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Crispim M, Damasceno FS, Hernández A, Barisón MJ, Pretto Sauter I, Souza Pavani R, Santos Moura A, Pral EMF, Cortez M, Elias MC, Silber AM. The glutamine synthetase of Trypanosoma cruzi is required for its resistance to ammonium accumulation and evasion of the parasitophorous vacuole during host-cell infection. PLoS Negl Trop Dis 2018; 12:e0006170. [PMID: 29320490 PMCID: PMC5779702 DOI: 10.1371/journal.pntd.0006170] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 01/23/2018] [Accepted: 12/16/2017] [Indexed: 11/19/2022] Open
Abstract
Trypanosoma cruzi, the etiological agent of Chagas disease, consumes glucose and amino acids depending on the environmental availability of each nutrient during its complex life cycle. For example, amino acids are the major energy and carbon sources in the intracellular stages of the T. cruzi parasite, but their consumption produces an accumulation of NH4+ in the environment, which is toxic. These parasites do not have a functional urea cycle to secrete excess nitrogen as low-toxicity waste. Glutamine synthetase (GS) plays a central role in regulating the carbon/nitrogen balance in the metabolism of most living organisms. We show here that the gene TcGS from T. cruzi encodes a functional glutamine synthetase; it can complement a defect in the GLN1 gene from Saccharomyces cerevisiae and utilizes ATP, glutamate and ammonium to yield glutamine in vitro. Overall, its kinetic characteristics are similar to other eukaryotic enzymes, and it is dependent on divalent cations. Its cytosolic/mitochondrial localization was confirmed by immunofluorescence. Inhibition by Methionine sulfoximine revealed that GS activity is indispensable under excess ammonium conditions. Coincidently, its expression levels are maximal in the amastigote stage of the life cycle, when amino acids are preferably consumed, and NH4+ production is predictable. During host-cell invasion, TcGS is required for the parasite to escape from the parasitophorous vacuole, a process sine qua non for the parasite to replicate and establish infection in host cells. These results are the first to establish a link between the activity of a metabolic enzyme and the ability of a parasite to reach its intracellular niche to replicate and establish host-cell infection.
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Affiliation(s)
- Marcell Crispim
- Laboratory of Biochemistry of Tryps—LaBTryps, Department of Parasitology, Institute for Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Flávia Silva Damasceno
- Laboratory of Biochemistry of Tryps—LaBTryps, Department of Parasitology, Institute for Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Agustín Hernández
- Laboratory of Biochemistry of Tryps—LaBTryps, Department of Parasitology, Institute for Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - María Julia Barisón
- Laboratory of Biochemistry of Tryps—LaBTryps, Department of Parasitology, Institute for Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Ismael Pretto Sauter
- Immunobiology of Leishmania-Macrophage Interaction Laboratory, Department of Parasitology, Institute for Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Raphael Souza Pavani
- Special Laboratory of Cell Cycle, Center of Toxins, Immunology and Cell Signalling, Butantan Institute, São Paulo, SP, Brazil
| | - Alexandre Santos Moura
- Laboratory of Biochemistry of Tryps—LaBTryps, Department of Parasitology, Institute for Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Elizabeth Mieko Furusho Pral
- Laboratory of Biochemistry of Tryps—LaBTryps, Department of Parasitology, Institute for Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Mauro Cortez
- Immunobiology of Leishmania-Macrophage Interaction Laboratory, Department of Parasitology, Institute for Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Maria Carolina Elias
- Special Laboratory of Cell Cycle, Center of Toxins, Immunology and Cell Signalling, Butantan Institute, São Paulo, SP, Brazil
| | - Ariel Mariano Silber
- Laboratory of Biochemistry of Tryps—LaBTryps, Department of Parasitology, Institute for Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
- * E-mail:
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