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Crystal structure and induction mechanism of AmiC-AmiR: a ligand-regulated transcription antitermination complex.

ABSTRACT: 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.

SUBMITTER: O'Hara BP

PROVIDER: S-EPMC1171588 | biostudies-other | 1999 Oct

REPOSITORIES: biostudies-other

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Crystal structure and induction mechanism of AmiC-AmiR: a ligand-regulated transcription antitermination complex.

O'Hara B P BP Norman R A RA Wan P T PT Roe S M SM Barrett T E TE Drew R E RE Pearl L H LH

The EMBO journal 19991001 19

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 i ...[more]

PMID: 10508151

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