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A gene cluster is a group of two or more genes found within an organism's DNA that encode similar polypeptides or proteins which collectively share a generalized function and are often located within a few thousand base pairs of each other. The size of gene clusters can vary significantly, from a few genes to several hundred genes. [1]
Examples of bacterial species that have been found to possess multiple replicons include Rhodobacter sphaeroides (two), Vibrio cholerae, [3] and Burkholderia multivorans (three). These "secondary" (or tertiary) chromosomes are often described as molecules that are intermediate between a true chromosome and a plasmid and are sometimes called ...
DnaA is a protein that activates initiation of DNA replication in bacteria. [1] Based on the Replicon Model, a positively active initiator molecule contacts with a particular spot on a circular chromosome called the replicator to start DNA replication. [2]
An example is the DNA repair gene ERCC1, where the CpG island-containing element is located about 5,400 nucleotides upstream of the transcription start site of the ERCC1 gene. [22] CpG islands also occur frequently in promoters for functional noncoding RNAs such as microRNAs .
Developed from a natural defense mechanism found in bacteria, CRISPR-Cas9 is the most commonly used system. Gene editing with CRISPR-Cas9 involves a Cas9 nuclease and an engineered guide RNA , which come together to allow for the precise "cutting" of one or both strands of DNA at specific locations within the genome. [ 179 ]
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.
Examples include the HU protein in Escherichia coli, a dimer of closely related alpha and beta chains and in other bacteria can be a dimer of identical chains. HU-type proteins have been found in a variety of bacteria (including cyanobacteria) and archaea, and are also encoded in the chloroplast genome of some algae. [4]
Several cell function specific transcription factor proteins (in 2018 Lambert et al. indicated there were about 1,600 transcription factors in a human cell [41]) generally bind to specific motifs on an enhancer [22] and a small combination of these enhancer-bound transcription factors, when brought close to a promoter by a DNA loop, govern the ...