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Trypanosomatid selenophosphate synthetase structure, function and interaction with selenocysteine lyase
Marco Túlio Alves da Silva1, Ivan Rosa E Silva1, Lívia Maria Faim1
1Laboratory of Structural Biology, Sao Carlos Institute of Physics, University of São Paulo, São Carlos, SP, Brazil.
Plos Neglected Tropical Diseases
|October 5, 2020
Summary
Selenophosphate synthetase is crucial for parasite survival under endoplasmic reticulum stress. This study reveals its role in regulating stress responses in Trypanosomatidae, impacting parasite viability.
Area of Science:
- Biochemistry
- Molecular Biology
- Parasitology
Background:
- Eukaryotes, particularly Excavata, serve as models for cellular evolution.
- Trypanosomatidae parasites (T. brucei, T. cruzi, L. major) possess complex selenocysteine machinery.
- Selenophosphate synthetase (SEPHS/SPS) is vital for selenocysteine synthesis.
Purpose of the Study:
- To investigate the structural and functional aspects of L. major selenophosphate synthetase.
- To elucidate the role of SEPHS/SPS in Trypanosomatidae cellular processes and stress response.
- To determine the necessity of selenoproteins in parasite viability.
Main Methods:
- Crystal structure determination of L. major SEPHS/SPS.
- Analysis of SEPHS/SPS interactions with other selenocysteine pathway components.
- Gene silencing (RNAi) of SEPHS/SPS and SELENOT in T. brucei under endoplasmic reticulum stress conditions (DTT, tunicamycin).
Main Results:
- The crystal structure of L. major SEPHS/SPS confirmed its functionally important dimeric organization.
- SEPHS/SPS interacts with selenocysteine lyase (SCLY) but not with PSTK-SEPSECS or eEFSec complexes.
- Ablation of SEPHS/SPS in T. brucei caused growth defects under ER stress, suggesting a role in stress response.
- SELENOT was found to be dispensable for parasite viability.
Conclusions:
- T. brucei SEPHS/SPS plays a significant role in regulating the parasite's response to endoplasmic reticulum stress.
- The study highlights the non-essential nature of certain selenoproteins for parasite survival under standard laboratory conditions.
- Structural and functional insights into SEPHS/SPS provide a basis for understanding selenium metabolism in parasites.
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