ORCID Profile
0000-0002-1278-7838
Current Organisation
Institut des Biomolécules Max Mousseron
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Publisher: Springer Science and Business Media LLC
Date: 24-01-2019
DOI: 10.1038/S41598-018-36839-6
Abstract: Ophidian accidents are considered an important neglected tropical disease by the World Health Organization. Particularly in Latin America, Bothrops snakes are responsible for the majority of the snakebite envenomings that are not efficiently treated by conventional serum therapy. Thus, the search for simple and efficient inhibitors to complement this therapy is a promising research area, and a combination of functional and structural assays have been used to test candidate ligands against specific ophidian venom compounds. Herein, we tested a commercial drug (acetylsalicylic acid, ASA) and a plant compound with antiophidian properties (rosmarinic acid, RA) using myographic, crystallographic and bioinformatics experiments with a phospholipase A 2 -like toxin, MjTX-II. MjTX-II/RA and MjTX-II/ASA crystal structures were solved at high resolution and revealed the presence of ligands bound to different regions of the toxin. However, in vitro myographic assays showed that only RA is able to prevent the myotoxic effects of MjTX-II. In agreement with functional results, molecular dynamics simulations showed that the RA molecule remains tightly bound to the toxin throughout the calculations, whereas ASA molecules tend to dissociate. This approach aids the design of effective inhibitors of PLA 2 -like toxins and, eventually, may complement serum therapy.
Publisher: Elsevier BV
Date: 12-2021
DOI: 10.1016/J.BIOCHI.2021.08.002
Abstract: The RVB proteins, composed of the conservative paralogs, RVB1 and RVB2, belong to the AAA+ (ATPases Associated with various cellular Activities) protein superfamily and are present in archaea and eukaryotes. The most distinct structural features are their ability to interact with each other forming the RVB1/2 complex and their participation in several macromolecular protein complexes leading them to be involved in many biological processes. We report here the biochemical and biophysical characterization of the Neurospora crassa RVB-1/RVB-2 complex. Chromatographic analyses revealed that the complex (APO) predominantly exists as a dimer in solution although hexamers were also observed. Nucleotides influence the oligomerization state, while ATP favors hexamers formation, ADP favors the formation of multimeric states, likely dodecamers, and the Molecular Dynamics (MD) simulations revealed the contribution of certain amino acid residues in the nucleotide stabilization. The complex binds to dsDNA fragments and exhibits ATPase activity, which is strongly enhanced in the presence of DNA. In addition, both GFP-fused proteins are predominantly nuclear, and their nuclear localization signals (NLS) interact with importin-α (NcIMPα). Our findings show that some properties are specific of the fungus proteins despite of their high identity to orthologous proteins. They are essential proteins in N. crassa, and the phenotypic defects exhibited by the heterokaryotic strains, mainly related to growth and development, indicate N. crassa as a promising organism to investigate additional biological and structural aspects of these proteins.
Publisher: Elsevier BV
Date: 03-2020
DOI: 10.1016/J.BIOCHI.2020.01.010
Abstract: Envenoming by snakebite is an important global health issue that has received little attention, leading the World Health Organization to naming it as neglected tropical disease. Several snakebites present serious local symptoms manifested on victims that may not be efficiently neutralized by serum therapy. Phospholipase A
Publisher: Elsevier BV
Date: 08-2021
Publisher: Springer Science and Business Media LLC
Date: 20-11-2019
DOI: 10.1038/S41598-019-53755-5
Abstract: The World Health Organization recently listed snakebite envenoming as a Neglected Tropical Disease, proposing strategies to significantly reduce the global burden of this complex pathology by 2030. In this context, effective adjuvant treatments to complement conventional antivenom therapy based on inhibitory molecules for specific venom toxins have gained renewed interest. Varespladib (LY315920) is a synthetic molecule clinically tested to block inflammatory cascades of several diseases associated with elevated levels of secreted phospholipase A 2 (sPLA 2 ). Most recently, Varespladib was tested against several whole snake venoms and isolated PLA 2 toxins, demonstrating potent inhibitory activity. Herein, we describe the first structural and functional study of the complex between Varespladib and a PLA 2 -like snake venom toxin (MjTX-II). In vitro and in vivo experiments showed this compound’s capacity to inhibit the cytotoxic and myotoxic effects of MjTX-II from the medically important South American snake, Bothrops moojeni . Crystallographic and bioinformatics analyses revealed interactions of Varespladib with two specific regions of the toxin, suggesting inhibition occurs by physical blockage of its allosteric activation, preventing the alignment of its functional sites and, consequently, impairing its ability to disrupt membranes. Furthermore, based on the analysis of several crystallographic structures, a distinction between toxin activators and inhibitors is proposed.
