Biosynthesis of porphyries and related macrocycles. Part 18. Proof by spectroscopy and synthesis that unrearranged hydroxymethylbilane is the product from deaminase and the substrate for cosynthetase in the biosynthesis of uroporphyrinogen-III

Battersby, Alan R.; Fookes, Christopher J. R.; Gustafson-Potter, Kerstin E.; McDonald, Edward; Matcham, George W. J.

doi:10.1039/p19820002427

Cited by 70 publications

(63 citation statements)

References 5 publications

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“…2 (A, lane 6), a shift was detected in the lower band ofthe exon 2 profile for proband 4, a moderately affected 35-yr-old South African Black female from the Baralong tribe, a subgroup of the Tswana chiefdom. Amplification and sequencing of this exon from genomic DNA of proband 4 identified a mutation in a CpG dinucleotide, a G to A transition of nt 27 (Fig. 3), which did not predict an amino acid change (designated A9A).…”

Section: Resultsmentioning

confidence: 99%

“…This enzyme normally catalyzes the rapid cyclization of the linear tetrapyrrole, hydroxymethylbilane (HMB), to form the uroporphyrinogen III isomer, the physiologic precursor of heme (3,4). In patients with this autosomal recessive disorder, the enzymatic defect leads to the accumulation ofHMB which is nonenzymatically cyclized to the uroporphyrinogen I isomer and then oxidized to uroporphyrin I (URO I), a nonphysiologic and pathogenic compound (1).…”

Section: Introductionmentioning

confidence: 99%

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Congenital erythropoietic porphyria: identification and expression of exonic mutations in the uroporphyrinogen III synthase gene.

Warner¹,

Yoo²,

Roberts³

et al. 1992

J. Clin. Invest.

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Congenital erythropoietic porphyria (CEP), an inborn error of heme biosynthesis, results from the deficient activity of uroporphyrinogen III synthase (URO-synthase). This autosomal recessive disorder is heterogeneous; patients with severe disease are often transfusion dependent, while milder patients primarily have cutaneous involvement. To investigate this phenotypic heterogeneity, exonic point mutations in the URO-synthase gene were identified in unrelated CEP patients. Four missense mutations were identified: (a) an A to G transition of nucleotide (nt) 184 that predicted a Thr to Ala substitution at residue 62 (designated T62A); (b) a C to T transition of nt 197 that encoded an Ala to Val replacement at residue 66 (A66V); (c) a T to C transition of nt 217 that predicted a Cys to Arg substitution at residue 73 (C73R); and (d) a C to T transition of nt 683 that resulted in a Thr to Met replacement at residue 228 (T228M). In addition, a G to A transition of nt 27 that did not change the encoded amino acid (A9A) was detected in an African patient. The T62A, C73R, and T228M alleles did not express detectable enzymatic activity, while the A66V allele expressed residual, but unstable activity. The C73R allele was present in eight of 21 unrelated CEP patients (21% of CEP alleles). In three patients, identification of both alleles permitted genotypephenotype correlations; the A66V/C73R, T228M/C73R, and C73R/C73R genotypes had mild, moderately severe, and severe disease, respectively. These findings provide the first genotype-phenotype correlations and permit molecular heterozygote detection in this inherited porphyria. (J. Clin. Invest.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Congenital erythropoietic porphyria: identification and expression of exonic mutations in the uroporphyrinogen III synthase gene.

Warner¹,

Yoo²,

Roberts³

et al. 1992

J. Clin. Invest.

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“…URO-synthase normally catalyzes the conversion of the linear tetrapyrrole, hydroxymethylbilane, to uroporphyrinogen III, the physiologic cyclic isomer which is metabolized in subsequent enzymatic steps to heme (9,10). The markedly deficient activity of URO-synthase results in the nonenzymatic conversion of hydroxymethylbilane to the uroporphyrinogen I isomer, which is then oxidized to the nonphysiologic and pathogenic compound, URO I.…”

Section: Introductionmentioning

confidence: 99%

Congenital erythropoietic porphyria: identification and expression of 10 mutations in the uroporphyrinogen III synthase gene.

Xu¹,

Warner²,

Desnick³

1995

J. Clin. Invest.

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To investigate the molecular basis of the phenotypic heterogeneity in congenital erythropoietic porphyria, the mutations in the uroporphyrinogen m synthase gene from unrelated patients were determined. Six missense (L4F, Y19C, V82F, V99A, A104V, and G225S), a nonsense (Q249X), a frameshift (633insA), and two splicing mutations (IVS2+ and IVS9AA+4) were identified. When L4F, Y19C, V82F, V99A, A104V, 633insA, G225S, and Q249X were expressed in Eseherichia cok, only the V82F, V99A, and A104V alleles expressed residual enzymatic activity. Of note, the V82F mutation, which occurs adjacent to the 5' donor site of intron 4, resulted in -54% aberrantly spliced transcripts with exon 4 deleted. Thus, this novel exonic single-base substitution caused two lesions, a missense mutation and an aberrantly spliced transcript. Of the splicing mutations, the IVS2+1 allele produced a single transcript with exon 2 deleted, whereas the IVS9AA+4 allele was alternatively spliced, -26% being normal transcripts and the remainder with exon 9 deleted. The amount of residual activity expressed by each allele provided a basis to correlate genotype with disease severity, thereby permitting genotype/phenotype predictions in this clinically heterogeneous disease. (J. Clin. Invest. 1995. 95:905-912.)

