Characterization of phosphofructokinase II and regulation of fructose 2,6-bisphosphate levels in Trichoderma reesei.
Phosphofructokinase II (PEK II) from Trichoderma reesei was partially purified (247-fold). The calculated Km values for fructose 6-phosphate and ATP were 0.7 mM and 40 microM, respectively. Upon incubation in the presence of [gamma-32P]ATP, the enzyme formed a radioactive phosphoprotein with molecular mass of 67 kDa in autoradiography analysis after SDS-PAGE. Upon incubation in the presence of ATP-Mg and the catalytic subunit of cAMP-dependent protein kinase, its activity was not modified. The same result was obtained when a cell-free extract of T. reesei was incubated with ATP-Mg and cAMP. 2,4-Dinitrophenol caused a transient rise in cAMP levels in the fungal cell. The results provide evidence that the fructose 2,6-bisphosphate level in T. reesei is independent of cAMP concentrations and not related to a cAMP-dependent mechanism, but to the availability of substrate fructose 6-phosphate.
Abrahao Neto
J
J
Department of Biochemistry, Institute of Chemistry, University of Sao Paulo, Brazil.
D019297:2,4-Dinitrophenol / Q000493:pharmacokinetics; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006597:Fructose-Bisphosphatase / Q000302:isolation & purification / Q000378:metabolism*; D005635:Fructosediphosphates / Q000378:metabolism*; D005947:Glucose / Q000493:pharmacokinetics; D007700:Kinetics; D010732:Phosphofructokinase-1 / Q000302:isolation & purification / Q000378:metabolism*; D025481:Phosphofructokinase-2; D010766:Phosphorylation; D051381:Rats; D014242:Trichoderma / Q000201:enzymology* / Q000378:metabolism
D005635:Fructosediphosphates; C027652:fructose 2,6-diphosphate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D025481:Phosphofructokinase-2; D010732:Phosphofructokinase-1; D017868:Cyclic AMP-Dependent Protein Kinases; D006597:Fructose-Bisphosphatase; D005947:Glucose; D019297:2,4-Dinitrophenol