A two-hybrid system analysis shows interactions between 6-phosphofructo-1-kinase and 6-phosphofracto-2-kinase but not between other glycolytic enzymes of the yeast Saccharomyces cerevisiae

The yeast two-hybrid system was used to investigate whether protein-protein interactions between enzymes of the early reactions of glycolysis exist in the yeast Saccharomyces cerevisiae. Various glycolytic enzymes were fused either to the GAL4 transcription-activating or DNA-binding domain and were tested for their ability to restore GAL4-dependent gene activation. All the different fusion proteins complemented the growth and enzymatic defects caused by the deletion of the respective genes, which indicates that these proteins are still functional. Interactions between the two phosphofructo-1-kinase subunits PFK1 and PFK2, interactions between the phosphofructo-2-kinase subunits, and dimerization of phosphoglucose isomerase were demonstrated. Dimerization of hexokinase 2, however, could not be demonstrated neither with N-terminal nor C-terminal fusions. A direct interaction between the hexose-6-phosphate interconverting enzymes hexokinase 2, phosphoglucose isomerase, and phosphofructo-1-kinase could also not be demonstrated. Nevertheless, our results indicate a weak interaction between phosphofructo-1-kinase and phosphofructo-2-kinase.