Publisher: Cold Spring Harbor Laboratory
Date: 06-09-2021
DOI: 10.1101/2021.09.06.458705
Abstract: Trypanosoma cruzi , the etiological agent of Chagas disease, faces a variety of environmental scenarios during its life cycle in both invertebrate and vertebrate hosts, which include changes in the redox environment that requires a fine regulation of a complex antioxidant arsenal of enzymes. Reversible post-translational modifications, as lysine acetylation, are a fast and economical way for cells to react to environmental conditions. Acetylation neutralizes the lysine positive charge conferring novel properties to the modified proteins, from changes in enzymatic activity to subcellular localization. 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 sirtuin 3 (TcSir2rp3) was involved in the activity control of TcSODA. We observed an increased resistance to hydrogen peroxide and menadione two oxidant compounds in parasites overexpressing TcSir2rp3. Increased resistance was also found for benznidazole and nifurtimox, the two drugs available for treatment of Chagas disease, known to induce reactive oxidative and nitrosactive species in the parasite. In parallel, TcSir2rp3 overexpressing parasites showed parasites showed a reduction in the ROS levels after treatment with benznidazole and nifurtimox, suggesting a role of TcSir2rp3 in the oxidative stress response. To better understand the way TcSir2rp3 could contributes to oxidative stress response, we analyzed the expression of a key antioxidant enzyme, TcSODA, in the TcSir2rp3 overexpressing parasites and did not detect any increase in protein levels of this enzyme. However, we found that parasites overexpressing TcSir2rp3 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 similar region in the protein structure as K68 in human manganese superoxide dismutase (MnSOD), responsible to regulates 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 of hydrogen bonding pattern to neighbor residues, specifically D94 and E96, suggesting a key participation of this residue to modulate the affinity to O 2 - by changing the charge availability on the surface of the enzyme. 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 and opening the opportunity to explore protein acetylation as potential drug target in this parasite.
Publisher: Springer Science and Business Media LLC
Date: 09-07-2018
DOI: 10.1038/S41598-018-28584-7
Abstract: Local myonecrosis is the main event resulting from snakebite envenomation by the Bothrops genus and, frequently, it is not efficiently neutralized by antivenom administration. Proteases, phospholipases A 2 (PLA 2 ) and PLA 2 -like toxins are found in venom related to muscle damage. Functional sites responsible for PLA 2 -like toxins activity have been proposed recently they consist of a membrane docking-site and a membrane rupture-site. Herein, a combination of functional, biophysical and crystallographic techniques was used to characterize the interaction between suramin and MjTX-I (a PLA 2 -like toxin from Bothrops moojeni venom). Functional in vitro neuromuscular assays were performed to study the biological effects of the protein-ligand interaction, demonstrating that suramin neutralizes the myotoxic effect of MjTX-I. Calorimetric assays showed two different binding events: (i) inhibitor-protein interactions and (ii) toxin oligomerization processes. These hypotheses were also corroborated with dynamic light and small angle X-ray scattering assays. The crystal structure of the MjTX-I/suramin showed a totally different interaction mode compared to other PLA 2 -like/suramin complexes. Thus, we suggested a novel myotoxic mechanism for MjTX-I that may be inhibited by suramin. These results can further contribute to the search for inhibitors that will efficiently counteract local myonecrosis in order to be used as an adjuvant of conventional serum therapy.
Location: Brazil
Location: Brazil
No related grants have been discovered for Antoniel Augusto Severo Gomes.