The density distribution of gene loci over the genetic map of Escherichia coli: its structural, functional and evolutionary implications.

A quantitative analysis was carried out on the dispersion of gene loci over the E. coli genetic map. Therefore, the map was divided into regions characterized by an homogeneous gene density. This created a distribution pattern of gene loci that contained a symmetry axis located near to the origin of DNA replication. The pattern could be subdivided into a set of 22 functional domains containing gene loci whose products revealed a biochemical or functional relatedness. A correlation was found between the boundary positions of these domains and the distribution of F plasmid- and DNA insertion sites over the E. coli chromosome. The structural, functional and evolutionary implications of these findings are discussed.