Bacterial trans translation is activated when translating ribosomes are unable to elongate or terminate properly. Small protein B (SmpB) and transfer-messenger RNA (tmRNA) are the two known factors required for and dedicated to trans translation. tmRNA, encoded by the ssrA gene, is a bifunctional molecule that acts both as a tRNA and as an mRNA during trans translation. The functions of tmRNA ensure that stalled ribosomes are rescued, the causative defective mRNAs are degraded, and the incomplete polypeptides are marked for targeted proteolysis. We present in vivo and in vitro evidence that demonstrates a direct role for the Lon ATP-dependent protease in the degradation of tmRNA-tagged proteins. In an endogenous protein tagging assay, lon mutants accumulated excessive levels of tmRNA-tagged proteins. In a reporter protein tagging assay with lambda-CI-N, the protein product of a nonstop mRNA construct designed to activate trans translation, lon mutant cells efficiently tagged the reporter protein, but the tagged protein exhibited increased stability. Similarly, a green fluorescent protein (GFP) construct containing a hard-coded C-terminal tmRNA tag (GFP-SsrA) exhibited increased stability in lon mutant cells. Most significantly, highly purified Lon preferentially degraded the tmRNA-tagged forms of proteins compared to the untagged forms. Based on these results, we conclude that Lon protease participates directly in the degradation of tmRNA-tagged proteins.
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http://dx.doi.org/10.1128/JB.00860-07 | DOI Listing |
ISA Trans
January 2025
Graduate School of Intelligent Data Science, National Yunlin University of Science and Technology, Douliou, Yunlin, Taiwan. Electronic address:
Relying on composite nonlinear feedback, an output-feedback controller is robustly addressed in the singular models with uncertainties, disturbances and time-delays. For this purpose, an observer-based compensator is utilized to realize the purpose. In the presence of disturbance and uncertainty, it is demonstrated that the tracking error and the states of the overall system are ultimately bounded.
View Article and Find Full Text PDFInt J Clin Health Psychol
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Département de Psychologie, Université de Montréal, Montréal, Canada.
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View Article and Find Full Text PDFCell Genom
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Department of Cell and Molecular Biology, Karolinska Institute, 171 65 Stockholm, Sweden. Electronic address:
Newts have large genomes harboring many repeat elements. How these elements shape the genome and relate to newts' unique regeneration ability remains unknown. We present here the chromosome-scale assembly of the 20.
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Department of Hepatology, Center for Pathogen Biology and Infectious Diseases, Institute of Translational Medicine, The First Hospital of Jilin University, Changchun, Jilin, China.
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Center for Translational Vision Research, Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA, United States; Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States; Department of Chemistry, University of California Irvine, Irvine, CA, United States; Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, United States. Electronic address:
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