mBio最新文献

{"title":"Correction for Grünebast et al., \"Degradation of ribosomal RNA during <i>Plasmodium falciparum</i> gametocytogenesis\".","authors":"Janne Grünebast, Ritwik Singhal, Robin Bromley, Sachie Kanatani, Kaylee Watson, Sophie Olson, Franck Dumetz, Tales Vicari Pascini, Abhai Tripathi, Julie C Dunning Hotopp, Photini Sinnis, Manuel Llinás, David Serre","doi":"10.1128/mbio.01098-26","DOIUrl":"https://doi.org/10.1128/mbio.01098-26","url":null,"abstract":"","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0109826"},"PeriodicalIF":5.4,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148891714","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":"Unique amino acid substitution within the spike glycoprotein S1 subunit promotes infectious bronchitis virus infection via enhancing viral attachment.","authors":"Tianyi Liu, Yujuan Zhang, Zongxi Han, Huixin Li, Yuhao Shao, Junfeng Sun, Shengwang Liu","doi":"10.1128/mbio.00884-26","DOIUrl":"https://doi.org/10.1128/mbio.00884-26","url":null,"abstract":"<p><p>Due to the scarcity of cell-adapted strains and limitations of current reverse genetics techniques, the factors determining cell tropism of infectious bronchitis virus (IBV), a prototype <i>gammacoronavirus</i>, remain unclear. Here, we demonstrated that the expanded cell tropism of CEA, a chicken embryo fibroblast-adapted strain derived from tl/CH/LDT3/03, was related to its enhanced attachment capacity. Then, a reverse genetics platform for IBV based on circular polymerase extension reaction (CPER) was established, enabling the successful recovery of rCEA and rLDT, which retained the biological properties of their respective parental viruses. Using this platform, we constructed a series of chimeric viruses based on the CEA strain by incorporating the entire S gene, the S1 and S2 subunits, and substitutions at differential sites derived from the tl/CH/LDT3/03 strain. Our findings indicated that subunit S1, rather than S2, was associated with viral adaptation in DF-1 cells, with the amino acid residue at position 413 in the C-terminal domain of the S1 protein as a key determinant. Evaluation with recombinant S1 proteins and chimeric viruses revealed that the histidine residue at position 413 (His413) promoted enhanced attachment of both S1 proteins and viruses to cells, while exerting no direct effect on viral entry. Mechanistically, His413 facilitated efficient viral binding to α-2,3-linked sialic acids presented on gangliosides rather than glycoproteins. This interaction activated Src kinase and triggered caveolae-mediated endocytosis, initiating viral entry and subsequent replication. Collectively, the CPER-based reverse genetics platform established in this study represents a significant technical advancement for IBV, and our findings provide novel insights into the cell adaptation and entry mechanisms of IBV.IMPORTANCEAlthough infectious bronchitis virus (IBV) was the first discovered coronavirus, the cellular receptors and cofactors that mediate successful infection, as well as the specific pathways and mechanisms of viral entry into host cells, remain to be elucidated. In this study, we established a reverse genetics platform for IBV using circular polymerase extension reaction for the first time. A series of chimeric viruses were subsequently recovered, and a specific amino acid substitution at position 413 in the C-terminal domain of the S1 subunit was identified as a key determinant for the expanded DF-1 cell tropism of IBV. The histidine residue at this site facilitated viral binding to α-2,3-linked sialic acids on gangliosides, thereby activating the caveola-mediated endocytosis and enabling viral entry into DF-1 cells. This study provides novel insights into the receptor-binding function of the IBV S protein and the strategies employed by the virus for cell adaptation. Additionally, our findings offer new perspectives for developing cell-culture-based vaccines.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0088426"},"PeriodicalIF":5.4,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148886939","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 conserved partner-switching system controls terminal differentiation in multicellular cyanobacteria.","authors":"Stéphanie Champ, Eva Furet, Frédérique Pompeo, Xiaomei Xu, Sylvain Lemeille, Marine Novelli, Zorah Dermoun, Matthieu Bergé, Emmanuel Talla, Amel Latifi","doi":"10.1128/mbio.01685-26","DOIUrl":"https://doi.org/10.1128/mbio.01685-26","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Canonical partner-switching systems (PSSs) regulate sigma factor activity through reversible phosphorylation, but their established roles have been largely limited to stress responses and sporulation in Firmicutes. Whether this