Endofungal bacteria as hidden facilitators of biotic interactions.

Fungi play pivotal roles in ecology and human health, driving nutrient cycling, supporting antibiotic production, and posing threats through toxin production. Less well-recognized, however, is their ability to harbour endosymbiotic bacteria. Advances in genomics and microscopy have revealed the prevalence of endofungal bacteria across diverse fungal phyla, though their functions are primarily inferred from genomic and transcriptomic studies.

Dual-use virulence factors of the opportunistic pathogen mediate hemolysis and colonization.

is an environmental bacterium that can cause severe and fatal opportunistic infections in humans and animals. Although is characterized by its strong β-hemolytic activity, the molecular basis of this phenotype has remained elusive over the more than 15 years since the species was first described. Herein, we report a family of cyclic lipodepsipeptides, the jagaricins, that are responsible for the potent hemolytic activity of .

A Catch-Release Strategy for the Genomics-Driven Discovery of Antiproliferative Furan-Functionalized Peptides.

Furan-functionalized peptides are of significant pharmacological interest due to their pronounced bioactivities and unique potential for orthogonal bioconjugation and derivatization. However, naturally occurring peptides with furyl side chains are exceedingly rare. This study presents a streamlined method to predict and assess the microbial production of peptides incorporating 3-furylalanine (Fua) moieties.

Inducing novel endosymbioses by implanting bacteria in fungi.

Endosymbioses have profoundly impacted the evolution of life and continue to shape the ecology of a wide range of species. They give rise to new combinations of biochemical capabilities that promote innovation and diversification. Despite the many examples of known endosymbioses across the tree of life, their de novo emergence is rare and challenging to uncover in retrospect.

Deazaflavin metabolite produced by endosymbiotic bacteria controls fungal host reproduction.

The endosymbiosis between the pathogenic fungus Rhizopus microsporus and the toxin-producing bacterium Mycetohabitans rhizoxinica represents a unique example of host control by an endosymbiont. Fungal sporulation strictly depends on the presence of endosymbionts as well as bacterially produced secondary metabolites. However, an influence of primary metabolites on host control remained unexplored.

Transcription activator-like effectors from endosymbiotic bacteria control the reproduction of their fungal host.

Interactions between fungi and bacteria are critically important in ecology, medicine, and biotechnology. In this study, we shed light on factors that promote the persistence of a toxin-producing, phytopathogenic symbiosis that causes severe crop losses in Asia. We present an unprecedented case where bacterially produced transcription activator-like (TAL) effectors are key to maintaining a stable endosymbiosis.

Transcription activator-like effector protects bacterial endosymbionts from entrapment within fungal hyphae.

As an endosymbiont of the ecologically and medically relevant fungus Rhizopus microsporus, the toxin-producing bacterium Mycetohabitans rhizoxinica faces myriad challenges, such as evading the host's defense mechanisms. However, the bacterial effector(s) that facilitate the remarkable ability of M. rhizoxinica to freely migrate within fungal hyphae have thus far remained unknown.

Toxin-Producing Endosymbionts Shield Pathogenic Fungus against Micropredators.

The fungus Rhizopus microsporus harbors a bacterial endosymbiont () for the production of the antimitotic toxin rhizoxin. Although rhizoxin is the causative agent of rice seedling blight, the toxinogenic bacterial-fungal alliance is, not restricted to the plant disease. It has been detected in numerous environmental isolates from geographically distinct sites covering all five continents, thus raising questions regarding the ecological role of rhizoxin beyond rice seedling blight.

Diversification by CofC and Control by CofD Govern Biosynthesis and Evolution of Coenzyme F and Its Derivative 3PG-F.

Coenzyme F is a microbial redox cofactor that mediates diverse physiological functions and is increasingly used for biocatalytic applications. Recently, diversified biosynthetic routes to F and the discovery of a derivative, 3PG-F, were reported. 3PG-F is formed via activation of 3-phospho-d-glycerate (3-PG) by CofC, but the structural basis of substrate binding, its evolution, as well as the role of CofD in substrate selection remained elusive.

Bacterial endosymbionts protect beneficial soil fungus from nematode attack.

Fungi of the genus occur ubiquitously in soils where they play pivotal roles in carbon cycling, xenobiont degradation, and promoting plant growth. These important fungi are, however, threatened by micropredators such as fungivorous nematodes, and yet little is known about their protective tactics. We report that NRRL 6337 harbors a bacterial endosymbiont that efficiently shields its host from nematode attacks with anthelmintic metabolites.

Metabolic Pathway Rerouting in Evolved Long-Overlooked Derivatives of Coenzyme F.

