Publications

• Structural and functional characterization of the c-terminal domain of the ecdysteroid phosphate phosphatase from bombyx mori reveals a new enzymatic activity.

  Chen Y., Jakoncic J., Wang J., Zheng X., Carpino N., Nassar N.

  Here, we present the crystal structure of the ecdysone phosphate phosphatase (EPPase) phosphoglycerate mutase (PGM) homology domain, the first structure of a steroid phosphate phosphatase. The structure reveals an alpha/beta-fold common to members of the two histidine (2H)-phosphatase superfamily ... >> More

  Here, we present the crystal structure of the ecdysone phosphate phosphatase (EPPase) phosphoglycerate mutase (PGM) homology domain, the first structure of a steroid phosphate phosphatase. The structure reveals an alpha/beta-fold common to members of the two histidine (2H)-phosphatase superfamily with strong homology to the Suppressor of T-cell receptor signaling-1 (Sts-1 PGM) protein. The putative EPPase PGM active site contains signature residues shared by 2H-phosphatase enzymes, including a conserved histidine (His80) that acts as a nucleophile during catalysis. The physiological substrate ecdysone 22-phosphate was modeled in a hydrophobic cavity close to the phosphate-binding site. EPPase PGM shows limited substrate specificity with an ability to hydrolyze steroid phosphates, the phospho-tyrosine (pTyr) substrate analogue para-nitrophenylphosphate ( pNPP) and pTyr-containing peptides and proteins. Altogether, our data demonstrate a new protein tyrosine phosphatase (PTP) activity for EPPase. They suggest that EPPase and its closest homologues can be grouped into a distinct subfamily in the large 2H-phosphatase superfamily of proteins. << Less

  Biochemistry 47:12135-12145(2008) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Phosphoconjugation and dephosphorylation reactions of steroid hormone in insects.

  Sonobe H., Ito Y.

  In insects, the major products of phase II metabolism of ecdysteroids, which include the molting hormone, are phosphate esters. The phosphoconjugation pathway is a reversible process, comprising two enzyme systems: ecdysteroid 22-kinase (EcKinase) and ecdysteroid-phosphate phosphatase (EPPase). We ... >> More

  In insects, the major products of phase II metabolism of ecdysteroids, which include the molting hormone, are phosphate esters. The phosphoconjugation pathway is a reversible process, comprising two enzyme systems: ecdysteroid 22-kinase (EcKinase) and ecdysteroid-phosphate phosphatase (EPPase). We report here that: (1) the biochemical characteristics of EcKinase and EPPase, (2) the physiological significance of the reciprocal conversion of ecdysteroids and ecdysteroid phosphates in the ovary-egg system in insects, (3) the biochemical mechanism by which ecdysteroid phosphates are synthesized in the ovary, transferred to eggs, and finally dephosphorylated in eggs, and (4) the possible catalytic steps of EcKinase and EPPase on the basis of the data obtained by an in silico study. From these studies, it is obvious that ecdysteroid phosphates as well as steroid sulfates, which are major products of phase II metabolism in mammals, function as precursors for the formation of biologically active hormones. << Less

  Mol Cell Endocrinol 307:25-35(2009) [PubMed] [EuropePMC]

• Purification, kinetic characterization, and molecular cloning of a novel enzyme ecdysteroid-phosphate phosphatase.

  Yamada R., Sonobe H.

  From eggs of the silkworm Bombyx mori, we isolated a novel enzyme that is involved in the conversion of physiologically inactive conjugated ecdysteroids, such as ecdysone 22-phosphate and 20-hydroxyecdysone 22-phosphate, to active free ecdysteroids. This enzyme, called ecdysteroid-phosphate phosph ... >> More

  From eggs of the silkworm Bombyx mori, we isolated a novel enzyme that is involved in the conversion of physiologically inactive conjugated ecdysteroids, such as ecdysone 22-phosphate and 20-hydroxyecdysone 22-phosphate, to active free ecdysteroids. This enzyme, called ecdysteroid-phosphate phosphatase (EPPase), was located in the cytosol fraction and differed from nonspecific lysosomal acid phosphatases in various enzymic properties. EPPase was purified about 3,000-fold to homogeneity by seven steps of column chromatography. The cDNA clone encoding EPPase was isolated by reverse transcription polymerase chain reaction using degenerate primers on the basis of the partial amino acid sequence obtained from purified EPPase and by subsequent 3'- and 5'-rapid amplification of cDNA ends. The full-length cDNA of EPPase was found to be composed of 1620 bp with an open reading frame encoding a protein of 331 amino acid residues. A data base search showed that there was no functional protein with the amino acid sequence identical to that of EPPase. Northern blot analysis revealed that EPPase mRNA was expressed predominantly during gastrulation and organogenesis in nondiapause eggs but was not detected in diapause eggs whose development was arrested at the late gastrula stage. In nondiapause eggs, the developmental changes in the expression pattern of EPPase mRNA corresponded closely to changes in the enzyme activity and in the amounts of free ecdysteroids in eggs. << Less

  J. Biol. Chem. 278:26365-26373(2003) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.