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An active role for a structured B‐linker in effector control of the σ 54 ‐dependent regulator DmpR
Author(s) -
O'Neill Eric,
Wikström Petra,
Shingler Victoria
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.4.819
Subject(s) - molecular cell biology , effector , library science , biology , cell and molecular biology , genetics , computer science , gene , microbiology and biotechnology , plant development
The activities of many prokaryotic σ 54 ‐dependent transcriptional activators are controlled by the N‐terminal A‐domain of the protein, which is linked to the central transcriptional activation domain via a short B‐linker. It used to be thought that these B‐linkers simply serve as flexible tethers. Here we show that the B‐linker of the aromatic‐responsive regulator DmpR and many other regulators of the family contain signature heptad repeats with regularly spaced hydrophobic amino acids. Mutant analysis of this region of DmpR demonstrates that B‐linker function is dependent on the heptad repeats and is critical for activation of the protein by aromatic effectors. The phenotypes of DmpR mutants refute the existing model that the level of ATPase activity directly controls the level of transcription it promotes. The mutant analysis also shows that the B‐linker is involved in repression of ATPase activity and that allosteric changes upon effector binding are transduced to alleviate both B‐linker repression of ATP hydrolysis and A‐domain repression of transcriptional activation. The mechanistic implications of these findings for DmpR and other family members are discussed.