Fig. 3
From: Bacteria increase host micronutrient availability: mechanisms revealed by studies in C. elegans
E. coli tetrahydrofolate synthesis and the one-carbon metabolism folate cycle. The THF precursors, para-aminobenzoic acid (PABA) (synthesized from chorismate and glutamine), and pteridine (synthesized from GTP) are conjugated to form dihydropteroate, which is glutamylated and reduced to form THF. THF derivatives are generated by the acceptance and transfer of one-carbon units in reactions that facilitate cellular biosynthesis and methylation reactions