mBio最新文献

{"title":"Adaptive evolution of sesquiterpene deoxyphomenone in mycoparasitism by <i>Hansfordia pulvinata</i> associated with horizontal gene transfer from <i>Aspergillus</i> species.","authors":"Kazuya Maeda, Takuya Sumita, Oumi Nishi, Hirotoshi Sushida, Yumiko Higashi, Hiroyuki Nakagawa, Tomoko Suzuki, Eishin Iwao, Much Zaenal Fanani, Yoshiaki Nishiya, Yuichiro Iida","doi":"10.1128/mbio.04007-24","DOIUrl":"10.1128/mbio.04007-24","url":null,"abstract":"<p><p>Leaf mold caused by the ascomycete fungus <i>Cladosporium fulvum</i> is a devastating disease of tomato plants. The mycoparasitic fungus <i>Hansfordia pulvinata</i> is an effective biocontrol agent that parasitizes <i>C. fulvum</i> hyphae on leaves and secretes 13-deoxyphomenone, an eremophilane-type sesquiterpene, which was also identified as a sporulation-inducing factor in <i>Aspergillus oryzae</i>. Here, we identified deoxyphomenone biosynthesis (<i>DPH</i>) gene clusters conserved in both <i>H. pulvinata</i> and <i>Aspergillus</i> section <i>Flavi</i>, including <i>A. oryzae</i> and <i>A. flavus</i>. Functional disruption of <i>DPH1</i> orthologous genes encoding sesquiterpene cyclase in <i>H. pulvinata</i>, <i>A. oryzae</i>, and its close relative <i>A. flavus</i> revealed that deoxyphomenone in <i>H. pulvinata</i> had exogenic antifungal activity against <i>C. fulvum</i> and controlled endogenic sporulation in <i>Aspergillus</i> species. Complete <i>DPH</i> clusters, highly similar to those in <i>H. pulvinata</i>, were exclusive to <i>Aspergillus</i> section <i>Flavi</i>, while species in other <i>Aspergillus</i> sections contained fragmented <i>DPH</i> clusters. A comparative genomics analysis revealed that these <i>DPH</i> gene clusters share a common origin and are horizontally transferred from an ancestor of <i>Aspergillus</i> to <i>H. pulvinata</i>. Our results suggest that after horizontal transfer, <i>H. pulvinata</i> maintained the <i>DPH</i> cluster as the inhibitory effect of deoxyphomenone on spore germination and mycelial growth contributed to its mycoparasitism on the host fungus <i>C. fulvum</i>.</p><p><strong>Importance: </strong>Tomato leaf mold disease caused by <i>C. fulvum</i> poses a significant economic threat to tomato production globally. Breeders have developed tomato cultivars with <i>Cf</i> resistance genes. <i>C. fulvum</i> frequently evolves new races that overcome these genetic defenses, complicating control efforts. Additionally, the pathogen has developed resistance to chemical fungicides, prompting the need for sustainable alternatives like biocontrol agents. The mycoparasitic fungus <i>H. pulvinata</i> is crucial as an effective agent against <i>C. fulvum</i>. Clarifying the mechanism of mycoparasitism is significant, as it enhances its application as a biocontrol agent against plant pathogens. This study revealed how <i>H. pulvinata</i> produces deoxyphomenone, an antifungal compound, through horizontal gene transfer from <i>Aspergillus</i> species. It is hypothesized that mycoparasitism could be one of the mechanisms that facilitated horizontal gene transfer between fungi. These insights facilitate the development of eco-friendly, sustainable agricultural practices by reducing dependence on chemical fungicides and promoting natural pathogen control methods.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0400724"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nuclear warfare: pathogen manipulation of the nuclear pore complex and nuclear functions.","authors":"Brianna Steiert, Mary M Weber","doi":"10.1128/mbio.01940-24","DOIUrl":"10.1128/mbio.01940-24","url":null,"abstract":"<p><p>Viruses and bacteria exploit the nuclear pore complex (NPC) and host nuclear functions to bypass cellular barriers and manipulate essential processes. Viruses frequently engage directly with NPC components, such as nucleoporins, to enable genome import and evade immune defenses. In contrast, bacterial pathogens rely on secreted effector proteins to disrupt nuclear transport and reprogram host transcription. These strategies reflect a remarkable evolutionary convergence, with both types of pathogens targeting the NPC and nuclear functions to promote infection. This minireview explores the overlapping and unique mechanisms by which pathogens hijack the host nucleus, shedding light on their roles in disease and potential avenues for therapeutic intervention.