Solution X-ray scattering studies of the yeast phosphofructokinase allosteric transition. Characterization of an ATP-induced conformation distinct in quaternary structure from the R and T states of the enzyme.
The allosteric transition of yeast phosphofructokinase has been studied by solution x-ray scattering. The scattering curves corresponding to the native enzyme (T conformation) were found to be similar to the curves recorded in the presence of saturating concentrations of fructose 6-phosphate (R conformation) or AMP (R or R' conformation). However, the curves obtained in the presence of ATP are clearly different: the radius of gyration increases and the secondary minima and maxima are systematically shifted to lower angles, suggesting a swelling of the enzyme in the presence of ATP. These results give the first direct evidence for the existence of an ATP-induced T' conformation, distinct in quaternary structure from the R and T states of the enzyme oligomer, in agreement with our previous modeling of yeast phosphofructokinase regulation. X-ray scattering data are discussed in relation to the distinct molecular mechanisms of the ATP and fructose 6-phosphate allosteric effects involving, respectively, sequential and concerted conformational changes of the enzyme oligomer.
D000494:Allosteric Regulation; D007700:Kinetics; D008970:Molecular Weight; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D014961:X-Ray Diffraction
D010732:Phosphofructokinase-1