Discovery of fatty acid synthase inhibitors and their biosynthetic pathways by a novel target-directed genome mining strategy

Abstract

In order to avoid self-toxicity, many antibiotic-producing microbes have developed self-resistance mechanisms, with target modification being one frequent example. We propose that extra copies of an essential housekeeping gene found within or adjacent to a biosynthetic pathway may indicate that the compound(s) produced will target the protein encoded by the corresponding housekeeping gene. Thus, a novel and rational target-directed genome mining strategy was developed, by which potential self-resistance genes were analyzed bioinformatically, followed by a PCR-independent cloning and heterologous expression of the intact gene clusters for rapid production of compounds with desired bioactivities. As a proof-of-principle study, two related orphan gene clusters with potential fabF resistance genes were identified and expressed, which led to the isolation of a group of unique thiotetronic acid natural products that inhibit bacterial fatty acid synthase (1 – 9). A notable advantage of this genome mining strategy is that specific molecular targets can be hypothesized in the absence of priori knowledge of the structures of the molecules biosynthesized, and may streamline mechanism of action studies for the products obtained.