The biosynthesis of high-value chemicals is commonly limited by redox imbalances in cells, where excess NADPH accumulation can have a toxic effect on the host cell, hindering production of the desired product. Transhydrogenase systems provide a solution to this problem by rebalancing NADPH and NADH concentrations to meet metabolic demands during biosynthesis. However, experimental testing and mechanistic understanding of transhydrogenase systems are incomplete, leaving room for improvement here. Recently, a unique counter-enzyme complex from Bacillus subtilis , composed of GudB and GltAB, was discovered as a counter-enzyme complex that coupled transhydrogenation to central metabolism. This project aims to characterize the biophysical basis of GltAB-GudB autoregulation using time-resolved cryoEM to fully disentangle the mechanisms of GltAB-GudB counter-enzyme regulation, such that it may be rationally engineered into synthetic circuits to optimize biosynthetic projects in various host organisms. This work will expand a toolkit of natural and engineered transhydrogenase systems toward modular, tunable systems for metabolic engineering.
Sherry et al. (Sun,) studied this question.