Subsystem: Phd-Doc, YdcE-YdcD toxin-antitoxin (programmed cell death) systems
This subsystem's description is:
Programmed cell death can be mediated through "addiction modules" consisting of two genes; the product of the second gene is long lived and toxic, whereas the product of the first is short lived and antagonizes the lethal action of the toxin.
P1 lysogens of Escherichia coli carry the prophage as a stable low copy number plasmid, which is ensured by a plasmid-encoded mechanism that causes death of cells that have lost P1. The lysogenic cells appear to be "addicted" to the presence of the prophage. The "plasmid addiction system" of bacteriophage P1 consists of two proteins: a stable toxin known as Doc (death on cure) and an unstable antidote named Phd (prevent host death).
Phd prevents the lethal action of Doc by forming a tight complex with it. The toxin Doc hosts the C-terminal domain of its antitoxin partner Phd through fold complementation. Phd folds into an {alpha}-helix upon binding to Doc. The complex resembles the Fic (filamentation induced by cAMP) proteins.
Free Phd is degraded by the serine protease ClpPX. The cellular target of Doc seems to be a step in protein synthesis.
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| Diagram | Functional Roles | Subsystem Spreadsheet | Description | |||||||||
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Programmed cell death can be mediated through "addiction modules" consisting of two genes; the product of the second gene is long lived and toxic, whereas the product of the first is short lived and antagonizes the lethal action of the toxin. P1 lysogens of Escherichia coli carry the prophage as a stable low copy number plasmid, which is ensured by a plasmid-encoded mechanism that causes death of cells that have lost P1. The lysogenic cells appear to be "addicted" to the presence of the prophage. The "plasmid addiction system" of bacteriophage P1 consists of two proteins: a stable toxin known as Doc (death on cure) and an unstable antidote named Phd (prevent host death). Phd prevents the lethal action of Doc by forming a tight complex with it. The toxin Doc hosts the C-terminal domain of its antitoxin partner Phd through fold complementation. Phd folds into an {alpha}-helix upon binding to Doc. The complex resembles the Fic (filamentation induced by cAMP) proteins. Free Phd is degraded by the serine protease ClpPX. The cellular target of Doc seems to be a step in protein synthesis. | ||||||||||||
