PLoS Pathogens最新文献

Work in the human pathobiont Haemophilus influenzae has pioneered functional genomics in bacteria such as genome-wide transposon mutagenesis combined with deep sequencing. These approaches unveiled a large set of likely essential genes, but functional studies are hampered due to a limited molecular toolbox. To bridge this gap, we engineered a titratable anhydrotetracycline-inducible CRISPRi (Clustered Regularly Interspaced Short Palindromic Repeats interference) platform for efficient regulation of gene expression in H. influenzae. Genome-wide fitness analyses in two different in vitro culture media by CRISPRi-seq revealed growth medium-dependent fitness cost for a panel of H. influenzae genes. We demonstrated that CRISPRi-programmed fitness defects can be rescuable, and we refined previous Tn-seq based essentialome studies. Finally, we introduce HaemoBrowse, an extensive user-friendly online resource for visual inspection of H. influenzae genome annotations, including sgRNA spacers. The inducible CRISPRi platform described here represents a valuable tool enabling functional genomics and the study of essential genes, thereby contributing to the identification of therapeutic targets for developing drugs and vaccines against H. influenzae.

Fungal pathogens employ conserved signaling pathways to survive in the host. The stress-activated MAP kinase Hog1 of the maize pathogen Cochliobolus heterostrophus undergoes dephosphorylation upon exposure to ferulic acid, a phenolic compound abundant in the host plant. Unlike its nuclear localization during osmotic stress, Hog1 forms cytoplasmic foci in response to FA, indicating its sequestering to a compartment or condensate. FA prevents several characteristic responses of the Hog1 pathway to osmotic stress: hyperphosphorylation of Hog1, nuclear localization, and expression of a monosaccharide transporter gene, MST1. Under FA stress, mRNA-containing foci are formed, as visualized by sm-FISH. Hog1 foci extensively colocalize with mRNA foci. Hog1 did not colocalize with nuclei or peroxisomes. Fragmented mitochondria, appearing upon FA exposure with a delayed time course compared to Hog1 sequestration, were mostly distinct from the Hog1 foci, with few instances of colocalization. With tagged Hog1 as an affinity purification bait, we isolated an FA-dependent sub-proteome from a subcellular fraction enriched with fluorescent foci. The identified proteins include RNA-binding proteins, translation initiation factors and mitochondrial proteins. The RRM and pumilio domain protein Puf2 was enriched, and live imaging confirmed the accumulation of a Puf2 fluorescent fusion and its colocalization with Hog1 foci following FA induction. Stress-induced sequestering of MAPK Hog1 to RNA-containing granules, together with dephosphorylation, has the potential to collectively promote survival on the plant host where stress might cause over-activation of Hog1. Conversely, FA as a host defense interferes with stress-induced Hog1 nuclear localization and downstream gene expression. The MAPK signaling mode defined by the response of Hog1 to FA is thus relevant to both host defense and pathogen survival.

Trace transition metals are required for cellular life processes, such as respiration, metabolism, and DNA replication. At high levels, nutrient metals can be toxic due to oxidative stress and mismetallation of critical metalloenzymes. All organisms tightly regulate intracellular trace metal levels to ensure sufficiency for essential processes while avoiding excess. Microbes including bacteria, viruses, fungi, and archaea colonize hosts forming the microbiota, which in vertebrates is most abundant in the gastrointestinal tract. Invading pathogens compete for metals not only with the host but also with the resident gut microbiota, which provides colonization resistance. To prevent severe infection by enteric pathogens, vertebrate hosts leverage the narrow viable range of trace metal concentrations via both metal sequestration and intoxication in a process called nutritional immunity. In response, microbes have evolved trace metal uptake and export mechanisms to maintain homeostatic levels. In this review, we discuss how the trace transition metals iron, zinc, manganese, and copper influence the composition of the gut microbiota and its subsequent ability to compete with enteric pathogens. We explore the specialized mechanisms that pathogens employ to successfully acquire nutrient metals during infection in the gut and describe how these systems could be exploited for therapeutic development. Finally, we report the powerful mechanisms utilized by the microbiota to compete with enteric pathogens for metals and how they can inspire potential antipathogenic tools.

