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In E. coli, DNA topoisomerase IV plays the major role in the separation of the catenated chromosomes, transiently breaking both DNA strands of one chromosome and allowing the other chromosome to pass through the break. There has been some confusion about the role DNA gyrase plays in decatenation. To define the nomenclature, there are two types ...
The haploid circular chromosome in E. coli consists of ~ 4.6 x 10 6 bp. If DNA is relaxed in the B form, it would have a circumference of ~1.5 millimeters (0.332 nm x 4.6 x 10 6). However, a large DNA molecule such as the E. coli chromosomal DNA does not remain a straight rigid molecule in a suspension. [5]
E. coli is a gram-negative, facultative anaerobe, nonsporulating coliform bacterium. [18] Cells are typically rod-shaped, and are about 2.0 μm long and 0.25–1.0 μm in diameter, with a cell volume of 0.6–0.7 μm 3. [19] [20] [21] E. coli stains gram-negative because its cell wall is composed of a thin peptidoglycan layer and an outer membrane.
Bacterial morphological plasticity refers to changes in the shape and size that bacterial cells undergo when they encounter stressful environments. Although bacteria have evolved complex molecular strategies to maintain their shape, many are able to alter their shape as a survival strategy in response to protist predators, antibiotics, the immune response, and other threats.
Genetic systems have also been developed which allow the production of recombinant proteins using E. coli. One of the first useful applications of recombinant DNA technology was the manipulation of E. coli to produce human insulin. [26] Modified E. coli have been used in vaccine development, bioremediation, and production of immobilised enzymes ...
More than five decades ago, Jacob, Brenner, and Cuzin proposed the replicon hypothesis to explain the regulation of chromosomal DNA synthesis in E. coli. [18] The model postulates that a diffusible, trans-acting factor, a so-called initiator, interacts with a cis-acting DNA element, the replicator, to promote replication onset at a nearby origin.
Bacteriophage Lambda binds to an E. coli cell by means of its J protein in the tail tip. The J protein interacts with the maltose outer membrane porin (the product of the lamB gene) of E. coli, [9] a porin molecule, which is part of the maltose operon. The linear phage genome is injected through the outer membrane.
On the other hand, the core genome has remain static since 2012. Currently, the E. coli pan-genome is composed of about 90,000 gene families. About one-third of these exist only in a single genome. Many of these, however, are merely gene fragments and the result of calling errors. Still, there are probably over 60,000 unique gene families in E ...