Coenzyme F is a specialized redox cofactor with a negative redox potential. It supports biochemical processes like methanogenesis, degradation of xenobiotics, and the biosynthesis of antibiotics. Although well-studied in methanogenic archaea and actinobacteria, not much is known about F in Gram-negative bacteria.

Cyclopropanol Warhead in Malleicyprol Confers Virulence of Human- and Animal-Pathogenic Burkholderia Species.

Burkholderia species such as B. mallei and B. pseudomallei are bacterial pathogens causing fatal infections in humans and animals (glanders and melioidosis), yet knowledge on their virulence factors is limited.

Development of a real-time polymerase chain reaction assay for the detection of the invasive Mediterranean fanworm, Sabella spallanzanii, in environmental samples.

The Mediterranean fanworm, Sabella spallanzanii Gmelin 1791, was first detected in the Southern Hemisphere in the 1990s and is now abundant in many parts of southern Australia and in several locations around northern New Zealand. Once established, it can proliferate rapidly, reaching high densities with potential ecological and economic impacts. Early detection of new S.

Tunicate pregnane X receptor (PXR) orthologs: transcript characterization and natural variation.

Vertebrate pregnane X receptor (PXR, NR1I2), a ligand-activated nuclear receptor (NR), regulates expression of detoxification genes. Vertebrate PXR orthologs may adaptively evolve to bind deleterious/toxic xenobiotics typically encountered by organisms from their diet. Tunicates (phylum Chordata) are marine filter-feeders that form a sister clade to the Vertebrata.

Detection of marine microalgal biotoxins using bioassays based on functional expression of tunicate xenobiotic receptors in yeast.

Marine microalgae can produce biotoxins that cause widespread poisoning in marine ecosystems and may also affect human health. While established microalgal biotoxins are detectable using chemical methods, a need remains for robust, inexpensive bioassays. Ligand-binding domains (LBDs) from a tunicate nuclear receptor, VDR/PXRα, which is orthologous to both the vertebrate pregnane X receptor (PXR) and the vitamin D receptor (VDR), can be activated by microalgal biotoxins when expressed in mammalian cell lines.

Marine invertebrate xenobiotic-activated nuclear receptors: their application as sensor elements in high-throughput bioassays for marine bioactive compounds.

Developing high-throughput assays to screen marine extracts for bioactive compounds presents both conceptual and technical challenges. One major challenge is to develop assays that have well-grounded ecological and evolutionary rationales. In this review we propose that a specific group of ligand-activated transcription factors are particularly well-suited to act as sensors in such bioassays.

Influence of soil properties on archaeal diversity and distribution in the McMurdo Dry Valleys, Antarctica.

Archaea are the least understood members of the microbial community in Antarctic mineral soils. Although their occurrence in Antarctic coastal soils has been previously documented, little is known about their distribution in soils across the McMurdo Dry Valleys, Victoria Land. In this study, terminal-restriction fragment length polymorphism (t-RFLP) analysis and 454 pyrosequencing were coupled with a detailed analysis of soil physicochemical properties to characterize archaeal diversity and identify environmental factors that might shape and maintain archaeal communities in soils of the three southern most McMurdo Dry Valleys (Garwood, Marshall, and Miers Valley).

Biological significance of DNA adducts: comparison of increments over background for various biomarkers of genotoxicity in L5178Y tk(+/-) mouse lymphoma cells treated with hydrogen peroxide and cumene hydroperoxide.

DNA is affected by background damage of the order of one lesion per one hundred thousand nucleotides, with depurination and oxidative damage accounting for a major part. This damage contributes to spontaneous mutation and cancer. DNA adducts can be measured with high sensitivity, with limits of detection lower than one adduct per one billion nucleotides.

Tests for genotoxicity and mutagenicity of furan and its metabolite cis-2-butene-1,4-dial in L5178Y tk+/- mouse lymphoma cells.

Furan is found in various food items and is cytotoxic and carcinogenic in the liver of rats and mice. Metabolism of furan includes the formation of an unsaturated dialdehyde, cis-2-butene-1,4-dial (BDA). In view of the multifunctional electrophilic reactivity of BDA, adduct formation with protein and DNA may explain some of the toxic effects.

Insights into the catalytic mechanism of human sEH phosphatase by site-directed mutagenesis and LC-MS/MS analysis.

We have recently reported that human soluble epoxide hydrolase (sEH) is a bifunctional enzyme with a novel phosphatase enzymatic activity. Based on a structural relationship with other members of the haloacid dehalogenase superfamily, the sEH N-terminal phosphatase domain revealed four conserved sequence motifs, including the proposed catalytic nucleophile D9, and several other residues potentially implicated in substrate turnover and/or Mg(2+) binding. To enlighten the catalytic mechanism of dephosphorylation, we constructed sEH phosphatase active-site mutants by site-directed mutagenesis.