The dihydroxyacetone kinase of Escherichia coli utilizes a phosphoprotein instead of ATP as phosphoryl donor

The dihydroxyacetone kinase (DhaK) of Escherichia coli consists of three so luble protein subunits, DhaK (YcgT; 39.5 kDa) and DhaL (YcgS; 22.6 kDa) are similar to the N- and C-terminal halves of the ATP-dependent DhaK ubiquito us in bacteria, animals and plants. The homodimeric DhaM (YcgC; 51.6 kDa) c onsists of three domains. The N-terminal dimerization domain has the same f old as the IIA domain (PDB code 1PDO) of the mannose transporter of the bac terial phosphoenolpyruvate:sugar phosphotransferase system (PTS), The middl e domain is similar to HPr and the C-terminus is similar to the N-terminal domain of enzyme I (EI) of the PTS, DhaM is phosphorylated three times by p hosphoenolpyruvate in an EI- and HPr-dependent reaction. DhaK and DhaL are not phosphorylated, The IIA domain of DhaM, instead of ATP, is the phosphor yl donor to dihydroxyacetone (Dha), Unlike the carbohydrate-specific transp orters of the PTS, DhaK, DhaL and DhaM have no transport activity.