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DNA gyrase is a tetrameric enzyme that consists of 2 GyrA ("A") and 2 GyrB ("B") subunits. [8] Structurally the complex is formed by 3 pairs of "gates", sequential opening and closing of which results into the direct transfer of DNA segment and introduction of 2 negative supercoils. N-gates are formed by ATPase domains of GyrB subunits.
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.
Found in E. coli and in chromosomes of other bacteria [29] yafO yafN: A system induced by the SOS response to DNA damage in E. coli [68] hicA hicB: Found in archaea and bacteria [69] kid kis: Stabilises the R1 plasmid and is related to the CcdB/A system [23] ζ ε: Found mostly in Gram-positive bacteria [64] ataT ataR: Found in enterohemorragic ...
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.
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 surface and the incoming DNA are both negatively charged, so the DNA is coated with lipids. By shielding the DNA and possibly merging with the membrane lipids, these liposomes can facilitate the entry of DNA. [8] Transformation of bacteria, plant cells and animal cells has important research and commercial functions.
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 ]
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.