Site-directed mutagenesis of rat muscle 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase: role of Asp-130 in the 2-kinase domain.
Asp-130 of the recombinant skeletal-muscle 6-phosphofructo-2-kinase (PFK-2)/fructose-2,6-bisphosphatase was mutated into Ala in order to study its role in catalysis and/or substrate binding. The D130A mutant displayed a 30- to 140-fold decreased 2-kinase Vmax, depending on the pH, and a 30- and 60-fold increase in Km for MgATP and Fru-6-P respectively at pH 8.5 compared with the wild-type. Mutagenesis of Asp-130 to Ala had no effect on the 2-phosphatase activity, and fluorescence measurements indicated that the changes in kinetic properties of PFK-2 in the D130A mutant were not due to instability. The role of Asp-130 in the 2-kinase reaction is discussed and compared with that of Asp-103 of 6-phosphofructo-1-kinase from Escherichia coli, which binds Mg2+.
Rider
M H
MH
Hormone and Metabolic Research Unit, International Institute of Cellular and Molecular Pathology, Brussels, Belgium.
Crepin
K M
KM
De Cloedt
M
M
Bertrand
L
L
Hue
L
L
D000595:Amino Acid Sequence; D000818:Animals; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015153:Blotting, Western; D002853:Chromatography, Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005454:Fluorescence Polarization; D007700:Kinetics; D008969:Molecular Sequence Data; D009132:Muscles / Q000201:enzymology*; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011487:Protein Conformation; D051381:Rats; D016415:Sequence Alignment
D009838:Oligodeoxyribonucleotides; D001224:Aspartic Acid; D017853:Phosphotransferases (Alcohol Group Acceptor); D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases