Fig. 2.

Schematic of reductive C1 metabolism initiated from rPFOR and reversed PFL. The question mark indicates a missing reaction in C. thermocellum DSM1313 genome annotations. Pink-shaded pathways illustrate the reduction of CO₂ to formate and CO₂ to pyruvate. Yellow-shaded pathways include steps of serine and methionine biosynthesis. Fdh is not annotated in C. thermocellum genome. Fhs, formyl-tetrahydrofolate synthase (clo1313_0030); FolD, methylene-tetrahydrofolate dehydrogenase/cyclohydrolase (clo1313_1120); GlyA, glycine hydroxymethyltransferase (clo1313_1155); MetF, methylene-tetrahydrofolate reductase (clo1313_2132); MS, methionine synthase (clo1313_1587-1588, clo1313_1581-1582, clo1313_0372). Dotted lines indicate multistep catalysis. Carbons in red indicate ¹³C-isotopes propagated from ¹³C-bicarbonate or ¹³C-formate in the tracer experiments.