A soybean coproporphyrinogen oxidase gene is highly expressed in root nodules

• Published in: Plant molecular biology 1993-10, Vol.23 (1), p.35-43
• Main Authors: MADSEN, O, SANDAL, L, SANDAL, N. N, MARCKER, K. A
• Format: Article
• Language: English
• Subjects: adn; Amino Acid Sequence; arn mensajero; arn messager; Base Sequence; Biological and medical sciences; Blotting, Northern; Cloning, Molecular; Coproporphyrinogen Oxidase - biosynthesis; Coproporphyrinogen Oxidase - genetics; DNA; expresion genica; expression des genes; Fundamental and applied biological sciences. Psychology; gene; gene expression; Gene Expression Regulation, Enzymologic; genes; Genes. Genome; Genetic Complementation Test; Glycine max; Glycine max - anatomy & histology; Glycine max - enzymology; Glycine max - genetics; Heme - biosynthesis; messenger rna; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; nodosite racinaire; nudosidades radiculares; oxidoreductases; oxidorreductasas; oxydoreductase; root nodules; Saccharomyces cerevisiae - genetics; Sequence Homology, Amino Acid
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1007/BF00021417

In plants the enzyme coproporphyrinogen oxidase catalyzes the oxidative decarboxylation of coproporphyrinogen III to protoporphyrinogen IX in the heme and chlorophyll biosynthesis pathway(s). We have isolated a soybean coproporphyrinogen oxidase cDNA from a cDNA library and determined the primary structure of the corresponding gene. The coproporphyrinogen oxidase gene encodes a polypeptide with a predicted molecular mass of 43 kDa. The derived amino acid sequence shows 50% similarity to the corresponding yeast amino acid sequence. The main difference is an extension of 67 amino acids at the N-terminus of the soybean polypeptide which may function as a transit peptide. A full-length coproporphyrinogen oxidase cDNA clone complements a yeast mutant deleted of the coproporphyrinogen oxidase gene, thus demonstrating the function of the soybean protein. The soybean coproporphyrinogen oxidase gene is highly expressed in nodules at the stage where several late nodulins including leghemoglobin appear. The coproporphyrinogen oxidase mRNA is also detectable in leaves but at a lower level than in nodules while no mRNA is detectable in roots. The high level of coproporphyrinogen oxidase mRNA in soybean nodules implies that the plant increases heme production in the nodules to meet the demand for additional heme required for hemoprotein formation.