Biology subjects

Bai, Y.

Publications and source records attributed to Bai, Y..

At least 73 records · Page 4Linked to original sources

bioRxiv2025

Mutation or deletion of the Avr6 avirulence effector gene of Fulvia fulva leads to breakdown of the Cf-6 leaf mold resistance locus in tomato

Genetic resistance mediated by Cf cell-surface receptors is a cornerstone of tomato breeding against leaf mold disease caused by the fungal pathogen Fulvia fulva. After widespread deployment of the Cf-9 resistance locus, breeders increasingly relied on Cf-6, yet Cf-6-mediated resistance has already been overcome in multiple regions. The molecular basis of this breakdown, and the identity of the matching avirulence (Avr) effector, have remained unresolved. Here, we use comparative genomics and functional genetics to identify the F. fulva effector Avr6 as the previously described apoplastic protein Ecp5. Sequencing of Cf-6-breaking strains revealed either deletion of the Ecp5 locus or non-synonymous mutations in its coding sequence. Using transient expression, targeted gene knockout, and complementation assays, we show that Ecp5 is both necessary and sufficient for Cf-6-mediated recognition and defence activation. We then use Avr6-triggered cell death as a phenotypic marker in a bulked segregant analysis combined with Comparative Subsequence Sets analysis (CoSSa) to map Cf-6 to a [~]2 Mb interval on the short arm of chromosome 12 that overlaps the previously described Cf-Ecp5.12 locus. Sequencing of Avr6 in a broad strain collection reveals a predominantly conserved allele under apparent purifying selection, with recent independent loss-of-function variants in Europe and South America that confer virulence on Cf-6 plants. Together, these findings establish the Avr6-Cf-6 gene-for-gene pair, explain the erosion of Cf-6-mediated resistance, and illustrate how effector loss or mutation provides a rapid route for F. fulva adaptation, with important implications for designing more durable resistance strategies against tomato leaf mold.

microbiology↗

bioRxiv2025

LSH-mediated resolution of R-loops mitigates transcription-replication conflicts to preserve genomic stability in prostate cancer cells

Prostate cancer cells exhibit heightened transcriptional activity to sustain their aggressive phenotype, yet this creates DNA topological stress, leading to RNA: DNA hybrids (R-loops) and DNA damage that compromise genomic stability. LSH, an SNF2-family chromatin remodeler, is frequently dysregulated in cancers and linked to tumor progression, but its mechanistic role in genome maintenance remains unclear. Here, we demonstrate that LSH resolves R-loops in an ATP-dependent manner, mitigating transcription- replication (TR) conflicts in prostate cancer cells. LSH depletion caused R- loop accumulation due to reduced FANCD2 recruitment, exacerbating DNA damage and impairing Rad51 filament formation. Strikingly, LSH deficiency also increased R-loops at promoters of MYC and E2F target genes, stalling RNA polymerase II elongation and disrupting transcriptional programs critical for proliferation. Our findings reveal LSH is a key guardian of genome integrity, resolving R-loops to prevent TR conflicts and maintaining DNA repair fidelity. By linking LSH to R-loop resolution and transcriptional regulation, this study reveals its dual role in prostate cancer pathogenesis-- supporting malignant proliferation while safeguarding genomic stability. These insights nominate LSH as a potential therapeutic target to disrupt oncogenic transcription and induce synthetic lethality in prostate cancer.

cancer biology↗

bioRxiv2025

Single-cell spatial map of cis-regulatory elements for disease-related genes in the macaque cortex

Single-cell spatial transcriptomes have demonstrated molecular and cellular diversity in the brain1, 2, 3, 4, 5, 6, 7, 8, but gene regulatory mechanisms underlying transcriptomic profiles and disease pathogenesis remain largely unknown in primates. Here we performed single-nucleus Assay for Transposase-Accessible Chromatin followed by sequencing (snATAC-seq) for [~]1.6 million cells from 142 cortical regions of two male cynomolgus monkeys (Macaca fascicularis), and identified distinct chromatin accessibility profiles of cis-regulatory elements (CREs) for various cell types. By integrative analysis with large-scale spatial transcriptome data, we found that these CREs showed laminar and regional preferences, with their regional accessibility exhibiting striking dependence on the regions hierarchical level. Cross-species comparison of snATAC-seq data revealed human/macaque-enriched layer-4 glutamatergic neurons and LAMP5/LHX6-expressing GABAergic neurons as well as human/macaque-biased CREs for genes related to neurodevelopment and psychiatric diseases. Importantly, risk single-nucleotide polymorphisms for many brain disorders strongly associated with human/macaque-biased CREs in glutamatergic neuronal types and those for Alzhemers disease strongly associated with CREs exclusively in microglia. Our results provided the basis for understanding the spatial gene regulatory mechanisms underlying cellular diversity and disease pathogenesis in the primate cortex.

