Sequence analysis of the cDNA encoding for SpCTx: a lethal factor from scorpionfish venom (Scorpaena plumieri)

Abstract

BackgroundLethal factors are multifunctional oligomeric proteins found in the venomous apparatus of Scorpaeniformes fish. These toxins elicit not only an array of biological responses in vitro but also cardiovascular disorders and strong hemolytic, nociceptive and edematogenic activities in vivo. This work describes the cloning and molecular identification of two toxin subunits, denominated Sp-CTx-α and Sp-CTx-β, from scorpionfish venom (Scorpaena plumieri).MethodsThe primary structures were deduced after cDNA amplification by PCR with primers from conserved sequences described in Scorpaeniformes toxins. Following DNA sequencing and bioinformatic analysis, the tridimensional structures of both subunits were modeled.ResultsThe translated sequences (702 amino acids, each subunit) show homology with other lethal factors, while alignment between Sp-CTx-α and Sp-CTx-β shows 54% identity. The subunits lack N-terminal signal sequences and display masses of approximately 80 kDa each. Both Sp-CTx subunits display a B30.2/SPRY domain at the C-terminal region with typically conserved motifs as described in these toxins. Secondary structure prediction identified six α-helices 18 residues long in both α and β subunits, some of them amphiphilic with their N-terminal flanked by many basic residues, creating a cationic site associated with the cytolytic activity of these toxins. Antimicrobial potential sites were identified in Sp-CTx and share some features with other peptides presenting variable and broad-spectrum activity. A phylogenetic tree built to represent these toxins supports the proximity between scorpionfish, lionfish and stonefish.ConclusionThe study identified a putative toxin protein whose primary structure is similar to other fish toxins and with potential for production of antivenom against scorpionfish envenomation in Brazil. As a prelude to structure-function studies, we propose that the toxin is structurally related to pore-forming marine toxins.Electronic supplementary materialThe online version of this article (10.1186/s40409-018-0158-7) contains supplementary material, which is available to authorized users.

Male Age Influences Re-mating Incidence and Sperm Use in Females of the Dengue Vector Aedes aegypti

“…Female Aedes aegypti mosquitoes—vectors of the dengue ( Guzman and Harris, 2015 ), Zika ( Alfonso-Parra and Avila, 2018 ) and yellow fever viruses ( Chippaux and Chippaux, 2018 ), among others—display significantly reduced sexual receptivity shortly after mating ( Degner and Harrington, 2016a ). The reduction in sexual receptivity is mediated by SFPs produced in the accessory gland of the male reproductive tract ( Craig, 1967 ; Helinski et al, 2012a ).…”

The perspective of fish venom: An overview of the physiology, evolution, molecular and genetics

“…Because there are few fish toxin sequences available as references, most of them are from Scorpaenidae and Synanceiidae families, it is challenging to research fish toxins and to create quick and effective techniques for wide exploration of toxin proteins or genes (Xie et al, 2017). Some recent studies have isolated and provided several toxins sequences using different techniques (Smith and Wheeler, 2006;Xie et al, 2016;Costa et al, 2018;Xie et al, 2019;Campos et al, 2021;Lopes-Ferreira et al, 2022), but due to a given number of venomous fish (>2000 species) (Saggiomo et al, 2021), it would be just a small portion of it.…”

“…However, this method takes a long time and uses a lot of crude venoms. Studies have shown, cDNA cloning and genomic sequencing were used to identify the full amino acids sequences of various toxins including SNTX (Chun, 2004), verrucotoxin (VTX) (Ziegman and Alewood, 2015), cytolysins (Campos et al, 2021), lectin (Nakagawa et al, 2015;Ziegman et al, 2019;Lopes-Ferreira et al, 2022), Sp-CTx (Costa et al, 2018), and hyaluronidases (Ziegman et al, 2019) and among the others in which most of them exhibit high sequence identity among and between species.…”

Fish Cytolysins in All Their Complexity

“…The complete amino acid sequences of several fish cytolysins were determined by cDNA cloning and/or genomic sequencing [13,14,39,40,45,[52][53][54] (Figure 2). Alignments were performed on Muscle server.…”

“…The presence of the MACPF/CDC domain in fish cytolysins [53,55] and the inhibitory effect of cholesterol on the hemolytic activity of Sp-CTx [43] suggest that this lipid is also required for the interaction between these toxins and the erythrocyte membrane, much like the MACPF/CDC proteins found in bacteria.…”