Expressão recombinante e ensaios de atividade de duas thaumatin-like proteins do Maqui (Aristotelia chilensis)

Abstract

Thaumatin-like Proteins (TLP) are members of the Pathogenesis-Related Proteins family 5 (PR-5), and are present in fungi, plants and invertebrates. In plants, these proteins are involved both in the host’s defense, often associated with antifungal properties, and in the regulation of physiological processes, such as floration or fruit maturation. Maqui (Aristotelia chilensis) is a plant native to South America and intimately related to Chile, being used in the food industry and traditional medicine of the chilean culture. Lately, this plant has received the title of “Superfruit” because of its high anthocyanin content. Since this is a species that has recently gained the spotlight, the prospect for the biotechnological potential of its proteins is still limited. Therefore, this work consisted in the identification, heterologous expression and activity assays of TLP from Maqui. From the transcriptome of the plant cultivated in Temporary Immersion Bioreactors, four sequences were identified, of which two were obtained by cDNA amplification. These were cloned in the expression vector pPICZɑA for the recombinant production in Pichia pastoris expression system. The purified proteins were submitted to assays of β-1,3-Glucanase, inhibition of fungal hyphae growth, osmotic stress tolerance and permeabilization of yeast plasmatic membrane. The results suggest that the TLP from Maqui are capable of hydrolyzing β-glucans and also able to permeabilize Pichia pastoris plasmatic membrane, although they did not show any inhibition on the growth of fungal hyphae or increased the host’s osmotic stress tolerance.