Characterization of mouse UDP-glucose pyrophosphatase, a Nudix hydrolase encoded by the Nudt14 gene.

Recombinant mouse UDP-glucose pyrophosphatase (UGPPase), encoded by the Nudt14 gene, was produced in Escherichia coli and purified close to homogeneity. The enzyme catalyzed the conversion of [beta-(32)P]UDP-glucose to [(32)P]glucose-1-P and UMP, confirming that it hydrolyzed the pyrophosphate of the nucleoside diphosphate sugar to generate glucose-1-P and UMP. The enzyme was also active toward ADP-ribose. Activity is dependent on the presence of Mg(2+) and was greatest at alkaline pH above 8. Kinetic analysis indicated a K(m) of approximately 4mM for UDP-glucose and approximately 0.3mM for ADP-ribose. Based on V(max)/K(m) values, the enzyme was approximately 20-fold more active toward ADP-ribose. UGPPase behaves as a dimer in solution and can be cross-linked to generate a species of M(r) 54,000 from a monomer of 30,000 as judged by SDS-PAGE. The dimerization was not affected by the presence of glucose-1-P or UDP-glucose. Using antibodies raised against the recombinant protein, Western analysis indicated that UGPPase was widely expressed in mouse tissues, including skeletal muscle, liver, kidney, heart, lung, fat, heart and pancreas with a lower level in brain. It was generally present as a doublet when analyzed by SDS-PAGE, suggesting the occurrence of some form of post-translational modification. Efforts to interconvert the species by adding or inhibiting phosphatase activity were unsuccessful, leaving the nature of the modification unknown. Sequence alignments and database searches revealed related proteins in species as distant as Drosophila melanogaster and Caenorhabditis elegans.

A report of an apparent new genetic syndrome consisting of joint contractures, keloids, large optic cup-to-disc ratio and renal stones.

We report on a family with an apparently undescribed syndrome involving joint contractures, keloids, an increased optic cup-to-disc ratio, and renal stones. The propositus presented at 9 years of age with congenital contractures of his distal interphalangeal (DIP) joints, progressive stiffness of the shoulders and neck, a large optic cup-to-disc ratio, and mildly dysmorphic facies. He otherwise has been normal. The propositus's brother, uncle, great-uncle, a half great-uncle, and six male half-cousins once removed also have DIP joint stiffness. The propositus' mother and brother also have an increased optic cup-to-disc ratio. In addition, the great-grandfather, the uncle, the same six male half-cousins once removed, and an affected daughter of a half-cousin have keloids with the earliest age of onset of the keloids being 12 years. Further, three of the above affected males have had uric acid renal stones. Dupuytren contractures and subcutaneous nodules were also present in some affected males. Given the family history, the pattern of inheritance appears to be X-linked. An extensive literature search failed to reveal any previous reports associating these manifestations and this inheritance pattern. Therefore, we think the condition in this family comprises a new genetic syndrome.