Recombinant expression and in silico evaluation of AreV1, an Arenin variant.

Abstract

In the last decades, plants and animals described in Traditional Medicine practices have gained importance as sources of bioactive molecules since a great number of compounds have been isolated and characterized to develop new drugs. Although most of the current ethnopharmacological studies have focused on research bioactive compounds from plants, members of the anuran family Hylidae have also demonstrated to possess a plethora of molecules in their skin secretions with diverse capabilities. Among peptides, proteins, and low molecular weight compounds secreted by amphibians, protease inhibitors (PIs) have been proposed to be used as antimicrobial and antitumoral drugs that may possess high efficacy and efficiency. Recently, Arenin a Kunitz-like PI was isolated from the skin secretions of the canyon tree frog Dryophytes arenicolor. The DNA sequence encoding Arenin was modified by site-directed mutagenesis via PCR and the resultant variant, AreV1, was cloned, expressed, and purified by IMAC. Its 3D-structure was analyzed in silico through I-TASSER and COFACTOR servers and the structure modelling platform UCSF Chimera to assess the impact of the mutagenesis on the structure and further functionality of AreV1. Dissimilarities between AreV1 and Arenin were found at the C-terminus of the DNA sequence, altering ten amino acids (Leu45, Pro47, Trp48, Lys49, Ile50, Val51, Arg52, Pro53, Pro54 and Ala55). Despite these changes, according to the in silico analysis, the structural stability of AreV1 remained almost identical to Arenin, although the size of the variant polypeptide is three amino acids smaller. The analysis on AreV1 suggests that it has a great potential as trypsin regulator with a Lys13 as the residue located at the centre of the reactive site (P1 site). A tyrosine triplet (Tyr21, Tyr22 and Tyr23) associated with analgesic properties was also observed in AreV1.This research work aims to expand the knowledge on the activity optimization of naturally occurring molecules by presenting the recombinant production, purification and structural analysis of a variant from Arenin.