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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 ...
E. coli is a chemoheterotroph whose chemically defined medium must include a source of carbon and energy. [16] E. coli is the most widely studied prokaryotic model organism, and an important species in the fields of biotechnology and microbiology, where it has served as the host organism for the majority of work with recombinant DNA. Under ...
The oriC site in E. coli has three A T rich 13 base pair regions followed by four 9 bp regions with the sequence TTAT(C or A)CA(C or A)A. [5] DnaA molecules bind to the 9 bp regions, which wrap around the proteins causing the DNA at the AT-rich region to unwind. [6]
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]
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.
In E. coli chromosomes, the origin and terminus of replication divide the genome into oppositely replicated halves called replichores. Replichore 1, which is replicated clockwise, has the presented strand of E. coli as its leading strand; in replichore 2 the complementary strand is the leading one.
Bacterial conjugation has been extensively studied in Escherichia coli, but also occurs in other bacteria such as Mycobacterium smegmatis. Conjugation requires stable and extended contact between a donor and a recipient strain, is DNase resistant, and the transferred DNA is incorporated into the recipient chromosome by homologous recombination.