Biology subjects

Prevost, K.

Publications and source records attributed to Prevost, K..

5 recordsLinked to original sources

bioRxiv2025

Ketogenic interventions prevent alterations of the gut microbiome in transgenic Alzheimer Disease mice

Alterations in the gut microbiome constitute a feature of aging and therefore represent a therapeutic target for aging-related diseases. In this study, we investigated the impact of ketogenic interventions on the microbiome of mice genetically predisposed to Alzheimers disease (AD). AD mice exhibited several microbial alterations, notably increased levels of Bifidobacterium and decreased levels of Bacteroidetes. Ketogenic interventions, either a medium-chain triglyceride-enriched diet (MCT) or carbohydrate-free high-fat diet (CFHF), administered for 1 month restored the levels of more than 50% of the bacteria altered in AD mice, including a strong reduction in Bifidobacterium levels. Ketogenic interventions induced a shift in the gut microbiome associated with increased levels of short-chain fatty acid-producing bacteria, such as Lachnospiraceae and Muribaculaceae. MCT and CFHF also triggered diet-specific microbial changes, which may contribute to the distinct physiological effects of these diets. In conclusion, ketogenic interventions may influence AD pathophysiology by modulating the gut microbiome.

neuroscience↗

bioRxiv2024

An unprecedented small RNA-riboswitch interaction controls expression of a bifunctional pump that is essential for Staphylococcus aureus infection

Maintaining manganese and iron homeostasis is critical for the human pathogen Staphylococcus aureus. To counteract metal-based host defense strategies (e.g., nutritional immunity, metal poisoning), S. aureus uses a combination of metal-sensing transcription factors and regulatory RNAs to maintain metal homeostasis. In this study, we uncovered an unprecedented interaction between a cis- and a trans-acting regulatory RNA controlling a conditionally essential gene, mntY, encoding a Mn efflux pump. This broadly conserved RNA-RNA interaction between a Fe-responsive sRNA and a Mn-sensing riboswitch allows the integration of Feand Mn-related stresses, notably encountered at the infection site, to fine-tune mntY expression. Remarkably, deletion of the mntY gene is strongly pleomorphic, causing growth defects, altering virulence factor expression, immune evasion, and survival during infection. We demonstrated that MntY is critical for the adaptation of S. aureus to both low and high Mn environments, due to its dual role in metalation of Mn-dependent exoenzymes and Mn detoxification. These findings point to MntY as a promising new therapeutic target to combat multidrug-resistant staphylococcal infections.

microbiology↗

bioRxiv2021

Escherichia coli ribosomal protein S1 enhances the kinetics of ribosome biogenesis and RNA decay

Escherichia coli ribosomal protein S1 is essential for translation initiation of mRNAs and for cellular viability. Two oligonucleotide binding (OB)-fold domains located in the C-terminus of S1 are dispensable for growth, but their deletion causes a cold-shock phenotype, loss of motility and deregulation of RNA mediated stress responses. Surprisingly, the expression of the small regulatory RNA RyhB and one of its repressed target mRNA, sodB, are enhanced in the mutant strain lacking the two OB domains. Using in vivo and in vitro approaches, we show that RyhB retains its capacity to repress translation of target mRNAs in the mutant strain but becomes deficient in triggering rapid turnover of those transcripts. In addition, the mutant is defective in of the final step of the RNase E-dependent maturation of the 16S rRNA. This work unveils an unexpected function of S1 in facilitating ribosome biogenesis and RyhB-dependent mRNA decay mediated by the RNA degradosome. Through its RNA chaperone activity, S1 participates to the coupling between ribosome biogenesis, translation, and RNA decay.

microbiology↗

bioRxiv2020

Dynamic interactions between the RNA chaperone Hfq, small regulatory RNAs and mRNAs in live bacterial cells

RNA binding proteins play myriad roles in controlling and regulating RNAs and RNA-mediated functions, often through simultaneous binding to other cellular factors. In bacteria, the RNA chaperone Hfq modulates post-transcriptional gene regulation. Absence of Hfq leads to the loss of fitness and compromises the virulence of bacterial pathogens. Using live-cell super-resolution imaging, we are able to distinguish Hfq binding to different sizes of cellular RNAs. We demonstrate that under normal growth conditions, Hfq exhibits widespread mRNA binding activity. Particularly, the distal face of Hfq contributes mostly to the mRNA binding in vivo. In addition, binding of Hfq to these mRNAs can recruit RNase E to promote turnover of these mRNAs in an sRNA-independent manner, providing one mechanism to release Hfq from the pre-bound mRNAs. Finally, our data indicate that sRNAs, once expressed, can either co-occupy Hfq with the mRNA or displace the mRNA from Hfq, suggesting mechanisms through which sRNAs rapidly access Hfq to induce sRNA-mediated gene regulation. Our data collectively demonstrate that Hfq dynamically changes its interactions with different RNAs in response to changes in cellular conditions.

biophysics↗

bioRxiv2019

CcnA, a novel non-coding RNA regulating the bacterial cell cycle

Bacteria are powerful models for understanding how cells divide and accomplish global regulatory programs. In Caulobacter crescentus, a cascade of essential master regulators supervises the correct and sequential activation of DNA replication, cell division and development of different cell types. Among them, the response regulator CtrA plays a crucial role coordinating all those functions. Here, for the first time we describe the role of a novel factor named CcnA, a cell cycle regulated ncRNA located at the origin of replication, presumably activated by CtrA and responsible for the accumulation of CtrA itself. In addition, CcnA may be also involved in the inhibition of translation of the S-phase regulator, GcrA, by interacting with its 5 untranslated region (5-UTR). Performing in vitro experiments and mutagenesis, we propose a mechanism of action of CcnA based on liberation (ctrA) or sequestration (gcrA) of their ribosome-binding site (RBS). Finally, its role may be conserved in other alphaproteobacterial species, such as Sinorhizobium meliloti, representing indeed a potentially conserved process modulating cell cycle in Caulobacterales and Rhizobiales.

microbiology↗