Exploring ATP-Grasp and Methyltransferase Activity in Actinopeptides in Streptomyces albus

Abstract

Recently, there has been increased interest in the potential biological and medical engineering applications of ribosomally synthesized and post-translationally modified peptides (RiPPs): these small molecules, which are generally easier to identify than other natural products, exist in a variety of organisms and carry out several diverse biological functions, including antimicrobial resistance. Structurally, it is thought that RiPPs contain one relatively short precursor protein sequence, surrounded by the enzymes that help stabilize the peptide group. One such family of enzyme, ATP-Grasp, has been shown to play some sort of role in generating greater yields of protein in Thermobifida fusca. This study seeks to continue investigating the function and importance of the ATP-Grasp enzyme but under native conditions in a strain of Streptomyces albus. Three different gene cluster samples, one consisting of just the precursor peptide sequence, one with the precursor and ATP-Grasp, and one with the precursor, ATP-Grasp, and methyltransferase, were transformed into the pQE80 vector and expressed and purified. Although ultimately the LCMS results proved inconclusive, initial gel bands seemed to reveal different modifications made by the ATP-Grasp enzyme and methytransferase to the precursor peptide sequence.