Biology subjects

El Mouali, Y.

Publications and source records attributed to El Mouali, Y..

5 recordsLinked to original sources

bioRxiv2025

Synergy between Enterobacteriaceae and dietary components shapes the competition between the dominant anaerobes of the human gut

The human gut microbiota is frequently dominated by the Bacteroidota phylum, with Bacteroidaceae and Prevotellaceae families prevailing in modern and traditional lifestyles, respectively. While these distinct profiles have been well-documented across cohorts, the underlying mechanisms remain poorly understood. Here, we combine defined gut community models and genetic tools to experimentally dissect the ecological principles that favor Prevotellaceae or Bacteroidaceae. Testing 94 dietary components in the community model shows these two families compete for overlapping nutritional niches. Notably, Segatella copri, a key Prevotellaceae representative, outcompetes Bacteroidaceae strains when preferred polysaccharides are available. Interestingly, this competitive advantage depends on the presence of Enterobacteriaceae, which synergize with dietary components to promote Segatella dominance. Accordingly, we observe that global Segatella-rich non-Westernized microbiomes correlate with higher Enterobacteriaceae content. Our results suggest a revised hypothesis in which the ecosystem-level dynamic interplay between dietary components and key commensals within the community contributes to distinct Bacteroidota family dominance.

microbiology↗

bioRxiv2024

The RNA landscape of the human commensal Segatella copri reveals a small RNA essential for gut colonization

The bacterium Segatella copri is a prevalent member of the human gut microbiota associated with both health and disease states, but intrinsic factors that determine its ability to effectively colonize the gut are not understood. By extensive transcriptome mapping of S. copri and examining human-derived samples, we discover a previously unknown small RNA named here Segatella RNA colonization factor (SrcF). We show that SrcF is essential for S. copri gut colonization in a gnotobiotic mouse model. SrcF regulates genes involved in nutrient acquisition, and its own expression is controlled by complex carbohydrates, particularly fructans. Furthermore, SrcF expression is strongly influenced by human microbiome composition and by the breakdown of fructans by cohabitating commensals, suggesting that the breakdown of complex carbohydrates mediates inter-species signaling among commensals beyond its established function in generating energy. Together, this study highlights the contribution of a small RNA as a key regulator in gut colonization.

microbiology↗

bioRxiv2023

An adapted method for Cas9-mediated editing reveals the species-specific role of β-glucoside utilization driving competition between Klebsiella species

Cas9-based gene editing tools have revolutionized genetics, enabling the fast and precise manipulation of diverse bacterial species. However, widely applicable genetic tools for non-model gut bacteria are unavailable. Here, we present a two-plasmid Cas9-based system designed for gene deletion and knock-in complementation in three members of the Klebsiella oxytoca species complex (KoSC), which we applied to study the genetic factors underlying the role of these bacteria in competition against Klebsiella pneumoniae. The system allowed efficient and precise editing via enhanced lambda Red expression and functionally-validated complementation with the use of universal bookmark targets in K. oxytoca, Klebsiella michiganensis, and Klebsiella grimontii. We revealed that the carbohydrate permease CasA is critical in ex vivo assays for K. pneumoniae inhibition by K. oxytoca but is neither sufficient nor required for K. michiganensis and K. grimontii. Thus, the adaptation of state-of-the-art genetic tools to KoSC allows the identification of species-specific functions in microbial competition. * ImportanceCas9-based gene editing tools have revolutionized bacterial genetics, yet, their application to non-model gut bacteria is frequently hampered by various limitations. We utilized a two-plasmid Cas9-based system designed for gene deletion in Klebsiella pneumoniae and demonstrate after optimization its utility for gene editing in three members of the Klebsiella oxytoca species complex (KoSC) namely K. oxytoca, K. michiganensis and K. grimontii. We then adapted a recently developed protocol for functional complementation based on universal bookmark targets applicable to all tested species. In summary, species specific adaptation of state-of-the-art genetic tools allow efficient gene deletion and complementation in types strains as well as natural isolates of KoSC members to study microbial interactions.

microbiology↗

bioRxiv2021

Scanning mutagenesis of RNA-binding protein ProQ reveals a quality control role for the Lon protease

The FinO-domain protein ProQ belongs to a widespread family of RNA-binding proteins (RBPs) involved in gene regulation in bacterial chromosomes and mobile elements. Whilst the cellular RNA targets of ProQ have been established in diverse bacteria, the functionally crucial ProQ residues remain to be identified under physiological conditions. Following our discovery that ProQ deficiency alleviates growth suppression of Salmonella with succinate as the sole carbon source, an experimental evolution approach was devised to exploit this phenotype. By coupling mutational scanning with loss-of-function selection, we identified multiple ProQ residues in both the N-terminal FinO domain and the variable C-terminal region required for ProQ activity. Two C-terminal mutations abrogated ProQ function and mildly impaired binding of a model RNA target. By contrast, several mutations in the FinO domain rendered ProQ both functionally inactive and unable to interact with target RNA in vivo. Alteration of the FinO domain stimulated the rapid turnover of ProQ by Lon-mediated proteolysis, suggesting a quality control mechanism that prevents the accumulation of non-functional ProQ molecules. We extend this observation to Hfq, the other major sRNA chaperone of enteric bacteria. The Hfq Y55A mutant protein, defective in RNA-binding and oligomerization, proved to be labile and susceptible to degradation by Lon. Taken together, our findings connect the major AAA+ family protease Lon with RNA-dependent quality control of Hfq and ProQ, the two major sRNA chaperones of Gram-negative bacteria. SIGNIFICANCEProteins that interact with RNA play a vital role in controlling key functions in pathogenic bacteria. RNA-binding proteins regulate how, when and where bacteria feed, swim or interact with a host, and it is critical that we understand how RNAs associate with these proteins. ProQ is one of the three major RNA-binding proteins (RBPs) in Gram-negative bacteria. In this study, we mapped the amino acid residues of ProQ that are essential for function. We successfully identified residue substitutions that rendered the ProQ RBP both non-functional and unable to interact with RNA. Our findings raise the possibility that the Lon protease mediates a quality control mechanism of ProQ that targets this RBP in the absence of RNA. A posttranslational quality control mechanism of this type could prevent the accumulation of nonfunctional RBPs in the bacterial cytoplasm.

microbiology↗

bioRxiv2020

Global discovery of bacterial RNA-binding proteins by RNase-sensitive gradient profiles reports a new FinO domain protein

RNA-binding proteins (RBPs) play important roles in bacterial gene expression and physiology but their true number and functional scope remain little understood even in model microbes. To advance global RBP discovery in bacteria, we here establish glycerol gradient sedimentation with RNase treatment and mass spectrometry (GradR). Applied to Salmonella enterica, GradR confirms many known RBPs such as CsrA, Hfq and ProQ by their RNase-sensitive sedimentation profiles, and discovers the FopA protein as a new member of the emerging family of FinO/ProQ-like RBPs. FopA, encoded on resistance plasmid pCol1B9, primarily targets a small RNA associated with plasmid replication. The target suite of FopA dramatically differs from the related global RBP ProQ, revealing context-dependent selective RNA recognition by FinO-domain RBPs. Numerous other unexpected RNase-induced changes in gradient profiles suggest that cellular RNA helps to organize macromolecular complexes in bacteria. By enabling poly(A)-independent generic RBP discovery, GradR provides an important element in the quest to build a comprehensive catalogue of microbial RBPs.

microbiology↗