Post-transcriptional regulation mediated by 3’-UTRs in bacteria
The presence of regulatory elements in the 3’ untranslated region (3’-UTR) of eukaryotic mRNAs controlling RNA stability and translation efficiency is widely recognized. In contrast, the relevance of 3’-UTRs in bacterial mRNA functionality has been disregarded. Here, we report evidences showing that...
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| Tipo de recurso: | tesis doctoral |
| Fecha de publicación: | 2014 |
| País: | España |
| Institución: | Universidad Pública de Navarra |
| Repositorio: | Academica-e. Repositorio Institucional de la Universidad Pública de Navarra |
| OAI Identifier: | oai:academica-e.unavarra.es:2454/29271 |
| Acceso en línea: | https://hdl.handle.net/2454/29271 |
| Access Level: | acceso abierto |
| Palabra clave: | Mecanismo de regulación post-transcripcional Expresión génica Temperatura ambiental Post-transcriptional regulatory mechanism Gene expression Temperature shifts |
| Sumario: | The presence of regulatory elements in the 3’ untranslated region (3’-UTR) of eukaryotic mRNAs controlling RNA stability and translation efficiency is widely recognized. In contrast, the relevance of 3’-UTRs in bacterial mRNA functionality has been disregarded. Here, we report evidences showing that around one-third of the mapped mRNAs of the major human pathogen Staphylococcus aureus carry 3’-UTRs longer than 100-nt and thus, potential regulatory functions. We also found that most of the long 3’-UTR ends in a Rho-independent transcriptional terminator. Based on this information, it is possible to predict 3’-UTRs in any bacteria. Thus, we analysed 25 genomes and found that 3’-UTRs longer than 100-nt are broadly distributed in prokaryotes. To evaluate the role that 3’-UTRs may play in controlling mRNA expression, we selected the long 3’-UTR of icaR mRNA, which encodes the repressor of the main exopolysaccharidic compound of the S. aureus biofilm matrix. We showed that base pairing between the 3’-UTR and the Shine-Dalgarno (SD) region of icaR mRNA interferes with the translation initiation complex and generates a double-stranded substrate for RNase III. We also unveiled that the icaR 5’-UTR controls the 5’-3’-UTRs interaction in response to temperature. At environmental temperature (23ºC), a three way-helical junction structure, generated by pairing of internal sequences from 5’-UTR and ORF regions, impairs the 5’-3’-UTR interaction, causing the accumulation of IcaR repressor and the inhibition of biofilm development. In contrast, at the human body temperature (37ºC), this structural conformation opens allowing the interaction of the 5’- and 3’- UTRs that inhibited IcaR translation leading to biofilm production. Our findings provide a singular example of a new potential post-transcriptional regulatory mechanism to modulate bacterial gene expression in response to temperature shifts through the interaction of a 3’-UTR with the 5’-UTR of the same mRNA. |
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