mBio® An ASM Access® Publication

In chronic, recalcitrant infections, Pseudomonas aeruginosa forms biofilm aggregates that are encapsulated in a protective extracellular matrix made of exopolysaccharides, extracellular DNA, and matrix proteins. Biofilm formation is a major cause of antibiotic clearance failure in P. aeruginosa, and there is growing pressure to elucidate biofilm preventative measures and develop novel anti-biofilm treatments. Toward this goal, much work has been done to understand the genetic adaptations P....

The striatin-interacting phosphatase and kinase (STRIPAK) complex is a conserved protein phosphatase 2A (PP2A)-associated signaling hub that integrates kinase-phosphatase networks, yet its roles in human fungal pathogens remain poorly defined. Here, we dissected STRIPAK functions in the opportunistic pathogen Cryptococcus neoformans by combining genetic, genomic, virulence, and phosphoproteomic analyses across mutants lacking individual STRIPAK subunits. Loss of the core STRIPAK components via...

Orthoflavivirus RNA genomes resist host 5'-3' exoribonucleases to produce subgenomic flaviviral RNAs (sfRNAs). This resistance is conferred by exoribonuclease-resistant RNA (xrRNA) structures within the viral 3' untranslated region that often occur in tandem, and whose function can be coupled. In dengue virus serotype 2 (DENV2), this coupling results in changing patterns of sfRNA identity and abundance associated with the ability of the virus to adapt to host vs. vector infections. The physical...

RNA viruses have evolved diverse strategies to evade host interferon (IFN)-stimulated gene (ISG) defenses; however, how they exploit host epitranscriptomic regulation remains poorly understood. Here, we identify an immune-evasion mechanism in which porcine reproductive and respiratory syndrome virus (PRRSV) targets the m6A demethylase fat mass and obesity-associated protein (FTO) to suppress antiviral signaling. Mechanistically, the viral endoribonuclease nsp11 inhibits STAT5-dependent...

Porcine deltacoronavirus (PDCoV) is an emerging enteric pathogen that causes severe diarrhea, vomiting, and dehydration in piglets, and a recent human infection report raises concerns about its zoonotic potential. The S1 subunit of the PDCoV-spike protein is the primary target of neutralizing antibodies and is critical for viral attachment and entry. In this study, we generated and characterized eight monoclonal antibodies (mAbs) against S1, two targeting the S1^(A) domain, five targeting the...

Killer plasmids are cytosolic linear dsDNA plasmids found in many species of Saccharomycotina, the budding yeasts. They encode toxins that give their hosts an advantage against competitor yeasts in the environment. They cause cell death in their prey by targeting non-coding RNAs of the translation apparatus, either tRNAs or rRNAs. We recently discovered that similar toxin systems are integrated into the nuclear genomes of many filamentous ascomycetes. Cytosolic linear plasmids similar to killer...

RNA phages are attractive platforms for the design of programmable bioparticles, but their development has been constrained by limited knowledge of genomic sites that can tolerate sequence insertion. Here, we combined MuA transposase-mediated in vitro insertion mutagenesis with our established reverse genetics systems to systematically identify insertion-tolerant regions (ITRs) in the RNA phages MS2 and PP7. Screening of 4,555 MS2 and 2,228 PP7 random insertion clones identified 29 and 26...

Neonatal infection is a leading cause of morbidity and mortality worldwide, particularly among preterm and low birth weight infants. Probiotic bacteria are widely used in peri- and postnatal care and can reduce neonatal intestinal dysbiosis. However, formulations and efficacy remain highly variable, highlighting a critical gap in our understanding of the mechanisms that drive successful interventions in this population. Furthermore, current studies on probiotic efficacy rely on indirect or...

Recent advances in systems biology and immunotherapy have spurred the use of bacteria as therapeutic vehicles for cancer treatment. Currently, Bacillus Calmette-Guérin remains the only FDA-approved bacterial strain for high-risk, non-muscle-invasive bladder cancer. Although safety concerns have been raised, attenuated Salmonella Typhimurium strains such as VNP20009 have advanced to clinical trials targeting fast-growing human tumors. Notably, this strain induces robust immunological control of...

Antibiotic resistance threatens the effectiveness of conventional antimicrobial agents, underscoring the need for host-directed therapies that enhance immune defense. Here, we present a cross-species discovery pipeline that couples a Caenorhabditis elegans-Staphylococcus aureus liquid-based infection screen with mammalian mechanistic validation to identify small-molecule immunomodulators. Using six C. elegans innate immunity reporter strains, we identified a known small molecule, SKI-II, as a...

Dentists account for roughly 10% of global antibiotic prescriptions and maintain a substantial patient contact footprint. As a result, dentistry is strategically positioned in the global response to the antimicrobial resistance (AMR) crisis, offering unique opportunities to impact antibiotic stewardship, AMR surveillance, and infection prevention. However, these opportunities are underleveraged because antibiotic stewardship is insufficiently emphasized in dental education curricula and...

CetZs are archaeal tubulin superfamily cytoskeletal proteins implicated in the control of cell shape and motility. In the pleomorphic archaeon Haloferax volcanii, CetZ1 is required for the transformation of a discoid, or plate-like, cell morphology to the rod shape in early log-phase cultures, and for the development of swimming motility. In this study, we found that the paralog CetZ2 is not required for rod development or reversion to plates in log phase but was strongly upregulated later in...

Understanding bacterial gene expression in natural environments remains challenging because most regulatory networks are inferred from in vitro models that poorly capture in situ environmental conditions. Here, we present NEMO (network transcriptomics of microbes in native environments), a generalizable pangenome-based metatranscriptomic framework for extracting microbial transcriptional programs from metatranscriptomes generated from natural samples. We applied NEMO to Staphylococcus aureus...

Bacterial endospores are encased in a thick layer of specialized peptidoglycan called the cortex that is essential for core dehydration and heat resistance. Spore germination and outgrowth require cortex degradation by enzymes that are deposited in the spore during sporulation. How these enzymes are held inactive during dormancy and activated during germination remains poorly understood. In Bacillus subtilis and many other endospore-forming bacteria, one of the lytic enzymes, SleB, is encoded in...

Streptococcus pneumoniae is a major colonizer of the human nasopharynx, where inter- and intra-strain competition plays a critical role in shaping population structure and influencing vaccine outcomes. Bacteriocins are key mediators of intra-species competition, yet many of their functions and regulatory mechanisms remain poorly understood. Here, we identify and characterize streptolancidin D, a previously uncharacterized bacteriocin encoded by the sldA-T locus, and demonstrate its contribution...