Key molecule in bacterial metabolism discovered

Animals (including humans) but also bacteria, can store sugar in cells as a polymer in the form of glycogen and mobilize it again when energy demand increases (Figure 1). A key reaction in both storage and mobilization is the rearrangement of phosphate residues on the sugar molecules. These rearrangement reactions are catalyzed by the Phosphohexomutase (PHM) group of enzymes. (Figure 2)

The large family of PHM enzymes can be divided into several subgroups. They all function on the same principle, but are specialized for different phosphate sugars as substrates. For the phosphate rearrangement reactions to occur, the enzymes must first be activated. This is done by the molecule glucose-1,6-bisphosphate. This molecule attaches a phosphate group to the reaction center of the enzymes, thereby placing them in an active state. How this activator molecule is formed in humans and other vertebrates has been the subject of research for some time and is largely understood: Responsible for the formation of the molecule is an enzyme (PGM-2) that also belongs to the PHM family, but does not occur outside vertebrates. Its central role in metabolism is shown by the fact that a defect in this enzyme results in a deficiency of G16bP. This deficiency leads, among other things, to neurodevelopmental disorders in newborns. In bacteria, it has been known for decades that G16bP plays an important role in sugar metabolism, but how this molecule is formed has now been shown for the first time.