Mitochondrial Sirtuin TcSir2rp3 Affects TcSODA Activity and Oxidative Stress Response in Trypanosoma cruzi.

Leila Dos Santos Moura,Marcos R M Fontes,Vinícius Santana Nunes,Nilmar Silvio Moretti,Sergio Schenkman,Ana Caroline De Castro Nascimento Sousa,Antoniel A S Gomes

doi:10.3389/fcimb.2021.773410

Abstract

Trypanosoma cruzi faces a variety of environmental scenarios during its life cycle, which include changes in the redox environment that requires a fine regulation of a complex antioxidant arsenal of enzymes. Reversible posttranslational modifications, as lysine acetylation, are a fast and economical way for cells to react to environmental conditions. Recently, we found that the main antioxidant enzymes, including the mitochondrial superoxide dismutase A (TcSODA) are acetylated in T. cruzi, suggesting that protein acetylation could participate in the oxidative stress response in T. cruzi. Therefore, we investigated whether mitochondrial lysine deacetylase TcSir2rp3 was involved in the activity control of TcSODA. We observed an increased resistance to hydrogen peroxide and menadione in parasites overexpressing TcSir2rp3. Increased resistance was also found for benznidazole and nifurtimox, known to induce reactive oxidative and nitrosactive species in the parasite, associated to that a reduction in the ROS levels was observed. To better understand the way TcSir2rp3 could contributes to oxidative stress response, we analyzed the expression of TcSODA in the TcSir2rp3 overexpressing parasites and did not detect any increase in protein levels of this enzyme. However, we found that these parasites presented higher levels of superoxide dismutase activity, and also that TcSir2rp3 and TcSODA interacts in vivo. Knowing that TcSODA is acetylated at lysine residues K44 and K97, and that K97 is located at a similar region in the protein structure as K68 in human manganese superoxide dismutase (MnSOD), responsible for regulating MnSOD activity, we generated mutated versions of TcSODA at K44 and K97 and found that replacing K97 by glutamine, which mimics an acetylated lysine, negatively affects the enzyme activity in vitro. By using molecular dynamics approaches, we revealed that acetylation of K97 induces specific conformational changes in TcSODA with respect to hydrogen-bonding pattern to neighbor residues, suggesting a key participation of this residue to modulate the affinity to . Taken together, our results showed for the first time the involvement of lysine acetylation in the maintenance of homeostatic redox state in trypanosomatids, contributing to the understanding of mechanisms used by T. cruzi to progress during the infection.

Highlights

Trypanosoma cruzi is a protozoan parasite of the Trypanosomatidae family responsible for Chagas disease, an illness endemic in 21 countries across Latin America and being detected in the southern USA and many other countries
As sirtuins regulate the levels of protein acetylation, and in T. cruzi, several proteins involved in redox reactions are acetylated (Moretti et al, 2015), we initially explored how TcSir2rp3 could impact parasite responses to oxidative stress
T. cruzi is exposed to different redox environments during its life cycle, and adaptation to these conditions determines the success of the infection (Perez-Molina and Molina, 2018; Lidani et al, 2019)

Summary

Introduction

Trypanosoma cruzi is a protozoan parasite of the Trypanosomatidae family responsible for Chagas disease, an illness endemic in 21 countries across Latin America and being detected in the southern USA and many other countries. The parasite has a heteroxenous life cycle shifting between an invertebrate and a vertebrate host. Metacyclic trypomastigote parasites are transmitted by triatomine bug feces during blood meal and can infect any nucleated cell type. Inside the vertebrate host cell, the metacyclic trypomastigotes differentiate to amastigote replicative forms, which latter on will differentiate to trypomastigotes that will be released upon cell lyses and can infect other cells or be ingested by triatomine bugs during a blood meal. During its life cycle transitions, T. cruzi faces variable environmental conditions, such as, changes in temperature, nutritional state, and oxidant products, and the parasite must adapt to these alterations to survive and succeed in the infection (Moretti and Schenkman, 2013)

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