Glutamyl-tRNA reductase from Escherichia coli and Synechocystis 6803: Gene structure and expression
| Autor: | Dieter Söll, Anuj Kumar, Martina Jahn, Dieter Jahn, Elizabeth Verkamp |
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| Předmět: |
Sequence analysis
Genes Fungal Molecular Sequence Data Restriction Mapping Gene Expression Saccharomyces cerevisiae Biology medicine.disease_cause Cyanobacteria Biochemistry Gene product Open Reading Frames Glutamyl-tRNA reductase Sequence Homology Nucleic Acid medicine Escherichia coli Amino Acid Sequence Molecular Biology Peptide sequence Base Sequence Synechocystis Genetic Complementation Test Cell Biology biology.organism_classification Molecular biology Aldehyde Oxidoreductases Complementation Open reading frame Genes Bacterial Chromatography Gel Plasmids |
| Zdroj: | Scopus-Elsevier |
| Popis: | In the cyanobacterium Synechocystis sp. PCC 6803 and in the enterobacterium Escherichia coli delta-amino-levulinic acid (ALA) is formed from glutamyl-tRNA by the sequential action of two enzymes, glutamyl-tRNA reductase (GluTR) and glutamate-1-semialdehyde aminotransferase. E. coli has two GluTR proteins with sizes of 45 kDa (GluTR45) and 85 kDa (GluTR85) (Jahn, D., Michelsen, U., and Soll, D. (1991) J. Biol. Chem. 266, 2542-2548). The hemA gene, isolated from E. coli and several other eubacteria, has been proposed to encode a structural component of GluTR. Because of the inability to overexpress this gene in E. coli, we demonstrate directly GluTR function for the E. coli hemA gene product by its expression and functional analysis in yeast, which does not form ALA from Glu-tRNA. Gel filtration experiments demonstrated definitively that the yeast-expressed HemA protein corresponded to GluTR45. Furthermore, analysis of GluTR activity in an E. coli strain with a disrupted hemA gene displayed GluTR85, but not GluTR45 activity. The hemA gene from Synechocystis 6803 was cloned by functional complementation in E. coli. DNA sequence analysis revealed an open reading frame capable of encoding a 427-amino acid polypeptide (molecular mass of 47,525 Da). The Synechocystis 6803 amino acid sequence shows significant similarity upon alignment with HemA sequences from E. coli, Bacillus subtilis, Salmonella typhimurium, and Chlorobium vibrioforme but does not contain the amino acid sequence derived from the N terminus of the previously purified GluTR protein (Rieble, S., and Beale, S. I. (1991) J. Biol. Chem. 266, 9740-9745). These experiments are the first direct demonstration of GluTR activity of the HemA protein and provide further evidence for two pathways of ALA formation in prokaryotes. |
| Databáze: | OpenAIRE |
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