Microbial Terpenes: A Perspective on Their Chemistry and Biosynthesis

Abstract

This personal account summarizes our ongoing work on the bioorganic chemistry of diverse microbial terpenoids. First, two selected total syntheses that were recently completed in our group are presented. We then show how the fundamental technique for our analytical work, closed-loop stripping apparatus (CLSA) in combination with gas chromatography/mass spectrometry (GC/MS), can be used to efficiently identify volatile natural products from various bacteria and fungi. The largest compound class among these volatiles is the terpenes. The CLSA technique can also be successfully applied to study interesting problems of the sometimes puzzling biosynthetic pathways towards terpenes. For this purpose we have developed two new CLSA-based methods, the first using 13C-labeled precursors in feeding studies which allow for structure elucidations of microgram amounts of terpenes in complex headspace mixtures, and the second, a genome-mining approach via heterologous expression for the rapid chemical characterization of bacterial terpene cyclases. Recent developments in our laboratory include mechanistic investigations based on enzyme structural data in combination with site-specific mutations of terpene cyclases. 1 Introduction 2 Total Synthesis of Glaciapyrrole A and Tricho-acorenol 3 Feeding Experiments with Deuterated Precursors 4 The IspH Reaction 5 Feeding Experiments with 13C-Labeled Precursors 6 Genome Mining and Closed-Loop Stripping Apparatus 7 Conclusion