Caracterização estrutural e avaliação do potencial antibacteriano em combinação com antibióticos de uma lectina da esponja marinha Aplysina fulva

Abstract

Sponges are animals belonging to the phylum Porifera and are among the organisms with the simplest cellular organization among the metazoans. Lectins are proteins and glycoproteins that bind reversibly to carbohydrates without altering their structure, and are identified in many different taxa. In marine sponges, lectins can perform a variety of functions, such as cell interaction, spiculogenesis and defense. In addition, some of these proteins show high biotechnological potential due to their interaction with carbohydrates and the ability to recognize specific carbohydrates from the bacterial plasma membrane. The determination of the amino acid sequence of these proteins is essential to better understand their functions, as well as to evaluate evolutionary and phylogenetic factors among species. Therefore, the present work aimed to perform the structural characterization of the lectin from the marine sponge Aplysina fulva (AFL) and to evaluate the antibacterial effect of the lectin in association with antibiotics, against strains of pathogenic bacteria. AFL was purified by affinity chromatography under reducing conditions. The primary structure was analyzed by sequential mass spectrometry (MS/MS). AFL is a protein that in the presence of reducing agent forms a 64 kDa tetramer and in the absence of reducing agent forms a 44 kDa trimer. The average molecular mass obtained by mass spectrometry resulted in a dimer of 31,673 Da. The peptides obtained after tryptic digestion were determined by mass spectrometry (MS/MS) and the sum of the amino acids represent 87% of the intact mass obtained by mass spectrometry. The partial amino acid sequence of the lectin was submitted to the Smart program and the tool indicated a galectin domain for AFL. In addition, AFL potentiated the effect of ampicillin and tetracycline antibiotics against Staphylococcus aureus ATCC 700698, Staphylococcus epidermidis ATCC 35984 and Escherichia coli ATCC 11303.