BoaγPLI: Structural and functional characterization of the gamma phospholipase A2plasma inhibitor from the non-venomous Brazilian snakeBoa constrictor.

Caroline Fabri Bittencourt Rodrigues,Victor Koiti Kavazoi,Tassia Chiarelli,Marcos Hikari Toyama,Caroline Serino-Silva,Karen De Morais-Zani,Alexandre Keiji Tashima,Kathleen Fernandes Grego,Marcelo Pires Nogueira Carvalho,Anita Mitico Tanaka-Azevedo,Israel Silman

doi:10.1371/journal.pone.0229657

Abstract

Plasma in several organisms has components that promote resistance to envenomation by inhibiting specific proteins from snake venoms, such as phospholipases A2 (PLA2s). The major hypothesis for inhibitor’s presence would be the protection against self-envenomation in venomous snakes, but the occurrence of inhibitors in non-venomous snakes and other animals has opened new perspectives for this molecule. Thus, this study showed for the first time the structural and functional characterization of the PLA2 inhibitor from the Boa constrictor serum (BoaγPLI), a non-venomous snake that dwells extensively the Brazilian territory. Therefore, the inhibitor was isolated from B. constrictor serum, with 0.63% of recovery. SDS-PAGE showed a band at ~25 kDa under reducing conditions and ~20 kDa under non-reducing conditions. Chromatographic analyses showed the presence of oligomers formed by BoaγPLI. Primary structure of BoaγPLI suggested an estimated molecular mass of 22 kDa. When BoaγPLI was incubated with Asp-49 and Lys-49 PLA2 there was no severe change in its dichroism spectrum, suggesting a non-covalent interaction. The enzymatic assay showed a dose-dependent inhibition, up to 48.2%, when BoaγPLI was incubated with Asp-49 PLA2, since Lys-49 PLA2 has a lack of enzymatic activity. The edematogenic and myotoxic effects of PLA2s were also inhibited by BoaγPLI. In summary, the present work provides new insights into inhibitors from non-venomous snakes, which possess PLIs in their plasma, although the contact with venom is unlikely.

Highlights

Snake envenomation, reclassified as a neglected tropical disease by the World Health Organization (WHO), can have serious pathophysiological consequences [1,2,3]
Contrasting with the number of PLA2 inhibitors (PLIs) isolated from venomous snakes [14,16], only a small number of this molecule were isolated from non-venomous snakes [19,22], suggesting that the PLI is not restricted to protection against self-envenomation, but it may be involved in other unknown physiological mechanisms that has yet to be determined [23]
The study showed the purification of a γPLI of the non-venomous snake Boa constrictor (BoaγPLI), which has a molecular mass of approximately 22 kDa, oligomerization capacity, and a primary structure similar to the PLI of Lachesis muta

Summary

Introduction

Snake envenomation, reclassified as a neglected tropical disease by the World Health Organization (WHO), can have serious pathophysiological consequences [1,2,3]. NO: The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Methods

Results

Conclusion