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DNA gyrase, or simply gyrase, is an enzyme within the class of topoisomerase and is a subclass of Type II topoisomerases [1] that reduces topological strain in an ATP dependent manner while double-stranded DNA is being unwound by elongating RNA-polymerase [2] or by helicase in front of the progressing replication fork.
DNA supercoiling is important for DNA packaging within all cells. Because the length of DNA can be thousands of times that of a cell, packaging this genetic material into the cell or nucleus (in eukaryotes) is a difficult feat. Supercoiling of DNA reduces the space and allows for DNA to be packaged.
The bacterial type IV secretion system, also known as the type IV secretion system or the T4SS, is a secretion protein complex found in gram negative bacteria, gram positive bacteria, and archaea. It is able to transport proteins and DNA across the cell membrane. [1] The type IV secretion system is just one of many bacterial secretion systems.
LigA is a relevant example as it is structurally similar to a clade of enzymes found across all types of bacteria. [7] Ligases have a metal binding site which is capable of recognizing nicks in DNA. The ligase forms a DNA-adenylate complex, assisting recognition. [8] With human DNA ligase, this forms a crystallized complex.
With DNA in its "relaxed" state, a strand usually circles the axis of the double helix once every 10.4 base pairs, but if the DNA is twisted the strands become more tightly or more loosely wound. [43] If the DNA is twisted in the direction of the helix, this is positive supercoiling, and the bases are held more tightly together.
The cell membrane of CaCl 2-treated cells is severely depolarized during the heat shock stage, and as a result, the drop in membrane potential reduces the negative nature of the cell's internal potential, allowing negatively charged DNA to flow into the interior of the cell. Afterwards, the membrane potential can be raised back to its initial ...
The restriction modification system (RM system) is found in bacteria and archaea, and provides a defense against foreign DNA, such as that borne by bacteriophages.. Bacteria have restriction enzymes, also called restriction endonucleases, which cleave double-stranded DNA at specific points into fragments, which are then degraded further by other endonucleases.
Major contributors of drug resistance are mobile genomic islands (MGIs), or segments in DNA that are found in similar strains of bacteria and are factors in diversification of bacteria. [3] [24] MGIs provide resistance to their host cells, and through bacterial conjugation, spread this advantage to other cells. [3]