Molecular modelling of human red blood cell pyruvate kinase: Structural implications of a novel G(1091) to A mutation causing severe nonspherocytic hemolytic anemia

We present a novel G(1091) to A mutation in the human liver and red blood cell (RBC) pyruvate kinase (PK) gene causing severe hemolytic anemia. In two families, three children were severely PK-deficient compound heterozygotes exhibiting the G(1091) to A mutation and a common G(1529) to A mutation on the other allele. In one family, the mother, a G(1091) to A heterozygote, later had a second baby with a new husband, also a G(1091) to A carrier. The baby was homozygous for the G(1091) to A mutation and died 6 weeks after birth from severe hemolysis. Bath mutant alleles were expressed at the RNA level. The G(1091) to A mutation results in the substitution of a conserved glycine by an aspartate in domain A of RBC PK, whereas the G(1529) to A mutation leads to the substitution of a conserved arginine residue with glutamine in the C-domain. Molecular modelling of human RBC PK, based on the crystal structure of cat muscle PK, shows that both mutations are located outside the catalytic site at the interface of domains A and C. The mutations are likely to disrupt the critical conformation of the interface by introducing alternative salt bridges. In this way the GlY(364) to ASP and Arg(510) to Gln substitutions may cause PK deficiency by influencing the allosteric properties of the enzyme. (C) 1997 by The American Society of Hematology.