Biology subjects

Serror, P.

Publications and source records attributed to Serror, P..

5 recordsLinked to original sources

bioRxiv2025

Mechanistic insights into Enterocin C targeting the undecaprenyl phosphate recycling protein BacA

Enterococcus faecalis is an important opportunistic pathogen responsible for healthcare-associated infections. It is intrinsically resistant to various antibiotics, particularly to cephalosporins and vancomycin, creating an urgent need for alternative therapeutics. In this context, bacteriocins warrant investigations as a potential source of medical-use antibiotics. Herein, we demonstrate that Enterocin C, a class IIb two-peptide bacteriocin, specifically targets the membrane embedded undecaprenyl phosphate recycling protein BacA from enterococci as a cell surface receptor. Using biochemical and biophysical methods, supported by AlphaFold2 modelling and mutagenesis, we deciphered the EntCs molecular interaction pattern with its target, marking the first mechanistic insight of a two-peptide bacteriocin. The two peptides act cooperatively at nanomolar concentrations to interact with the outward-open catalytic pocket of BacA: the peptide EntC1 docks deeply into the catalytic site, inhibits BacAs enzymatic activity and enables the binding of peptide EntC2, eliciting membrane permeabilization, eventually leading to cell death. A comparative analysis with LcnG, a homologous bacteriocin, reveals a conserved interaction pattern, paving the way for bioengineering of these bacteriocins and developing tailored antimicrobial strategies.

biochemistry↗

bioRxiv2024

Guided assembly of multispecies positive biofilms targeting undesirable bacteria

The use of synthetic microbial communities (SynComs) engineered to form positive biofilms that prevent the settlement of harmful bacteria is emerging as a promising strategy in biotechnology, particularly in reducing reliance on chemical antimicrobials. Despite this potential, the rationale for selecting specific strains in SynComs and the mechanisms underlying their antagonistic effects remains insufficiently understood. In this study, we present a bottom-up approach integrating live-cell imaging with high-throughput analysis of multi-strain biofilms across diverse scenarios. Through this method, we identified beneficial strains based on their superior ability to exclude undesirable bacteria and form mixed biofilms. Notably, our findings revealed that competitive strains against undesirable bacteria could also exclude other beneficial strains, emphasising the need for compatibility control in SynComs design. SynComs composed of B. velezensis and Pediococcus spp. demonstrated enhanced pathogen exclusion compared to single strains. Temporal analysis of biofilm interactions, supported by mathematical models, showed that pathogen exclusion was primarily driven by nutritional competition (Jameson effect) with additional specific interference mechanisms (prey-predator Lotka-Volterra model). Furthermore, pre-establishing SynComs to surfaces significantly increased pathogen inhibition, indicating a distinct biofilm-associated exclusion effect. These insights offer a framework for rational SynCom design and deepen our understanding of the mechanisms underpinning positive biofilm applications. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=153 SRC="FIGDIR/small/618781v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@a8ca36org.highwire.dtl.DTLVardef@173dc16org.highwire.dtl.DTLVardef@1764af2org.highwire.dtl.DTLVardef@1328cfc_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2022

Comparative genome analysis of Enterococcus cecorum reveals intercontinental spread of a lineage of clinical poultry isolates.

