UMR8261 (CNRS-Université Paris Diderot), Institut de Biologie Physico-Chimique, Paris, France tRNA Maturation Defects Lead to Inhibition of rRNA Processing via Synthesis of pppGpp Molecular Cell (74) 1–12, June 20, 2019, https://doi.org/10.1016/j.molcel.2019.03.030Trinquier, A., Ulmer, J. E., Gilet, L., Figaro, S., Hammann, P., Kuhn, L., Braun, F., & Condon, C.
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Aude Trinquier, 24 years old, is a third-year PhD. student in Ciarán Condon’s team in the “Laboratoire d’Expression Génétique Microbienne” at the Institute of Biology and Physico-chemistry in Paris. After two years of study at the University of Montpellier, she joined the European Magistère of Genetics program at University Paris Diderot where she completed a Bachelor and a Master in genetics. Her PhD. project is about transfer RNA (tRNA) processing and ribosomal RNA (rRNA) maturation and is supervised by Dr. Frédérique Braun and Dr.Ciarán Condon. tRNA and rRNA are two central components of the translation apparatus, they are synthesized as precursor molecules and require processing to become stable and functional. Aude Trinquier and coworkers identified that tRNA maturation defects trigger production of the alarmone pppGpp (guanosine pentaphosphate) in the Gram positive bacteria Bacillus subtilis. This molecule not only shuts-down rRNA transcription but also impairs its incorporation into ribosomes. Results indicate that immature tRNAs prompt pppGpp production via a mechanism that was thought to be specific for uncharged tRNA, and that this alarmone production leads to inhibition of ribosome assembly and rRNA maturation.
Contact
Aude TRINQUIER
Address : UMR8261 (CNRS-Université de Paris), IBPC, 13 rue Pierre et Marie Curie, 75005 Paris
Abstract
rRNAs and tRNAs universally require processing from longer primary transcripts to become functional for translation. Here, we describe an unsuspected link between tRNA maturation and the 3' processing of 16S rRNA, a key step in preparing the small ribosomal subunit for interaction with the Shine-Dalgarno sequence in prokaryotic translation initiation. We show that an accumulation of either 5' or 3' immature tRNAs triggers RelA-dependent production of the stringent response alarmone (p)ppGpp in the Gram-positive model organism Bacillus subtilis. The accumulation of (p)ppGpp and accompanying decrease in GTP levels specifically inhibit 16S rRNA 3' maturation. We suggest that cells can exploit this mechanism to sense potential slowdowns in tRNA maturation and adjust rRNA processing accordingly to maintain the appropriate functional balance between these two major components of the translation apparatus.
