Catalyzes the phosphorylation of D-fructose 6-phosphate, the first committing step of glycolysis. Uses inorganic phosphate (PPi) as phosphoryl donor instead of ATP like common ATP-dependent phosphofructokinases (ATP-PFKs), which renders the reaction reversible, and can thus function both in glycolysis and gluconeogenesis. Consistently, PPi-PFK can replace the enzymes of both the forward (ATP-PFK) and reverse (fructose-bisphosphatase (FBPase)) reactions. beta-D-fructose 6-phosphate + diphosphate = beta-D-fructose 1,6-bisphosphate + H(+) + phosphate Non-allosteric. Optimum pH is 7.5 for both the forward and the reverse reactions. Optimum temperature is 35-46 degrees Celsius. Carbohydrate degradation; glycolysis; D-glyceraldehyde 3-phosphate and glycerone phosphate from D-glucose: step 3/4. Homotetramer. Present when grown on glucose. Belongs to the phosphofructokinase type A (PFKA) family. Mixed-substrate PFK group III subfamily.