Topic
Escherichia coli
About: Escherichia coli is a research topic. Over the lifetime, 59041 publications have been published within this topic receiving 2050337 citations. The topic is also known as: E. coli & E coli jdj.
Papers published on a yearly basis
Papers
More filters
TL;DR: Replicative synthesis, as distinguished from repair synthesis, occurs at a rate comparable to that observed in vivo; it is dependent on the presence of all four deoxyribonucleoside triphosphates, but does not require exogenous DNA; and it is stimulated by ATP.
Abstract: DNA synthesis has been studied in Escherichia coli cells made permeable to nucleotides by treatment with toluene. Replicative synthesis, as distinguished from repair synthesis, occurs at a rate comparable to that observed in vivo; it is dependent on the presence of all four deoxyribonucleoside triphosphates, but does not require exogenous DNA; and it is stimulated by ATP. Furthermore, replicative synthesis can be abolished at the restrictive temperature in DNA temperature-sensitive mutants. N-ethylmaleimide completely inhibits this type of synthesis, whereas it does not inhibit repair synthesis. Repair synthesis further differs from replicative synthesis in the following points: it does not require ATP; it persists at the restrictive temperature in DNA temperature-sensitive mutants; it can be induced by endogenous or exogenous nuclease activity; and its demonstration requires a Pol+ strain.
304 citations
TL;DR: Fimbriae are long, threadlike protein polymers found on the surface of many strains of Escherichia coli that confer on pathogenic strains the ability to adhere to and colonize various specific host epithelia.
Abstract: Fimbriae are long, threadlike protein polymers found on the surface of many strains of Escherichia coli. The presence of fimbriae has been found to be significantly correlated with pathogenicity, and specific fimbriae confer on pathogenic strains the ability to adhere to and colonize various specific host epithelia. A surprising variety of fimbrial adhesions have been found in E. coli; several unrelated groups of such proteins have been extensively characterized. Fimbriae of E. coli are strongly immunogenic. Their continuous interaction with host defenses has imposed heavy selective pressure on them, leading to a fine balance between functional necessity and maximal immunologic diversity. These important virulence factors may be exploited in various ways in the production of vaccination agents. Vaccines based on E. coli fimbriae have proved extremely successful in the veterinary sector, and several types of immunization are currently being tested in humans.
304 citations
TL;DR: It is proposed that E. coli messages beginning with a single-stranded RNA segment of significant length are preferentially targeted by a degradative ribonuclease that interacts with the mRNA 5' terminus before cleaving internally at one or more distal sites.
Abstract: The 5'-untranslated region of the long-lived Escherichia coli ompA transcript functions as an mRNA stabilizer capable of prolonging the lifetime in E. coli of a number of heterologous messages to which it is fused. To elucidate the structural basis of differential mRNA stability in bacteria, the domains of the ompA 5'-untranslated region that allow it to protect mRNA from degradation have been identified by mutational analysis. The presence of a stem-loop no more than 2-4 nucleotides from the extreme 5' terminus of this RNA segment is crucial to its stabilizing influence, whereas the sequence of the stem-loop is relatively unimportant. The potential to form a hairpin very close to the 5' end is a feature common to a number of stable prokaryotic messages. Moreover, the lifetime of a normally labile message {bla mRNA) can be prolonged in £. coli by adding a simple hairpin structure at its 5' terminus. Accelerated degradation of ompA mRNA in the absence of a 5'-terminal stem-loop appears to start downstream of the 5' end. We propose that E. coli messages beginning with a single-stranded RNA segment of significant length are preferentially targeted by a degradative tibonuclease that interacts with the mRNA 5' terminus before cleaving internally at one or more distal sites.
303 citations
303 citations
TL;DR: In this article, a plasmid vector was constructed which expressed three adenovirus tumor antigens fused to a portion of the trpE protein of Escherichia coli.
Abstract: Plasmid vectors were constructed which expressed three adenovirus tumor antigens fused to a portion of the trpE protein of Escherichia coli. Insertion of adenovirus type 2 DNA from early region 1A (E1A) into such a plasmid led to a fusion protein which contained the C-terminal 266 amino acids of the 289-amino acid protein encoded by the viral 13S mRNA. Similarly, insertion of adenovirus type 5 DNA corresponding to the E1B 55- and 21-kilodalton proteins led to production of fusion proteins containing amino acid sequences from these proteins. After induction with indoleacrylic acid, fusion proteins accumulated stably in the E. coli cells. By using a simple extraction of insoluble protein, 1 to 10 mg of fusion protein per liter of culture was obtained. The fusion proteins were purified on preparative polyacrylamide gels and used to immunize rabbits. Specific antisera for the E1A 289- and closely related 243-amino acid proteins and the E1B 55- and 21-kilodalton proteins were obtained. These sera were used to immunoprecipitate the tumor antigens in cells infected with wild-type and various mutants of adenovirus or to analyze them by an immunoblotting procedure. Mutant E1A proteins in which the C-terminal 70 amino acids are deleted were phosphorylated to much lower extents than the wild-type E1A proteins. This indicates that the deleted region is important for the process of phosphorylation. The E1A proteins were extracted, sedimented in glycerol gradients, analyzed by immunoprecipitation, and found to sediment primarily as monomers.
303 citations