The wealth of knowledge about central carbon metabolism has allowed organisms to be engineered for the production of useful molecules and has provided insight into many diseases, including obesity, diabetes, atherosclerosis, and some cancers (1, 2). Further advances in metabolic engineering have the potential to significantly impact both environmental protection and human health. For example, CO2 levels in the atmosphere are rising as human consumption of carbon-based fuels increases (3, 4), and the consequences on a 50-year timescale are expected to be dramatic. The goal of this proposal is to improve our understanding of central carbon metabolism by determining the changes needed to convert an organism from a heterotrophic to autotrophic mode of growth. Specifically, I propose to convert the well-characterized heterotrophic bacterium E. coli to an autotrophic mode of growth in which it fixes CO2 as its sole carbon source, using the Calvin cycle. This will involve introduction of foreign genes, targeted mutation of endogenous genes, quantitative modeling and measurement of metabolic fluxes, and directed evolution. The results will provide information about the regulation, evolution and plasticity of central carbon metabolism, and may enable new methods for carbon sequestration from the atmosphere.
Furthering our understanding of how the E. coli metabolic network can adapt to major changes will have at least a two-fold benefit. First, we hope to shed light on how bacterial metabolism can adapt to compensate for major changes to key steps of carbon utilization. Secondly, we hope to use this knowledge to drive the development of a rationally engineered strain of E. coli capable of surviving solely on carbon dioxide for the purpose of coupling atmospheric CO2 remediation with the production of molecules with medicinal or other useful properties.