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0194024"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The HOPS and vCLAMP protein Vam6 connects polyphosphate with mitochondrial function and oxidative stress resistance in <i>Cryptococcus neoformans</i>.","authors":"Eddy Sánchez-León, Kabir Bhalla, Guanggan Hu, Christopher W J Lee, Melissa Lagace, Won Hee Jung, James W Kronstad","doi":"10.1128/mbio.00328-25","DOIUrl":"10.1128/mbio.00328-25","url":null,"abstract":"<p><p><i>Cryptococcus neoformans</i> is considered one of the most dangerous fungal threats to human health, and the World Health Organization recently ranked it in the critical priority group for perceived public health importance. Proliferation of <i>C. neoformans</i> within mammalian hosts is supported by its ability to overcome nutritional limitations and endure stress conditions induced by the host immune response. Previously, we reported that the Vam6/Vps39/TRAP1-domain protein Vam6 was crucial for vacuolar morphology, iron acquisition, and virulence. However, the molecular mechanisms underlying the pleiotropic phenotypes resulting from loss of Vam6 remain poorly understood. In this study, we determined that Vam6 has roles in the HOPS complex for endomembrane trafficking to the vacuole and in the vCLAMP membrane contact site between the vacuole and mitochondria. Importantly, both of these roles regulate polyphosphate (polyP) metabolism, as demonstrated by a defect in trafficking of the VTC complex subunit Vtc2 for polyphosphate synthesis and by an influence on mitochondrial functions. In the latter case, Vam6 was required for polyP accumulation in response to electron transport chain inhibition and for overcoming oxidative stress. Overall, this work establishes connections between endomembrane trafficking, mitochondrial functions, and polyP homeostasis in <i>C. neoformans</i>.IMPORTANCEA detailed understanding of stress resistance by fungal pathogens of humans may provide new opportunities to improve antifungal therapy and combat life-threatening diseases. Here, we used a <i>vam6</i> deletion mutant to investigate the role of the homotypic fusion and vacuole protein sorting (HOPS) complex in mitochondrial functions and polyphosphate homeostasis in <i>Cryptococcus neoformans</i>, an important fungal pathogen of immunocompromised people including those suffering from HIV/AIDS. Specifically, we made use of mutants defective in late endocytic trafficking steps to establish connections to oxidative stress and membrane trafficking with mitochondria. In particular, we found that mutants lacking the Vam6 protein had altered mitochondrial function, and that the mutants were perturbed for additional mitochondria and vacuole-related phenotypes (e.g., membrane composition, polyphosphate accumulation, and drug sensitivity). Overall, our study establishes connections between endomembrane trafficking components, mitochondrial functions, and polyphosphate homeostasis in an important fungal pathogen of humans.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0032825"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143492703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel type II toxin-antitoxin systems with VapD-like proteins.","authors":"Konstantin Gilep, Dmitry Bikmetov, Aleksandr Popov, Anastasiia Rusanova, Shunsuke Tagami, Svetlana Dubiley, Konstantin Severinov","doi":"10.1128/mbio.00003-25","DOIUrl":"10.1128/mbio.00003-25","url":null,"abstract":"<p><p>Type II toxin-antitoxin (TA) systems are widespread in prokaryotes. They consist of neighboring genes encoding two small proteins: a toxin that inhibits a critical cellular process and an antitoxin that binds to and neutralizes the toxin. The VapD nuclease and the VapX antitoxin comprise a type II TA system that contributes to the virulence of the human pathogen <i>Haemophilus influenzae</i>. We analyzed the diversity and evolution of VapD-like proteins. By examining loci adjacent to genes coding for VapD-like proteins, we identified two novel families of antitoxins, which we named VapY and VapW. VapD toxins cognate to novel antitoxins induce the SOS response when overproduced, suggesting they target cellular processes related to genomic DNA integrity, maintenance, or