Bisphosphoglycerate mutase

Abstract: The crystal structure of recombinant rat prostatic acid phosphatase was determined to 3 A resolution with protein crystallographic methods. The enzyme subunit is built up of two domains, an alpha/beta domain consisting of a seven-stranded mixed beta-sheet with helices on both sides of the sheet and a smaller alpha domain. Two disulfide bridges between residues 129-340 and 315-319 were found. Electron density at two of the glycosylation sites for parts of the carbohydrate moieties was observed. The dimer of acid phosphatase is formed through two-fold interactions of edge strand 3 from one subunit with strand 3 from the second subunit, thus extending the beta-sheet from seven to 14 strands. Other subunit-subunit interactions involve conserved residues from loops between helices and beta-strands. The fold of the alpha/beta domain is similar to the fold observed in phosphoglycerate mutase. The active site is at the carboxy end of the parallel strands of the alpha/beta domain. There is a strong residual electron density at the phosphate binding site which probably represents a bound chloride ion. Biochemical properties and results from site-directed mutagenesis experiments of acid phosphatase are correlated to the three-dimensional structure.

Abstract: Bisphosphoglyceromutase, 2,3-bisphosphoglycerate phosphatase and phosphoglyceromutase have been purified from human red cells. Three enzymes were co-purified throughout all purification steps. Three fractions (peaks I, II and III) which were chromatographically separable and had three activities in different ratios were obtained. Peak III which contained the main bisphosphoglyceromutase and 2,3-bisphosphoglycerate phosphatase activities was purified to homogeneity by electrophoretic and ultracentrifugal analyses. The homogeneous preparation had the phosphoglyceromutase activity. The three activities were lost at the same rate during thermal inactivation. Thus, bisphosphoglyceromutase and 2,3-bisphosphoglycerate phosphatase activities, which are responsible for 2,3-bisphosphoglycerate metabolism in red cells, are displayed by the same enzyme protein which has phosphoglyceromutase activity. Peaks I and II were rich in the phosphoglyceromutase activity. Both peaks showed bisphosphoglyceromutase and 2,3-bisphosphoglycerate phosphatase activities, although these two activities were much smaller than those of peak III. Some of the enzymic properties of peak III are described. Comparative studies on three peaks showed that the phosphoglyceromutase of peak III differed from that of peaks I and II in the kinetic property and thermostability.

Abstract: We previously isolated a partial soybean cDNA clone whose transcript abundance is increased upon infection by the sedentary, endoparasitic soybean cyst nematode Heterodera glycines. We now isolated the corresponding full-length cDNA and determined that the predicted gene product was similar to the group of cofactor-dependent phosphoglycerate mutase/bisphosphoglycerate mutase enzymes (PGM/bPGM; EC 5.4.2.1/5.4.2.4). We designated the corresponding soybean gene GmPGM. PGM and bPGM are key catalysts of glycolysis that have been well characterized in animals but not plants. Using the GmPGM cDNA sequence, we identified a homologous Arabidopsis thaliana gene, which we designatedAtPGM. Histochemical GUS analyses of transgenic Arabidopsis plants containing theAtPGM promoter::GUS construct revealed that the AtPGM promoter directs GUS expression in uninfected plants only to the shoot and root apical meristems. In infected plants, GUS staining also is evident in the nematode feeding structures induced by the cyst nematode Heterodera schachtii and by the root-knot nematode Meloidogyne incognita. Furthermore, we discovered that the AtPGM promoter was down-regulated by abscisic acid and hydroxyurea, whereas it was induced by sucrose, oryzalin, and auxin, thereby revealing expression characteristics typical of genes with roles in meristematic cells. Assessment of the auxin-inducible AUX1 gene promoter (a gene coding for a polar auxin transport protein) similarly revealed feeding cell and meristem expression, suggesting that auxin may be responsible for the observed tissue specificity of the AtPGM promoter. These results provide first insight into the possible roles of PGM/bPGM in plant physiology and in plant-pathogen interactions.