Biology subjects

Contarin, R.

Publications and source records attributed to Contarin, R..

3 recordsLinked to original sources

bioRxiv2024

The interplay between Mobilome and Resistome in Staphylococcus aureus

Antibiotic resistance genes (ARGs) in Staphylococcus aureus can disseminate vertically through successful clones, but also horizontally through the transfer of genes conveyed by mobile genetic elements (MGEs). The underexplored MGE/ARG associations in S. aureus favor the emergence of multidrug-resistant clones, posing a significant threat to human and animal health. This study investigated the interplay between the mobilome, encompassing MGEs, and the resistome, the collection of ARGs, in more than 10,000 S. aureus genomes from human and animal sources. The analysis revealed a remarkable diversity of MGEs and ARGs, with plasmids and transposons being the main carriers of resistance genes. Numerous MGE/ARG associations were identified, suggesting that MGEs play a critical role in the dissemination of resistance. A high degree of similaritywas observed in MGE/ARG associations between human and animal isolates, highlighting the potential for unrestricted spread of ARGs between hosts. While clonal expansion is a major driver of resistance dissemination in S. aureus, our results showed that MGEs and their associated ARGs can spread across different strain types (STs), favoring the evolution of these clones and their adaptation in selective environments. The high variability of MGE/ARG associations within individual STs and the ir spread across several STs highlight the crucial role of MGEs in shaping the S. aureus resistome. Overall, this study provides valuable insights into the complex interplay between MGEs and ARGs in S. aureus, emphasizing the need to elucidate the mechanisms governing the epidemic success of MGEs, particularly those implicated in ARG transfer. ImportanceThe research presented in this article highlights the crucial importance of understanding the interactions between mobile genetic elements (MGEs) and antibiotic resistance genes (ARGs) carried by Staphylococcus aureus, a versatile bacterium that can be both a harmless commensal and a dangerous pathogen for humans and animals. S. aureus strains represent a major threat due to their ability to rapidly acquire and disseminate ARGs. By analyzing a large dataset of S. aureus genomes, we highlighted the substantial role of MGEs, in particular plasmids and transposons, in the dissemination of ARGs within and between S. aureus populations, bypassing the host barrier. Given that multidrug-resistant S. aureus strains are classified as a high-prioritypathogenby global health organizations, this knowledge is crucial for understanding the complex dynamics of transmission of antibiotic resistance in this species.

microbiology↗

bioRxiv2024

Interplay between the Xer recombination system and the dissemination of antibioresistance in Acinetobacter baumannii

Antibiotic-resistant infections pose a pressing challenge in clinical settings. Plasmids are widely recognized for hastening the emergence of resistance by facilitating horizontal gene transfer of antibiotic resistance genes among bacteria. We explore this inquiry in Acinetobacter baumannii, a globally emerging nosocomial pathogen responsible for a wide array of infections with worrying accumulation of resistances, notably involving plasmids. In this specie, plasmids of the Rep_3 family harbor adaptive genes within variable regions edged by potential site-specific recombination sites recognized by the XerCD recombinase. We first show that the Xer system of Acinetobacter baumannii functions as described in Escherichia coli, resolving chromosome dimers at the dif site as well as recombining plasmid-borne sites. The multiple Xer recombination sites found in Rep_3 plasmids do not, however, allow excising plasmid fragments. They rather recombine to co-integrate plasmids, which may then further evolve to exchange genes. Co-integrates represent a significative part of the plasmid population and their formation is controlled by the sequence of the recombination sites determining their compatibility between the recombining sites. We conclude that plasmids frequently exchange genes in Acinetobacter baumannii using Xer recombination, allowing a high level yet controlled plasticity involved in the acquisition and combination of resistance genes.

microbiology↗

bioRxiv2021

Impacts of Mycoplasma agalactiae restriction-modification systems on pan-epigenome dynamics and genome plasticity

DNA methylation plays an important role in the biology of bacteria. Often associated with restriction modification (RM) systems, they also provide a defence against foreign DNA. Little is known regarding the methylome of the mycoplasma genus, which encompasses several pathogenic species with small genomes. Here, single molecule real-time (SMRT) and bisulphite sequencing combined with whole-genome analysis identified 19 methylated motifs associated with three orphan methyltransferases (MTases) and eight RM systems in Mycoplasma agalactiae, a ruminant pathogen and a model organism. All systems had a homolog in at least one phylogenetically distinct Mycoplasma spp. Our study also revealed that several superimposed genetic events may participate in the M. agalactiae dynamic epigenome landscape. These included (i) DNA shuffling and frameshift mutations that affect the MTase and restriction endonuclease content of a clonal population and (ii) gene duplication, erosion, and horizontal transfer that modulate MTase and RM repertoires of the species. Some of these systems were experimentally shown to play a major role in mycoplasma conjugative, horizontal DNA transfer. While the versatility of DNA methylation may contribute to regulating essential biological functions at cell and population levels, RM systems may be key in mycoplasma genome evolution and adaptation by controlling horizontal gene transfers.

microbiology↗