of cell membrane. To find out the reason that CCSP1 expression was decreased in the ALI model, we predicted, by means of bioinformatics, putative transcription factors which would bind to CCSP1 promoter, examined their background and expression, and found that a transcription factor, CCAAT/enhancer binding protein β (C/EBP β), was correlated with the transcription of CCSP1 in the in vitro ALI model, and its phosphorylation in the model was decreased. CHIP-PCR and luciferase reporter assay revealed that C/EBP β bound to CCSP1 promoter and facilitated its transcription. Therefore, we conclude that there is a C/EBP β/CCSP1/PLA2 pathway in the in vitro ALI model. The study of underlying mechanism show that the activity of C/EBP β depends on its phosphorylation:LPS stimulation reduced C/EBP β phosphorylation and suppressed the transcription of CCSP1 in BEAS-2B cells, which resulted in enhanced PLA2 and the consequent membrane damage. And further study shows that overexpression of CDK2(Cyclindependent kinase 2), promoted the phosphorylation of C/EBP β and inhibited PLA2 through the C/EBP β/CCSP1/PLA2 pathway, so as to attenuate membrane damage. The significance of this study lies in that artificial C/EBP β phosphorylation regulation may ease the membrane damage in ALI and improve membrane repair. CDK2 over-expression promotes C/EBPβ phosphorylation and improves membrane repair through C/EBPβ/CCSP/PLA2 pathway in ALI.
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Affiliation(s)
- Shiyu Shu
- Anesthesiology Department, Children's Hospital of FudanUniversity,Shanghai,201102, China.
| | - Yan Xu
- Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing, 400014,China
| | - Ling Xie
- Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing, 400014,China
| | - Yufang Ouyang
- Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing, 400014,China
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3-Hydroxykynurenic Acid and Type 2 Diabetes: Implications for Aging, Obesity, Depression, Parkinson’s Disease, and Schizophrenia. TRYPTOPHAN METABOLISM: IMPLICATIONS FOR BIOLOGICAL PROCESSES, HEALTH AND DISEASE 2015. [DOI: 10.1007/978-3-319-15630-9_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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10
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Biochemical identification and crystal structure of kynurenine formamidase from Drosophila melanogaster. Biochem J 2012; 446:253-60. [PMID: 22690733 DOI: 10.1042/bj20120416] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
KFase (kynurenine formamidase), also known as arylformamidase and formylkynurenine formamidase, efficiently catalyses the hydrolysis of NFK (N-formyl-L-kynurenine) to kynurenine. KFase is the second enzyme in the kynurenine pathway of tryptophan metabolism. A number of intermediates formed in the kynurenine pathway are biologically active and implicated in an assortment of medical conditions, including cancer, schizophrenia and neurodegenerative diseases. Consequently, enzymes involved in the kynurenine pathway have been considered potential regulatory targets. In the present study, we report, for the first time, the biochemical characterization and crystal structures of Drosophila melanogaster KFase conjugated with an inhibitor, PMSF. The protein architecture of KFase reveals that it belongs to the α/β hydrolase fold family. The PMSF-binding information of the solved conjugated crystal structure was used to obtain a KFase and NFK complex using molecular docking. The complex is useful for understanding the catalytic mechanism of KFase. The present study provides a molecular basis for future efforts in maintaining or regulating kynurenine metabolism through the molecular and biochemical regulation of KFase.