replication. Though VapY has no sequence similarity to VapX, they share the same SH3 fold characterized by the five anti-parallel β sheets that form a barrel. VapW is a homolog of VapD without conserved catalytic residues required for nuclease activity. The crystal structure of the VapD-VapW complex reveals that VapW lacks the dimerization interface essential for the catalytic activity of VapD but retains the second interaction interface that enables VapD hexamerization. This allows VapW to bind VapD in the same manner that VapD dimers bind to each other in hexamers. Thus, though the VapD catalytic cleft remains accessible in the VapD-VapW complex, VapW may disrupt VapD oligomerization. To our knowledge, VapWD provides a unique example of TA systems evolution when a toxin loses its activity and becomes an antitoxin to itself.</p><p><strong>Importance: </strong>Genes encoding virulence-associated protein D (VapD) homologs are found in many pathogens such as <i>Helicobacter pylori</i>, <i>Haemophilus influenzae</i>, and <i>Xylella fastidiosa</i>. There are many indications that VapD proteins contribute to virulence, even though the exact mechanism is not known. VapD proteins are either encoded by stand-alone genes or form toxin-antitoxin pairs with VapX. We performed a comprehensive census of vapD-like genes and found two new antitoxins, VapW and VapY. The VapW antitoxins are catalytically inactivated variants of VapD, revealing a new evolutionary mechanism for the appearance of toxin-antitoxin pairs.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0000325"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143573183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel micronemal protein MP38 is involved in the invasion of merozoites into erythrocytes.","authors":"Tuyet-Kha Nguyen, Sy-Thau Nguyen, Van-Truong Nguyen, Sung-Hun Na, Robert W Moon, Jetsumon Sattabongkot, Yee Ling Lau, Won-Sun Park, Wan-Joo Chun, Feng Lu, Seong-Kyun Lee, Jin-Hee Han, Eun-Taek Han","doi":"10.1128/mbio.03917-24","DOIUrl":"https://doi.org/10.1128/mbio.03917-24","url":null,"abstract":"<p><p>The absence of an <i>in vitro</i> cultivation system for <i>Plasmodium vivax</i> hinders the exploration of molecular targets for vaccine development. To address this, functional studies often rely on alternative models, such as <i>P. knowlesi</i>, due to its genetic similarity to <i>P. vivax</i>. This study investigated the role of a novel micronemal protein, PvMP38 (PVX_110945), in both <i>P. vivax</i> and <i>P. knowlesi</i> merozoite invasion of erythrocytes. The full-length ectodomain of PvMP38 was expressed, and polyclonal antibodies were generated to assess its function. PvMP38 was confirmed to localize on micronemal organelle in both <i>P. vivax</i> and <i>P. knowlesi</i> merozoites. <i>In vitro</i> protein-protein interaction assays revealed that PvMP38 binds to Pv12 with high-affinity interaction. A conserved novel complex of Pv12-Pv41-PvMP38 was identified by immunoprecipitation of <i>P. vivax</i> antibodies on <i>P. knowlesi</i> schizont lysates. Linear epitopes of PvMP38 with high and moderate antigenicity were identified in clinical isolates of both species. Invasion inhibition assays demonstrated that a triple antibody combination targeting the PvMP38, Pv12, and Pv41 significantly reduced <i>P. knowlesi</i> merozoite invasion of erythrocytes compared to a single antibody. In addition, CRISPR/Cas9-mediated knockout of <i>P. knowlesi mp38</i> markedly impaired parasite growth, underscoring its essential role during the asexual stage. These findings identify PvMP38 and its associated complex as promising targets for malaria interventions and highlight the utility of <i>P. knowlesi</i> as a model for investigating <i>P. vivax</i> erythrocyte invasion mechanisms.IMPORTANCEThis manuscript reported an effort in malaria eradication by identifying and functionally characterizing a novel <i>Plasmodium vivax</i> micronemal protein, PvMP38, involved in erythrocyte invasion. A narrow repertoire of an efficacious vaccine targeting <i>P. vivax</i> candidates is being developed due to the lack of continuous <i>in vitro</i> culture. This study addresses a gap in <i>P. vivax</i> research using <i>P. knowlesi</i> as a model for both genome editing and antibody functionality validation. By enhancing the protein-protein interaction screening framework, this study demonstrated that PvMP38 forms a complex with Pv12 and Pv41, opening the approaches to multi-antigen vaccines. The successful application of CRISPR/Cas9 gene editing techniques to disrupt its homolog, the <i>pkmp38</i> gene, further assesses the protein's significance in the growth and invasion of the parasite. These findings provided valuable insights into the biology of <i>P. vivax</i> and proposed PvMP38 as a promising candidate for malaria intervention strategies.