The first engineered pathway as shown in FIGS. 2 and 3 includes first decarboxylation of 2-ketopimelate to amino caproic acid as described above in the amino caproic engineered pathway (enzymatic steps I followed by enzymatic step 4 or enzymatic step II followed by enzymatic step 8). In some embodiments, an aldehyde dehydrogenase enzyme is expressed and catalyzes the conversion of the amino caproic acid to a 6-aminohexanal intermediate (enzymatic step 5) and a 1-amintransferase enzyme is expressed and catalyzes the conversion of the 6-aminohexanal to HMD (enzymatic step 6). Alternatively, the engineered pathway comprises a phosphorylation step (using a kinase) before the dehydrogenation and the amino transfer enzymatic reactions described above. One should appreciate that the phosphorylation step and the dehydrogenation steps are analogous to the phosphorylation step (catalyzed by an aspartokinase EC 2.7.2.4) and the dehydrogenation step (catalyzed by EC 1.2.1.11 enzyme) involved in the synthesis of aspartate semialdehyde in the Lysine pathway. According to the second engineered pathway, the conversion of 2-aminopimelate produced from α-ketopimelate (enzymatic step II, FIG. 3) to hexamethylenediamine consists of enzymatic steps 9, 10 or 11, and 12 which combine enzymes or homologous enzymes characterized in the Lysine biosynthetic IV pathway. The pathway includes the following substrate to product conversions:
