mBio最新文献

{"title":"Not gently down the stream: flow induces amyloid bonding in environmental and pathological fungal biofilms.","authors":"Peter N Lipke","doi":"10.1128/mbio.00203-25","DOIUrl":"https://doi.org/10.1128/mbio.00203-25","url":null,"abstract":"<p><p>Surface-bound biofilms are the predominant microbial life form in the environment and host organisms. Many biofilms survive and thrive under physical stress from liquid flow in streams, fuel lines, blood, and airways. Strategies for biofilm persistence include shear-dependent adhesion (called catch bonding). In some cases, biofilms are physically strengthened by the formation of cross-β bonds between proteins: the same process that generates amyloids. Cross-β bonds have low dissociation rates. In biofilms, they bind cells to substrates, each other, and the biofilm matrix. Most fungal adhesins include amino acid sequences that can form amyloids. Shear flow activates these adhesins by unfolding pseudo-stable protein domains. The unfolding exposes sequence segments that can form cross-β bonds. These segments interact to form high-avidity adhesin patches on the cell surface. Thus, cross-β bonding is a consequence of flow-induced exposure of the cross-β core sequences. Liquid flow leads to both biofilm establishment through catch bonding and biofilm strengthening through amyloid-like bonds. This shear-dependent induction of biofilm establishment and persistence is a model for many microbial systems.IMPORTANCEThe microbes in biofilms persist in many environments, including industrial and pathological settings. These surface-associated communities show high resistance to antibiotics and microbicides. Biofilms also resist scouring by liquid flow. Amyloid-like cross-β bonds allow the establishment, strengthening, and persistence of many biofilms. This discovery opens a window on the novel use of anti-amyloid strategies to control microbes in biofilms.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0020325"},"PeriodicalIF":5.1,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144078962","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":"Resistance to oxyimino-cephalosporins conferred by an alternative mechanism of hydrolysis by the <i>Acinetobacter</i>-derived cephalosporinase-33 (ADC-33), a class C β-lactamase present in carbapenem-resistant <i>Acinetobacter baumannii</i> (CR<i>Ab</i>).","authors":"Rachel A Powers, Bradley J Wallar, Hannah R Jarvis, Zoe X Ziegler, Cynthia M June, Christopher R Bethel, Andrea M Hujer, Magdalena A Taracila, Susan D Rudin, Kristine M Hujer, Fabio Prati, Emilia Caselli, Robert A Bonomo","doi":"10.1128/mbio.00287-25","DOIUrl":"https://doi.org/10.1128/mbio.00287-25","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Antimicrobial resistance in &lt;i&gt;Acinetobacter baumannii&lt;/i&gt; is partly mediated by chromosomal class C β-lactamases, the &lt;i&gt;Acinetobacter&lt;/i&gt;-derived cephalosporinases (ADCs). Recently, a growing number of emerging variants were described, expanding this threat. Consistent with other β-lactamases, one of the main areas of variance exists in the Ω-loop region near the site of cephalosporin binding. Interestingly, a common alanine duplication (Adup) is found in this region. Herein, we studied specific Adup variants expressed in a uniform &lt;i&gt;Escherichia coli&lt;/i&gt; genetic background that demonstrated high-level resistance to multiple oxyimino-cephalosporins. For ceftolozane and ceftazidime, the Adup ADCs significantly increased levels of resistance (minimum inhibitory concentration [MIC] ≥ 512 µg/mL and MIC ≥ 1,024 µg/mL, respectively). These observations were consistent with the increased &lt;i&gt;k&lt;/i&gt;&lt;sub&gt;cat&lt;/sub&gt;/&lt;i&gt;K&lt;/i&gt;&lt;sub&gt;&lt;i&gt;M&lt;/i&gt;&lt;/sub&gt; for ceftazidime. For cefiderocol, three Adup variants exhibited increased MICs and increased &lt;i&gt;k&lt;/i&gt;&lt;sub&gt;cat&lt;/sub&gt;/&lt;i&gt;K&lt;/i&gt;&lt;sub&gt;&lt;i&gt;M&lt;/i&gt;&lt;/sub&gt; for this compound. Timed electrospray ionization mass spectrometry demonstrated stable cephalosporin:ADC adducts with ADC-30 (non-Adup), but not with ADC-33 (Adup), consistent with turnover. The X-ray crystal structure of Adup variant ADC-33 in complex with ceftazidime was determined (1.57 Å resolution) and suggests that increased turnover is facilitated by conformational changes (shift in Tyr221 and orientation of the oxyimino portion of the R1 side chain) and repositioning of water in the active site. These changes appear to favor substrate-assisted catalysis as an alternative mechanism to base-assisted catalysis. These studies also provide unprecedented insight into the mechanism underlying oxyimino-cephalosporin hydrolysis by expanded-spectrum ADC β-lactamases and possibly other class C β-lactamases, which is of critical importance to future drug design.IMPORTANCEThe characterization of emerging &lt;i&gt;Acinetobacter&lt;/i&gt;-derived cephalosporinase (ADC) variants is necessary to understand the increasing resistance to β-lactam antibiotics in &lt;i&gt;Acinetobacter&lt;/i&gt; spp. In this study, cefiderocol retains effectiveness against