|
|
|
Obtaining the complete DNA sequence of the E. coli genome has been a goal of the Human Genome Project, both to help develop sequencing and gene-finding technology and to facilitate studies on gene function and organization. More than 4200 E. coli genes have been identified, although the functions of over one-third of them remain unknown. Because of similarities found in genes across species, this work provides a valuable starting point for identifying and understanding genes in other organisms, including humans. Determination of the complete inventory of the genes of organisms is one of the major goals 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. For more than 70 years E. coli, a natural inhabitant of the lower intestinal tract of animals, has been one of the most studied organisms for scientists exploring fundamental processes in biochemistry, genetics, and physiology. In recent years it has become the workhorse of biotechnology and serves as a living factory for producing human insulin and other medicines. The strain used in this study does not cause disease, but related toxic strains have been associated with an increasing number of human food poisonings. The new data provide a reference strain against which scientists are already comparing the genes of pathogenic strains. At the Ninth International Genome Sequencing and Analysis Conference (Hilton Head, South Carolina) in September 1997, Blattner described his groups study of sequences from the genome of E. coli 0157:H7, the strain responsible for many recent outbreaks of fast-food poisoning associated with hemolytic uremic syndrome. A sample of 20,000 random sequences compared against the K-12 genome and the public databases revealed about 1 Mb of DNA not present in K-12. Homology searches revealed matches to virulence genes from a variety of species. These and future studies will lay the groundwork for developing drugs to help prevent or to treat diseases associated with toxic E. coli strains. |
加入最爱