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Molecular cloning of the human UMP synthase gene and characterization of point mutations in two hereditary orotic aciduria families. Am J Hum Genet 1997 Mar;60(3):525-39

Date

03/01/1997

Pubmed ID

9042911

Pubmed Central ID

PMC1712531

Scopus ID

2-s2.0-0031028360   47 Citations

Abstract

Uridine monophosphate (UMP) synthase is a bifunctional enzyme catalyzing the last two steps of de novo pyrimidine biosynthesis, orotate phosphoribosyltransferase (OPRT) and orotidine-5'-monophosphate decarboxylase (ODC). Loss of either enzymatic activity results in hereditary orotic aciduria, a rare autosomal recessive disorder characterized by retarded growth, anemia, and excessive urinary excretion of orotic acid. We have isolated the UMP synthase chromosomal gene from a lambdaEMBL-3 human genomic library and report a single-copy gene spanning approximately 15 kb. The UMP synthase genomic structure encodes six exons ranging in size from 115 bp to 672 bp, and all splicing junctions adhere to the canonical GT/AG rule. Cognate promoter elements implicated in glucocorticoid- and cAMP-mediated regulation as well as in liver-, myeloid-, and lymphocyte-specific expression are located within the 5' flanking sequence. Molecular investigation of UMP synthase deficiency in a Japanese orotic aciduria patient revealed mutations R96G (A-to-G transition; nt 286) and G429R (G-to-C transversion; nt 1285) in one allele and V109G (T-to-G transversion; nt 326) in the other allele. Expression of human UMP synthase cDNAs containing these mutations in pyrimidine auxotrophic Escherichia coli and in recombinant baculovirus-infected Sf21 cells demonstrates impaired activity presumably associated with the urinary orotic acid substrate accumulations observed in vivo. We further establish the identity of two polymorphisms, G213A (v = .26) and 440Gpoly (v = .27) located in exons 3 and 6, respectively, which did not significantly compromise either OPRT or ODC function.

Author List

Suchi M, Mizuno H, Kawai Y, Tsuboi T, Sumi S, Okajima K, Hodgson ME, Ogawa H, Wada Y

Author

Mariko Suchi MD, PhD Associate Professor in the Pathology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Adult
Animals
Base Sequence
Cell Line
Cell Line, Transformed
Child, Preschool
Cloning, Molecular
DNA
Escherichia coli
Exons
Female
Genes, Bacterial
Humans
Introns
Japan
Male
Molecular Sequence Data
Multienzyme Complexes
Orotate Phosphoribosyltransferase
Orotic Acid
Orotidine-5'-Phosphate Decarboxylase
Point Mutation
Polymorphism, Genetic
Recombinant Proteins
Spodoptera
Uridine
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a