Identification of the repressor subdomain within the signal reception module of the prokaryotic enhancer-binding protein XylR of Pseudomonas putida.
In the presence of m-xylene, the protein XylR encoded by the TOL plasmid of Pseudomonas putida, activates the final sigma54-dependent promoter Pu. Early activation stages involve the release of the intramolecular repression caused by the signal reception N-terminal (A domain) of XylR on the central module of the protein. A genetic approach has been followed to locate the specific segment within A domain of XylR that is directly responsible for its down-regulation in the absence of inducer, as compared to that involved in effector (m-xylene) binding. For this, a reporter Escherichia coli strain carrying a monocopy transcriptional fusion of Pu to lacZ was transformed with a collection of plasmids encoding equivalent truncated varieties of XylR, consisting of nested and internal deletions throughout the entire A domain. Examination of the resulting phenotypes allowed the assignment of the A domain region near the central activation domain, as the portion of the protein responsible for the specific repression of XylR activity in the absence of m-xylene.
Pérez-Martín
J
J
Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Velázquez 144, 28006 Madrid, Spain.
de Lorenzo
V
V
D001426:Bacterial Proteins / Q000737:chemistry*; D004268:DNA-Binding Proteins; D015964:Gene Expression Regulation, Bacterial; D011401:Promoter Regions, Genetic; D016958:Pseudomonas putida / Q000235:genetics*; D017384:Sequence Deletion; D012808:Sigma Factor / Q000378:metabolism; D013329:Structure-Activity Relationship; D014157:Transcription Factors; D015533:Transcriptional Activation; D014992:Xylenes / Q000378:metabolism
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C074322:XylR protein, Pseudomonas; D014992:Xylenes; C031285:3-xylene