regulatory mechanism also controls developmental cell fate decisions in other bacterial phyla has remained unknown. Here, we identify a canonical PSS that governs heterocyst differentiation in the multicellular cyanobacterium &lt;i&gt;Anabaena&lt;/i&gt; sp. PCC 7120. This system comprises the anti-sigma factor All2284 (NfsS) and the anti-anti-sigma factor All2283 (NfsR). Structural predictions and biochemical assays showed that NfsS phosphorylates NfsR on a conserved serine residue, whereas bacterial two-hybrid and co-purification assays demonstrated that NfsS binds the developmental sigma factors SigC and SigE. Deletion of &lt;i&gt;nfsR&lt;/i&gt; abolished heterocyst formation and diazotrophic growth, and transcriptomic analysis revealed broad failure to induce late heterocyst genes, including nitrogen fixation functions such as &lt;i&gt;nifHDK&lt;/i&gt; and &lt;i&gt;fdxH&lt;/i&gt;. Phylum-wide comparative genomics further showed that PSS genes and putative functional clusters are strongly enriched in filamentous and heterocyst-forming taxa, indicating an association between the expansion of these signaling modules and the emergence of multicellularity and developmental specialization. Together, these findings establish a PSS as a direct regulator of terminal cell differentiation in a gram-negative bacterium and reveal partner switching as a conserved regulatory principle linking environmental signaling to developmental fate in a major bacterial phylum.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Importance: &lt;/strong&gt;While partner-switching systems are classically associated with stress responses and sporulation control in Firmicutes, whether this regulatory logic governs developmental decisions in other bacterial phyla has remained unknown. Here, we establish that a related partner-switching mechanism operates in a distinct bacterial lineage, the cyanobacteria, where it controls a major developmental transition involving terminal cell differentiation. Specifically, we show that a phosphorylation-dependent checkpoint involving the anti-sigma factor NfsS and the anti-anti-sigma factor NfsR directly regulates heterocyst formation. Disruption of this switch abolishes cell differentiation and diazotrophic growth, revealing that this system is an obligate gatekeeper for terminal differentiation. Conceptually, these findings substantially extend the known functional repertoire of partner-switching circuits: rather than controlling stress adaptation or spore dormancy, this module has been co-opted to govern a complex, multicellular developmental program in an organism that underpins global carbon and nitrogen cycles. This work, therefore, establishes a new paradigm for phosphorylation-based control of developmental sigma factors and provides a tractable model for dissecting how conserved signaling m","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0168526"},"PeriodicalIF":5.4,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148887857","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 uniquely human sebum lipid drives streptococcal skin infection severity.","authors":"Doris L LaRock, Christopher N LaRock","doi":"10.1128/mbio.01856-26","DOIUrl":"10.1128/mbio.01856-26","url":null,"abstract":"<p><p>Free fatty acids (FAs) secreted by the sebaceous glands are critical components of the skin barrier. Here, we investigate the activity of the major FA species present in the skin against <i>Streptococcus pyogenes</i> (group A <i>Streptococcus</i> [GAS]), a major cause of skin infections, such as impetigo, erysipelas, cellulitis, and necrotizing fasciitis. Several relevant FAs had antimicrobial activity against GAS, and linoleic acid was found to be therapeutic when applied in a murine skin infection model. However, sapienic acid, a FA abundant only in human sebum, significantly worsened disease severity despite possessing antimicrobial activity. Transcriptional profiling and molecular genetic analysis showed that sapienic acid, but not other structurally similar FAs, induced the <i>sag</i> operon. The <i>sag</i> operon encodes streptolysin S (SLS), and sapienic acid induction of this cytolytic toxin significantly increased hemolysis of human red blood cells by GAS. Screening of additional FAs identified forms with combined antimicrobial and anti-lytic activity useful as therapeutics. Taken together, we report a species- and tissue-specific trigger for GAS virulence and limitations to the use of FAs as therapeutics against infectious disease.IMPORTANCEGAS naturally only infects humans. Here, we report that the human-specific sebum lipid sapienic acid induces production of streptolysin S (SLS), the hemolysin responsible for the hallmark β-hemolytic phenotype of GAS. Reliance on detection of a human-specific FA for expression of a critical virulence factor exposes a vulnerability of GAS and suggests a potentially variable role for SLS at different infection sites. Furthermore, it details a limitation of existing infection models, which all lack sapienic acid, for understanding the role of SLS in disease.