Antitoxin phd from phage p1 in complex with its operator DNA inverted repeat
Structure:
Antitoxin phd. Chain: a, b, c, d. Synonym: addiction protein pdh,prevent host death protein. Engineered: yes. Other_details: thE C-terminal region of the protein is intrinsically disordered. DNA/RNA (5'-d(cp Tp Tp Gp Tp Gp Tp Ap Cp Ap Cp Ap T)-3'). Chain: e, g. Engineered: yes.
Conditional cooperativity is a common mechanism involved in transcriptional
regulation of prokaryotic type II toxin-antitoxin operons and is intricately
related to bacterial persistence. It allows the toxin component of a
toxin-antitoxin module to act as a co-repressor at low doses of toxin as
compared to antitoxin. When toxin level exceeds a certain threshold, however,
the toxin becomes a de-repressor. Most antitoxins contain an intrinsically
disordered region (IDR) that typically is involved in toxin neutralization and
repressor complex formation. To address how the antitoxin IDR is involved in
transcription regulation, we studied the phd-doc operon from bacteriophage P1.
We provide evidence that the IDR of Phd provides an entropic barrier precluding
full operon repression in the absence of Doc. Binding of Doc results in a
cooperativity switch and consequent strong operon repression, enabling
context-specific modulation of the regulatory process. Variations of this theme
are likely to be a common mechanism in the autoregulation of bacterial operons
that involve intrinsically disordered regions.
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