Biology subjects

Tilquin, F.

Publications and source records attributed to Tilquin, F..

3 recordsLinked to original sources

bioRxiv2024

Role of a TonB-dependent receptor and an oxygenase in iron-dependent copper resistance in Caulobacter crescentus

Copper (Cu) is potentially threatening for living organisms owing to its toxicity at high concentrations, requiring the onset of diverse detoxification strategies to maintain fitness. We previously showed that the environmental conditions modulate the response of the oligotrophic alphaproteobacterium Caulobacter crescentus to Cu excess. In the present study, we investigated the role of the Fe-importing TonB-dependent receptor (TBDR) CciT and its partner, CciO, a 2-oxoglutarate/Fe2+-dependent oxygenase, in Cu resistance. CciT is specifically involved in Cu resistance in both rich and poor media. Using inductively coupled plasma optical emission spectrometry, we found that under Cu stress, the cellular Cu content is reduced by overexpression of cciT, while Fe content increases. Mutations of the three known Fe-importing TBDRs reveal that CciT is the primary Fe importer in these conditions and the only TBDR required for Cu resistance. In addition, the extracellular Fe concentration is positively correlated with the cellular Fe content and negatively correlated with the cellular Cu content, resulting in the protection of the cells against Cu excess. The operon organization of cciT and cciO is highly conserved across bacteria, indicating a functional link between the two proteins. Deletion of cciT, cciO, or both genes leads to similar Cu sensitivity. Catalytic mutations in CciT and CciO also result in Cu sensitivity. While CciO is not required for Cu and Fe transport, its precise function remains unknown. Overall, this study provides new insights into the role of Fe uptake in Cu resistance, emphasizing the critical influence of environmental conditions on bacterial physiology. ImportanceCopper is an essential metal for many living organisms, as it helps to drive crucial chemical reactions. However, when present in excess, copper turns toxic due to its high reactivity with biological molecules. Bacteria may encounter excess copper in various environments, such as polluted soils, agricultural copper treatments, and within the vacuoles of infected macrophages. In this study, we investigated the copper response in the environmental bacterium Caulobacter crescentus. Our findings reveal that environmental iron levels play a critical role in copper resistance, as increased iron prevents cellular copper accumulation and toxicity. We identified two essential proteins, CciT and CciO, that are involved in iron transport, providing protection against copper excess.

microbiology↗

bioRxiv2022

Reactive oxygen species-based sensing by a single chemoreceptor controls bacterial chemotaxis to copper

Chemotaxis is a widespread strategy used by unicellular and multicellular living organisms to maintain their fitness in stressful environments. We previously showed that bacteria can trigger a negative chemotactic response to a copper (Cu)-rich environment. Cu ions toxicity on bacterial cell physiology has been mainly linked to mismetallation events and ROS production, although the precise role of Cu-generated ROS remains largely debated. Here, we found that the cytoplasmic Cu ions content mirrors variations of the extracellular Cu ions concentration and triggers a dose-dependent oxidative stress, which can be abrogated by superoxide dismutase and catalase overexpression. The inhibition of ROS production in the cytoplasm not only improves bacterial growth but also impedes Cu-chemotaxis, indicating that ROS derived from cytoplasmic Cu ions mediate the control of bacterial chemotaxis to Cu. We also identified the Cu chemoreceptor McpR, which binds Cu ions with low affinity, suggesting a labile interaction. In addition, we demonstrate that the cysteine 75 and histidine 99 within the McpR sensor domain are key residues in Cu chemotaxis and Cu coordination. Finally, we discovered that in vitro both Cu(I) and Cu(II) ions modulate McpR conformation in a distinct manner. Overall, our study provides mechanistic insights on a redox-based control of Cu chemotaxis, indicating that the cellular redox status can play a key role in bacterial chemotaxis.

microbiology↗

bioRxiv2018

An interdisciplinary study around the reliquary of the late cardinal Jacques de Vitry

The reliquary of Jacques de Vitry, a prominent clergyman and theologian in the early 13th century, has experienced several transfers over the last centuries, which seriously question the attribution of the remains to the late Cardinal. Uncertainty about the year of his birth poses an additional question regarding his age at death in 1240. The reliquary, located in the Saint Marie dOigines church, Belgium, was reopened in 2015 for an interdisciplinary study around his relics as well as the Treasure of Oignies, a remarkable cultural heritage notably built from Jacques de Vitrys donation. Anthropological, isotopic and genetic analyses were performed independently on the remains found in the reliquary. Results of the analyses provided evidence that the likelihood that these remains are those of Jacques de Vitry is very high: the remains belong to the same human male individual and the historical tradition about his age is confirmed. In addition, a separate relic (left tibia) was analysed and found to match with the remains of the reliquary (right tibia). The unique Jacques de Vitrys mitre, made of parchment, was sampled non-destructively and the extracted parchment collagen was analysed by a proteomic method in order to determine the animal species. The results showed that, surprisingly, not all parts of the mitre were made from the same species. All together, these findings are expected to fertilize knowledge carried by historical tradition around the relics of Jacques de Vitry and his related cultural heritage.

genetics↗