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Dispersin B
Dispersin B (also known as DspB or DispersinB) is a 40 kDa glycoside hydrolase produced by the periodontal pathogen, ''Aggregatibacter actinomycetemcomitans''. The bacteria secrete Dispersin B to release adherent cells from a mature biofilm colony by disrupting biofilm formation. The enzyme catalyzes the hydrolysis of linear polymers of N-acetyl-D-glucosamines found in the biofilm matrices. Poly-acetyl glucosamines are integral to the structural integrity of the biofilms of various Gram-positive bacteria and Gram-negative bacteria and are referred to as PIA (PNAG,PS/A) in ''Staphylococcus'' species and PGA in ''Escherichia coli''.〔; 〕 By degrading the biofilm matrix, Dispersin B allows for the release of bacterial cells that can adhere to new surfaces close by and extend the biofilm or start new colonies. Currently there is interest in Dispersin B as a commercial anti-biofilm agent that could be combined with antibiotics for the treatment of bacterial infections.
== Biological Function ==
Dispersin B is produced by ''Aggregatibacter actinomycetemcomitans'', a Gram-negative oral bacterium, when it needs to detach and disperse adherent bacterial cells. ''A. actinomycetemcomitans'' forms asymmetric biofilm lobed colonies that release single cells or small clusters of bacterial cells, which can attach to nearby surfaces, form new colonies, and enable the biofilm to spread.〔 A biofilm is a matrix of extracellular polymeric substances that are synthesized by the bacteria. The biofilm's structural integrity is dependent on poly-N-acetylglucosamine (PGA), extracellular DNA, and proteinaceous adhesins. It allows bacteria to adhere to host surfaces, protects the bacterial cells from host defenses, results in increased resistance to antibiotics, and provides a protected environment with microchannels for the flow of water and other essential nutrients.〔
By hydrolyzing PGA, Dispersin B disrupts the formation of the biofilm matrix and allows adherent cells to be released. Dispersin B has also been shown to cause the detachment of biofilm cells that have adhered to abiotic surfaces as well as cause the disaggregaton of highly auto-aggregated clumps of bacterial cells.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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