Cytokines & Cells Online Pathfinder Encyclopaedia
|
Horst Ibelgaufts' COPE:
Cytokines & Cells Online Pathfinder Encyclopaedia |
 |
 |
 |
 |
 |
 |
 |
| COPE Homepage | Previous entry: ESCGF |
Next entry: Escherichia coli Cytolethal distending toxin |
Random entry: LIM domain only-2 |
abbr. E. coli.
A small rod-shaped facultative anaerobic Gram-negative bacterium named after its discoverer, the German physician Theodor Escherich.
Escherichia coli has a length of approximately 2-4 micrometers and a diameter of approximately 1 micrometer. Most wild-type strains are motile although most laboratory strains do not possess flagellae.
Escherichia coli is a member of the larger family Enterobacteriaceae and thus is related closely to Salmonella typhimurium, Shigella spp, Klebsiella, and the plant pathogen Erwinia spp. Escherichia coli can be identified by specific biochemical and physiological characteristics and by specific antigenic reactions (see also: endotoxins).
Escherichia coli is found in the human intestinal tract and constitutes approximately 1 % of all micro-organisms that can be cultivated from human faeces (approximately10**7 bacteria/gram of faeces). It can survive for some time in the normal environment. Escherichia coli is usually not pathogenic but it is a potential pathogen elsewhere in the body. Some strains of Escherichia coli cause urinary tract infections, bacteremia, peritonitis, and neonatal meningitis.
Work with Escherichia coli has many advantages for molecular biologists. Escherichia coli can be cultivated in simple media containing mineral salts, ammonium salts as a source of nitrogen, and simple sugars that serve as carbon sources. In rich media supplemented with undefined meat or yeast extracts and/or protein hydrolysates Escherichia coli has a doubling time of approximately 30 min. This yields so-called overnight cultures containing approximately 3x10**9 bacteria per mL.
Discoveries such as the exchange of genetic material between bacterial cells by means of plasmids, and numerous experiments with bacterial viruses (bacteriophages) are milestones in the history of molecular biology and bacterial genetics. Work with bacteria, plasmids, and bacterial viruses has been of decisive importance in developing and refining the concept of genes (see also: gene expression), and in elucidating the genetic code, mechanisms of DNA replication and DNA repair, and protein biosynthesis and numerous biochemical reaction pathways. This work has been the foundation also of modern techniques of genetic engineering.
Today Escherichia coli is the best characterized micro-organism known to science. Many thousands of different and well-characterized mutants have been described. The genome of Escherichia coli consists of approximately 4.6 kb (kilobases) of circular double-stranded DNA and approximately 70 % of it has been sequenced. More than 1500 genes have been identified, and approximately 80 % of its biochemical reactions are known.
As a result of its ease of manipulation and the quantity of protein obtainable by heterologous gene expression (see also: Recombinant cytokines) Escherichia coli is still one of the standard organisms used to clone and express foreign genes. Escherichia coli can be manipulated to synthesize more than 50 % of its total cell protein as a recombinant product.
Escherichia coli has been used to study heterologous expression of many cytokine genes and other proteins of interest in research on cytokines although not all proteins are amenable to high-level expression.
Several features of heterologous coding sequences have been shown to be responsible for limited translation efficiency, affecting both translation initiation and elongation. Moreover, high-level production of proteins often correlates with poor quality, leading, for example, to variable amounts of N-terminal heterogeneity.
Unlike eukaryotic expression systems Escherichia coli cannot be used to express foreign genes containing intron sequences (see also: gene expression). In addition, Escherichia coli does not possess the molecular machinery allowing correct post-translational processing of foreign proteins, which may be of importance in view of medical applications of cytokines as absence of glycosylation may negatively affect immunogenicity, biological activity or such factors as biological half life in vivo. Nevertheless, many of the bacteria-derived cytokines have been found to be biologically active.
For eukaryotic expression systems employed in molecular biology and research on cytokines see also: BHK cells, CHO cells, COS cells, Namalwa cells, Baculovirus expression system, Saccharomyces cerevisiae.
See REFERENCES for entry Escherichia coli
| SUPPORT COPE | Intro | Subdictionaries | New Entries | Contribute data | COPE Credentials |
| # | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
|
Space for your TEXTLINK ADVERTISEMENTS. Please Inquire
|
 |
 |
 |
 |
 |
 |
 |
supports the COPE bioinformatics project with an unrestricted educational grant |
Created, developed, and maintained by Prof Dr H Ibelgaufts
|
| Access to COPE is free only for academic institutions and non-profit organizations. OTHER USERS: must contact COPE and pay a site licence fee. Non-payment of the site licence fee is a serious breach of COPE's binding Usage Agreement. If you do not wish to be bound by this agreement, do not use COPE |
| COPE is not in the public domain! The commercial use of COPE contents is not allowed. Download of complete offline-readable copies and the use of automatic extraction methods are prohibited! Usage Agreement, Disclaimer, Copyright Notice | All rights reserved by H Ibelgaufts | Privacy Statement U L T R A P O S S E N E M O O B L I G A T U R |