Recent studies of the cytochrome o terminal oxidase complex of Escherichia coli
| Autor: | Visala Chepuri, James O. Alben, John Walter Hill, Robert B. Gennis, Laura Lemieux |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Hemeproteins
Models Molecular Hemeprotein Cytochrome Spectrophotometry Infrared Ubiquinol oxidase Molecular Sequence Data Biophysics Biochemistry Electron Transport Complex IV Cytochrome C1 Metalloproteins Escherichia coli Cytochrome c oxidase Amino Acid Sequence Cloning Molecular Binding Sites biology Cytochrome c peroxidase Cytochrome c Cell Biology Alkaline Phosphatase Genes Bacterial Coenzyme Q – cytochrome c reductase biology.protein |
| Zdroj: | Biochimica et biophysica acta. 1018(2-3) |
| ISSN: | 0006-3002 |
| Popis: | The cytochrome o complex is the predominant terminal oxidase in the aerobic respiratory chain of Escherichia coli when the bacteria are grown under conditions of high aeration. The oxidase is a ubiquinol oxidase and reduces molecular oxygen to water. Electron transport through the enzyme is coupled to the generation of a protonmotive force. The purified cytochrome o complex contains four or five subunits, two protoheme IX (heme b ) prosthetic groups, plus at least one Cu. The subunits are all encoded by the cyo operon. Sequence comparisons show that the cytochrome o complex is closely related to the aa 3 -type cytochrome c oxidase family. Gene fusions have been used to define the topology of each of the gene products. Subunits I, II, III and IV are proposed to have 15, 2, 5 and 3 transmembrane spans, respectively. The fifth gene product ( cyo E) encodes a protein with 7 membrane spanning segments, and this may also be a subunit of this enzyme. Fourier transform infrared spectroscopy has been used to monitor CO bound in the active site where oxygen is reduced. These data provide definitive proof that the cytochrome o complex has a heme-copper binuclear center, similar to that present in the aa 3 -type cytochrome c oxidases. Site-directed mutagenesis is being utilized to define which amino acids are ligands to the heme iron and copper prosthetic groups. |
| Databáze: | OpenAIRE |
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