neuroscience↗

bioRxiv2025

Single-cell Characterization of DNA Hydroxymethylation of the Mouse Brain During Aging

DNA methylation dynamics, including 5-hydroxymethylcytosine (5hmC) and 5-methylcytosine (5mC), critically regulate brain function, yet conventional methods cannot distinguish these modifications, obscuring their distinct roles in gene regulation and aging. We present Joint- Cabernet, a bisulfite-free single-cell platform enabling simultaneous profiling of 5hmC, 5mC, and transcriptomes. Applying Joint-Cabernet to 84,071 nuclei from adult and aged mouse brains, we resolved cell-type-specific DNA hydroxymethylation landscapes, revealing elevated 5hmCG and 5hmCH levels in transcriptionally active genes across neuronal subtypes and spatial gradients in cortical layers. During aging, 5hmCG accumulates globally but is selectively enriched at open chromatin loci, aligning with the upregulation of cell-type-specific genes in distinct brain cell types. This single-cell DNA methylation brain cell atlas provides a framework for studying methylation- driven mechanisms in brain aging and neurodegenerative diseases.

genetics↗

bioRxiv2025

Extrusion-modulated DnaA activity oscillations coordinate DNA replication with biomass growth

Robust control of DNA replication is fundamental to bacterial proliferation. In Escherichia coli, replication initiation is thought to be regulated by oscillations in DnaA activity, driven by DnaA-chromosome interactions that differ among leading models. However, direct evidence linking these oscillations to replication initiation has been lacking, and existing models fail to explain the observed decoupling of replication initiation from dnaA expression. Here, we establish a direct link between DnaA activity and replication initiation by demonstrating robust oscillations in DnaA activity, which peak precisely at replication initiation across diverse growth conditions and genetic perturbations. Notably, these oscillations persist even when dnaA transcription remains constant, suggesting a regulatory mechanism that modulates DnaA activity independently of its expression. Additionally, we propose an extrusion model in which DNA-binding proteins sense biomass-DNA imbalance and extrude DnaA from the chromosome to trigger replication, overcoming limitations of existing models. Consistent with this model, perturbation of the nucleoid-associated protein H-NS modulates DnaA activity and replication timing, supporting its mechanistic validity.

microbiology↗

bioRxiv2025

Environmental stress sensitivity determines bacterial Mn(II) oxidation

Bacterial Mn(II) oxidation is a widespread and ecologically significant process, with Mn oxides playing essential roles in biogeochemical cycling and environmental remediation. However, the environmental cues that initiate this microbial activity remain enigmatic. In this study, a spontaneous mutant was isolated from the previously characterized Arthrobacter strain that exhibited autonomous Mn(II)-oxidizing capacity, in contrast to the parental strain, which required cocultivation with other bacteria to initiate Mn(II) oxidation1. Comparative transcriptomic analysis suggested that a gene system encoding an environmental stress-sensing receptor controlled the transcription of boxA, a Mn(II)-oxidizing gene. These findings indicate that two conditions are required for bacterial Mn(II) oxidation: the presence of a Mn(II)-oxidizing gene and an environmentally responsive regulatory system capable of activating its expression. Based on this knowledge, eight additional bacterial strains were isolated that triggered Arthrobacter Mn(II) oxidation. Transcriptomic profiling revealed a robust positive correlation between boxA expression and genes encoding two-component signal transduction systems. Given their widespread distribution (approximately 23% of environmental bacterial genomes harbor Mn(II)-oxidizing gene homologs2) and constant exposure to diverse biotic and abiotic stressors, these bacteria are likely to undergo frequent Mn(II) oxidation triggered by microbial interactions or chemical signals. This study provides critical mechanistic insight into the environmental regulation of bacterial Mn(II) oxidation, addressing a longstanding gap in understanding its natural occurrence.

microbiology↗

bioRxiv2025

PASTA: Versatile Tyramine-oligonucleotide Amplification for Multi-modal Spatial Biology

