Probing Intracellular Yeast Metabolism With Deuterium Magnetic Resonance Spectroscopy

Metabolomics provides snapshots of states of metabolites under specific conditions, with nuclear magnetic resonance (NMR) being one of the few noninvasive techniques. However, when applied to intact cells (e.g., yeast or mammalian cells) or tissues, traditional 1H NMR often suffers from overlapping signals from numerous metabolites and intracellular macromolecules such as proteins. To address this, we employed deuterium-labeled tracers that do not suffer from background interference and streamline targeted flux analysis. Deuterium magnetic resonance spectroscopy (DMRS) enables rapid, noninvasive measurement of metabolic flux without specialized equipment. In our study, we first measured T1, T2, and chemical shifts for 26 deuterium-labeled compounds in phosphate-buffered saline: parameters functional for optimal DMRS settings. Among the 26 deuterated compounds tested with food-grade baker's yeast (Saccharomyces cerevisiae) as an easily accessible model solution, we observed and tracked the real-time consumption of pyruvate, glucose, fumarate, acetone, and nicotinamide. We redirected yeast metabolism by (i) varying concentrations of added pyruvate and (ii) osmotic pressure by changing buffer density. This study underscores DMRS's potential as a robust, versatile tool for dissecting metabolic transformations exemplified here with the convenient yeast cell systems active for hundreds of minutes under typical NMR observation conditions.