De novo Synthesis and Assembly of rRNA into Ribosomal Subunits during Cold Acclimation in Escherichia coli
| Autor: | Anna Brandi, Cynthia L. Pon, Lolita Piersimoni, Claudio O. Gualerzi, Paolo Marchi, Mara Giangrossi |
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| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Time Factors Transcription Genetic Acclimatization 030106 microbiology Biology Ribosome Ribosome assembly Phosphates 03 medical and health sciences Structural Biology Polysome RNA Ribosomal 16S Operon Protein biosynthesis Cold acclimation Escherichia coli Ribosome Subunits Promoter Regions Genetic Molecular Biology Genetics Escherichia coli Proteins Temperature Translation (biology) DNA-Directed RNA Polymerases Gene Expression Regulation Bacterial Ribosomal RNA RRNA transcription Cell biology Cold Temperature RNA Bacterial RNA Ribosomal 23S Polyribosomes Protein Biosynthesis Ribosomes |
| Zdroj: | Journal of molecular biology. 428(8) |
| ISSN: | 1089-8638 |
| Popis: | During the cold adaptation that follows a cold stress, bacterial cells undergo many physiological changes and extensive reprogramming of their gene expression pattern. Bulk gene expression is drastically reduced, while a set of cold shock genes is selectively and transiently expressed. The initial stage of cold acclimation is characterized by the establishment of a stoichiometric imbalance of the translation initiation factors (IFs)/ribosomes ratio that contributes to the preferential translation of cold shock transcripts. Whereas de novo synthesis of the IFs following cold stress has been documented, nothing was known concerning the activity of the rrn operons during the cold acclimation period. In this work, we focus on the expression of the rrn operons and the fate of rRNA after temperature downshift. We demonstrate that in Escherichia coli, rRNA synthesis does not stop during the cold acclimation phase, but continues with greater contribution of the P2 compared to the P1 promoter and all seven rrn operons are active, although their expression levels change with respect to pre-stress conditions. Eight hours after the 37°→10 °C temperature downshift, the newly transcribed rRNA represents up to 20% of total rRNA and is preferentially found in the polysomes. However, with respect to the de novo synthesis of the IFs, both rRNA transcription and maturation are slowed down drastically by cold stress, thereby accounting in part for the stoichiometric imbalance of the IFs/ribosomes. Overall, our data indicate that new ribosomes, which are possibly suitable to function at low temperature, are slowly assembled during cold acclimation. |
| Databáze: | OpenAIRE |
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