Diverse Metabolic Control of Phosphoglucomutases by Bisphosphorylated Sugars in Heterotrophic Bacteria

Phosphoglucomutases (PGM) are crucial for bacterial fitness, environmental survival, pathogenicity, and cell envelope stability, making them potential new targets for combating bacterial infection and transmission. PGM functionality relies on initial phosphorylation by the activator glucose-1,6-bisphosphate (glucose-1,6-BP). While the origin of glucose-1,6-BP in vertebrates is well investigated, a bacterial glucose-1,6-BP synthase was only recently identified in the cyanobacterium Synechocystis. In this photoautotroph, a secondary PGM (SynPGM2) efficiently catalyzes glucose-1,6-BP synthesis from fructose-1,6-bisphosphate (fructose-1,6-BP) and glucose-1-phosphate or glucose-6-phosphate . A homologous PGM from the heterotrophic Bacteroides salyersiae, belonging to the same conserved domain subfamily (cd05800) as SynPGM2, exhibited similar activity, suggesting that bacterial glucose-1,6-BP synthesis is a feature of this specific subfamily.

To investigate the specificity and regulation of various PGM enzymes from different heterotrophic bacteria, recombinant enzymes were purified and analyzed using enzymatic assays and HPLC-MS.

We demonstrate that glucose-1,6-BP synthesis extends beyond the cd5800 subfamily to the cd05801, cd05799, and cd03089 subfamilies. PGMs from Escherichia coli (cd05801 and cd03089), Enterococcus faecium (cd05799), Yersinia enterocolitica (cd05801), and Candidatus Gastranaerophilales (cd05800) catalyze the same fructose-1,6-BP-dependent synthesis reaction of glucose-1,6-BP as SynPGM2. Notably, fructose-1,6-BP, a known inhibitor of some PGM, does not inhibit these bacterial PGMs. Moreover, E. faecium PGM, belonging to the same subfamily as the mammalian glucose 1,6 BP synthase, efficiently catalyzes the mammalian-type 1,3-bisphosphoglycerate-dependent glucose 1,6-BP synthesis reaction.

All investigated heterotrophic bacteria appear to use their primary PGM for both PGM activity and activator synthesis, suggesting a more versatile and less specialized role for PGMs in heterotrophic bacteria.