ADC variants with and without an Ω-loop alanine duplication (Adup). However, the presence of the Adup appears to introduce loop flexibility and structural alterations resulting in increased resistance and steady-state turnover of larger cephalosporins. Further characterization provides unprecedented insight into the mechanism of cephalosporin hydrolysis by ADC β-lactamases and supports a concomitant increase in ADC structural flexibility and cephalosporin affinity that leads to more efficient hydrolysis. In addition, the crystal structure of ADC-33 in complex with ceftazidime is consistent with a substrate-assisted catalysis mechanism. The structural differences in the ADC-33 active site leading to ceftazidime catalysis provide a better understanding of β-","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0028725"},"PeriodicalIF":5.1,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144078966","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":"Flagellar motility and the mucus environment influence aggregation-mediated antibiotic tolerance of <i>Pseudomonas aeruginosa</i> in chronic lung infection.","authors":"Matthew G Higgs, Matthew A Greenwald, Cristian Roca, Jade K Macdonald, Ashelyn E Sidders, Brian P Conlon, Matthew C Wolfgang","doi":"10.1128/mbio.00831-25","DOIUrl":"https://doi.org/10.1128/mbio.00831-25","url":null,"abstract":"&lt;p&gt;&lt;p&gt;&lt;i&gt;Pseudomonas aeruginosa&lt;/i&gt; routinely causes chronic lung infection in individuals with muco-obstructive airway diseases (MADs). In MADs, &lt;i&gt;P. aeruginosa&lt;/i&gt; forms antibiotic-tolerant biofilm-like aggregates within hyperconcentrated airway mucus. While the contribution of mucin hyper-concentration to antibiotic tolerance and bacterial aggregation has been described, less is known about the bacterial factors involved. We previously found that &lt;i&gt;P. aeruginosa&lt;/i&gt; populations isolated from people with MADs exhibited significant variability in antibiotic tolerance. This variability is not explained by antibiotic resistance or the mucus environment, suggesting bacterial-driven mechanisms play a crucial role in treatment outcomes. Here, we investigated the contribution of flagellar motility to aggregate formation and tolerance by manipulating motility behaviors. Similar to prior studies, we found that loss of flagellar motility resulted in increased aggregation and tolerance to various antibiotics. We identified novel differential roles of the MotAB and MotCD stators, which power flagellar rotation, in antimicrobial tolerance and aggregate formation. In addition, we found that control of &lt;i&gt;fliC&lt;/i&gt; expression was important for aggregate formation and antibiotic tolerance. Constitutive expression of &lt;i&gt;fliC&lt;/i&gt; allowed &lt;i&gt;P. aeruginosa&lt;/i&gt; to overcome entropic forces of mucin, antagonizing aggregate formation and increasing antibiotic efficacy. Lastly, we demonstrate that neutrophil elastase, an abundant antimicrobial protease in chronic lung infection, promotes antibiotic treatment failure by impairing flagellar motility leading to antibiotic-tolerant aggregate formation. These results underscore the crucial role of flagellar motility in aggregate formation and antibiotic tolerance, enhancing our understanding of how &lt;i&gt;P. aeruginosa&lt;/i&gt; adapts to the MADs lung environment&lt;i&gt;.&lt;/i&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Importance: &lt;/strong&gt;Antibiotic treatment failure of &lt;i&gt;Pseudomonas aeruginosa&lt;/i&gt; infection is a key driver of mortality in muco-obstructive airway diseases (MADs). The bacterial mechanisms that contribute to antibiotic tolerance in MADS infection are poorly understood. We investigated the impact of swimming motility behaviors on &lt;i&gt;P. aeruginosa&lt;/i&gt; antibiotic tolerance in the context of the diseased mucus environment. Loss of flagellar motility, a common adaptation in chronic lung infection, drives antibiotic tolerance by promoting aggregate formation under physiologically relevant mucin concentrations. We uncovered novel roles of the flagellar stators in motility and mucus aggregate formation. Furthermore, neutrophil elastase, an abundant host-derived antimicrobial protease, promotes antibiotic tolerance and aggregation by impairing flagellar motility. These results further our understanding of the formation of antibiotic-tolerant aggregates within the MADs airway, revealing potential new targets to improve antibiotic treatment of chronic &lt;i&gt;P. ae","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0083125"},"PeriodicalIF":5.1,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144078958","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":"<i>Tetrahymena</i> ATG8 homologs, TtATG8A and TtATG8B, are responsible for mitochondrial degradation induced by starvation.","authors":"Shinya Matsuda, Chieko Saito, Mami Nomura, Hitomi Kawahara, Noboru Mizushima, Kentaro Nakano","doi":"10.1128/mbio.00783-25","DOIUrl":"https://doi.org/10.1128/mbio.00783-25","url":null,"abstract":"<p><p>The majority of heterotrophic unicellular eukaryotes have evolved