Spatial proteomics techniques have revolutionized our understanding of tissue architecture, but are frequently limited by detection sensitivity, bioconjugation limitations, multiplexing capacity, and multi-modal integration. Here we present Protein and nucleic Acid Serial Tyramine Amplification (PASTA), a novel signal amplification approach that significantly enhances detection sensitivity while maintaining compatibility with diverse spatial profiling methodologies. PASTA utilizes horseradish peroxidase (HRP) recruitment pathways to generate tyramine radicals that deposit oligonucleotides, enabling adaptable signal amplification across multiple biomarkers at high-plex via cyclical imaging using complementary fluorophore-labeled oligonucleotides. We demonstrate that PASTA achieves up to 100-fold signal enhancement for markers with minimal background in blank controls. The method is compatible with in situ hybridization for DNA/RNA detection, proximity ligation assays for protein-protein interactions, sequential antibody staining protocols, or any modular combination thereof. PASTA enables antibody rescue of markers with suboptimal signal-to-noise ratios and is versatile in its applications to unconjugated antibodies, and multi-round probe-based RNA detection systems beyond current capabilities. This technique addresses key limitations in spatial-omics by enhancing sensitivity for challenging targets while maintaining compatibility with established multiplexing strategies, providing a versatile, cost-efficient, and valuable tool for comprehensive spatial tissue analysis in both research and clinical applications.

molecular biology↗

bioRxiv2025

mmu-miR-1291 Alleviates Oxidative Damage in Myocytes by Modulating the Process of Gene-Mediated Ubiquitination

BS exhibited a significant restorative effect on PA-induced oxidative damage in C2C12 cells. And a set of miRNAs that were significantly differentially expressed under oxidative stress conditions was identified. Through target gene prediction, a key miRNA potentially involved in oxidative stress regulation was selected. Additionally, differential expression and enrichment analyses led to the identification of a series of mRNAs affected by oxidative stress. Based on miRNA target prediction, the Wsb1 gene was selected for further investigation. A dual-luciferase reporter assay confirmed that this miRNA directly regulates Wsb1. This suggests that the identified miRNA may influence the oxidative stress process by regulating Wsb1 expression and potentially be involved in modulating the NF-{kappa}B signaling pathway.

molecular biology↗

bioRxiv2025

Lamin A/C safeguards replication initiation by orchestrating chromatin accessibility and PCNA recruitment

Lamin A/C, a nuclear lamina protein, is essential for maintaining nuclear architecture, organizing chromatin and preserving genomic stability. However, its role in regulating DNA replication remains unclear. This study investigates how Lamin A/C regulates proper activation of replication origins by orchestrating the chromatin structure and recruitment of proliferating cell nuclear antigen (PCNA). We demonstrate that Lamin A/C stabilizes replication domains (RDs) by restricting chromatin mobility, preserving spatial organization, and maintaining accessibility. Furthermore, Lamin A/C interacts with PCNA and sequesters a pool of PCNA, to regulate its recruitment to replication machinery. The loss of Lamin A/C leads to an increase in chromatin dynamics, RD accessibility, and PCNA availability at RDs, which together trigger excessive activation of replication origins, leading to replication stress and DNA damage. These disruptions prolong the S phase and compromise genome stability, highlighting Lamin A/C as a critical gatekeeper of balanced replication initiation. Our findings reveal Lamin A/Cs dual role in chromatin organization and replication machinery regulation, offering valuable insights into its involvement in replication-associated diseases and potential therapeutic opportunities through targeting replication dynamics.

biophysics↗

bioRxiv2025

Bacillus velezensis 9912 enhances rice growth by triggering plant hormone modulation and complex miRNA-mRNA regulatory networks

Bacillus velezensis, a prominent member of plant growth-promoting bacteria, effectively suppresses pathogens and promotes plant growth. Despite its well-recognized efficacy, the intricate molecular mechanisms of its growth-promoting attributes remain largely unexplored. In this study, a commercial biopesticide B. velezensis 9912 significantly enhanced leaf photosynthesis and improved rice root development in the field experiment. And then, a rigorous hydroponic experiment was performed to investigate its underlying mechanism in plant growth promotion. High-throughput sequencing and bioinformatics analysis revealed 2,938 rice genes and 30 miRNAs responsive to strain 9912. Notably, differentially expressed genes encompassed key transcription factors like ERF, WRKY, and AP2. Remarkably, auxin-and ethylene-related genes were up-regulation significantly at day 1 and pectinesterase-related genes were up-regulation considerably at day 3, which revealed an unusual growth mechanism for strain 9912 to promote rice root development. In addition, DNA replication, cell cycle, cell division, and cytoskeleton organization were significantly enriched in GO and KEGG pathways. Biosynthetic pathways of secondary metabolites, such as carotenoid, lipid, diterpenoid, and brassinosteroid were also significantly enriched. An integrated analysis of the transcriptome and miRNAome identified several miRNA-mRNA regulatory networks, including miR166-Os08g14940, miR396-Os07g9320, miR529-Os12g31540, and miR6249-Os05g07880, which are involved in the process of growth promotion. In conclusion, our investigation offers insightful thoughts into the dynamic responses of rice genes and miRNAs to B. velezensis 9912, unveiling plant hormone modulation and potential miRNA-mRNA regulatory networks that are imperative in the growth promotion mechanism.

