Role of dihydroxyacetone kinases I and II in the dha regulon of Klebsiella pneumoniae

Dha regulon is responsible for anaerobic glycerol metabolism and 1,3-propanediol production in Klebsiella pneumoniae. DhaK encodes an ATP-dependent dihydroxyacetone kinase I, whereas dhaK123 encodes a dihydroxyacetone kinase II that uses phosphoenolpyruvate as a phosphate donor. The functions of dihydroxyacetone kinases I and II in K. pneumoniae have not been discriminated. In this study, four individual genes of the two kinases were knocked out, and the metabolic characteristics of these mutants were investigated. DhaK1 or dhaK2 mutation inhibited dha regulon expression. DhaK3 mutation reduced glycerol utilization, and the growth was slower than the wild stain. However, dhaK mutation exerted no significant effects on glycerol metabolism. The metabolic characteristics of these mutants showed that the subunits of dihydroxyacetone kinase II were involved in the regulation of dha regulon expression, similar to the dha regulon of E. coli. Dihydroxyacetone kinase II catalyzed dihydroxyacetone conversion to dihydroxyacetone phosphate, whereas dihydroxyacetone kinase I showed no significant contribution to this reaction.