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0185626"},"PeriodicalIF":5.4,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148887789","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":"Redox control and mechanisms of transmembrane signaling in CSS domain c-di-GMP phosphodiesterases that control biofilm formation in <i>Escherichia coli</i>.","authors":"Katharina Pressler, Martin Lorkowski, Regine Hengge","doi":"10.1128/mbio.01325-26","DOIUrl":"https://doi.org/10.1128/mbio.01325-26","url":null,"abstract":"<p><p>Bis-(3',5')-cyclic dimeric guanosine monophosphate (c-di-GMP) control of biofilm formation in <i>Escherichia coli</i> K-12 is balanced by multiple diguanylate cyclases (DGCs) and c-di-GMP-specific phosphodiesterases (PDEs). Five of the 13 PDEs feature a periplasmic CSS domain with two conserved cysteines, flanked by transmembrane (TM) regions, and an enzymatically active cytoplasmic EAL domain. One of these (PdeC) was previously shown to be redox-regulated by DsbA/DsbB-mediated disulfide bond (DSB) formation in the cysteine serine serine (CSS) domain. Comparing all five CSS domain PDEs, we found them to fall into two groups with similar biochemical features, resulting in different consequences for PDE activity. PdeB, PdeC, and PdeG are more active when lacking the periplasmic DSB, resulting in diminished biofilm formation, while PdeN and PdeD are active in their oxidized forms. Using PdeB and PdeN as prototypes for the two groups, not only the periplasmic DSB but also differently charged amino acid motifs close to the transmembrane (TM) domains and a putative additional DSB in PdeN were identified as important for transmembrane signaling. All these elements, including its stable structural DSB in the periplasm, which can form independently of DsbA, maintain PdeN in a rigid, proteolysis-resistant active conformation. By contrast, for PdeB, the more rigid DSB-containing conformation is inactive, with mutations in the stabilizing elements leading to a structurally less constrained, more active enzyme. Notably, low PdeN levels are post-transcriptionally upregulated at acidic pH, resulting in less biofilm formation. Overall, the five CSS domain PDEs enable <i>E. coli</i> to adapt to diverse environmental niches.IMPORTANCESensing environmental cues and transmembrane signal transduction via membrane-embedded proteins is a process of key importance in all living cells. To investigate the molecular mechanisms involved, we performed a systematic functional comparison of the five CSS domain phosphodiesterases of <i>Escherichia coli</i>, which degrade the bacterial second messenger c-di-GMP in response to redox and other signals. With a sensory domain in the periplasm linked to a cytoplasmic enzymatic domain, these proteins represent minimal devices for transmembrane signaling. We demonstrate that these signal-transducing enzymes fall into two functional classes with a similar periplasmic redox biochemistry resulting in opposite states of cytoplasmic enzymatic activity. Several characteristic sequence elements convey redox and structural information in the periplasmic and transmembrane protein segments to their ability to dimerize into an enzymatically active form in the cytoplasm. Comparing the five enzymes also shows that evolution has played with these elements to facilitate adaptation to various environmental niches.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0132526"},"PeriodicalIF":5.4,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148865595","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":"Temperature during conidiophore development primes <i>Aspergillus fumigatus</i> spore transcriptome for asexual or sexual reproduction.","authors":"Justina M Stanislaw, Michelle Momany","doi":"10.1128/mbio.01831-26","DOIUrl":"https://doi.org/10.1128/mbio.01831-26","url":null,"abstract":"<p><p><i>Aspergillus fumigatus</i> is a thermotolerant saprobe found in soils and plant debris worldwide and an important pathogen of humans, causing two million deaths annually. <i>A. fumigatus</i> makes abundant asexual spores (conidia), which are widely distributed by wind and can be inhaled from the environment. In susceptible individuals, inhaled conidia break dormancy, germinate, and grow in the lung, leading to serious disease. Recent work has shown that conidia made at 37°C and 50°C have different morphologies and germination kinetics. While the asexual cycle is well-characterized at 