Enterococcus cecorum is an emerging pathogen responsible for osteomyelitis, spondylitis, and femoral head necrosis causing animal suffering, mortality, and requiring antimicrobial use in poultry. Paradoxically, E. cecorum is a common inhabitant of the intestinal microbiota of adult chickens. Despite evidence suggesting the existence of clones with pathogenic potential, the genetic and phenotypic relatedness of disease-associated isolates remains little investigated. Here, we sequenced and analyzed the genomes and characterized the phenotypes of more than 100 isolates, the majority of which were collected over the last ten years in 16 French broiler farms. Comparative genomics, genome-wide association study, and measured susceptibility to serum, biofilm forming capacity, and adhesion to chicken type II collagen were used to identify features associated with clinical isolates. We found that none of the tested phenotypes could discriminate origin of the isolates or phylogenetic group. Instead, we found that most clinical isolates are grouped phylogenetically and our analyses selected six genes that discriminate 94% of isolates associated with disease from those that are not. Analysis of the resistome and the mobilome revealed that multidrug-resistant clones of E. cecorum cluster in few clades and that integrative conjugative elements and genomic islands are the main carriers of antimicrobial resistance. This comprehensive genomic analysis shows that disease-associated clones of E. cecorum belong mainly to one phylogenetic clade. IMPORTANCEEnterococcus cecorum is an important pathogen in poultry worldwide. It causes a number of locomotor disorders and septicemia, particularly in fast-growing broilers. Animal suffering, antimicrobial use, and associated economic losses require a better understanding of disease-associated E. cecorum isolates. To address this need, we performed whole genome sequencing and analysis of a large collection of isolates responsible for outbreaks in France. By providing the first dataset on the genetic diversity and resistome of E. cecorum strains circulating in France, we pinpoint an epidemic lineage probably also circulating elsewhere and which should be targeted preferentially by preventive strategies in order to reduce the burden of E. cecorum-related diseases.

genomics↗

bioRxiv2022

Antimicrobial resistance of Enterococcus cecorum: ECOFF determination

Enterococcus cecorum, a commensal Gram-positive bacterium of the chicken gut, has emerged as a worldwide cause of lameness in poultry, particularly in fast-growing broilers. It is responsible for osteomyelitis, spondylitis and femoral head necrosis, causing animal suffering, mortality and antimicrobial use. Research on the antimicrobial resistance of E. cecorum clinical isolates in France is scarce, and epidemiological cut-off (ECOFF) values unknown. To determine tentative ECOFF (COWT) values for E. cecorum and to investigate the antimicrobial resistance patterns of isolates from mainly French broilers, we tested the susceptibility of a collection of commensal and clinical isolates (n=208) to 29 antimicrobials by the disc diffusion (DD) method. We also determined the minimum inhibitory concentrations (MICs) of 23 antimicrobials by the broth micro-dilution method. To detect chromosomal mutations conferring antimicrobial resistance, we investigated the genomes of 118 E. cecorum isolates mainly obtained from infectious sites and previously described in the literature. We determined the COWT values for more than 20 antimicrobials and identified two chromosomal mutations explaining fluoroquinolone resistance. The DD method appears better suited for detecting E. cecorum antimicrobial resistance. Although tetracycline and erythromycin resistances were persistent in clinical and non-clinical isolates, we found little or no resistance to medically important antimicrobials.

microbiology↗

bioRxiv2018

Decoration of the enterococcal polysaccharide antigen EPA is essential for virulence, cell surface charge and sensitivity to effector molecules of innate immunity

Enterococcus faecalis is an opportunistic pathogen with an intrinsically high resistance to lysozyme, a key effector of the innate immune system. This high level of resistance requires several genes (oatA, pgdA, dltA and sigV) acting synergistically to inhibit both the enzymatic and cationic antimicrobial peptide activities of lysozyme. We sought to identify novel genes modulating E. faecalis resistance to lysozyme. Random transposon mutagenesis carried out in the quadruple oatA/pgdA/dltA/sigV mutant led to the identification of several independent insertions clustered on the chromosome. These mutations were located in a locus referred to as the enterococcal polysaccharide antigen (EPA) variable region located downstream of the highly conserved epaA-epaR genes proposed to encode a core synthetic machinery. The epa variable region was previously proposed to be responsible for EPA decorations, but the role of this locus remains largely unknown. Here, we show that EPA decoration contributes to resistance towards charged antimicrobials and underpins virulence in the zebrafish model of infection by conferring resistance to phagocytosis. Collectively, our results indicate that the production of the EPA rhamnopolysaccharide backbone is not sufficient to promote E. faecalis infections and reveal an essential role of the modification of this surface polymer for enterococcal pathogenesis.

microbiology↗