Biology subjects

Arsenault, D.

Publications and source records attributed to Arsenault, D..

3 recordsLinked to original sources

bioRxiv2025

Identification and characterization of the surface layer protein AvsA in outer membrane vesicles, antibiotic resistance, and in vivo host colonization in Aeromonas veronii

Outer membrane vesicles (OMVs) are important in bacterial communication and the transfer of virulence factors. In this study, we identified and characterized the surface layer protein (SLP) AvsA (Aeromonas veronii surface protein A) in the OMVs of Aeromonas veronii Hm21, a strain isolated from the medicinal leech Hirudo verbana. The surface layer proteins (SLPs) play critical roles in how bacteria interact with each other and their environments, particularly in mediating antibiotic resistance and facilitating host colonization. Furthermore, we investigate the ability of AvsA to confer protection against antibiotics, affect biofilm formation, and contribute to host colonization, providing insight into antibiotic resistance and two crucial factors contributing to the persistence of the bacteria in its host. Our findings suggest that AvsA enhances antibiotic tolerance, facilitates biofilm development, and is important for successful colonization of the leech digestive tract. These data demonstrate that AvsA performs important roles in a wide range of critical phenotypes. This work provides insights into the functional significance of SLPs in A. veronii and highlights AvsA as a potential target for modulating bacterial colonization and resilience against antibiotics. ImportanceOuter membrane vesicles (OMVs) are important for bacterial communication, pathogenesis, and stress adaptation, yet how this is accomplished remains poorly understood. Here, we identify and characterize a surface layer protein (SLP), AvsA, associated with OMVs in Aeromonas veronii Hm21. Bioinformatic, phylogenetic, and mass spectrometry analyses suggest that Aeromonas veronii ORF M001_06550 encodes a surface layer protein (SLP) with high similarity to a characterized A. hydrophila SLP, supporting its designation as Aeromonas veronii Surface Protein A (AvsA). AvsA forms a paracrystalline layer on bacterial cells and OMVs. Functionally, AvsA contributes to antibiotic resistance, enhances biofilm formation, and is essential for colonization in a symbiotic host, the medicinal leech. These findings highlight a novel role of SLPs in bacterial physiology and host interactions. Given the widespread presence of AvsA homologs, our study provides insights into conserved bacterial mechanisms that may be relevant for both pathogenic and beneficial host-microbe interactions.

microbiology↗

bioRxiv2025

Actinobacteriophage Inteins: Host Diversity, Local Dissemination, and Non-Canonical Architecture

Intein presence within Actinobacteriophages (within PhagesDB) was last surveyed in 2016, and despite a 5-fold increase in the size of the database, has not been updated since. To address this, we present a modern survey of the current iteration of the PhagesDB database. We developed a new algorithm -- Iterative Cluster Expansion BLAST (ICE-BLAST) -- to expand our search to more divergent sequences. Nearly 800 inteins were retrieved through this process; the majority of which were previously unreported. We describe the nature of these inteins, their classes, integration target sites, distribution within phage clusters, and explore the geographical location of nearly identical intein sequences found in divergent exteins. Our findings suggest that these inteins recently invaded local phage populations. We also find two instances of a Cas4 exonuclease intein evolving from a terminase large subunit intein, and propose a model by which one of these inteins was able to utilize sequence similarity conferred by a shared nucleotide binding site to jump between genes. Additionally, we find inteins with never-before-reported homing endonucleases, and inteins with homing endonucleases encoded in a reading frame separate from that which encodes the extein and the inteins self-splicing domain. We provide predicted structures for these elements and hypothesize on their evolution and relation to free-standing homing endonucleases within phage genomes. Finally, we provide evidence that these "non-canonical" inteins are still transferring between host genomes, in a fashion similar to other inteins with canonical homing endonucleases within the dataset.

bioinformatics↗

bioRxiv2023

Using the pan-genomic framework for the discovery of genomic islands in the haloarchaeon Halorubrum ezzemoulense

In this study, we use pan-genomics to characterize the organized variability from the widely dispersed halophilic archaeal species Halorubrum ezzemoulense. We include a multi-regional sampling of newly sequenced, high-quality draft genomes. Using the pan-genome graph of the species, we discover 50 genomic islands which represent rare accessory genetic capabilities available to members of the species. 19 of these islands are likely the remnant of mobile genetic elements and are enriched for genomic dark matter. 10 islands encode for niche adapting solute transporters, with a cosmopolitan but limited distribution throughout the strains. We also observe rearrangements which have led to the insertion/recombination/replacement of mutually exclusive genomic islands in equivalent genome positions ("homeocassettes"). These conflicting islands encode for similar functions, but homologs from islands located between the same core genes exhibit extreme divergence on the amino acid level. Homeocasettes provide variations for a homologous function, which may confer a greater range of adaptability to the species group. We observe some islands that appear geographically restricted; however, we also observe the coexistence of genomes, in a single geographic region, with and without certain genomic islands, demonstrating the retention and spread of rare genes in the pan-genome. ImportanceUnderstanding the evolution of genome content is a key puzzle in evolutionary biology. Despite its importance, this area hasnt received thorough investigation. This is especially true of Archaeal organisms, which constitute a large fraction of Earths diversity, but are often referred to as the "forgotten" or "third" domain of life. This study dives into those questions by finding rare genes amongst a group of closely related Archaeal species, and describes how their transfer, utilization and persistence may contribute to the speciation and specialization of the group.

microbiology↗