37°C, much less is known about the asexual cycle at 50°C. Here, we combine flow cytometry and transcriptomics to track morphology and gene expression in the hyphae, conidiophores, and conidia of <i>A. fumigatus</i> during asexual development at 37°C or 50°C. We show that the temperature during a narrow time window in late-stage conidiophore development dictates resulting conidial morphology, transcriptional program, and germination kinetics. As expected, conidiation at 37°C resulted in upregulation of <i>brlA</i>, encoding the master regulator of asexual development, and its downstream targets in conidiophores and conidia. Surprisingly, conidiation at 50°C resulted in upregulation of <i>MAT1-1-1</i>, encoding the master regulator of sexual development, and its downstream targets in conidiophores and conidia. Our findings suggest that temperature during late conidiophore development transcriptionally primes conidia for asexual, parasexual, or sexual development, enhancing chances of survival for progeny. Our findings are especially relevant for agricultural compost, where a wide gradient of temperatures exists, abundant <i>A. fumigatus</i> has been isolated, and resistance to antifungals is thought to evolve.IMPORTANCEThe human pathogen <i>Aspergillus fumigatus</i> has been found in natural and agricultural environments around the world. Disease is acquired when susceptible individuals inhale airborne asexual spores from the environment, which in agriculture generally includes proximity to compost and plant debris piles. This work shows that the environmental temperature when <i>A. fumigatus</i> spores are made determines the transcriptomes of those spores, priming them for future asexual or sexual development. The survival of asexual and sexual spores is very different at different temperatures, so these results are important for understanding how this pathogen survives in varied hostile environments. In addition, there are very few antifungal drugs with which to treat <i>A. fumigatus</i> infections, and resistance is increasing, driven in part by agricultural use of fungicides. These results suggest that higher temperatures during asexual spore formation can lead to increased sexual reproduction and greater chances to evolve antifungal resistance.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0183126"},"PeriodicalIF":5.4,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148865618","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":"Dynamic and distinct physiological responses by a soil bacterium promote survival along a desiccation continuum.","authors":"Jarek V Kwiecinski, Georgia R Squyres, Dani Or, Dianne K Newman","doi":"10.1128/mbio.01903-26","DOIUrl":"https://doi.org/10.1128/mbio.01903-26","url":null,"abstract":"<p><p>Soil bacteria play a central role in global biogeochemical cycles and are critical for soil health and agricultural productivity. The dynamic nature of soil hydration status affects bacterial habitats by changing the energy state of soil water and disrupting aqueous connections critical for nutrient diffusion. To study how soil bacteria respond to desiccation, we used the rhizobacterium <i>Pseudomonas synxantha</i> 2-79 as a model organism and quantified its response to co-occurring water and nutrient limitations at the single-cell level. We hypothesized that the relative importance of osmolyte synthesis and starvation responses to desiccation tolerance is context dependent, with the optimal strategy determined by the trajectory of nutrient and water deprivation. We constructed a transcriptional reporter to track <i>P. synxantha</i>'s expression of biosynthesis genes for the osmolyte N-acetylglutaminylglutamine amide (NAGGN) and collected extensive single-cell growth rate, cell size, and reporter expression data through experiments that mimicked different rates and extents of soil drying. Only actively growing cells responded to an osmotic shock by synthesizing NAGGN; this response was not observed for pre-starved bacteria. Despite the lack of osmolyte NAGGN synthesis, prior starvation enhanced <i>P. synxantha'</i>s ability to recover from osmotic stress once water and nutrients were restored. In line with our observation that prior starvation prevented cell lysis upon rewetting, starved cells had more rigid membranes. Together, our results indicate that diverse cellular properties contribute to soil bacterial desiccation tolerance, whose relative response and fitness are tuned to different challenges imposed by soil drying dynamics.IMPORTANCESoil bacteria are critical to agriculture, but it is unclear how these organisms respond to desiccation, a common and worsening stress. Desiccation both dehydrates bacterial cells and eliminates the liquid water connections between soil pores that bacteria use to access nutrients. We studied how a model soil bacterium responds to (co)-occurring starvation and water stress at the single-cell level, focusing on osmolyte synthesis and physiological adjustments that take place under starvation. We describe the desiccation and regrowth trajectories in these conditions at single-cell resolution. We find that starvation restricts synthesis of a dipeptide osmolyte but rigidifies the membrane, enabling bacteria to withstand more severe water stress. Distinct cellular factors thus contribute differentially to desiccation tolerance along a drying trajectory.