formaldehyde assimilation via RuMP pathway formaldehyde assimilation via ribulose monophosphate cycle KEGG:map01120 KEGG:map00680 KEGG:map00040 pathway UPa:UPA00294 GO:0019647 Formaldehyde is the key intermediate in C1 metabolism and can be assimilated via the ribulose monophosphate (RuMP) pathway. The ribulose monophosphate (RuMP) pathway, involving 3-hexulose-6-phosphate synthase (HPS) and 6-phospho-3-hexuloisomerase (PHI), is now recognized as a widespread prokaryotic pathway for formaldehyde fixation and detoxification. The RuMP pathways consists of three main parts: i) fixation, ii) cleavage and iii) rearrangement. i) Fixation stage: formaldehyde and ribulose-5-phosphate (RuMP) are condensed to form hexulose-6-phosphate (HuMP), which in turn is converted to fructose-6-phosphate (FMP) by hexulosephosphate isomerase (HPI). By the assimilation of three formaldehyde molecules, three molecules of FMP are created. RuMP cycle ribulose monophosphate pathway PMID:16788179 carbohydrate metabolism one-carbon metabolism