Involvement of the Global Crp Regulator in Cyclic AMP-Dependent Utilization of Aromatic Amino Acids by Pseudomonas putida
The phhAB operon encodes a phenylalanine hydroxylase involved in the conversion of L-phenylalanine into L-tyrosine in Pseudomonas putida. The phhAB promoter is transcribed by RNA polymerase sigma-70 and is unusual in that the specific regulator PhhR acts as an enhancer protein that binds to two dist...
| Autores: | , , , |
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| Formato: | artículo |
| Fecha de publicación: | 2011 |
| País: | España |
| Recursos: | Universidad Miguel Hernández de Elche |
| Repositorio: | REDIUMH. Depósito Digital de la UMH |
| OAI Identifier: | oai:dspace.umh.es:11000/39245 |
| Acesso em linha: | https://hdl.handle.net/11000/39245 |
| Access Level: | acceso abierto |
| Palavra-chave: | Aromatic Amino Acids Global Crp Regulator Pseudomonas putida |
| Resumo: | The phhAB operon encodes a phenylalanine hydroxylase involved in the conversion of L-phenylalanine into L-tyrosine in Pseudomonas putida. The phhAB promoter is transcribed by RNA polymerase sigma-70 and is unusual in that the specific regulator PhhR acts as an enhancer protein that binds to two distant upstream sites ( 75 to 92 and 132 to 149). There is an integration host factor (IHF) binding site that overlaps the proximal PhhR box, and, consequently, IHF acts as an inhibitor of transcription. Use of L-phenylalanine is compromised in a crp-deficient background due to reduced expression from the phhAB promoter. Electrophoretic mobility shift assays and DNase I footprinting assays reveal that Crp binds at a site centered at 109 only in the presence of cyclic AMP (cAMP). We show, using circular permutation analysis, that the simultaneous binding of Crp/cAMP and PhhR bends DNA to bring positive regulators and RNA polymerase into close proximity. This nucleoprotein complex promotes transcription from phhA only in response to L-phenylalanine. |
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