A Systems Biology Approach to Detect the Hidden Reactions of Terpenoid Quinone Metabolism

Terpenoid quinones are electron and proton carriers that are at the core of the energy production machinery of most living organisms. Historically, studying the metabolism of these essential compounds has been difficult, owing to cognate biosynthetic mutants that are often lethal as well as to the minute and unstable pools of metabolites involved. Using specific examples taken from the biosynthetic pathways of phylloquinone (vitamin K1), plastoquinone, and ubiquinone (coenzyme Q), I will show how gene‐network modeling and comparative genomics can be used to identify candidate genes for missing ‐or even unsuspected‐ enzymatic steps, and how these can be tested via in vivo isotopic labeling and targeted metabolite profiling in weak allele mutants.