title: Fructose 2,6-bisphosphate and fructose-6-P 2-kinase in Saccharomyces cerevisiae in relation to metabolic state in wild type and fructose-6-P 1-kinase mutant strains.
abstract: In wild type Saccharomyces cerevisiae, fructose-6-P is known to be in much lower amounts than needed to saturate fructose-6-P 1-kinase in vitro, and the same is true for a mutant with reduced affinity for fructose-6-P, even though its in vivo fructose-6-P concentration is much higher than normal. Both the wild type and mutant fructose-6-P 1-kinases were activated in vitro by fructose-2,6-P2 in the 0.1 microM concentration range, and the effector was present in more than adequate amounts. Hence, it is likely to be necessary for sufficient flux through the fructose-6-P 1-kinase reaction in vivo, and the data also fit with fructose-2,6-P2 acting at different sites on the enzyme from fructose-6-P. In growth on glucose, a variety of wild type strains contained 5-10 microM fructose-2,6-P2, and various fructose-6-P 1-kinase mutant strains had levels of up to 150 microM in the presence of glucose. Fructose-2,6-P2 was also found (0.5-10 microM) in derepressed cultures after glucose exhaustion and in growth on pyruvate. Activities of fructose-6-P 2-kinase in the various strains and situations are also presented. The data generally indicate a correlation between levels of fructose-2,6-P2 and fructose-6-P and suggest that fructose-2,6-P2 is not rapidly degraded after glucose exhaustion.
mesh_terms: D004789:Enzyme Activation; D005635:Fructosediphosphates / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006598:Hexosediphosphates / Q000378:metabolism*; D009154:Mutation; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D025481:Phosphofructokinase-2; D010770:Phosphotransferases / Q000378:metabolism*; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*
chemical_list: D005635:Fructosediphosphates; D006598:Hexosediphosphates; D011773:Pyruvates; C027652:fructose 2,6-diphosphate; D019289:Pyruvic Acid; D010770:Phosphotransferases; D025481:Phosphofructokinase-2; D010732:Phosphofructokinase-1; D005947:Glucose