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). 2-dehydro-3-deoxy-D-gluconate + ATP = 2-dehydro-3-deoxy-6-phospho-D-gluconate + ADP + H(+) kcat is 11 sec(-1) for KDG and 2.2 sec(-1) for 2-keto-D-gluconate (at 35 degrees Celsius and pH 7.4). Optimum pH is between 6 and 9. 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; trimer of dimers. Belongs to the carbohydrate kinase pfkB family.