Cytochromes/genetics; Electron Transport Chain Complex Proteins/genetics; Escherichia coli Proteins/genetics; Evolution, Molecular; Oxidoreductases/genetics; Alleles; Amino Acid Sequence; Computational Biology/methods; Conserved Sequence; Cytochrome b Group; Cytochromes/chemistry; Cytochromes/metabolism; Electron Transport Chain Complex Proteins/chemistry; Electron Transport Chain Complex Proteins/metabolism; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/metabolism; Gene Order; Gene Transfer, Horizontal; Genetic Complementation Test; Genome, Bacterial; Genomics; Hydrophobic and Hydrophilic Interactions; Markov Chains; Molecular Sequence Annotation; Molecular Sequence Data; Mutation; Operon; Oxidoreductases/chemistry; Oxidoreductases/metabolism; Phylogeny; Position-Specific Scoring Matrices; Protein Interaction Domains and Motifs; Proteobacteria/genetics; Proteobacteria/metabolism; Sequence Alignment; Sequence Analysis, DNA