Rational Engineering of Non-Ubiquinone Containing Corynebacterium glutamicum for Enhanced Coenzyme Q(10) Production

Coenzyme Q(10) (CoQ(10)) is a lipid-soluble compound with important physiological functions and is sought after in the food and cosmetic industries owing to its antioxidant properties. In our previous proof of concept, we engineered for CoQ(10) biosynthesis the industrially relevant Corynebacterium glutamicum, which does not naturally synthesize any CoQ. Here, liquid chromatography–mass spectrometry (LC–MS) analysis identified two metabolic bottlenecks in the CoQ(10) production, i.e., low conversion of the intermediate 10-prenylphenol (10P-Ph) to CoQ(10) and the accumulation of isoprenologs with prenyl chain lengths of not only 10, but also 8 to 11 isopentenyl units. To overcome these limitations, the strain was engineered for expression of the Ubi complex accessory factors UbiJ and UbiK from Escherichia coli to increase flux towards CoQ(10), and by replacement of the native polyprenyl diphosphate synthase IspB with a decaprenyl diphosphate synthase (DdsA) to select for prenyl chains with 10 isopentenyl units. The best strain UBI6-Rs showed a seven-fold increased CoQ(10) content and eight-fold increased CoQ(10) titer compared to the initial strain UBI4-Pd, while the abundance of CoQ(8), CoQ(9), and CoQ(11) was significantly reduced. This study demonstrates the application of the recent insight into CoQ biosynthesis to improve metabolic engineering of a heterologous CoQ(10) production strain.