Burgos, RaulWeber, MarcGallo López, Carolina, 1984-Lluch-Senar, Maria 1982-Serrano Pubull, Luis, 1982-2022-01-242022-01-242021Burgos R, Weber M, Gallo C, Lluch-Senar M, Serrano L. Widespread ribosome stalling in a genome-reduced bacterium and the need for translational quality control. iScience. 2021 Aug 16;24(9):102985. DOI: 10.1016/j.isci.2021.1029852589-0042http://hdl.handle.net/10230/52298Trans-translation is a ubiquitous bacterial mechanism of ribosome rescue mediated by a transfer-messenger RNA (tmRNA) that adds a degradation tag to the truncated nascent polypeptide. Here, we characterize this quality control system in a genome-reduced bacterium, Mycoplasma pneumoniae (MPN), and perform a comparative analysis of protein quality control components in slow and fast-growing prokaryotes. We show in vivo that in MPN the sole quality control cytoplasmic protease (Lon) degrades efficiently tmRNA-tagged proteins. Analysis of tmRNA-mutants encoding a tag resistant to proteolysis reveals extensive tagging activity under normal growth. Unlike knockout strains, these mutants are viable demonstrating the requirement of tmRNA-mediated ribosome recycling. Chaperone and Lon steady-state levels maintain proteostasis in these mutants suggesting a model in which co-evolution of Lon and their substrates offer simple mechanisms of regulation without specialized degradation machineries. Finally, comparative analysis shows relative increase in Lon/Chaperone levels in slow-growing bacteria suggesting physiological adaptation to growth demand.application/pdfeng© 2021 Raul Burgos et al. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)GenèticaGenòmicaBacteriologiaProteïnesinfo:eu-repo/semantics/articlehttp://dx.doi.org/10.1016/j.isci.2021.102985info:eu-repo/semantics/openAccess