microbiology↗

bioRxiv2025

VPS35/Retromer-dependent MT1-MMP regulation confers melanoma metastasis

Retromer is a conserved endosomal trafficking complex responsible for recycling transmembrane protein cargoes. Membrane-type I matrix metalloproteinase (MT1-MMP), a well-studied membrane-type metalloprotease, is highly expressed in metastatic melanomas. Previously, we reported that inducing MT1-MMP perinuclear localization and inhibiting MT1-MMP membrane localization significantly reduce melanoma metastasis. However, the regulation of MT1-MMP subcellular localization and recycling is still largely unknown. Here, we performed target gene shRNA screening and found that shRNA targeting the retromer complex subunit vacuolar protein sorting 35 (VPS35) inhibited MT1-MMP membrane localization and induced its perinuclear localization. We found that inhibiting VPS35/retromer decreased MT1-MMP recycling and increased MT1-MMP-lysosome localization, which significantly affected the stability of MT1-MMP. Furthermore, our results indicated that VPS35/retromer regulates the transcription of MT1-MMP through the activation of the IL6/STAT3 inflammatory signaling pathway. Tissue microarray analysis indicated that VPS35/retromer positively correlated with MT1-MMP levels and distant metastasis. Xenograft experiments showed that targeting VPS35/retromer significantly inhibited melanoma lung metastasis, which is dependent on MT1-MMP. Our results implicate the importance of VPS35/retromer in metastatic dissemination. Our study suggests that targeting the VPS35/retromer-MT1-MMP axis will contribute to inhibiting the metastasis of melanoma.

cancer biology↗

bioRxiv2025

The immunometabolic topography of tuberculosis granulomas governs cellular organization and bacterial control

Despite being heavily infiltrated by immune cells, tuberculosis (TB) granulomas often subvert the host response to Mycobacterium tuberculosis (Mtb) infection and support bacterial persistence. We previously discovered that human TB granulomas are enriched for immunosuppressive factors typically associated with tumor-immune evasion, raising the intriguing possibility that they promote tolerance to infection. In this study, our goal was to identify the prime drivers for establishing this tolerogenic niche and to determine if the magnitude of this response correlates with bacterial persistence. To do this, we conducted a multimodal spatial analysis of 52 granulomas from 16 non-human primates (NHP) who were infected with low dose Mtb for 9-12 weeks. Notably, each granulomas bacterial burden was individually quantified allowing us to directly ask how granuloma spatial structure and function relate to infection control. We found that a universal feature of TB granulomas was partitioning of the myeloid core into two distinct metabolic environments, one of which is hypoxic. This hypoxic environment associated with pathologic immune cell states, dysfunctional cellular organization of the granuloma, and a near-complete blockade of lymphocyte infiltration that would be required for a successful host response. The extent of these hypoxia-associated features correlated with worsened bacterial burden. We conclude that hypoxia governs immune cell state and organization within granulomas and is a potent driver of subverted immunity during TB.

immunology↗

bioRxiv2025

A SNP Foundation Model: Application in Whole-Genome Haplotype Phasing and Genotype Imputation

Millions of human genomes have been genotyped by national biobanks worldwide. Training large language models (LLM) with this data may lead to a universal model of human genome with tremendous potential. Yet the quadrillions (1015) of nucleotides-- resulting from genome length multiplied by population size--pose formidable challenges for modeling. In this study, we propose a novel AI framework designed to scale with this data and support diverse analytical tasks. To demonstrate this scheme, we developed SNPBag--a foundation model focusing on single nucleotide polymorphism (SNP). With 0.8 billion parameters, it is trained on one million synthesized human genomes, corresponding to a total of 6 trillion SNP tokens. SNPBag showed superior performance in benchmarking of multiple tasks. In genotype imputation, it achieves state-of-the-art (SOTA) accuracy. In haplotype phasing, it rivals the best method with a 72-fold speedup. By encoding 6 million SNPs per genome into a 0.75 MB embedding, SNPBag enables efficient storage, transfer and downstream applications. In particular, the genome embeddings facilitate rapid ancestry inference across global populations and detection of genetic relationships up to 12th-degree relatives. Collectively, SNPBag introduces a new paradigm for scalable, unified and multitask analysis of the ever-growing human variation data.

