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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.
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.
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 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.
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.
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.
This is the first instance of phenylacetic acid found in the murein of bacterial cells. The composition and peptide cross-bridges found in this murein layer are typical of Gram-positive bacterium, but the amount, the degree of the cross-linkage and length of the glycan chain gives this bacterium its Gram-negative properties. [5]