Genetic fusion of subunits I, II, and III of the cytochrome bo ubiquinol oxidase from Escherichia coli results in a fully assembled and active enzyme
| Autor: | Robert B. Gennis, Laura Lemieux, Jixiang Ma |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Oxidase test
Base Sequence Recombinant Fusion Proteins Protein subunit Molecular Sequence Data Ubiquinol oxidase Periplasmic space Biology Biochemistry Transmembrane protein Electron Transport Complex IV Enzyme Activation Transmembrane domain Enzyme activator Oligodeoxyribonucleotides Operon Escherichia coli biology.protein Cytochrome c oxidase Plasmids |
| Zdroj: | Biochemistry. 32:7692-7697 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi00081a013 |
| Popis: | The cytochrome bo ubiquinol oxidase from Escherichia coli is a five-subunit enzyme which is a member of the superfamily of heme-copper respiratory oxidases. Three of the subunits (I, II, and III) are homologous to the three mitochondrial encoded subunits of the eukaryotic aa3-type cytochrome c oxidase. Subunits, I, II, and III of the eukaryotic oxidase contain 12, 2, and 7 putative transmembrane spans, respectively. The hydropathy profiles of the subunits of most other members of this oxidase superfamily are consistent with these structures. However, subunit I from the E. coli oxidase contains 15 transmembrane spans, with one additional span at the N-terminus and two additional spans at the C-terminus in comparison to the eukaryotic oxidase. The additional transmembrane helix at the N-terminus predicts that the amino terminal residue should be on the periplasmic side of the membrane. By deleting the intergenic region between the cyoA and cyoB genes, an in-frame fusion between subunit II (cyoA) and subunit I (cyoB) was generated. This links the C-terminus of subunit II, known to be on the periplasmic side of the membrane, to the N-terminus of subunit I. The resulting oxidase is fully active, and supports the toplogical folding pattern previously suggested for subunit I with the N-terminus in the periplasm. Whereas subunit I of the E. coli oxidase has two additional membrane-spanning helices at the C-terminus, subunit III has two fewer helices than does the corresponding subunit III of the eukaryotic oxidase.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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