Biology subjects

Galinier, A.

Publications and source records attributed to Galinier, A..

2 recordsLinked to original sources

bioRxiv2025

Remodeling of RNA-Binding Proteome and RNA-mediated regulation as a new layer of control of sporulation

Sporulation allows certain bacteria to survive extreme conditions for extended periods posing challenges to public health and food safety. Transcriptional level of regulation relying on {sigma} factors has been well studied in the non-pathogenic model bacterium Bacillus subtilis, while post-transcriptional control remains poorly understood. RNA-binding proteins (RBPs) and small non-coding RNAs (sRNAs) modulate gene expression by affecting mRNA stability or translation. Recent studies suggest that RNA-mediated regulation plays a role in sporulation, but its networks and interactions remain largely uncharacterized, highlighting the need for further investigation. To address this knowledge gap, we adapted OOPS (Orthogonal Organic Phase Separation), a high-throughput method to specifically purify RNA binding proteome (RBPome). By monitoring its dynamics, we observed RBPome is highly remodeled during B. subtilis process. Our approach led to the identification of novel RBPs and potential RNA-mediated post-transcriptional regulators of sporulation. This work provides important insights into the interplay between RNAs and RBPs, advancing the understanding of post-transcriptional regulation in Gram-positive spore-forming bacteria. It also offers new resources for exploring the molecular mechanisms that govern sporulation. IMPORTANCEUnderstanding how bacteria survive extreme conditions is key to tackling challenges in health, food safety, and industry. This study reveals a previously unexplored layer of control in Bacillus subtilis, a model organism for spore-forming bacteria--those that can produce spores, which are highly resistant, dormant cells able to endure harsh environments. By mapping, for the first time, the full set of proteins that interact with RNA during sporulation, this work uncovers how bacteria fine-tune their internal programs. The identification of novel RNA-binding proteins sheds light on how bacteria adapt at the molecular level and lays a valuable foundation for future mechanistic studies that will deepen our understanding of bacterial adaptation and resilience.

microbiology↗

bioRxiv2022

Periplasmic oxidized-protein repair during copper stress in E. coli: a focus on the metallochaperone CusF.

Methionine residues are particularly sensitive to oxidation by reactive oxygen or chlorine species (ROS/RCS), leading to the appearance of methionine sulfoxide in proteins. This post-translational oxidation can be reversed by omnipresent protein repair pathways involving methionine sulfoxide reductases (Msr). In the periplasm of Escherichia coli, the enzymatic system MsrPQ, whose expression is triggered by the RCS, controls the redox status of methionine residues. Here we report that MsrPQ synthesis is also induced by copper stress via the CusSR two-component system, and that MsrPQ plays a role in copper homeostasis by maintaining the activity of the copper efflux pump, CusCFBA. Genetic and biochemical evidence suggest the metallochaperone CusF is the substrate of MsrPQ and our study reveal that CusF methionines are redox sensitive and can be restored by MsrPQ. Thus, the evolution of a CusSR-dependent synthesis of MsrPQ allows keeping copper homeostasis under aerobic conditions by maintenance of the reduced state of Met residues in copper-trafficking proteins. AUTHOR SUMMARYOur study investigates the interconnection between the copper stress response and the methionine redox homeostasis in the Gram-negative bacterium Escherichia coli. We report that the copper-activation of the CusSR two-component system induces the expression of the periplasmic oxidized-protein repair system, MsrPQ. We demonstrate that MsrPQ is crucial for CusCFBA copper efflux pump activity under aerobic conditions as it maintains the periplasmic component CusF in its functional reduced form. Methionine emerges as a critical residue in copper trafficking proteins: however this naturally-selected advantage must be balanced by methionines high susceptibility to oxidation. Therefore the induction of MsrPQ by copper allows copper homeostasis under aerobic conditions, illustrating that E. coli has developed an integrated and dynamic circuit for sensing and counteracting stress caused by copper and oxidants, thus allowing bacteria to adapt to host cellular defences.

microbiology↗