Functional and structural studies of a Phospholipase A(2)-like protein complexed to zinc ions: Insights on its myotoxicity and inhibition mechanism

Author(s)

Borges, Rafael J. ; Cardoso, Fabio F. ; Fernandes, Carlos A. H. ; Dreyer, Thiago R. ; de Moraes, Delkia S. ; Floriano, Rafael S. ; Rodrigues-Simioni, Lea ; Fontes, Marcos R. M.

• Document type: Journal article
• Source: BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS; v. 1861, n. 1, p. 11-pg., 2017-01-01.

Abstract

Background: One of the main challenges in snakebite envenomation treatment is the development of stable, versatile and efficient and-venom therapies. Local myotoxicity in accidents involving snakes from the Bothrops genus is still a consequence of serum therapy inefficient neutralization that may lead to permanent sequelae in their victims. One of the classes of toxins that participate in muscle necrosis is the PLA(2)-like proteins. The aim of this work was to investigate the role of zinc ions in the inhibition of PLA(2)-like proteins and to advance the current knowledge of their action mechanism. Methods: Myographic and electrophysiological techniques were used to evaluate the inhibitory effect of zinc ions, isothermal titration calorimetry assays were used to measure the affinity between zinc ions and the toxin and Xray crystallography was used to reveal details of this interaction. Results: We demonstrated that zinc ions can effectively inhibit the toxin by the interaction with two different sites, which are related to two different mechanism of inhibition: preventing membrane disruption and impairing the toxin state transition. Furthermore, structural study presented here included an additional step in the current myotoxic mechanism improving the comprehension of the allosteric transition that PLA(2)-like proteins undergo to exert their function. Conclusions: Our findings show that zinc ions are inhibitors of PLA(2)-like proteins and suggest two different mechanisms of inhibition for these ions. General significance: Zinc is a new candidate that can assist in and-venom treatments and can promote the design of new and even more accurate structure-based inhibitors for PLA(2)-like proteins. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 15/17286-0 - Structural and functional studies aiming to understand the role of snake venoms toxins and how to inhibit their biological activity
• Grantee: Marcos Roberto de Mattos Fontes
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/00873-4 - Structural studies of phospholipases A2 myotoxic of bothropic venom complexed with inhibitor and optimization of new crystallographic methodologies
• Grantee: Rafael Junqueira Borges
• Support Opportunities: Scholarships in Brazil - Doctorate