Plausible novel ribose metabolism catalyzed by enzymes of the methionine salvage pathway in Bacillus subtilis.

The methionine salvage pathway (MSP) recycles reduced sulfur from 5-methylthioribose. Here we propose a novel ribose metabolic pathway performed by MSP enzymes of Bacilli. MtnK, an initial catalyst of MSP, had significant ribose kinase activity, with Vmax and Km values of 2.9 µmol min(-1) mg of protein(-1) and 4.8 mM. Downstream enzymes catalyzed the isomerization of ribose-1-phosphate and subsequent dehydration, enolization, dephosphorylation, and dioxygenation.