Base Composition, Base Sequence, Codon, DNA-Directed RNA Polymerases, Escherichia coli, Gene Expression Regulation, Bacterial, Genotype, Kinetics, Mutagenesis, Operon, Plasmids, Promoter Regions, Genetic, RNA, Bacterial, Recombination, Genetic, Templates, Genetic, Transcription, Genetic, Uridine Triphosphate