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0190326"},"PeriodicalIF":5.4,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148865652","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":"Laccase-mediated biotransformation potential for fluorinated compounds by geographically diverse human gut microbiota.","authors":"Milo R Schärer, Yaochun Yu, Aaron Grawe, James K Christenson, Serina L Robinson, Nicholas A Bokulich","doi":"10.1128/mbio.01026-26","DOIUrl":"https://doi.org/10.1128/mbio.01026-26","url":null,"abstract":"<p><p>The growing prevalence of synthetic organofluorine substances in agrochemicals, food packaging, and consumer products has led to increasing gastrointestinal exposure, with potential consequences for human health. Despite the extreme stability of fluorinated compounds, several microbial pathways for their transformation are known, including those involving laccases, a type of multicopper oxidase. However, the functionality of laccases in the gut microbiome, a natural contact point between food-associated chemicals and microbial biotransformation pathways, is poorly defined. Through a multi-study analysis of 1,578 human gut metagenomes spanning a global gradient from hunter-gatherer societies to industrialized urban populations, we found that laccase-coding gene homologs are widely distributed in the human gut microbiome. We identified a significant association between both the abundance and phylogenetic diversity of laccase homologs and the degree of urbanization. As human gut microbial laccase activity has not been experimentally demonstrated, eight gut metagenome-derived laccases were heterologously expressed and screened for activity with a redox mediator system. Six of the eight laccases demonstrated activity. One of these gut microbial laccases, derived from <i>Veillonella</i>, and three previously characterized laccases were then tested for their capacity to deplete 11 different food-associated chemicals. The <i>Veillonella</i> laccase depleted the agrochemicals cyflumetofen and fluazinam, as well as the industrial chemical bisphenol AF, to a lesser extent. By linking global gut metagenomes with activity assays, this work demonstrates the untapped potential of mining human gut metagenomes for laccases and other microbial enzymes that can actively modify various agricultural and industrial chemicals.IMPORTANCEAs adverse effects of fluorinated compounds on human health are emerging, the responsible enzymes from the human gut microbiome of geographically diverse human cohorts mediating interactions with fluorinated compounds in the gastrointestinal tract remain poorly characterized. In a multi-study analysis of publicly available microbiome sequencing data, we linked the abundance, diversity, and phylogeny of laccases within the gut microbiome to the degree of urbanization of human cohorts and experimentally demonstrated the ability of these laccases to deplete a range of food-associated fluorochemicals. Another significant contribution of our study is in the integration of rural catchment areas as a quantitative metric of urbanization in gut microbiome metagenomics and enzyme activity surveys.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0102626"},"PeriodicalIF":5.4,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148865638","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":"Growth-dependent tRNA reprogramming and codon bias link translation to metabolic state in <i>Enterococcus faecalis</i>.","authors":"Michelle M Mitchener, Caleb M Anderson, Mark Veleba, Kayla Teo, Mélanie Roch, Ruixi Chen, Yifeng Yuan, Isaiah Han, Agnieszka Dziergowska, Kevin Pethe, Thomas J Begley, Kimberly A Kline, Peter C Dedon","doi":"10.1128/mbio.01474-26","DOIUrl":"https://doi.org/10.1128/mbio.01474-26","url":null,"abstract":"<p><p><i>Enterococcus faecalis</i> is a gram-positive commensal bacterium of the human gut microbiome and an opportunistic pathogen responsible for many hospital-acquired infections. Despite the clinical importance of <i>E. faecalis</i>, how gene and protein expression are coordinated with growth remains poorly defined. Here, we profiled