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0391724"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143811746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"RNA toehold switch-based reporter assay to assess bacterial uptake of antisense oligomers.","authors":"Paramita Sarkar, Linda Popella, Sandra Pérez-Jiménez, Jörg Vogel","doi":"10.1128/mbio.03983-24","DOIUrl":"10.1128/mbio.03983-24","url":null,"abstract":"<p><p>Antisense oligomers (ASOs) hold promise as antibiotics for the selective targeting of bacterial pathogens and as tools for the modulation of gene expression in microbes that are not amenable to genetic engineering. However, their efficient delivery across the complex bacterial envelope remains a major challenge. There are few methods to assess the efficiency of carrier-mediated ASO uptake by bacteria. Here, we have developed a \"switch-on\" reporter assay to measure ASO uptake efficiency in a semi-quantitative manner. The assay uses a synthetic RNA toehold switch fused to the mRNA of a fluorescent reporter protein, which is activated <i>in vivo</i> by a peptide nucleic acid (PNA)-based ASO upon delivery into the bacterial cytosol. We have used this assay to screen different cell-penetrating peptides (CPPs) as ASO carriers in <i>Escherichia coli</i> and <i>Salmonella enterica</i> and observed up to 60-fold activation, depending on the CPP and bacterial strain used. Our assay shows high dynamic range and sensitivity, which should enable high-throughput screens for bacterial ASO carriers. We also show that the reporter can be used to study routes of PNA uptake, as demonstrated by reduced reporter activity in the absence of the inner membrane protein SbmA. In summary, we present a tool for the discovery of species-specific and efficient ASO carriers that will also be useful for a broader investigation of cellular uptake mechanisms of antibacterial ASOs.IMPORTANCEThe rise of antimicrobial resistance presents a major global health challenge. If not addressed, the death toll from resistant infections is expected to rise dramatically in the coming years. As a result, it is essential to explore alternative antimicrobial therapies. One promising approach is to target bacterial mRNAs using antisense oligomers (ASOs) to silence genes involved in essential functions, virulence, or resistance. However, delivering ASOs across bacterial membranes remains a major challenge and effective methods to monitor their uptake are limited. In this study, we develop a reporter assay to facilitate the high-throughput discovery of bacterial ASO carriers. This research paves the way for developing novel precision antisense-based antibacterial therapies.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0398324"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143541531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SARS-CoV-2 infectivity can be modulated through bacterial grooming of the glycocalyx.","authors":"Cameron Martino, Benjamin P Kellman, Daniel R Sandoval, Thomas Mandel Clausen, Robert Cooper, Alhosna Benjdia, Feryel Soualmia, Alex E Clark, Aaron F Garretson, Clarisse A Marotz, Se Jin Song, Stephen Wandro, Livia S Zaramela, Rodolfo A Salido, Qiyun Zhu, Erick Armingol, Yoshiki Vázquez-Baeza, Daniel McDonald, James T Sorrentino, Bryn Taylor, Pedro Belda-Ferre, Promi Das, Farhana Ali, Chenguang Liang, Yujie Zhang, Luca Schifanella, Alice Covizzi, Alessia Lai, Agostino Riva, Christopher Basting, Courtney Ann Broedlow, Aki S Havulinna, Pekka Jousilahti, Mehrbod Estaki, Tomasz Kosciolek, Rayus Kuplicki, Teresa A Victor, Martin P Paulus, Kristen E Savage, Jennifer L Benbow, Emma S Spielfogel, Cheryl A M Anderson, Maria Elena Martinez, James V Lacey, Shi Huang, Niina Haiminen, Laxmi Parida, Ho-Cheol Kim, Jack A Gilbert, Daniel A Sweeney, Sarah M