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Passera E, Campanini B, Rossi F, Casazza V, Rizzi M, Pellicciari R, Mozzarelli A. Human kynurenine aminotransferase II - reactivity with substrates and inhibitors. FEBS J 2011; 278:1882-900. [DOI: 10.1111/j.1742-4658.2011.08106.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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12
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Meng Y, Katsuma S, Mita K, Shimada T. Abnormal red body coloration of the silkworm,Bombyx mori, is caused by a mutation in a novel kynureninase. Genes Cells 2009; 14:129-40. [DOI: 10.1111/j.1365-2443.2008.01257.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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13
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Substrate specificity and structure of human aminoadipate aminotransferase/kynurenine aminotransferase II. Biosci Rep 2008; 28:205-15. [PMID: 18620547 DOI: 10.1042/bsr20080085] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
KAT (kynurenine aminotransferase) II is a primary enzyme in the brain for catalysing the transamination of kynurenine to KYNA (kynurenic acid). KYNA is the only known endogenous antagonist of the N-methyl-D-aspartate receptor. The enzyme also catalyses the transamination of aminoadipate to alpha-oxoadipate; therefore it was initially named AADAT (aminoadipate aminotransferase). As an endotoxin, aminoadipate influences various elements of glutamatergic neurotransmission and kills primary astrocytes in the brain. A number of studies dealing with the biochemical and functional characteristics of this enzyme exist in the literature, but a systematic assessment of KAT II addressing its substrate profile and kinetic properties has not been performed. The present study examines the biochemical and structural characterization of a human KAT II/AADAT. Substrate screening of human KAT II revealed that the enzyme has a very broad substrate specificity, is capable of catalysing the transamination of 16 out of 24 tested amino acids and could utilize all 16 tested alpha-oxo acids as amino-group acceptors. Kinetic analysis of human KAT II demonstrated its catalytic efficiency for individual amino-group donors and acceptors, providing information as to its preferred substrate affinity. Structural analysis of the human KAT II complex with alpha-oxoglutaric acid revealed a conformational change of an N-terminal fraction, residues 15-33, that is able to adapt to different substrate sizes, which provides a structural basis for its broad substrate specificity.
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14
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Biochemical and structural properties of mouse kynurenine aminotransferase III. Mol Cell Biol 2008; 29:784-93. [PMID: 19029248 DOI: 10.1128/mcb.01272-08] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Kynurenine aminotransferase III (KAT III) has been considered to be involved in the production of mammalian brain kynurenic acid (KYNA), which plays an important role in protecting neurons from overstimulation by excitatory neurotransmitters. The enzyme was identified based on its high sequence identity with mammalian KAT I, but its activity toward kynurenine and its structural characteristics have not been established. In this study, the biochemical and structural properties of mouse KAT III (mKAT III) were determined. Specifically, mKAT III cDNA was amplified from a mouse brain cDNA library, and its recombinant protein was expressed in an insect cell protein expression system. We established that mKAT III is able to efficiently catalyze the transamination of kynurenine to KYNA and has optimum activity at relatively basic conditions of around pH 9.0 and at relatively high temperatures of 50 to 60 degrees C. In addition, mKAT III is active toward a number of other amino acids. Its activity toward kynurenine is significantly decreased in the presence of methionine, histidine, glutamine, leucine, cysteine, and 3-hydroxykynurenine. Through macromolecular crystallography, we determined the mKAT III crystal structure and its structures in complex with kynurenine and glutamine. Structural analysis revealed the overall architecture of mKAT III and its cofactor binding site and active center residues. This is the first report concerning the biochemical characteristics and crystal structures of KAT III enzymes and provides a basis toward understanding the overall physiological role of mammalian KAT III in vivo and insight into regulating the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.
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15
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Vidhyanandhini R, Kumar NP. Characterization of the 3-HKT gene in important malaria vectors in India, viz: Anopheles culicifacies and Anopheles stephensi (Diptera: Culicidae). Mem Inst Oswaldo Cruz 2008; 103:595-7. [PMID: 18949331 DOI: 10.1590/s0074-02762008000600014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 06/24/2008] [Indexed: 11/21/2022] Open
Abstract
The 3-hydroxykynurenine transaminase (3-HKT) gene plays a vital role in the development of malaria parasites by participating in the synthesis of xanthurenic acid, which is involved in the exflagellation of microgametocytes in the midgut of malaria vector species. The 3-HKT enzyme is involved in the tryptophan metabolism of Anophelines. The gene had been studied in the important global malaria vector, Anopheles gambiae. In this report, we have conducted a preliminary investigation to characterize this gene in the two important vector species of malaria in India, Anopheles culicifacies and Anopheles stephensi. The analysis of the genetic structure of this gene in these species revealed high homology with the An. gambiae gene. However, four non-synonymous mutations in An. stephensi and seven in An. culicifacies sequences were noted in the exons 1 and 2 of the gene; the implication of these mutations on enzyme structure remains to be explored.
