2an7
Solution structure of the bacterial antidote ParDSolution structure of the bacterial antidote ParD
Structural highlights
FunctionPARD_ECOLX Antitoxin component of a toxin-antitoxin (TA) module involved in plasmid partition. Inhibits the anti-DNA gyrase activity of toxin ParE; reverses and restores gyrase catalytic activity in vitro. The parDE operon alone is capable of stabilizing an RK2-derived minireplicon under defined growth conditions in several different Gram-negative bacteria. It does so by the post-segregational killing (PSK) of plasmid-free cells, also referred to as a plasmid addiction system. Binds its own promoter, autorepressing it; gentically only ParD is required for full autorepression.[1] [2] [3] [4] Publication Abstract from PubMedParD is the antidote of the plasmid-encoded toxin-antitoxin (TA) system ParD-ParE. These modules rely on differential stabilities of a highly expressed but labile antidote and a stable toxin expressed from one operon. Consequently, loss of the coding plasmid results in loss of the protective antidote and poisoning of the cell. The antidote protein usually also exhibits an autoregulatory function of the operon. In this paper, we present the solution structure of ParD. The repressor activity of ParD is mediated by the N-terminal half of the protein, which adopts a ribbon-helix-helix (RHH) fold. The C-terminal half of the protein is unstructured in the absence of its cognate binding partner ParE. Based on homology with other RHH proteins, we present a model of the ParD-DNA interaction, with the antiparallel beta-strand being inserted into the major groove of DNA. The fusion of the N-terminal DNA-binding RHH motif to the toxin-binding unstructured C-terminal domain is discussed in its evolutionary context. The solution structure of ParD, the antidote of the ParDE toxin antitoxin module, provides the structural basis for DNA and toxin binding.,Oberer M, Zangger K, Gruber K, Keller W Protein Sci. 2007 Aug;16(8):1676-88. PMID:17656583[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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