Structural studies of spirocyclases involved in the polyketide biosynthesis

Abstract

The discovery of new secondary metabolites is a challenge for biotechnologists due to the emergence of superbugs and drug resistance. Therefore, Streptomyces sp. have been widely studied by the pharmaceutical industry in the development of compounds with biological activity, such as antibiotics, antitumor and antiviral drugs. Among the metabolites biosynthesized by Streptomyces sp., there are the polyketides produced by polyketide synthases (PKSs) and modified by tailoring enzymes, which perform a large number of reactions. Recently, these enzymes have attracted attention because of their peculiarities and also by their biotechnological potential in biocatalysis. Among these enzymes, spirocyclases, which are involved in the formation of spirocetal systems, have only recently been characterized. In this project, we will carry out structural studies of spirocyclases found in several gene clusters of polyketides, which the structural bases of their folding and catalytic mechanisms are not yet known. For this, we aim to obtain these enzymes through heterologous expression, purify them by affinity and gel filtration methods and undergo crystallization tests. The crystals obtained will be diffracted using synchrotron radiation and the structures will be solved. The analysis of the structures may reveal new enzymatic and molecular mechanisms involved in the formation of spirocetal systems in avermectins, reveromycins and ionophore polyethers. The results of this project will bring significant contributions to the comprehension of the natural products biosynthesis and biocatalysis, aiming at the production of new antibiotics or antitumors. (AU)