Allard, Austin D Swafford, Susan Cheng, Michael Inouye, Teemu Niiranen, Mohit Jain, Veikko Salomaa, Karsten Zengler, Nichole R Klatt, Jeff Hasty, Olivier Berteau, Aaron F Carlin, Jeffrey D Esko, Nathan E Lewis, Rob Knight","doi":"10.1128/mbio.04015-24","DOIUrl":"10.1128/mbio.04015-24","url":null,"abstract":"<p><p>The gastrointestinal (GI) tract is a site of replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and GI symptoms are often reported by patients. SARS-CoV-2 cell entry depends upon heparan sulfate (HS) proteoglycans, which commensal bacteria that bathe the human mucosa are known to modify. To explore human gut HS-modifying bacterial abundances and how their presence may impact SARS-CoV-2 infection, we developed a task-based analysis of proteoglycan degradation on large-scale shotgun metagenomic data. We observed that gut bacteria with high predicted catabolic capacity for HS differ by age and sex, factors associated with coronavirus disease 2019 (COVID-19) severity, and directly by disease severity during/after infection, but do not vary between subjects with COVID-19 comorbidities or by diet. Gut commensal bacterial HS-modifying enzymes reduce spike protein binding and infection of authentic SARS-CoV-2, suggesting that bacterial grooming of the GI mucosa may impact viral susceptibility.IMPORTANCESevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease 2019, can infect the gastrointestinal (GI) tract, and individuals who exhibit GI symptoms often have more severe disease. The GI tract's glycocalyx, a component of the mucosa covering the large intestine, plays a key role in viral entry by binding SARS-CoV-2's spike protein via heparan sulfate (HS). Here, using metabolic task analysis of multiple large microbiome sequencing data sets of the human gut microbiome, we identify a key commensal human intestinal bacteria capable of grooming glycocalyx HS and modulating SARS-CoV-2 infectivity <i>in vitro</i>. Moreover, we engineered the common probiotic <i>Escherichia coli</i> Nissle 1917 (EcN) to effectively block SARS-CoV-2 binding and infection of human cell cultures. Understanding these microbial interactions could lead to better risk assessments and novel therapies targeting viral entry mechanisms.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0401524"},"PeriodicalIF":5.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143492688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Immunotherapy with nebulized pattern recognition receptor agonists restores severe immune paralysis and improves outcomes in mice with influenza-associated pulmonary aspergillosis.","authors":"Jezreel Pantaleón García, Sebastian Wurster, Nathaniel D Albert, Uddalak Bharadwaj, Keerthi Bhoda, Vikram K Kulkarni, Mbaya Ntita, Paris Rodríguez Carstens, Madeleine Burch-Eapen, Daniela Covarrubias López, Jania Foncerrada Lizaola, Katherine E Larsen, Lauren M Matula, Seyed J Moghaddam, Yongxing Wang, Dimitrios P Kontoyiannis, Scott E Evans","doi":"10.1128/mbio.04061-24","DOIUrl":"https://doi.org/10.1128/mbio.04061-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Influenza-associated pulmonary aspergillosis (IAPA) is a potentially deadly superinfection in patients with influenza pneumonia, especially those with severe disease, underlying immunosuppression, corticosteroid therapy, or requiring intensive care support. Given the high mortality of IAPA, adjunct immunomodulatory strategies remain a critical unmet need. Previously, the desensitization of pattern recognition pathways has been described as a hallmark of IAPA pathogenesis and a predictor of mortality in IAPA patients. Therefore, we studied the impact of nebulized Toll-like receptor 2/6/9 agonists Pam2 CSK4 (Pam2) and CpG oligodeoxynucleotides (ODNs) on infection outcomes and pulmonary immunopathology in a corticosteroid-immunosuppressed murine IAPA model. Mice with IAPA receiving mock therapy showed rapidly progressing disease and a paralyzed immune response to secondary &lt;i&gt;Aspergillus fumigatus&lt;/i&gt; infection. Nebulized Pam2ODN was well tolerated and significantly prolonged event-free survival. Specifically, dual-dose Pam2ODN therapy before and after &lt;i&gt;A. fumigatus&lt;/i&gt; infection led to 81% survival and full recovery of all survivors. Additionally, transcriptional analysis of lung tissue homogenates