3hs2 | pdb_00003hs2
Crystal structure of PHD truncated to residue 57 in an orthorhombic space group
Structural highlights
Function[PHD_BPP1] Antitoxin component of a toxin-antitoxin (TA) module. A labile antitoxin that binds to the doc toxin and neutralizes its toxic effect. Bacteriophage P1 lysogenizes bacteria as a low-copy number plasmid. Phd and doc proteins function in unison to stabilize plasmid number by inducing a lethal response to P1 plasmid prophage loss.[1] [2] Binds to its own promoter repressing its expression; toxin doc acts as a corepressor or derepressor depending on the ratio, repressing or inducing expression.[3] [4] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedRegulation of the phd/doc toxin-antitoxin operon involves the toxin Doc as co- or derepressor depending on the ratio between Phd and Doc, a phenomenon known as conditional cooperativity. The mechanism underlying this observed behavior is not understood. Here we show that monomeric Doc engages two Phd dimers on two unrelated binding sites. The binding of Doc to the intrinsically disordered C-terminal domain of Phd structures its N-terminal DNA-binding domain, illustrating allosteric coupling between highly disordered and highly unstable domains. This allosteric effect also couples Doc neutralization to the conditional regulation of transcription. In this way, higher levels of Doc tighten repression up to a point where the accumulation of toxin triggers the production of Phd to counteract its action. Our experiments provide the basis for understanding the mechanism of conditional cooperative regulation of transcription typical of toxin-antitoxin modules. This model may be applicable for the regulation of other biological systems. Allostery and intrinsic disorder mediate transcription regulation by conditional cooperativity.,Garcia-Pino A, Balasubramanian S, Wyns L, Gazit E, De Greve H, Magnuson RD, Charlier D, van Nuland NA, Loris R Cell. 2010 Jul 9;142(1):101-11. PMID:20603017[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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