Figure 1: Menaquinone biosynthesis pathways.

Classical menaquinone and alternative futalosine pathways from chorismate. MqnA: futalosine synthase, MqnB: futalosine hydrolase, MqnC: dehypoxanthinyl futalosine cyclase, MqnD: 1,4-dihydroxy-6-naphthoate synthase. MenF: isochorismate synthase, MenC: o-succinylbenzoate synthase. MenD: 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylate synthase. MenH: (1R, 6R)-6-hydroxy-2-succinylcyclohexa-2, 4-diene-1-carboxylate synthase.