Fig. 1

Schematic representation of the natural metabolism and the implemented Shemin pathway for PBG and porphyrin biosynthesis in E. coli from glycerol. Metabolic pathways outlined: glycolysis, glycine biosynthesis, pyruvate carboxylation, and oxidative TCA cycle (in black); glyoxylate shunt in the TCA cycle (in light brown); reductive branch of TCA cycle (in blue); Shemin/C4 pathway and its key precursors (in green); porphyrin formation (in red). Colored proteins: mutations (in red); heterologous expression (in purple); carbon source: glycerol (in blue). Metabolite abbreviations: 5,10-MTH 5,10-methenyltetrahydrofolic acid, 5-ALA 5-aminolevulinic acid, 3-PG 3-phosphoglycerate, 3-PP 3-phosphooxypyruvate, O-P-Serine O-phospho-L-serine, PBG porphobilinogen; HMB hydroxymethylbilane, PEP phosphoenolpyruvate, CoA coenzyme A. The number of carbon atoms for each metabolite is specified in orange/red. Protein abbreviations: AceA isocitrate lyase, AceB malate synthase A, AceK isocitrate dehydrogenase kinase/phosphatase, AckA acetate kinase, AdhE aldehyde-alcohol dehydrogenase, FHL formate hydrogenlyase, HemA 5-aminolevulinate synthase, HemB 5-aminolevulinate dehydratase, HemC porphobilinogen deaminase, IclR AceBAK operon repressor, IDH isocitrate dehydrogenase, IDH-P isocitrate dehydrogenase-phosphate, LdhA lactate dehydrogenase A, PC pyruvate carboxylase, PckA phosphoenolpyruvate carboxykinase, PDH pyruvate dehydrogenase, PFL pyruvate formate-lyase, PK pyruvate kinase, PPC phosphoenolpyruvate carboxylase, Pta phosphotransacetylase, SdhA succinate dehydrogenase complex (subunit A)