genomics↗

bioRxiv2025

Temporal and spatial composition of the tumor microenvironment predicts response to immune checkpoint inhibition

Immune checkpoint inhibition (ICI) has fundamentally changed cancer treatment. However, only a minority of patients with metastatic triple negative breast cancer (TNBC) benefit from ICI, and the determinants of response remain largely unknown. To better understand the factors influencing patient outcome, we assembled a longitudinal cohort with tissue from multiple timepoints, including primary tumor, pre-treatment metastatic tumor, and on-treatment metastatic tumor from 117 patients treated with ICI (nivolumab) in the phase II TONIC trial. We used highly multiplexed imaging to quantify the subcellular localization of 37 proteins in each tumor. To extract meaningful information from the imaging data, we developed SpaceCat, a computational pipeline that quantifies features from imaging data such as cell density, cell diversity, spatial structure, and functional marker expression. We applied SpaceCat to 678 images from 294 tumors, generating more than 800 distinct features per tumor. Spatial features were more predictive of patient outcome, including features like the degree of mixing between cancer and immune cells, the diversity of the neighboring immune cells surrounding cancer cells, and the degree of T cell infiltration at the tumor border. Non-spatial features, including the ratio between T cell subsets and cancer cells and PD-L1 levels on myeloid cells, were also associated with patient outcome. Surprisingly, we did not identify robust predictors of response in the primary tumors. In contrast, the metastatic tumors had numerous features which predicted response. Some of these features, such as the cellular diversity at the tumor border, were shared across timepoints, but many of the features, such as T cell infiltration at the tumor border, were predictive of response at only a single timepoint. We trained multivariate models on all of the features in the dataset, finding that we could accurately predict patient outcome from the pre-treatment metastatic tumors, with improved performance using the on-treatment tumors. We validated our findings in matched bulk RNA-seq data, finding the most informative features from the on-treatment samples. Our study highlights the importance of profiling sequential tumor biopsies to understand the evolution of the tumor microenvironment, elucidating the temporal and spatial dynamics underlying patient responses and underscoring the need for further research on the prognostic role of metastatic tissue and its utility in stratifying patients for ICI.

cancer biology↗

bioRxiv2025

Single-Cell Genomics Elucidates Molecular Variations and Regulatory Mechanisms in Circulating Immune Cells

The human peripheral blood displays diverse molecular characteristics across populations, understanding the drivers and underlying mechanisms of which remains challenging. Here, we introduce the Chinese Immune Multi-Omics Atlas (CIMA), elucidating sex-, age-, and genetic-related molecular variations by analyzing multi-omics data from 428 adults with over 10 million immune cells. CIMA generated an enhancer-driven gene regulatory network, identifying 237 high-quality regulons and revealing cell type-specific regulatory mechanisms. Additionally, 11,521 lead cis-expression quantitative trait loci (eQTLs) and 46,339 chromatin accessibility QTLs (caQTLs) were identified at cell type level. CIMA also uncovered pleiotropic associations among immune-related disease risk loci, eQTLs, and caQTLs in a cell type-specific manner. Lastly, a novel cell language model, CIMA-CLM, was developed to predict chromatin accessibility and noncoding variant effects using chromatin sequences and gene expressions. This work represents a population-scale multi-omics resource of human immune cells, providing a valuable reference for future investigation of immune-related diseases.

immunology↗

bioRxiv2025

Isolation of a novel plant growth-promoting Dyella sp. from a Danish natural soil

Environmental soils are natural reservoirs of unexplored microbes, including potentially beneficial microbes to improve plant performance. Here, we isolated 75 bacterial strains from surface-sterilized roots of Arabidopsis thaliana (Arabidopsis) grown in a natural soil derived from an alder swamp. Culture-dependent isolation of individual strains from the roots followed by monoassociation-based screening identified seven bacteria that promoted Arabidopsis seedling weight. Of those, we identified a new species from the Dyella genus which increased biomass of tomato and Arabidopsis seedlings in agar as well as the shoot biomass of Arabidopsis grown in both the alder swamp soil and potting soil. Dyella sp. A4 specifically promoted the elongation of lateral roots without affecting lateral root number and primary root elongation. The new Dyella sp. A4 expands the toolbox of biostimulants for plant growth promotion via modulating root architecture.

