Spatial Distribution and Biochemical Characterization of Serine Peptidase Inhibitors in the Venom of the Brazilian Sea Anemone <i>Anthopleura cascaia</i> Using Mass Spectrometry Imaging
Daiane Laise da Silva,
Rodrigo Valladão,
Emidio Beraldo-Neto,
Guilherme Rabelo Coelho,
Oscar Bento da Silva Neto,
Hugo Vigerelli,
Adriana Rios Lopes,
Brett R. Hamilton,
Eivind A. B. Undheim,
Juliana Mozer Sciani,
Daniel Carvalho Pimenta
Affiliations
Daiane Laise da Silva
Programa de Pós-Graduação em Ciências-Toxinologia, Instituto Butantan, Av. Vital Brasil 1500, Butantã, São Paulo 05503-900, Brazil
Rodrigo Valladão
Laboratório de Bioquímica, Instituto Butantan, Av. Vital Brasil 1500, São Paulo 05503-900, Brazil
Emidio Beraldo-Neto
Programa de Pós-Graduação em Ciências-Toxinologia, Instituto Butantan, Av. Vital Brasil 1500, Butantã, São Paulo 05503-900, Brazil
Guilherme Rabelo Coelho
Programa de Pós-Graduação em Ciências-Toxinologia, Instituto Butantan, Av. Vital Brasil 1500, Butantã, São Paulo 05503-900, Brazil
Oscar Bento da Silva Neto
Laboratório de Bioquímica, Instituto Butantan, Av. Vital Brasil 1500, São Paulo 05503-900, Brazil
Hugo Vigerelli
Programa de Pós-Graduação em Ciências-Toxinologia, Instituto Butantan, Av. Vital Brasil 1500, Butantã, São Paulo 05503-900, Brazil
Adriana Rios Lopes
Programa de Pós-Graduação em Ciências-Toxinologia, Instituto Butantan, Av. Vital Brasil 1500, Butantã, São Paulo 05503-900, Brazil
Brett R. Hamilton
Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, QLD 4072, Australia
Eivind A. B. Undheim
Centre for Advanced Imaging, University of Queensland, St. Lucia, QLD 4072, Australia
Juliana Mozer Sciani
Laboratório de Farmacologia Molecular e Compostos Bioativos, Universidade São Francisco, Av. São Francisco de Assis, 218, São Paulo 12916-900, Brazil
Daniel Carvalho Pimenta
Programa de Pós-Graduação em Ciências-Toxinologia, Instituto Butantan, Av. Vital Brasil 1500, Butantã, São Paulo 05503-900, Brazil
Sea anemones are known to produce a diverse array of toxins with different cysteine-rich peptide scaffolds in their venoms. The serine peptidase inhibitors, specifically Kunitz inhibitors, are an important toxin family that is believed to function as defensive peptides, as well as prevent proteolysis of other secreted anemone toxins. In this study, we isolated three serine peptidase inhibitors named Anthopleura cascaia peptide inhibitors I, II, and III (ACPI-I, ACPI-II, and ACPI-III) from the venom of the endemic Brazilian sea anemone A. cascaia. The venom was fractionated using RP-HPLC, and the inhibitory activity of these fractions against trypsin was determined and found to range from 59% to 93%. The spatial distribution of the anemone peptides throughout A. cascaia was observed using mass spectrometry imaging. The inhibitory peptides were found to be present in the tentacles, pedal disc, and mesenterial filaments. We suggest that the three inhibitors observed during this study belong to the venom Kunitz toxin family on the basis of their similarity to PI-actitoxin-aeq3a-like and the identification of amino acid residues that correspond to a serine peptidase binding site. Our findings expand our understanding of the diversity of toxins present in sea anemone venom and shed light on their potential role in protecting other venom components from proteolysis.
