The objective of this research is delineation of biochemical and genetic mechanisms which regulate the rate of human purine nucleotide synthesis and coordinate the activities of this and other biosynthetic pathways. Several discrete hereditary enzyme abnormalities have been identified which account for the excessive purine production of a small proportion of patients with gout. Studies of these enzyme defects have contributed to current concepts of the biochemical control of purine nucleotide synthesis, emphasizing the importance of the antagonistic interaction between the regulatory substrate 5-phosphoribosyl 1-pyrophosphate (PRPP) and inhibitory purine nucleotide products. The frequency with which kinetic variation within known enzyme abnormalities contributes to the purine overproduction of additional patients with gout will be evaluated and an attempt will be made to identify and characterize other enzyme aberrations among such patients. The delineation of additional regulatory determinants will also be the aim of studies of (1) the effects of chemical agents on human purine metabolism in vivo, and (2) the importance of rates of generation of pentose phosphates, particularly ribose-5-P, in determining PRPP synthesis in human fibroblasts in culture. Synthesis of PRPP is catalyzed by the enzyme PRPP synthetase, the structure and activity of which is subject to modification by a number of effector compounds. Structural and kinetic characteristics of PRPP synthetase will be investigated in purified enzyme preparations and in cultured cells derived from normal individuals and from patients with mutant forms of PRPP synthetase which result in excessive enzyme activity, increased PRPP synthesis and purine overproduction. The role of PRPP in the regulation of the rate of pyrimidine nucleotide synthesis and its coordination with purine nucleotide synthetic rate will be evaluated in cultured fibroblasts and lymphoblasts utilizing normal cells and cells containing specific genetic alterations in enzymes of purine and pyrimidine metabolism.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK028554-09
Application #
3228890
Study Section
Biochemistry Study Section (BIO)
Project Start
1980-09-01
Project End
1989-12-14
Budget Start
1988-05-01
Budget End
1989-12-14
Support Year
9
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Chicago
Department
Type
Schools of Medicine
DUNS #
225410919
City
Chicago
State
IL
Country
United States
Zip Code
60637
Garcia-Pavia, Pablo; Torres, Rosa J; Rivero, Manuel et al. (2003) Phosphoribosylpyrophosphate synthetase overactivity as a cause of uric acid overproduction in a young woman. Arthritis Rheum 48:2036-41
Becker, M A (2001) Phosphoribosylpyrophosphate synthetase and the regulation of phosphoribosylpyrophosphate production in human cells. Prog Nucleic Acid Res Mol Biol 69:115-48
Becker, M A; Ahmed, M (2000) Cell type-specific differential expression of human PRPP synthetase (PRPS) genes. Adv Exp Med Biol 486:10-May
Ahmed, M; Taylor, W; Smith, P R et al. (1999) Accelerated transcription of PRPS1 in X-linked overactivity of normal human phosphoribosylpyrophosphate synthetase. J Biol Chem 274:7482-8
Becker, M A; Taylor, W; Smith, P R et al. (1998) Regulation of human PRS isoform expression. Adv Exp Med Biol 431:215-20
Becker, M A; Taylor, W; Smith, P R et al. (1996) Overexpression of the normal phosphoribosylpyrophosphate synthetase 1 isoform underlies catalytic superactivity of human phosphoribosylpyrophosphate synthetase. J Biol Chem 271:19894-9
Becker, M A; Smith, P R; Taylor, W et al. (1995) The genetic and functional basis of purine nucleotide feedback-resistant phosphoribosylpyrophosphate synthetase superactivity. J Clin Invest 96:2133-41
Fry, D W; Becker, M A; Switzer, R L (1995) Inhibition of human 5-phosphoribosyl-1-pyrophosphate synthetase by 4-amino-8-(beta-D-ribofuranosylamino)-pyrimido[5,4-d]pyrimidine-5'- monophosphate: evidence for interaction at the ADP allosteric site. Mol Pharmacol 47:810-5
Becker, M A; Nosal, J M; Switzer, R L et al. (1994) Point mutations in PRPS1, the gene encoding the PRPP synthetase (PRS) 1 isoform, underlie X-linked PRS superactivity associated with purine nucleotide inhibitor-resistance. Adv Exp Med Biol 370:707-10
Roessler, B J; Nosal, J M; Smith, P R et al. (1993) Human X-linked phosphoribosylpyrophosphate synthetase superactivity is associated with distinct point mutations in the PRPS1 gene. J Biol Chem 268:26476-81

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