mechanisms to survive periods of starvation, allowing them to endure until conditions are favorable for regrowth. The ciliate <i>Tetrahymena</i> exhibits active swimming behavior in water, preying on microorganisms and growing exponentially at a rate of 0.5-0.75 h⁻¹ under optimal conditions. In this organism, numerous mitochondria localize to the cell cortex along the ciliary rows, likely ensuring an efficient ATP supply necessary for vigorous cell movement. Although mitochondrial reduction occurs immediately under starvation, the underlying mechanism remains unknown. Here, we demonstrated that autophagy is responsible for mitochondrial reduction in <i>Tetrahymena thermophila</i>. Among the five <i>T. thermophila</i> ATG8 homologs, TtATG8A and TtATG8B formed granule- and cup-shaped structures in response to starvation. Fluorescent microscopy further showed that TtATG8A and TtATG8B associate with mitochondria. Moreover, correlative light and electron microscopy analysis revealed that mitochondria colocalized with TtATG8A or TtATG8B were engulfed by autophagosomes and displayed abnormal appearances with disrupted cristae structures. Additionally, repression of TtATG8A or TtATG8B expression significantly attenuated starvation-induced mitochondrial reduction. These findings suggest that TtATG8A- and TtATG8B-mediated autophagy is a key mechanism underlying mitochondrial reduction in starved <i>T. thermophila</i>.</p><p><strong>Importance: </strong>This study is the first comprehensive description of the mitochondrial degradation process under nutrient starvation in the ciliate <i>Tetrahymena</i>. It is well known that the cell surface structure of ciliates consists of an elaborate spatial arrangement of microtubule networks and associated structures and that this surface repetitive pattern is inherited by the next generation of cells like genetic information. Our findings provide a basis for understanding how ciliates maintain an adequate amount of mitochondria on the cell surface in response to nutritional conditions. Furthermore, we have successfully demonstrated the usefulness of <i>Tetrahymena</i> as an experimental system for studying mitochondrial quality control and turnover. Further studies of <i>Tetrahymena</i> will facilitate comparative studies among diverse biological systems on how eukaryotes other than opisthokonta (yeast, cultured cells, etc.) control their mitochondria.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0078325"},"PeriodicalIF":5.1,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144078955","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":"Complex roles for proliferating cell nuclear antigen in restricting human cytomegalovirus replication.","authors":"Pierce Longmire, Olivia Daigle, Sebastian Zeltzer, Matias Lee, Marek Svoboda, Marco Padilla-Rodriguez, Carly Bobak, Giovanni Bosco, Felicia Goodrum","doi":"10.1128/mbio.00450-25","DOIUrl":"10.1128/mbio.00450-25","url":null,"abstract":"<p><p>DNA viruses at once elicit and commandeer host pathways, including DNA repair pathways, for virus replication. Despite encoding its own DNA polymerase and processivity factor, human cytomegalovirus (HCMV) recruits the cellular processivity factor, proliferating cell nuclear antigen (PCNA) and specialized host DNA polymerases involved in translesion synthesis (TLS) to replication compartments (RCs) where viral DNA (vDNA) is synthesized. While the recruitment of TLS polymerases is important for viral genome stability, the role of PCNA is poorly understood. PCNA function in DNA repair is regulated by monoubiquitination (mUb) or SUMOylation of PCNA at lysine 164 (K164). We find that mUb-PCNA increases over the course of infection, and modification of K164 is required for PCNA-mediated restriction of virus replication. mUb-PCNA plays important known roles in recruiting TLS polymerases to DNA, which we have shown are important for viral genome integrity and diversity, represented by structural variants and single nucleotide variants (SNVs), respectively. We find that PCNA drives SNVs on vDNA similar to Y-family TLS polymerases, but this did not require modification at K164. Unlike TLS polymerases, depeletion of PCNA did not result in large-scale rearrangements on vDNA. These striking results suggest separable PCNA-dependent and -independent functions of TLS polymerases on vDNA. By extension, these results imply roles for TLS polymerase beyond their canonical function in TLS in host biology. These findings highlight PCNA as a complex restriction factor for HCMV infection, likely with multiple distinct roles, and provide new insights into the PCNA-mediated regulation of DNA synthesis and repair in viral infection.IMPORTANCEGenome synthesis is a critical step of virus life cycles and a major target of antiviral drugs. Human cytomegalovirus (HCMV), like other herpesviruses, encodes machinery sufficient for viral DNA synthesis and relies on host factors for efficient replication. We have shown that host DNA repair factors play important roles in HCMV replication, but our understanding of this is incomplete. Building on previous findings that specialized host DNA polymerases contribute to HCMV genome integrity and diversity, we sought to determine the importance of proliferating cell nuclear antigen (PCNA), the central polymerase regulator. PCNA is associated with nascent viral DNA and restricts HCMV replication. While PCNA is dispensable for genome integrity, it contributes to genome diversity. Our findings suggest that host polymerases function on viral genomes by separable PCNA-dependent and -independent mechanisms. Through revealing complex roles for PCNA in HCMV replication, this study expands the repertoire of host DNA synthesis and repair proteins hijacked by this ubiquitous herpesvirus.