CANCELED - CBE Seminar (Zoom): The Reductive Glycine Pathway, a Plug-and-Play Tool for One-carbon Assimilation

Zoom link to be distributed by CBE department
Arren Bar-Even, Ph.D.

Systems and Synthetic Metabolism Laboratory
Max Planck Institute of Molecular Plant Physiology
Potsdam, Germany

Abstract: Engineering a biotechnological microorganism for growth on one-carbon (C1) compounds is a key step toward a circular carbon economy. This strategy integrates abiotic and biotic catalysis, harnessing their respective advantages while bypassing their drawbacks: CO2 is chemically activated to produce a C1 compound at high specificity and efficiency, while a microorganism utilizes the C1 intermediate for the production of a complex product.

Unlike C1 gases, formate and methanol can be easily stored and transported and are completely miscible, bypassing mass transfer barriers and potentially supporting higher microbial productivities. Moreover, we have recently shown that microbial conversion of methanol and formate can support higher energetic efficiencies than possible with other C1 compounds.

As natural formatotrophs and methylotrophs are generally less suitable for industrial use, adapting a model biotechnological microorganism for growth on formate or methanol has been a key goal of the synthetic biology community in the last decade.

We designed the reductive glycine pathway as the most efficient route for the assimilation of C1 compounds under aerobic conditions. We engineered the model bacterium Escherichia coli for growth on formate via reductive glycine pathway. Sequential genomic introduction of the four metabolic modules of the pathway resulted in a strain capable of growth on formate with a doubling time of ~70 hours and growth yield of ~1.5 gCDW / mol-formate. Further evolution decreased doubling time to less than six hours and improved biomass yield to 3.2 gCDW / mol-formate. Growth on methanol was achieved by the expression of methanol dehydrogenase in the evolved strain.

We also redesigned C. necator metabolism for formate assimilation via the reductive glycine pathway. By integrating glycine biosynthesis and assimilation modules, we were able to replace C. necator’s Calvin cycle with the synthetic pathway and achieve formatotrophic growth. We then engineered more efficient glycine metabolism and used short-term evolution to optimize pathway activity, doubling the growth yield on formate and quadrupling the growth rate.

These studies indicate that the reductive glycine pathway is a flexible tool that can be implemented in various hosts, granting them the ability to assimilate C1 carbon sources, and thus paving the way toward a sustainable carbon economy.

Bio: Arren Bar-Even completed his bachelor's degree as part of the excellence program at the Technion, the Israeli Institute of Technology. His master’s degree in bioinformatics was completed at the Weizmann Institute of Science. He spent several years in the biotech industry before returning to academia to complete a doctorate in biochemistry at the Weizmann Institute of Science, specializing in the design principles of cellular metabolism. He joined the Max Planck Institute of Molecular Plant Physiology in 2015, as head of the Systems and Synthetic Metabolism Lab, studying the biochemical logic of metabolic pathways and their applications for the design and implementation of metabolic designs that address humanity’s needs in food, chemical and energy production.