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Bacterial antitoxin of ParD toxin-antitoxin type II system and RHH ParD is the antitoxin of a bacterial toxin-antitoxin gene pair. The cognate toxin is ParE in, pfam05016. The family contains several related antitoxins from Cyanobacteria, Proteobacteria and Actinobacteria. Antitoxins of this class carry an N-terminal ribbon-helix-helix domain, RHH, that is highly conserved across all type II bacterial antitoxins, which dimerizes with the RHH domain of a second VapB molecule. A hinge section follows the RHH, with an additional pair of flexible alpha helices at the C-terminus. This C-terminus is the toxin-binding region of the dimer, and so is specific to the cognate toxin, whereas the RHH domain has the specific function of lying across the RNA-binding groove of the toxin dimer and inactivating the active-site - a more general function of all type II antitoxins. |
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