Pathogenic bacteria utilize a type III secretion system to translocate effector proteins into plant cells, where they inhibit plant immunity or interfere with normal cellular functions to facilitate infection. Whether and how pathogen effectors manipulate plant adenosine 5'-triphosphate (ATP) to facilitate infection remains largely unknown. In this work, we show that an effector protein, RipAF1, from the plant pathogen Ralstonia solanacearum suppresses flg22-induced immune activation and contributes to virulence. RipAF1 physically interacts with plant ferredoxin-NADP+ reductase (FNR), which is involved in NADPH and ATP production, in chloroplast. Transient expression of FNR leads to increased ATP accumulation and resistance against R. solanacearum, while co-expression of FNR with RipAF1 significantly reduced ATP levels. We further show that exogenous application of ATP enhances plant resistance to R. solanacearum infection. Our findings indicate a key role of ATP in plant resistance against R. solanacearum, and elucidate a bacterial virulence strategy wherein pathogenicity is enhanced through targeted modification of host ATP homeostasis via bacterial effector proteins.

[This corrects the article DOI: 10.1371/journal.ppat.1012795.].

Zinc finger NFX1-type containing 1 (ZNFX1) has been established as a critical mediator of the antiviral response in mammals, functioning through dsRNA recognition and priority activation of the retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) signaling pathway. However, the role of its fish ortholog, particularly in relation to aquatic virus interactions, remains elusive. The absence of the RIG-I homolog, a key pattern recognition receptor, in multiple Actinopterygii may compromise their innate antiviral immune responses. Here, ZNFX1 in Epinephelus coioides (EcZNFX1) is identified as an evolutionarily primitive, interferon (IFN)-stimulated dsRNA sensor that compensates for the absence of RIG-I in Actinopterygii. EcZNFX1 is rapidly upregulated by orange-spotted grouper nervous necrosis virus (OGNNV) infection and restricts viral replication in grouper brain-derived (GB) and spleen-derived (GS) cells after binding to viral dsRNA intermediates via its conserved P-loop NTPase domain. Notably, EcZNFX1 exerts a dual immunoregulatory role in modulating virus-induced inflammatory responses in diverse cellular contexts. In GB cells that are highly susceptible to OGNNV and have attenuated regenerative capacity, EcZNFX1 suppresses IFN-I/ISGs production and pyroptosis mediated by viral infection, thereby limiting neurotoxicity by precise tuning of the antiviral response. Conversely, in GS cells with stronger resistance to OGNNV, EcZNFX1 directly interacts with TBK1 to promote its phosphorylation and subsequent nuclear translocation of IRF3, activating a robust IFN-I signaling. Overall, this study elucidates that ZNFX1 is a compensatory receptor for dsRNA sensing in RIG-I-deficient teleost, which exerts context-dependent antiviral effects in cell-type-specific microenvironments, providing mechanistic insights for aquatic virus countermeasures.

Phytopathogens are a growing global threat to food security, economies, and ecosystems, yet public awareness and policy support often lag behind scientific innovations. Despite widespread pesticide use, 20-40% of global crop yields are lost to pests and diseases (FAO). Biotechnology and novel breeding strategies provide powerful tools to counter these threats, but their deployment hinges on public trust. Here, we review the societal risks posed by phytopathogens and cultural differences in public acceptance and regulatory frameworks. We discuss key challenges in plant science communication and the importance of trusted role-model communicators, including a concrete example where science-led storytelling and participatory engagement have accelerated adoption. We further propose that Botanical Gardens can act as scalable and adoptable platforms for plant health science communication to facilitate the translation into real-world applications.