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. Author manuscript; available in PMC: 2020 Apr 18.
Published in final edited form as: Cell Chem Biol. 2019 Apr 18;26(4):465–467. doi: 10.1016/j.chembiol.2019.04.005

Figure 2.

Figure 2.

The steps of UQ8 biosynthesis in E. coli. IspB produces octaprenyl-diphosphate. The octaprenyl group (designated by R) is transferred to 4-hydroxybenzoic acid (4HB) by UbiA, to form 3-octaprenyl-4-hydroxybenzoic acid (OHB). UbiD and UbiX work together to mediate decarboxylation and produce octaprenyl phenol (OPP). OPP is then subjected to alternating steps of hydroxylation (shown in blue) and methylation (shown in pink) in the order of UbiI, UbiG, UbiH, UbiE, UbiF and UbiG to form the fully substituted product, UQ8H2. UbiJ and UbiK are required accessory proteins, and UbiJ binds OPP and the other UQ8-intermediates. The order of steps in eukaryotic UQ biosynthesis is slightly different. The first hydroxylation and methylation steps in yeast and human cells are thought to precede the decarboxylation step.