plant biology↗

bioRxiv2025

Infant RSV infection desensitizes β2-adrenergic receptor via CXCL11-CXCR7 signaling in airway smooth muscle

RationaleAirflow obstruction refractory to {beta}2 adrenergic receptor ({beta}2AR) agonists is an important clinical feature of infant respiratory syncytial virus (RSV) bronchiolitis, with limited treatment options. This resistance is often linked to poor drug delivery and potential viral infection of airway smooth muscle cells (ASMCs). Whether RSV inflammation causes {beta}2AR desensitization in infant ASMCs is unknown. ObjectivesTo investigate the interaction of RSV inflammation with the {beta}2AR signaling pathway in infant ASMCs MethodsInfant precision-cut lung slices (PCLSs) and mouse pup models of RSV infection were subjected to airway physiological assays. Virus-free, conditioned media from RSV-infected infant bronchial epithelial cells in air-liquid interface (ALI) culture and nasopharyngeal aspirates (NPA) from infants with severe RSV bronchiolitis were collected and applied to infant PCLSs and ASMCs. Cytokines in these samples were profiled and assessed for the effects on {beta}2AR expression, cell surface distribution, and relaxant function in ASMCs. Measurements and Main ResultsConditioned media and NPA induced similar resistance to {beta}2AR agonists in ASMCs as RSV infection. Cytokine profiling identified CXCL11 as one of the most elevated signals following RSV infection. CXCL11 activated its receptor CXCR7 in a complex with {beta}2AR in ASMCs to promote {beta}2AR phosphorylation, internalization, and degradation. Blockade of CXCR7 partially restored airway relaxation in response to {beta}2AR agonists in infant PCLSs and mouse pup models of RSV infection. ConclusionsThe CXCL11-CXCR7 pathway plays a critical role in {beta}2AR desensitization in ASMCs during RSV infection and represents a potential therapeutic target in alleviating airflow obstruction in infant RSV bronchiolitis.

cell biology↗

bioRxiv2025

Pseudopaline-mediated zinc uptake by Pseudomonas aeruginosa determines specific clinically relevant phenotypes and infection outcome

AUTHOR SUMMARYThe host-pathogen interface is a biological niche in which two entities competes for essential resources. The hosts nutritional immunity restrict access to metals, while a successful pathogen overcomes these restrictions using dedicated uptake pathways. Pseudopaline is a high-affinity metallophore allowing Pseudomonas aeruginosa to acquire zinc in chelated environments. We demonstrate that this pathway is the last-resort solution to acquire zinc for this dreadful pathogen. The capacity to provide this metal to zinc-metalloproteins drives clinically relevant phenotypes, such as the capacity to form a mature and antibiotic-tolerant biofilm, or to affect the outcome of an infection. These results place pseudopaline as a potential drug target for blocking P. aeruginosa pathogenic capacity and resensitizing established biofilm to classic antibiotic treatment. ABSTRACTBiological metals are essential trace elements which are required by metalloproteins, involved in virtually every cellular, structural and catalytic function of the bacterial cell. Bacterial pathogenesis involves a tug-of-war between the host nutritional immunity, sequestering essential metals and the invading pathogens that deploy high-metal affinity uptake strategies in order to overcome these defence mechanisms. Metallophores are high-affinity, low-molecular mass metal chelators produced and secreted by bacteria to access chelated metals from the environment. Pseudopaline is a metallophore produced and secreted by Pseudomonas aeruginosa to acquire zinc when the bioavailability of this metal is severely restricted, as in the presence of a strong metal chelator such as EDTA, or during infections when the nutritional immunity of the host is active, in mammals through the production of the zing binding protein calprotectin. We show that under the conditions of metal deprivation, a pseudopaline-deficient P. aeruginosa strain exhibit a severe intracellular zinc deficiency, establishing that the pseudopaline pathway is the last-resort and unique pathway for the bacteria to acquire zinc under these restricted growth conditions. The present study explores the pleiotropic role of pseudopaline-mediated zinc acquisition on several clinically relevant phenotypes and its capacity to drive infection outcomes, placing this machinery as a promising therapeutic target for P. aeruginosas infection, acting synergistically as a pathogenicity determinant as well as an adaptative trait allowing the establishment of a mature and antibiotic resistance biofilm necessary for recalcitrant chronic infections.

microbiology↗