Related Experiment Video
Updated: May 7, 2026

Single Liposome Measurements for the Study of Proton-Pumping Membrane Enzymes Using Electrochemistry and Fluorescent Microscopy
Published on: February 21, 2019
Menaquinone biosynthesis: formation of aminofutalosine requires a unique radical SAM enzyme
Nilkamal Mahanta1, Dmytro Fedoseyenko, Tohru Dairi
1Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
Abstract:
Menaquinone (MK, vitamin K2) is a lipid-soluble molecule that participates in the bacterial electron transport chain. In mammalian cells, MK functions as an essential vitamin for the activation of various proteins involved in blood clotting and bone metabolism. Recently, a new pathway for the biosynthesis of this cofactor was discovered in Streptomyces coelicolor A3(2) in which chorismate is converted to aminofutalosine in a reaction catalyzed by MqnA and an unidentified enzyme. Here, we reconstitute the biosynthesis of aminofutalosine and demonstrate that the missing enzyme (aminofutalosine synthase, MqnE) is a radical SAM enzyme that catalyzes the addition of the adenosyl radical to the double bond of 3-[(1-carboxyvinyl)oxy]benzoic acid. This is a new reaction type in the radical SAM superfamily.
Related Concept Videos
Oxidation of Phenols to Quinones
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
The Electron Transport Chain
Inhibitors of the electron transport chain
Rotenone, a widely used pesticide, prevents electron transfer from Fe-S cluster to ubiquinone or Q in...
Radical Formation: Elimination
Electron Transport Chain: Complex I and II
ROS generation is regulated and maintained at moderate levels necessary...
Biosynthesis of Nucleic Acids
Radical Formation: Addition
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an unpaired...

