A physical map of the Escherichia coli bio operon

The endpoints of the Escherichia coli bio DNA insertions in 24 lambda bio transducing phage were mapped electron micrographically in heteroduplexes of the type lambda bio/lambda att2, which permit simultaneous measurement of the lambda deletion and bio insertion endpoints. A physical map of the bio operon was constructed and correlated with the genetic map, the molecular sizes of the bio gene products, and the restriction map. The order att lambda-bioA-pBopA-bioBFCD-uvrB was confirmed. The maximum size of the bio operon was estimated at 5.5 kb, and the locus was found to be fully saturated with genes. There appears to be little space between the bioA gene and att lambda, while bioD mapped within 0.7 kb from uvrB. The size of the uvrB locus was estimated not to exceed 2.6 kb.