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Affiliation(s)
- R Vidhyanandhini
- Vector Control Research Centre, Indian Council of Medical Research, Medical Complex, Indira Nagar, Pondicherry, India
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16
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Han Q, Robinson H, Li J. Crystal structure of human kynurenine aminotransferase II. J Biol Chem 2007; 283:3567-3573. [PMID: 18056995 DOI: 10.1074/jbc.m708358200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Human kynurenine aminotransferase II (hKAT-II) efficiently catalyzes the transamination of knunrenine to kynurenic acid (KYNA). KYNA is the only known endogenous antagonist of N-methyl-D-aspartate (NMDA) receptors and is also an antagonist of 7-nicotinic acetylcholine receptors. Abnormal concentrations of brain KYNA have been implicated in the pathogenesis and development of several neurological and psychiatric diseases in humans. Consequently, enzymes involved in the production of brain KYNA have been considered potential regulatory targets. In this article, we report a 2.16 A crystal structure of hKAT-II and a 1.95 A structure of its complex with kynurenine. The protein architecture of hKAT-II reveals that it belongs to the fold-type I pyridoxal 5-phosphate (PLP)-dependent enzymes. In comparison with all subclasses of fold-type I-PLP-dependent enzymes, we propose that hKAT-II represents a novel subclass in the fold-type I enzymes because of the unique folding of its first 65 N-terminal residues. This study provides a molecular basis for future effort in maintaining physiological concentrations of KYNA through molecular and biochemical regulation of hKAT-II.
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Affiliation(s)
- Qian Han
- Department of Biochemistry, Virginia Tech University, Blacksburg, Virginia 24061
| | - Howard Robinson
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech University, Blacksburg, Virginia 24061.
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17
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Han Q, Beerntsen BT, Li J. The tryptophan oxidation pathway in mosquitoes with emphasis on xanthurenic acid biosynthesis. JOURNAL OF INSECT PHYSIOLOGY 2007; 53:254-63. [PMID: 17070835 PMCID: PMC2577175 DOI: 10.1016/j.jinsphys.2006.09.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Revised: 09/01/2006] [Accepted: 09/04/2006] [Indexed: 05/12/2023]
Abstract
Oxidation of tryptophan to kynurenine and 3-hydroxykynurenine (3-HK) is the major catabolic pathway in mosquitoes. However, 3-HK is oxidized easily under physiological conditions, resulting in the production of reactive radical species. To overcome this problem, mosquitoes have developed an efficient mechanism to prevent 3-HK from accumulating by converting this chemically reactive compound to the chemically stable xanthurenic acid. Interestingly, 3-HK is a precursor for the production of compound eye pigments during the pupal and early adult stages; consequently, mosquitoes need to preserve and transport 3-HK for compound eye pigmentation in pupae and adults. This review summarizes the tryptophan oxidation pathway, compares and contrasts the mosquito tryptophan oxidation pathway with other model species, and discusses possible driving forces leading to the functional adaptation and evolution of enzymes involved in the mosquito tryptophan oxidation pathway.
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Affiliation(s)
- Qian Han
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
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18
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Han Q, Robinson H, Gao YG, Vogelaar N, Wilson SR, Rizzi M, Li J. Crystal structures of Aedes aegypti alanine glyoxylate aminotransferase. J Biol Chem 2006; 281:37175-82. [PMID: 16990263 DOI: 10.1074/jbc.m607032200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mosquitoes are unique in having evolved two alanine glyoxylate aminotransferases (AGTs). One is 3-hydroxykynurenine transaminase (HKT), which is primarily responsible for catalyzing the transamination of 3-hydroxykynurenine (3-HK) to xanthurenic acid (XA). Interestingly, XA is used by malaria parasites as a chemical trigger for their development within the mosquito. This 3-HK to XA conversion is considered the major mechanism mosquitoes use to detoxify the chemically reactive and potentially toxic 3-HK. The other AGT is a typical dipteran insect AGT and is specific for converting glyoxylic acid to glycine. Here we report the 1.75A high-resolution three-dimensional crystal structure of AGT from the mosquito Aedes aegypti (AeAGT) and structures of its complexes with reactants glyoxylic acid and alanine at 1.75 and 2.1A resolution, respectively. This is the first time that the three-dimensional crystal structures of an AGT with its amino acceptor, glyoxylic acid, and amino donor, alanine, have been determined. The protein is dimeric and adopts the type I-fold of pyridoxal 5-phosphate (PLP)-dependent aminotransferases. The PLP co-factor is covalently bound to the active site in the crystal structure, and its binding site is similar to those of other AGTs. The comparison of the AeAGT-glyoxylic acid structure with other AGT structures revealed that these glyoxylic acid binding residues are conserved in most AGTs. Comparison of the AeAGT-alanine structure with that of the Anopheles HKT-inhibitor complex suggests that a Ser-Asn-Phe motif in the latter may be responsible for the substrate specificity of HKT enzymes for 3-HK.
