Menaquinone (vitamin K2) biosynthesis in bacteria is a crucial metabolic pathway involved in the production of this essential electron carrier, which plays a central role in anaerobic and aerobic respiration. The process begins with chorismate, a product of the shikimate pathway, which is converted into o-succinylbenzoate (OSB) through a series of enzymatic steps involving chorismate lyase, o-succinylbenzoate synthase, and other enzymes. OSB is then ligated with Coenzyme A (CoA) to form o-succinylbenzoyl-CoA, which undergoes cyclization and further modifications, including the attachment of a polyprenyl side chain by polyprenyltransferase, yielding menaquinone. The length of the side chain varies among species, depending on the type of polyprenyl synthase. Menaquinone serves as a critical component of the electron transport chain in many bacteria, especially during anaerobic respiration, by shuttling electrons between membrane-bound complexes and facilitating proton motive force generation. This pathway is particularly significant in Gram-positive bacteria, such as Bacillus and Staphylococcus species, and some facultative anaerobes. Beyond energy metabolism, menaquinone also has antioxidant properties, protecting cells from oxidative stress. Given its importance, menaquinone biosynthesis is a potential target for developing antibiotics against pathogenic bacteria.

Menaquinone biosynthesis References