Methanol is an important feedstock in the chemical industry but has had trouble gaining traction as a feedstock in biotechnological processes due to the difficulty of bacteria utilizing it as a carbon and energy source. The first enzyme, methanol dehydrogenase (MDH), which converts methanol to formaldehyde favors the reverse reaction and this is the key in limiting engineered E. coli cells from utilizing methanol at a fast rate. In metabolic engineering there are myriad ways to increase flux through a pathway to drive product formation. To bypass this thermodynamic barrier, we created a “kinetic trap” to prevent formaldehyde from accumulating and enable methanol to be consumed continuously at the highest rate.  Several protein-ligand interaction pairs were used to link methanol dehydrogenase (MDH) with hexulose phosphate synthase (HPS) and hexulose phosphate isomerase (PHI), which irreversibly converts formaldehyde and ribulose 5 phosphate to fructose 6-phosphate.  To promote further methanol consumption, an “NADH sink” was created by using <i>E. coli </i>lactate dehydrogenase (LDH) as an NADH scavenger to consume NADH following methanol oxidation, thereby enhancing methanol consumption by the MDH. Combining the assembly of MDH-HPS-PHI complexes with the “NADH sink” enabled a 100-fold improvement in fructose 6-phosphate production compared to unassociated enzymes confirming that enzymatic assembly improves methanol utilization.

Enzyme assembly for increased methanol utilization

251st National Meeting (2016)

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