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Affiliation(s)
- Qian Han
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
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19
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Abstract
In the mosquito, transamination of 3-HK (3-hydroxykynurenine) to XA (xanthurenic acid) is catalysed by an AGT (alanine glyoxylate aminotransferase) and is the major branch pathway of tryptophan metabolism. Interestingly, malaria parasites hijack this pathway to use XA as a chemical signal for development in the mosquito. Here, we report that the mosquito has two AGT isoenzymes. One is the previously cloned AeHKT [Aedes aegypti HKT (3-HK transaminase)] [Han, Fang and Li (2002) J. Biol. Chem. 277, 15781-15787], similar to hAGT (human AGT), which primarily catalyses 3-HK to XA in mosquitoes, and the other is a typical dipteran insect AGT. We cloned the second AGT from Ae. aegypti mosquitoes [AeAGT (Ae. aegypti AGT)], overexpressed the enzyme in baculovirus/insect cells and determined its biochemical characteristics. We also expressed hAGT for a comparative study. The new cloned AeAGT is highly substrate-specific when compared with hAGT and the previously reported AeHKT and Drosophila AGT, and is translated mainly in pupae and adults, which contrasts with AeHKT that is expressed primarily in larvae. Our results suggest that the physiological requirements of mosquitoes and the interaction between the mosquito and its host appear to be the driving force in mosquito AGT evolution.
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Affiliation(s)
- Qian Han
- *Department of Pathobiology, University of Illinois, Urbana, IL 61802, U.S.A
- †Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, U.S.A
| | - Seong Ryul Kim
- *Department of Pathobiology, University of Illinois, Urbana, IL 61802, U.S.A
| | - Haizhen Ding
- *Department of Pathobiology, University of Illinois, Urbana, IL 61802, U.S.A
- †Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, U.S.A
| | - Jianyong Li
- *Department of Pathobiology, University of Illinois, Urbana, IL 61802, U.S.A
- †Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, U.S.A
- To whom correspondence should be addressed (email )
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20
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Rossi F, Garavaglia S, Giovenzana GB, Arcà B, Li J, Rizzi M. Crystal structure of the Anopheles gambiae 3-hydroxykynurenine transaminase. Proc Natl Acad Sci U S A 2006; 103:5711-6. [PMID: 16585514 PMCID: PMC1458638 DOI: 10.1073/pnas.0510233103] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Indexed: 11/18/2022] Open
Abstract
In Anopheles gambiae, the vector for the most deadly malaria parasite Plasmodium falciparum, xanthurenic acid (XA) plays a key role in parasite gametogenesis and fertility. In mosquitoes, XA is produced by transamination of 3-hydroxykynurenine (3-HK), a reaction that represents the main route to prevent the accumulation of the potentially toxic 3-HK excess. Interfering with XA metabolism in A. gambiae therefore appears an attractive avenue for the development of malaria transmission-blocking drugs and insecticides. We have determined the crystal structure of A. gambiae 3-HK transaminase in its pyridoxal 5'-phosphate form and in complex with a newly synthesized competitive enzyme inhibitor. Structural inspection of the enzyme active site reveals the key molecular determinants for ligand recognition and catalysis. Major contributions toward inhibitor binding are provided by a salt bridge between the inhibitor carboxylate and Arg-356 and by a remarkable hydrogen bond network involving the anthranilic moiety of the inhibitor and backbone atoms of residues Gly-25 and Asn-44. This study may be useful for the structure-based design of specific enzyme inhibitors of potential interest as antimalarial agents.
