Molecular cloning of the human UMP synthase gene and characterization of point mutations in two hereditary orotic aciduria families

Journal Article · Sat Mar 01 04:00:00 EST 1997 · American Journal of Human Genetics

OSTI ID:518536

Suchi, Mariko; Mizuno, Haruo; Tsuboi, Takashi ^[1]

---

1. Nagoya City Univ. Medical School (Japan); and others

Uridine monophosphate (UMP) synthase is a bifunctional enzyme catalyzing the last two steps of de novo pyrimidine biosynthesis, orotate phosphoribosyltransferase (OPRT) and orotidine-5{prime}-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 {lambda}EMBL-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{prime} 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 ({nu} = .26) and 440 Gpoly ({nu} = .27) located in exons 3 and 6, respectively, which did not significantly compromise either OPRT or ODC function. 76 refs., 5 figs., 7 tabs.

• OSTI ID: 518536
• Journal Information: American Journal of Human Genetics, Journal Name: American Journal of Human Genetics Journal Issue: 3 Vol. 60; ISSN AJHGAG; ISSN 0002-9297
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
ANEMIAS
BIOSYNTHESIS
DNA SEQUENCING
DNA-CLONING
ENZYME ACTIVITY
ESCHERICHIA COLI
EXONS
GENE MUTATIONS
GENE REGULATION
GENETIC MAPPING
HEREDITARY DISEASES
HUMAN CHROMOSOME 3
IN-SITU HYBRIDIZATION
NUCLEOTIDES
OROTIC ACID
PATIENTS
PLASMIDS
POLYMERASE CHAIN REACTION
PYRIMIDINES
RECESSIVE MUTATIONS
SPLICING
STRUCTURE-ACTIVITY RELATIONSHIPS
UMP