Efecto de una mutación de mimetismo alcalino en el factor de transcripción PacC de Acremonium chrysogenum sobre la producción de antibióticos beta-lactámicos
Cephalosporin C (CPC) belongs to the beta-lactam antibiotics group, which are currently the most prescribed antimicrobials, and economically the most important drugs. This compound is the core of overall semisynthetic cephalosporins for clinical use. Cephalosporins have low toxicity and wide spectru...
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| Tipo de recurso: | tesis de maestría |
| Estado: | Versión publicada |
| Fecha de publicación: | 2010 |
| País: | México |
| Institución: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:q811kj83h |
| Acceso en línea: | https://doi.org/10.24275/uami.q811kj83h |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/LEM/Ingeniería genética info:eu-repo/classification/LEM/Antibióticos beta lactámicos -- Investigación info:eu-repo/classification/LEM/Genetic engineering info:eu-repo/classification/LEM/Biotechnology info:eu-repo/classification/LEM/Biotecnología info:eu-repo/classification/LEM/Acremonium chrysogenum info:eu-repo/classification/LEM/Beta lactam antibiotics -- Research info:eu-repo/classification/cti/6 |
| Sumario: | Cephalosporin C (CPC) belongs to the beta-lactam antibiotics group, which are currently the most prescribed antimicrobials, and economically the most important drugs. This compound is the core of overall semisynthetic cephalosporins for clinical use. Cephalosporins have low toxicity and wide spectrum against Gram-negative and Grampositive bacteria, in small concentrations. CPC is exclusively produced by the filamentous fungus Acremonium chrysogenum. The biosynthesis pathway of CPC is strongly regulated by environmental pH signaling through transcription factor PacC. When environmental pH is acidic to neutral, transcription factor PacC (621 aminoacid residues) has a closed conformation. When environmental pH becomes alkaline, a signal transduction pathway is activated which results in processing of PacC by two successive proteolytic steps, turning it to an active form (~ 250 aminoacid residues). At this point, activated PacC migrates to nucleus and stimulates the transcription of the majority of the CPC biosynthetic genes. In this work, using genetic engineering techniques, we designed a mutation in the A. chrysogenum transcription factor PacC, removing 366 aminoacid residues from the Cterminal end, so that the mutated pacC resulted directly in its active form. Mutated PacC was expressed in A. chrysogenum wild type under the control of a constitutive promoter and its own promoter, with the aim to demonstrate the hypothesis that this mutation would allow an alkaline mimicking phenotype, so that we could obtain an increase of beta-lactams titers, including CPC, irrespective of the pH values in the fermentation broth. We obtained eleven strains with our mutation, and three of them showed a significant increase of beta-lactams production, in comparison with the parental strain, both in alkaline fermentation medium or in acidic buffered medium. In this way, the majority of the mutated strains showed higher levels than parental strain, in a chemically defined medium whith pH buffered to 5.5. These results confirm that our genetic engineering strategy increased significantly beta-lactams production in A. chrysogenum wild type. |
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