Publicação
The LRS system : a switcher for bacterial behaviours?
| Resumo: | Quorum sensing is a cell-to-cell communication mechanism that enables bacteria to monitor population density and synchronize behaviors on a community-wide scale by collectively regulating their gene expression. This process is mediated by the production, release and detection of signaling molecules called autoinducers. The Best-studied signal that mediates inter-species communication is autoinducer-2 (AI-2). This molecule has been shown to regulate important bacterial behaviors such as virulence, biofilm formation and antibiotic resistance. In enteric bacteria, this signal is imported and processed by a system called Lsr. The biological function of Lsr is still a matter of debate. It was proposed that through this system AI-2 regulates phenotypes other than only its incorporation and degradation. However, further studies are needed to fully prove this hypothesis. The aim of this research work is to elucidate the role of Lsr in the regulation of AI-2-dependent behaviors, by constructing and testing phenotypically a set of mutants on the AI-2 signalling system in two different model organisms: Escherichia coli and Photorhabdus luminescens. E. coli mutants were tested for their ability to form biofilms. Results from this study indicate that AI-2 signalling through the Lsr system is not involved in the regulation of biofilm formation in this bacterium. However, this work reveals for the first time a phenotype for the lsrF mutant, which raises the hypothesis that LsrF, an enzyme involved in AI-2 processing, is important for the detoxification of the AI-2 degradation subproducts. Furthermore, mutants of the Lsr system in P. luminescens were constructed and the function of this system in AI-2 internalization was determined. The constructed mutants are currently being analyzed for their ability to form biofilms. In future work these mutants can be used to test the role of Lsr in symbiosis and pathogenesis using in vivo models for P. luminescens. Understanding how the ability to communicate and regulate bacterial behaviors is dependent on the Lsr system could aid the development of novel strategies to manipulate bacterial controlled phenotypes to our profit. |
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| Autores principais: | Pereira, Jorge André Matias |
| Assunto: | Detecção de quórum Autoindutor-2 Sistema Lsr Comunicação célula-a-célula Formação de biofilmes Interacções bactéria-hospedeiro Teses de mestrado - 2013 |
| Ano: | 2013 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Quorum sensing is a cell-to-cell communication mechanism that enables bacteria to monitor population density and synchronize behaviors on a community-wide scale by collectively regulating their gene expression. This process is mediated by the production, release and detection of signaling molecules called autoinducers. The Best-studied signal that mediates inter-species communication is autoinducer-2 (AI-2). This molecule has been shown to regulate important bacterial behaviors such as virulence, biofilm formation and antibiotic resistance. In enteric bacteria, this signal is imported and processed by a system called Lsr. The biological function of Lsr is still a matter of debate. It was proposed that through this system AI-2 regulates phenotypes other than only its incorporation and degradation. However, further studies are needed to fully prove this hypothesis. The aim of this research work is to elucidate the role of Lsr in the regulation of AI-2-dependent behaviors, by constructing and testing phenotypically a set of mutants on the AI-2 signalling system in two different model organisms: Escherichia coli and Photorhabdus luminescens. E. coli mutants were tested for their ability to form biofilms. Results from this study indicate that AI-2 signalling through the Lsr system is not involved in the regulation of biofilm formation in this bacterium. However, this work reveals for the first time a phenotype for the lsrF mutant, which raises the hypothesis that LsrF, an enzyme involved in AI-2 processing, is important for the detoxification of the AI-2 degradation subproducts. Furthermore, mutants of the Lsr system in P. luminescens were constructed and the function of this system in AI-2 internalization was determined. The constructed mutants are currently being analyzed for their ability to form biofilms. In future work these mutants can be used to test the role of Lsr in symbiosis and pathogenesis using in vivo models for P. luminescens. Understanding how the ability to communicate and regulate bacterial behaviors is dependent on the Lsr system could aid the development of novel strategies to manipulate bacterial controlled phenotypes to our profit. |
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