PMID:8399242
| Citation |
Thomas, JW, Puustinen, A, Alben, JO, Gennis, RB and Wikström, M (1993) Substitution of asparagine for aspartate-135 in subunit I of the cytochrome bo ubiquinol oxidase of Escherichia coli eliminates proton-pumping activity. Biochemistry 32:10923-8 |
|---|---|
| Abstract |
The terminal quinol oxidase, cytochrome bo, of Escherichia coli is a member of the large terminal oxidase family, which includes cytochrome aa3-type terminal oxidases from bacteria, plants, and animals. These enzymes conserve energy by linking electron transfer to vectorial proton translocation across mitochondrial or bacterial cell membranes. Site-directed mutagenesis of the five most highly conserved acidic amino acids in subunit I of cytochrome bo was performed to study their role in proton transfer. Mutation of only one of these sites, Asp135, to the corresponding amide, results in a dramatic decrease in proton pumping but with little change in electron-transfer activity. However, the conservative mutation Asp135Glu is active in proton translocation. It is proposed that an acidic residue at position 135 in subunit I may be important to form a functional proton input channel of the proton pump. |
| Links | |
| Keywords |
Amino Acid Sequence; Asparagine; Aspartic Acid; Cloning, Molecular; Conserved Sequence; Electron Transport Complex IV/chemistry; Electron Transport Complex IV/metabolism; Escherichia coli/enzymology; Hydrogen-Ion Concentration; Kinetics; Macromolecular Substances; Models, Structural; Molecular Sequence Data; Mutagenesis, Site-Directed; Protein Structure, Secondary; Recombinant Proteins/chemistry; Recombinant Proteins/metabolism; Spectroscopy, Fourier Transform Infrared/methods |
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