Structural and functional properties of mutant Arg203Pro from yeast phosphoglycerate kinase, as a model of phosphoglycerate kinase-Uppsala

A pathological variant of human phosphoglycerate kinase, phosphoglycerate kinase-Uppsala, associated with chronic nonspherocytic hemolytic anemia has been found to differ from the normal enzyme by substitution of an arginine at position 206 (corresponding to position 203 in yeast) by a proline. In order to understand the structural and functional consequences of this mutation, the corresponding mutant in yeast phosphoglycerate kinase was constructed. The three-dimensional structure of this mutant was resolved at 2.9 Å. Although the overall structure is not modified, small local changes were observed. The kinetic parameters of the mutant were not found to be greatly affected, the catalytic constant being lowered by only 10–20%. The most significant difference when compared with the wild-type enzyme is a decrease in stability by about 3 kcal/mol. The physiological implications of this instability are discussed.