FIG 1.
Proposed metabolic pathways for lignin-to-PHA bioconversion. Key genes and metabolic intermediates are highlighted in red. Identifications (IDs) of the corresponding genes in A514 are shown. (A) Lignin degradation pathways. Dashed arrows indicate multiple steps. (B) De novo fatty acid biosynthesis. (C) β-Oxidation pathway. After each turn of the cycle, an acyl-CoA (indicated as Cn) that is two carbons shorter than the initial one (indicated as Cn + 2) is generated. The dashed line connects acyl-CoA intermediates of different chain lengths. (D) PHA biosynthesis pathways. (E, F, and G) Expression ratios for alkK homologs and phaG and phaJ genes, as well as for PHA synthetic genes, in A514 that were grown under the low-N conditions, compared to those grown under the high-N conditions. The ratios that were >1 were defined as induced. (H) Expression levels of the phaJ4, phaG, and alkK (PputA514_1839) genes in A514 under both high-N and low-N conditions. The inset in panel H shows the expression level of phaJ4 at an appropriate scale. The expression levels and expression ratios are defined in Materials and Methods.