revealed induction of pattern recognition receptor signaling and several key effector cytokine pathways after Pam2ODN therapy. Moreover, transcriptional and flow cytometric analyses suggested increased frequencies of macrophages, natural killer cells, and T cells in the lungs of Pam2ODN-treated mice. Collectively, immunomodulatory treatment with nebulized Pam2ODN strongly improved morbidity and mortality outcomes and alleviated paralyzed antifungal immunity in an otherwise lethal IAPA model. These findings suggest that Pam2ODN might be a promising candidate for locally delivered immunomodulatory therapy to improve outcomes of virus-associated mold infections such as IAPA.IMPORTANCEThe COVID-19 pandemic has highlighted the significant healthcare burden, morbidity, and mortality caused by secondary fungal pneumonias. Given the heightened prevalence of severe viral pneumonias, such as influenza, and poor outcomes of secondary mold pneumonias, adjunct immunotherapies are needed to prevent and treat secondary infections. We herein demonstrate severely paralyzed immunity to secondary &lt;i&gt;Aspergillus fumigatus&lt;/i&gt; infection in a corticosteroid-immunosuppressed mouse model of influenza-associated pulmonary aspergillosis (IAPA), partially due to dysregulated pathogen-sensing pathways. To overcome immune paralysis and IAPA progression, we used a dyad of nebulized immunomodulators (Toll-like receptor agonists). Nebulized immunotherapy significantly improved morbidity and mortality compared to mock therapy, increased frequencies of mature mononuclear phagocytes and natural killer cells in the lung, and stimulated antimicrobial signaling. Collectively, this proof-of-concept study demonstrates the feasibility and efficacy of locally delivered immunomodulatory t","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0406124"},"PeriodicalIF":5.1,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143803494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The juxtamembrane domain of StkP is phosphorylated and influences cell division in <i>Streptococcus pneumoniae</i>.","authors":"Mélisse Hamidi, Sathya Narayanan Nagarajan, Vaishnavi Ravikumar, Virginie Gueguen-Chaignon, Cédric Laguri, Céline Freton, Ivan Mijakovic, Jean-Pierre Simorre, Stéphanie Ravaud, Christophe Grangeasse","doi":"10.1128/mbio.03799-24","DOIUrl":"https://doi.org/10.1128/mbio.03799-24","url":null,"abstract":"<p><p>Eukaryotic-like membrane Ser/Thr protein kinases play a pivotal role in different aspects of bacterial physiology. In contrast to the diversity of their extracellular domains, their cytoplasmic catalytic domains are highly conserved. However, the function of a long juxtamembrane domain (JMD), which connects the catalytic domain to the transmembrane helix, remains elusive. In this study, we investigated the function of the JMD of the Ser/Thr protein kinase StkP in the cell division of <i>Streptococcus pneumoniae</i>. We observed that the deletion of the JMD affected the ability of StkP to phosphorylate some of its endogenous substrates, thereby resulting in significant cell morphogenesis defects. Furthermore, multiple threonine residues were identified as being phosphorylated in the JMD. To investigate the functional significance of these phosphorylation sites, we conducted an integrative analysis, combining structural biology, proteomics, and bacterial cell imaging. Our results revealed that the phosphorylation of the JMD did not perturb the phosphorylation of StkP substrates. However, we observed that it modulated the timing of StkP localization to the division septum and the dynamics of cell constriction. We further demonstrated that phosphorylation of the JMD facilitated the recruitment of several cell division proteins, suggesting that it is required to assemble the division machinery at the division septum. In conclusion, this study demonstrates that the function of the JMD of StkP is modulated by phosphorylation and is critical for the cell division of <i>S. pneumoniae</i>. These observations may serve as a model for understanding the regulatory function of other bacterial Ser/Thr protein kinases.IMPORTANCEHow bacterial serine/threonine protein kinases are activated remains highly debated. In particular, models rely on the observations made with their eukaryotic counterparts, and only a