transcript, protein, and tRNA pool dynamics across distinct phases of <i>E. faecalis</i> growth. Differences in protein abundance and corresponding mRNA levels suggested growth phase-dependent posttranscriptional regulation. Growth-associated genes exhibited biased synonymous codon usage, with ribosomal and glycolytic proteins enriched in low-abundance codons read by queuosine-modifiable tRNAs. Analysis of tRNA modification and tRNA isoacceptor abundance revealed growth phase-dependent changes, particularly in anticodon stem-loop modifications that influence synonymous codon translation. Changes in queuosine levels preceded shifts in ribosomal proteins, suggesting a contribution to codon-biased translation. Collectively, these findings reveal growth phase-associated remodeling of the <i>E. faecalis</i> tRNA pool and support a model in which queuosine-dependent translational reprogramming shapes protein expression during bacterial growth.IMPORTANCE<i>Enterococcus faecalis</i> is a common cause of hospital-acquired infections. Despite its clinical importance, a comprehensive understanding of the organism's physiology and adaptation to environmental changes remains incomplete. Here, we characterized protein, transcript, and tRNA dynamics across bacterial growth phases, uncovering a role for posttranscriptional regulation marked by tRNA reprogramming and biased synonymous codon usage. These findings enhance our understanding of <i>E. faecalis</i> growth and support a model of translational reprogramming therein.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0147426"},"PeriodicalIF":5.4,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148865600","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 suite of eight <i>Toxoplasma gondii</i> effectors cooperates to activate the non-canonical NF-κB pathway.","authors":"Kenna Berg, Michael W Panas, Samarchith P Kurup, John C Boothroyd, Alex Rosenberg","doi":"10.1128/mbio.01652-26","DOIUrl":"10.1128/mbio.01652-26","url":null,"abstract":"<p><p>As a master of host-cell reprogramming, <i>Toxoplasma gondii</i> (<i>T. gondii</i>) tachyzoites manipulate diverse signaling networks to establish a niche permissive for long-term infection. While the parasite's subversion of canonical NF-κB signaling (p65/p50) is well established, how infection impacts the non-canonical NF-κB pathway has been largely unexplored. Here, we report that <i>T. gondii</i> infection induces nuclear accumulation of the non-canonical NF-κB subunits RelB and p52 in both human and murine fibroblasts. This response is conserved across both type I and type II parasite genetic backgrounds. We demonstrate that this reprogramming is dependent on the MYR1-mediated export of dense granule effectors. Mechanistically, <i>T. gondii</i> infection drives the depletion of the negative regulator TRAF3, leading to the stabilization of NF-κB-inducing kinase (NIK), phosphorylation of p100, and its subsequent processing into p52. Utilizing a panel of combinatorial knockout parasites, we reveal that no single effector is responsible for this phenotype. Instead, a suite of eight MYR1-dependent effectors, IST, NSM, HCE1/TEEGR, GRA16, GRA18, GRA24, GRA28, and GRA84, functions through a collaborative, additive network to drive most of the non-canonical response. These findings highlight a distributed regulatory strategy used by the parasite to overcome host transcriptional robustness and shape host signaling.</p><p><strong>Importance: </strong><i>Toxoplasma gondii</i> infects nearly one-third of the global population and establishes infection by extensively rewiring host immune signaling. While decades of work have focused on how the parasite modulates canonical NF-κB activity, whether it also engages the alternative, non-canonical arm of this pathway has remained unclear. Here, we show that <i>T. gondii</i> tachyzoites activate non-canonical NF-κB signaling, driving nuclear accumulation of RelB/p52 through MYR1-dependent effector export. Unexpectedly, no single effector is responsible. Instead, eight secreted proteins act cooperatively to enable NIK stabilization and engage the non-canonical NF-κB cascade, revealing a networked mode of immune control. This discovery highlights a regulatory logic evolved by the parasite to overcome host transcriptional robustness. Together, these findings identify non-canonical NF-κB activation as a new axis of host-parasite interaction and expand our understanding of how <i>T. gondii</i> reprograms central immune signaling circuits through multi-effector networks.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0165226"},"PeriodicalIF":5.4,"publicationDate":"2026-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148840381","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}