Biology subjects

Gillet, R.

Publications and source records attributed to Gillet, R..

5 recordsLinked to original sources

bioRxiv2025

Structural characterization of hibernating ribosomes in four Gram-negative pathogenic bacteria

Ribosomes are universal molecular machines that translate messenger RNA into proteins. Depending on what the cells needs for protein synthesis, ribosomes exist in various functional states, and when cells face stressful conditions, their ribosomes may enter into an inactive hibernation state. In bacteria, this ability to become dormant through ribosomal hibernation plays a crucial role in their survival, especially when the cells are targeted by ribosome-targeting antibiotics. The phenomenon occurs when ribosomes bind with hibernation factors. In this work, we examine how these special proteins interact with ribosomes from four different Gram-negative pathogens, and how this leads to translation inhibition, reporting the single-particle cryo-electron microscopy structures of hibernating ribosomes from P. aeruginosa, E. hormaechei, K. quasipneumoniae, and A. baumannii. We show that these ribosomal complexes contain either short HPF or YfiA tightly bound to the 30S A-site, P-site, and even occasionally to the E-site. Our results provide valuable insights into the ribosomal hibernation mechanism, paving the way to both a better understanding of bacterial dormancy and the possibility of developing antibiotics which will target hibernating ribosomes rather than just active ones.

biochemistry↗

bioRxiv2024

Developing Biosensors for Specific Assessment of Trans-translation in Pseudomonas aeruginosa.

Trans-translation is a crucial bacterial process and a target for new antibiotics. We developed two Pseudomonas aeruginosa biosensor strains that detect trans-translation inhibitors by exploiting the bacteriums natural red fluorescence, linked to protoporphyrin IX accumulation. The first biosensor monitors tmRNA-SmpB-mediated tagging, while the second serves as control for biosensor 1 by keeping track of ClpP1-related proteolysis and porphyrin biosynthesis. Validation through gene deletions and complementation confirmed their specificity. These biosensors were effective in screening antibiotics and designed inhibitors, demonstrating their potential for high-throughput identification of trans-translation inhibitors in drug-resistant P. aeruginosa.

microbiology↗

bioRxiv2020

Safe and easy evaluation of tmRNA-SmpB-mediated trans-translation in ESKAPE pathogenic bacteria

Bacteria cope with ribosome stalling thanks to trans-translation, a major quality control system of protein synthesis that is mediated by tmRNA, an hybrid RNA with properties of both a tRNA and an mRNA, and the small protein SmpB. Because trans-translation is absent in eukaryotes but necessary for bacterial fitness or survival, it is a promising target for the development of novel antibiotics. To facilitate screening of chemical libraries, various reliable in vitro and in vivo systems have been created for assessing trans-translational activity. However, none of these permits the safe and easy evaluation of trans-translation in pathogenic bacteria, which are obviously the ones we should be targeting. Based on green fluorescent protein (GFP) reassembly during active trans-translation, we have created a cell-free assay adapted to the rapid evaluation of trans-translation in ESKAPE bacteria, with 24 different possible combinations. It can be used for easy high-throughput screening of chemical compounds as well as for exploring the mechanism of trans-translation in these pathogens.

biochemistry↗

bioRxiv2020

Reflux of Endoplasmic Reticulum proteins to the cytosol yields inactivation of tumor suppressors

In the past decades many studies reported Endoplasmic Reticulum (ER) resident proteins to localize to the cytosol but the mechanisms by which this occurs and whether these proteins exert cytosolic functions remain unknown. We found that select ER luminal proteins accumulate in the cytosol of glioblastoma cells isolated from mouse and human tumors. In cultured cells ER protein reflux to the cytosol occurs upon proteostasis perturbation. As such we investigated whether refluxed proteins gain new functions in the cytosol thus providing advantage to tumor cells. Using the ER luminal protein AGR2 as a model, we showed that it is refluxed to the cytosol where it binds and inhibits the tumor suppressor p53. We named this phenomenon ER to Cytosol Signaling (ERCYS) as an ER surveillance mechanism conserved in Eukaryotes to relieve the ER from its contents upon stress and to provide selective advantage to tumor cells through gain-of-cytosolic functions.

cell biology↗

bioRxiv2017

Numerous cultivated and uncultivated viruses encode ribosomal proteins

Text Text METHODS References Viruses modulate ecosystems by directly altering host metabolisms through auxiliary metabolic genes, which are obtained through random sampling of the host genome and rise to fixation, presumably through improved viral fitness by alleviating key metabolic bottlenecks during infection. Conspicuously, however, viral genomes are not known to encode the core components of translation machinery, such as ribosomal proteins (RPs), though genes for RPs S1 and S21 have been detected in viral metagenomes1,2. Here we augment this little-noticed observation using available reference genomes, global-scale viral metagenomic datasets, and functional assays for select proteins. We identify 15 different RPs across diverse viral genomes arising from cultivated viral isolates (5 RPs in 16 genomes) and metag ...

microbiology↗