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Crystal structure and induction mechanism of AmiC–AmiR: a ligand‐regulated transcription antitermination complex
Author(s) -
O'Hara Bernard P.,
Norman Richard A.,
Wan Paul T.C.,
Roe S. Mark,
Barrett Tracey E.,
Drew Robert E.,
Pearl Laurence H.
Publication year - 1999
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/18.19.5175
Subject(s) - antitermination , biology , regulator , ligand (biochemistry) , operon , transcription (linguistics) , repressor , microbiology and biotechnology , signal transduction , inducer , biochemistry , rna , genetics , transcription factor , rna polymerase , receptor , gene , philosophy , escherichia coli , linguistics
Inducible expression of the aliphatic amidase operon in Pseudomonas aeruginosa is controlled by an antitermination mechanism which allows production of the full‐length transcript only in the presence of small‐molecule inducers, such as acetamide. Ligand‐regulated antitermination is provided by AmiC, the ligand‐sensitive negative regulator, and AmiR, the RNA‐binding positive regulator. Under non‐inducing or repressing growth conditions, AmiC and AmiR form a complex in which the activity of AmiR is silenced. The crystal structure of the AmiC–AmiR complex identifies AmiR as a new and highly unusual member of the response‐regulator family of bacterial signal transduction proteins, regulated by sequestration rather than phosphorylation. Comparison with the structure of free AmiC reveals the subtle mechanism of ligand‐induced release of AmiR.