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“…3 and 4). It is now recognized that HMB-synthase catalyzes the head to tail condensation offour molecules of porphobilinogen to form the linear tetrapyrrole HMB (4,5). In the presence of URO-synthase, HMB is rapidly converted to uroporphyrinogen III by an intramolecular rearrangement of the D-pyrrole group and ring closure (5)(6)(7).…”

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confidence: 99%

Human uroporphyrinogen III synthase: molecular cloning, nucleotide sequence, and expression of a full-length cDNA.

Tsai

Bishop

Desnick

1988

Proc. Natl. Acad. Sci. U.S.A.

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Uroporphyrinogen III synthase [URO-synthase; hydroxymethylbilane hydro-lyase (cyclizing), EC 4.2.1.75], the fourth enzyme in the heme biosynthetic pathway, is responsible for conversion of the linear tetrapyrrole, hydroxymethylbilane, to the cyclic tetrapyrrole, uroporphyrinogen III. The deficient activity of URO-synthase is the enzymatic defect in the autosomal recessive disorder congenital erythropoietic porphyria. To facilitate the isolation of a full-length cDNA for human URO-synthase, the human erythrocyte enzyme was purified to homogeneity and 81 nonoverlapping amino acids were determined by microsequencing the N terminus and four tryptic peptides. Two synthetic oligonucleotide mixtures were used to screen 1.2 x 106 recombinants from a human adult liver cDNA library. Eight clones were positive with both oligonucleotide mixtures. Of these, dideoxy sequencing of the 1.3 kilobase insert from clone pUROS-2 revealed 5' and 3' untranslated sequences of 196 and 284 base pairs, respectively, and an open reading frame of 798 base pairs encoding a protein of 265 amino acids with a predicted molecular mass of 28,607 Da. The authenticity of this clone was established by colinearity of the predicted amino acid sequence with 81 microsequenced residues from the purified enzyme. In addition, high levels of enzymatic activity and immunoreactive protein were expressed when a blunt-ended 971-base-pair Ava II cDNA fragment containing the entire coding region was inserted into vectors for expression in Escherichia coli. The isolation and expression of this full-length cDNA for human URO-synthase should facilitate studies of the structure, organization, and chromosomal localization of this heme biosynthetic gene as well as the characterization of the molecular lesions causing congenital erythropoietic porphyria. were required for the conversion of the monopyrrole, porphobilinogen, to the cyclic tetrapyrrole, uroporphyrinogen III (2). During the next two decades, the precise function of the two enzymes in uroporphyrinogen III biosynthesis was the subject of active investigation and debate, particularly with regard to their reaction mechanisms and intermediates and their potential interaction in a cytosolic enzyme complex (for reviews, see refs. 3 and 4). It is now recognized that HMB-synthase catalyzes the head to tail condensation offour molecules of porphobilinogen to form the linear tetrapyrrole HMB (4, 5). In the presence of URO-synthase, HMB is rapidly converted to uroporphyrinogen III by an intramolecular rearrangement of the D-pyrrole group and ring closure (5-7). In the absence of URO-synthase, HMB nonenzymatically cyclizes to form the nonphysiologic uroporphyrinogen I isomer.The deficient activity of URO-synthase is the enzymatic defect in congenital erythropoietic porphyria, an inborn error of heme biosynthesis that is inherited as an autosomal recessive trait (8). Enzymatic diagnosis of affected homozygotes and asymptomatic heterozygous carriers can be made by the demonstration of deficient or intermediate lev...

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Biosynthesis of porphyries and related macrocycles. Part 18. Proof by spectroscopy and synthesis that unrearranged hydroxymethylbilane is the product from deaminase and the substrate for cosynthetase in the biosynthesis of uroporphyrinogen-III

Cited by 70 publications

References 5 publications

Congenital erythropoietic porphyria: identification and expression of exonic mutations in the uroporphyrinogen III synthase gene.

Congenital erythropoietic porphyria: identification and expression of exonic mutations in the uroporphyrinogen III synthase gene.

Congenital erythropoietic porphyria: identification and expression of 10 mutations in the uroporphyrinogen III synthase gene.

Human uroporphyrinogen III synthase: molecular cloning, nucleotide sequence, and expression of a full-length cDNA.

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