Molecular cloning, sequencing, and functional expression of a cDNA encoding human coproporphyrinogen oxidase.

Abstract

Coproporphyrinogen oxidase (EC 1.3.3 To facilitate the characterization of the structure of CPX, to determine the molecular defects in hereditary coproporphyria, and to study the role of CPX in the regulation of the heme biosynthetic pathway, molecular cloning ofa cDNA for human CPX was an important step.To achieve this goal, murine CPX was purified; the aminoterminus of the intact protein and an internal peptide fragment were sequenced; and degenerate oligonucleotides were designed to amplify a specific portion ofthe murine cDNA by using reverse transcription (RT) and the polymerase chain reaction (PCR). By this approach a murine cDNA probe was obtained that was used to isolate a human cDNA. In this communication the primary sequence of human CPXi and

Human Coproporphyrinogen Oxidase Is Not a Metalloprotein

“…2). The absorption at 280 nm was used to quantitate the protein using an estimated molar extinction coefficient of 52,000 as determined by Peptidesort (23) using the published amino acid sequence (7,8). The absorption band at 406 nm was determined by fluorescence emission and excitation scans to be due to a small amount of contaminating porphyrin (data not shown).…”

“…In this reaction two molecules of O 2 are consumed, and two molecules CO 2 and two protons are released in the conversion of the 2-and 4-propinyl groups to vinyl groups (1). CPO has been cloned and its DNA sequence has been determined for a number of prokaryotic and eukaryotic organisms including, yeast (2), soybean (3), Salmonella typhimurium (4), Escherichia coli (5), mouse (6), and human (7,8). The enzyme has been purified from several sources including bovine liver (9), mouse liver (10), yeast (11), and mouse (recombinant) (12).…”

Two novel mutations and coexistence of the 991C.T and the 1339C.T mutation on a single allele in the coproporphyrinogen oxidase gene in Swedish patients with hereditary coproporphyria

“…The gene encoding human CPO has been cloned, sequenced (Martasek et al 1994a;Taketani et al 1994), and mapped to chromosome 3q12 (Cacheux et al 1994). The gene contains seven exons, encoding a 454-amino acid peptide, of which the 110 N-terminal amino acid residues constitute a putative mitochondrial target sequence (Delfau-Larue et al 1994).…”

Structural basis of hereditary coproporphyria

“…Other factors, including drugs, alcohol, stress, or infection, can precipitate HCP in susceptible individuals (21). Since the cloning of human CPO gene (22,23), several mutations that diminish enzyme activity have been identified (24).CPO is an extraordinary enzyme of particular interest to chemistry and medicine. As a homodimer (25), it catalyzes the oxidative decarboxylation of propionic acid side chains of rings A and B of coproporphyrinogen Fig.…”

“…Other factors, including drugs, alcohol, stress, or infection, can precipitate HCP in susceptible individuals (21). Since the cloning of human CPO gene (22,23), several mutations that diminish enzyme activity have been identified (24).…”