A genome is the sum total of the genes of an organism. Genes are encoded in the sequence of chemical base pairs that make up the intertwining strands of DNA. In the case of E. coli, a total of 4,403 genes have been identified in the 4,639,221 base pairs of DNA sequenced by the Wisconsin team. Of these, one-third are of completely unknown function.
E. coli holds a unique place in modern biology. It is arguably the single most studied cell in all of science. Humans have about 25 times as many genes as E. coli, but in the future a similar complete analysis will be possible for human DNA. For this reason E. coli is considered a model organism in the Human Genome Initiative of the National Institutes of Health (NIH).
For more than 70 years, Escherichia coli has been a mainstay of basic biology, and recent developments in biotechnology and genetic engineering have depended heavily on it. Related strains of E. coli are also responsible for several human diseases. Although not the first bacterial genome to be completed, E. coli is by far the most complex and the most eagerly awaited by scientists around the world.
"Determination of the complete inventory of the genes of organisms is one of the holy grails of biology, analogous to development of the periodic table of the elements in chemistry," said Blattner. "Once they are all known and relationships between them become evident, a classification system for understanding the basic functions of life can be erected."
E. coli's natural habitat is the lower intestinal tract of animals, including humans.
Originally isolated in 1922 from a convalescent diphtheria patient, the strain
of E. coli sequenced
Contact: Terry Devitt
University of Wisconsin-Madison