few studies have investigated the molecular activation mechanism of bacterial serine/threonine protein kinases. This is particularly the case with regard to the juxtamembrane domain (JMD), which is proposed to contribute to kinase activation in numerous eukaryotic kinases. This study demonstrates that the juxtamembrane domain is likely not essential for the activation of the serine/threonine protein kinase StkP of <i>S. pneumoniae</i>. Rather, our findings reveal that it is required for cell division, where its phosphorylation affects the assembly of the division machinery at the division septum. These observations allow us to assign a function to the JMD in StkP-mediated regulation of pneumococcal cell division, thereby providing a new avenue for understanding the contribution of membrane serine/threonine protein kinases in the physiology of other bacteria.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0379924"},"PeriodicalIF":5.1,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143803517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Larval zebrafish burn wound infection model reveals conserved innate immune responses against diverse pathogenic fungi.","authors":"Nayanna M Mercado Soto, Adam Horn, Nancy P Keller, Anna Huttenlocher, Andrew S Wagner","doi":"10.1128/mbio.03480-24","DOIUrl":"https://doi.org/10.1128/mbio.03480-24","url":null,"abstract":"<p><p>Secondary fungal infections represent a major complication following thermal injuries. However, the mechanisms of fungal colonization of burn tissue and how the host subsequently responds to fungi within this niche remain unclear. We have previously reported a zebrafish model of thermal injury that recapitulates many of the features of human burn wounds. Here, we characterize host-fungal interaction dynamics within the burn wound niche using two of the most common fungal pathogens isolated from burn injuries, <i>Aspergillus fumigatus</i> and <i>Candida albicans</i>. Both <i>A. fumigatus</i> and <i>C. albicans</i> colonize burned tissue in zebrafish larvae and induce a largely conserved innate immune response following colonization. Using drug-induced cell-depletion strategies and transgenic zebrafish lines with impaired innate immune function, we found that macrophages control fungal burden, whereas neutrophils primarily control invasive hyphal growth at the early stages of infection. However, we also found that loss of either immune cell can be compensated by the other at the later stages of infection and that fish with both macrophage and neutrophil deficiencies show more invasive hyphal growth that is sustained throughout the infection process, suggesting redundancy in their antifungal activities. Finally, we demonstrate that <i>C. albicans</i> strains with increased β(1,3)-glucan exposure are cleared faster from the burn wound, demonstrating a need for shielding this immunogenic cell wall epitope for the successful fungal colonization of burn tissue. Together, our findings support the use of zebrafish larvae as a model to study host-fungal interaction dynamics within burn wounds.IMPORTANCESecondary fungal infections within burn wound injuries are a significant problem that delays wound healing and increases the risk of patient mortality. Currently, little is known about how fungi colonize and infect burn tissue or how the host responds to pathogen presence. In this report, we expand upon an existing thermal injury model using zebrafish larvae to begin elucidating both the host immune response to fungal burn colonization and fungal mechanisms for persistence within burn tissue. We found that both <i>Aspergillus fumigatus</i> and <i>Candida albicans</i>, common fungal burn wound isolates, successfully colonize burn tissue and are effectively cleared in immunocompetent zebrafish by both macrophages and neutrophils. We also find that <i>C. albicans</i> mutants harboring mutations that impact their ability to evade host immune system recognition are cleared more readily from burn tissue. Collectively, our work highlights the efficacy of using zebrafish to study host-fungal interaction dynamics within burn wounds.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0348024"},"PeriodicalIF":5.1,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143803498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}