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Affiliation(s)
- Franca Rossi
- Dipartimento di Scienze Chimiche, Alimentari Farmaceutiche e Farmacologiche-Drug and Food Biotechnology Center, University of Piemonte Orientale “Amedeo Avogadro,” Via Bovio 6, 28100 Novara, Italy
| | - Silvia Garavaglia
- Dipartimento di Scienze Chimiche, Alimentari Farmaceutiche e Farmacologiche-Drug and Food Biotechnology Center, University of Piemonte Orientale “Amedeo Avogadro,” Via Bovio 6, 28100 Novara, Italy
| | - Giovanni Battista Giovenzana
- Dipartimento di Scienze Chimiche, Alimentari Farmaceutiche e Farmacologiche-Drug and Food Biotechnology Center, University of Piemonte Orientale “Amedeo Avogadro,” Via Bovio 6, 28100 Novara, Italy
| | - Bruno Arcà
- Dipartimento di Biologia Strutturale e Funzionale, University of Napoli “Federico II,” 80134 Napoli, Italy; and
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, 111 Engel Hall, Blacksburg, VA 24060
| | - Menico Rizzi
- Dipartimento di Scienze Chimiche, Alimentari Farmaceutiche e Farmacologiche-Drug and Food Biotechnology Center, University of Piemonte Orientale “Amedeo Avogadro,” Via Bovio 6, 28100 Novara, Italy
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21
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Rossi F, Lombardo F, Paglino A, Cassani C, Miglio G, Arcà B, Rizzi M. Identification and biochemical characterization of the Anopheles gambiae 3-hydroxykynurenine transaminase. FEBS J 2005; 272:5653-62. [PMID: 16262702 DOI: 10.1111/j.1742-4658.2005.04961.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spontaneous oxidation of 3-hydroxykynureine (3-HK), a metabolic intermediate of the tryptophan degradation pathway, elicits a remarkable oxidative stress response in animal tissues. In the yellow fever mosquito Aedes aegypti the excess of this toxic metabolic intermediate is efficiently removed by a specific 3-HK transaminase, which converts 3-HK into the more stable compound xanthurenic acid. In anopheline mosquitoes transmitting malaria, xanthurenic acid plays an important role in Plasmodium gametocyte maturation and fertility. Using the sequence information provided by the Anopheles gambiae genome and available ESTs, we adopted a PCR-based approach to isolate a 3-HK transaminase coding sequence from the main human malaria vector A. gambiae. Tissue and developmental expression analysis revealed an almost ubiquitary profile, which is in agreement with the physiological role of the enzyme in mosquito development and 3-HK detoxification. A high yield procedure for the expression and purification of a fully active recombinant version of the protein has been developed. Recombinant A. gambiae 3-HK transaminase is a dimeric pyridoxal 5'-phosphate dependent enzyme, showing an optimum pH of 7.8 and a comparable catalytic efficiency for both 3-HK and its immediate catabolic precursor kynurenine. This study may be useful for the identification of 3-HK transaminase inhibitors of potential interest as malaria transmission-blocking drugs or effective insecticides.
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Affiliation(s)
- Franca Rossi
- DiSCAFF, University of Piemonte Orientale Amedeo Avogadro, Novara, Italy
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22
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Xu X, Dong Y, Abraham EG, Kocan A, Srinivasan P, Ghosh AK, Sinden RE, Ribeiro JMC, Jacobs-Lorena M, Kafatos FC, Dimopoulos G. Transcriptome analysis of Anopheles stephensi-Plasmodium berghei interactions. Mol Biochem Parasitol 2005; 142:76-87. [PMID: 15907562 DOI: 10.1016/j.molbiopara.2005.02.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2004] [Revised: 02/23/2005] [Accepted: 02/25/2005] [Indexed: 11/28/2022]
Abstract
Simultaneous microarray-based transcription analysis of 4987 Anopheles stephensi midgut and Plasmodium berghei infection stage specific cDNAs was done at seven successive time points: 6, 20 and 40h, and 4, 8, 14 and 20 days after ingestion of malaria infected blood. The study reveals the molecular components of several Anopheles processes relating to blood digestion, midgut expansion and response to Plasmodium-infected blood such as digestive enzymes, transporters, cytoskeletal and structural components and stress and immune responsive factors. In parallel, the analysis provide detailed expression patterns of Plasmodium genes encoding essential developmental and metabolic factors and proteins implicated in interaction with the mosquito vector and vertebrate host such as kinases, transcription and translational factors, cytoskeletal components and a variety of surface proteins, some of which are potent vaccine targets. Temporal correlation between transcription profiles of both organisms identifies putative gene clusters of interacting processes, such as Plasmodium invasion of the midgut epithelium, Anopheles immune responses to Plasmodium infection, and apoptosis and expulsion of invaded midgut cells from the epithelium. Intriguing transcription patterns for highly variable Plasmodium surface antigens may indicate parasite strategies to avoid recognition by the mosquito's immune surveillance system.
