Dynamic quinone repertoire accompanied the diversification of energy metabolism in Pseudomonadota.

It is currently unclear how Pseudomonadota, a phylum that originated around the time of the Great Oxidation Event, became one of the most abundant and diverse bacterial phyla on Earth, with metabolically versatile members colonizing a wide range of environments with different O2 concentrations. Here, we address this question by studying isoprenoid quinones, which are central components of energy metabolism covering a wide range of redox potentials. We demonstrate that a dynamic repertoire of quinone biosynthetic pathways accompanied the diversification of Pseudomonadota.

An organic O donor for biological hydroxylation reactions.

All biological hydroxylation reactions are thought to derive the oxygen atom from one of three inorganic oxygen donors, O, HO or HO. Here, we have identified the organic compound prephenate as the oxygen donor for the three hydroxylation steps of the O-independent biosynthetic pathway of ubiquinone, a widely distributed lipid coenzyme. Prephenate is an intermediate in the aromatic amino acid pathway and genetic experiments showed that it is essential for ubiquinone biosynthesis in under anaerobic conditions.

Diversification of Ubiquinone Biosynthesis via Gene Duplications, Transfers, Losses, and Parallel Evolution.

The availability of an ever-increasing diversity of prokaryotic genomes and metagenomes represents a major opportunity to understand and decipher the mechanisms behind the functional diversification of microbial biosynthetic pathways. However, it remains unclear to what extent a pathway producing a specific molecule from a specific precursor can diversify. In this study, we focus on the biosynthesis of ubiquinone (UQ), a crucial coenzyme that is central to the bioenergetics and to the functioning of a wide variety of enzymes in Eukarya and Pseudomonadota (a subgroup of the formerly named Proteobacteria).