Involved in the degradation of glucose via the semi-phosphorylative Entner-Doudoroff pathway. Catalyzes the phosphorylation of 2-keto-3-deoxygluconate (KDG) to produce 2-keto-3-deoxy-6-phosphogluconate (KDPG). Also catalyzes efficiently the phosphorylation of 2-keto-3-deoxygalactonate (KDGal) to 2-keto-3-deoxy-6-phosphogalactonate (KDPGal). 2-dehydro-3-deoxy-D-gluconate + ATP = 2-dehydro-3-deoxy-6-phospho-D-gluconate + ADP + H(+) 2-dehydro-3-deoxy-D-galactonate + ATP = 2-dehydro-3-deoxy-6-phospho-D-galactonate + ADP + H(+) Carbohydrate acid metabolism; 2-dehydro-3-deoxy-D-gluconate degradation; D-glyceraldehyde 3-phosphate and pyruvate from 2-dehydro-3-deoxy-D-gluconate: step 1/2. Homohexamer. Constitutively expressed. Deletion of the gene abolishes growth on glucose, but does not affect growth on galactose. Double deletion mutant kdgK1/kdgK2 loses the ability to grow on galactose. Belongs to the carbohydrate kinase PfkB family.