Catalyzes the phosphorylation of D-fructose 6-phosphate to fructose 1,6-bisphosphate by ATP, the first committing step of glycolysis (PubMed:33540748). Can also catalyze the phosphorylation of tagatose-6-phosphate. The catalytic efficiency with tagatose-6-phosphate is about 1.8 times lower than that with fructose 6-phosphate (PubMed:33540748). Can use phosphate donors other than ATP (GTP and ITP), with lower efficiency (PubMed:33540748). In addition, can catalyze the reverse gluconeogenic reaction, albeit with low efficiency (PubMed:33540748). May support and maintain basic glycolysis and metabolic fluxes during conditions inhibiting PfkA (PubMed:33540748). ATP + beta-D-fructose 6-phosphate = ADP + beta-D-fructose 1,6-bisphosphate + H(+) ATP + D-tagatofuranose 6-phosphate = ADP + D-tagatofuranose 1,6-bisphosphate + H(+) The magnesium does not function as an allosteric effector but is essential for glycolytic reaction. Not inhibited by an excess of substrates and common allosteric inhibitors. Inhibited by high concentrations of the reaction products, fructose 1,6-bisphosphate and ADP. Carbohydrate degradation; glycolysis; D-glyceraldehyde 3-phosphate and glycerone phosphate from D-glucose: step 3/4. A member of the dormancy regulon. Induced in response to reduced oxygen tension (hypoxia), low levels of nitric oxide (NO) and carbon monoxide (CO). It is hoped that this regulon will give insight into the latent, or dormant phase of infection. Has strong T-cell and IFN-gamma inducing capacity in human tuberculin skin test positive patients, indicating this might be a good vaccine candidate. Activity of PfkB is tenfold lower than that of PfkA (PubMed:33540748). Activity with tagatose-6-phosphate suggests that PfkA and/or PfkB may substitute for tagatose-6-phosphate kinase and further support glycolysis (PubMed:33540748). Was identified as a high-confidence drug target. Belongs to the carbohydrate kinase PfkB family.