Figure 1. Metabolic schematic of glycolysis and gluconeogenesis.

GlpX (rv1099c) encodes the only known FBPase in the Mtb genome and controls the rate-limiting step of gluconeogenesis. Other enzymes of the gluconeogenesis pathway are encoded by pckA (phosphoenolpyruvate carboxykinase), eno (enolase), gpm1 (phosphoglycerate mutase), pgk (phosphoglycerate kinase), gap (glyceraldehyde 3-phosphate dehydrogenase), tpi (triose phosphate isomerase), fba (fructose bisphosphate aldolase) and pgi (glucose 6-phosphate isomerase). Also shown are ppgK (polyphosphate glucokinase), glkA (glucokinase) and pfkA and pfkB (phosphofructokinases), which encode glycolysis-specific enzymes. 1,3BPG, 1,3-bisphosphoglycerate; 2PG, 2-phosphoglycerate; 3PG, 3-phosphoglycerate; DHAP, dihydroxyacetone phosphate; F6P, fructose 6-phosphate; FBP, fructose 1,6-bisphosphate; G3P, glyceraldehyde 3-phosphate; G6P, glucose 6-phosphate; OAA, oxaloacetate; PEP, phosphoenolpyruvate; PYR, pyruvate.