A reverse glyoxylate shunt to build a non-native route from C-4 to C-2 in Escherichia coli

作者：Mainguet Samuel E; Gronenberg Luisa S; Wong Sio Si; Liao James C^*

来源：Metabolic Engineering, 2013, 19: 116-127.

DOI：10.1016/j.ymben.2013.06.004

• Glyoxylate shunt
• Central metabolism
• Non-native pathways
• Acetyl-coA biosynthesis
• Reversibility
• Primary metabolism

Most central metabolic pathways such as glycolysis, fatty acid synthesis, and the TCA cycle have complementary pathways that run in the reverse direction to allow flexible storage and utilization of resources. However, the glyoxylate shunt, which allows for the synthesis of four-carbon TCA cycle intermediates from acetyl-CoA, has not been found to be reversible to date. As a result, glucose can only be converted to acetyl-CoA via the decarboxylation of the three-carbon molecule pyruvate in heterotrophs. A reverse glyoxylate shunt (rGS) could be extended into a pathway that converts C-4 carboxylates into two molecules of acetyl-CoA without loss of CO2. Here, as a proof of concept, we engineered in Escherichia coli such a pathway to convert malate and succinate to oxaloacetate and two molecules of acetyl-CoA. We introduced ATP-coupled heterologous enzymes at the thermodynamically unfavorable steps to drive the pathway in the desired direction. This synthetic pathway in essence reverses the glyoxylate shunt at the expense of ATP. When integrated with central metabolism, this pathway has the potential to increase the carbon yield of acetate and biofuels from many carbon sources in heterotrophic microorganisms, and could be the basis of novel carbon fixation cycles.

• 出版日期2013-9