HARNESSING NATURE’S MACHINERY: CHARACTERIZATION OF BACTERIAL BIOSYNTHETIC ENZYMES FOR CHALLENGES IN ORGANIC SYNTHESIS
Bacteria appeared on Earth as early at 4.1 billion years ago. Since then, these microorganisms have evolved to compete and communicate using secondary metabolites, or natural products. This billion-year molecular “arms race” has enabled bacteria to biosynthesize complex molecules that are challenging for humans to access via traditional organic synthesis. This dissertation presents three distinct projects involving the characterization of bacterial enzymes from secondary metabolism and their applications in green synthesis. In Chapters 1-3, we discuss the identification of enzymes involved in aziridine-containing natural product biosynthesis and our characterization of key cryptic sulfotransferases from ficellomycin, vazabitide A, and the azinomycins production; and the development of our novel method for biocatalytic N-heterocycle formation. We also include a discussion of our attempts towards enzymatic cofactor generation and recycling to improve the activity of our cryptic sulfotransferases. In Chapter 4, we report novel activity of DszA, a C–S bond cleavage enzyme in the ‘4S’ sulfur pathway. In Chapter 5, we describe our on-going efforts to characterize the chemo- and atroposelectivity of DszA and novel homologs. We anticipate future engineering campaigns will provide a novel biocatalytic approach to the production of high value, enantioenriched biaryl compounds like 1,1'-bi-2-naphthol (BINOL). Finally, in Chapter 6, we report the first in vitro characterization of Mas10, a putative amide synthase proposed to forge the 13-membered macrolactam in the biosynthesis of the microansamycins. Here, we demonstrate the selectivity for N-acetylation over O-acetylation by Mas10 and related homologs with simple model substrates, setting the stage for use in future chemoenzymatic total syntheses.
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