Fig. 2

Cupriavidus necator genes involved on 3-HP degradation (a) and the C₃ metabolic network (b). a Putative operons involved in 3-HP metabolism in P. denitrificans (i) and C. necator H16 (ii), together with the proposed upstream-located regulatory genes. Genes encode the following enzymes: (methyl)malonate semialdehyde dehydrogenase (mmsA1, H16_A0273; mmsA2, H16_A3664; mmsA3, H16_B1191), 3-hydroxy-propionate/iso-butyrate dehydrogenase (hpdH, H16_A3663; hbdH, H16_B1190), β-alanine pyruvate transaminase (aptA, H16_A0272), branched-chain acyl-CoA dehydrogenase (acaD, H16_B1192), enoyl-CoA dehydratase (crt, H16_B1189) and 3-hydroxyisobutyryl-CoA hydrolase (hibH; note: the gene is currently annotated to encode an enoyl-CoA hydratase/isomerase, H16_B1188). Divergently transcribed transcriptional regulator genes encode putative homologues of MocR (H16_A0271), LysR (H16_A3665) and AraC (H16_B1193), respectively. Note that only some of the encoded activities contribute to 3-HP metabolism as shown in (b). Sizes of genes and intergenic regions not drawn to scale. b Metabolism of 3-HP and related C₃ compounds in C. necator. Acc, acetyl-CoA carboxylase; Mcd, malonate decarboxylase; PanD, l-aspartate decarboxylase; Pct, propionyl-CoA transferase; PrpE, propionyl-CoA synthase. For all other protein names see (a). Question marks indicate reactions for which C. necator enzymes may exist but have not been experimentally demonstrated