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Affiliation(s)
- Xiaojin Xu
- Department of Biological Sciences, Imperial College, London SW7 2AZ, UK
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23
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Han Q, Li J. Cysteine and keto acids modulate mosquito kynurenine aminotransferase catalyzed kynurenic acid production. FEBS Lett 2005; 577:381-5. [PMID: 15556614 PMCID: PMC2855840 DOI: 10.1016/j.febslet.2004.09.088] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Revised: 09/09/2004] [Accepted: 09/11/2004] [Indexed: 11/17/2022]
Abstract
Kynurenine aminotransferase (KAT) catalyzes the formation of kynurenic acid (KYNA), the natural antagonist of ionotropic glutamate receptors. This study tests potential substrates and assesses the effects of amino acids and keto acids on the activity of mosquito KAT. Various keto acids, when simultaneously present in the same reaction mixture, display a combined effect on KAT catalyzed KYNA production. Moreover, methionine and glutamine show inhibitory effects on KAT activity, while cysteine functions as either an antagonist or an inhibitor depending on the concentration. Therefore, the overall level of keto acids and cysteine might modulate the KYNA synthesis. Results from this study will be useful in the study of KAT regulation in other animals.
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Affiliation(s)
| | - Jianyong Li
- Corresponding author. Fax: +1-217-244-7421. (J. Li)
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Han Q, Calvo E, Marinotti O, Fang J, Rizzi M, James AA, Li J. Analysis of the wild-type and mutant genes encoding the enzyme kynurenine monooxygenase of the yellow fever mosquito, Aedes aegypti. INSECT MOLECULAR BIOLOGY 2003; 12:483-490. [PMID: 12974953 PMCID: PMC2629591 DOI: 10.1046/j.1365-2583.2003.00433.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Kynurenine 3-monooxygenase (KMO) catalyses the hydroxylation of kynurenine to 3-hydroxykynurenine. KMO has a key role in tryptophan catabolism and synthesis of ommochrome pigments in mosquitoes. The gene encoding this enzyme in the yellow fever mosquito, Aedes aegypti, is called kynurenine hydroxylase (kh) and a mutant allele that produces white eyes has been designated khw. A number of cDNA clones representative of wild-type and mutant genes were isolated. Sequence analyses of the wild-type and mutant cDNAs revealed a deletion of 162 nucleotides in the mutant gene near the 3'-end of the deduced coding region. RT-PCR analyses confirm the transcription of a truncated mRNA in the mutant strain. The in-frame deletion results in a loss of 54 amino acids, which disrupts a major alpha-helix and which probably accounts for the loss of activity of the enzyme. Recombinant Ae. aegypti KMO showed high substrate specificity for kynurenine with optimum activity at 40 degrees C and pH = 7.5. Kinetic parameters and inhibition of KMO activity by Cl- and pyridoxal-5-phosphate were determined.
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Affiliation(s)
- Q Han
- Department of Pathobiology, University of Illinois at Urbana-Champaign, IL, USA
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25
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Han Q, Li J. Comparative characterization of Aedes 3-hydroxykynurenine transaminase/alanine glyoxylate transaminase and Drosophila serine pyruvate aminotransferase. FEBS Lett 2002; 527:199-204. [PMID: 12220660 PMCID: PMC2857927 DOI: 10.1016/s0014-5793(02)03229-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study describes the comparative analysis of two insect recombinant aminotransferases, Aedes aegypti 3-hydroxykynurenine (3-HK) transaminase/alanine glyoxylate aminotransferase (Ae-HKT/AGT) and Drosophila melanogaster serine pyruvate aminotransferase (Dm-Spat), which share 52% identity in their amino acid sequences. Both enzymes showed AGT activity. In addition, Ae-HKT/AGT is also able to catalyze the transamination of 3-HK or kynurenine with glyoxylate, pyruvate or oxaloacetate as the amino acceptor. Kinetic analysis and other data suggest that Ae-HKT/AGT plays a critical role in mosquito tryptophan catabolism by detoxifying 3-HK and that Dm-Spat is primarily involved in glyoxylate detoxification.
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Affiliation(s)
| | - Jianyong Li
- Corresponding author. Fax: (1)-217-244 7421. (J. Li)
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