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0045025"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077088/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143699566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Chlamydia trachomatis</i> exploits sphingolipid metabolic pathways during infection of phagocytes.","authors":"Adriana Moldovan, Fabienne Wagner, Fabian Schumacher, Dominik Wigger, David Komla Kessie, Marcel Rühling, Kathrin Stelzner, Regina Tschertok, Louise Kersting, Julian Fink, Jürgen Seibel, Burkhard Kleuser, Thomas Rudel","doi":"10.1128/mbio.03981-24","DOIUrl":"10.1128/mbio.03981-24","url":null,"abstract":"<p><p><i>Chlamydiae</i> are obligate intracellular pathogens that utilize host cell metabolites for catabolic and anabolic processes. The bacteria replicate in epithelial cells from which they take up sphingolipids (SL) and incorporate them into the chlamydial membrane and the vacuole (termed <i>inclusion</i>). SL uptake is essential for <i>Chlamydia trachomatis</i> (<i>Ctr</i>) in epithelial cells; however, they can also infect phagocytes, but the consequences for the SL metabolism have not yet been investigated in these cells. We performed a quantitative sphingolipidome analysis of infected primary neutrophils, macrophages, and immortalized fallopian tube epithelial cells. Sphingosine (Sph) levels are elevated in primary M2-like macrophages and human neutrophils infected with <i>C. trachomatis</i>. Human neutrophils respond to the pathogen by markedly upregulating sphingosine kinase 1 (<i>SPHK1</i>). We show in M2-like macrophages, by RNAseq, that two counteracting pathways involving upregulation of <i>SPHK1</i>, but also sphingosine-1-phosphate phosphatases 1 and 2 (<i>SGPP1</i> and <i>SGPP2</i>) and sphingosine-1-phosphate lyase (<i>SGPL1</i>), maintain a steady pool of S1P. Using click chemistry, we show that exogenously added sphingomyelin (SM) and ceramide (Cer) are efficiently taken up into the chlamydial inclusion and are integrated into bacterial membranes in infected M2-like macrophages. Exogenous Sph reduces chlamydial infectivity, is transported into the inclusion lumen, and integrates into chlamydial membranes, suggesting that this particular SL species could represent a host defense mechanism. Taken together, our data indicate an important role for Sph/Sph kinase vs S1P/S1P phosphatase balance in infected phagocytes and a previously unrecognized role for sphingosine in the immune defense against chlamydial infection.IMPORTANCE<i>Chlamydia trachomatis</i> (<i>Ctr</i>) is the leading cause of sexually transmitted diseases worldwide. Left untreated, it can cause severe complications such as blindness, pelvic inflammatory disease, or infertility. To date, no vaccines are available, and antibiotic treatment represents the only therapeutic approach to cure the infection. Limited access to antibiotics and displaced antibiotic intake increase the risk of developing recurring infections. Immune cells which fail to clear the infection and serve as a niche for chlamydial survival and replication, favor this outcome. Our research aims to elucidate the influence of sphingolipids (SL) during chlamydial infection, especially of phagocytic cells. Identifying relevant targets offers new strategies to develop alternative treatment methods.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":"16 5","pages":"e0398124"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077188/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143989593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanisms and immune crosstalk of neutrophil extracellular traps in response to infection.","authors":"Qi Liu, Ruke Chen, Ziyan Zhang, Zhou Sha, Haibo Wu","doi":"10.1128/mbio.00189-25","DOIUrl":"10.1128/mbio.00189-25","url":null,"abstract":"<p><p>Neutrophil extrusion of neutrophil extracellular traps (NETs) in a process called NETosis provides immune defense against extracellular bacteria. It has been observed that bacteria are capable of activating neutrophils to release NETs that subsequently kill them or at least prevent their local spread within host tissue. However, existing studies have mainly focused on the isolated function of NETs, with less attention given to their anti-bacterial mechanisms through interactions with other immune cell populations. The net effect of these complex intercellular interactions, which may act additively, synergistically, or antagonistically, is a critical determinant in the outcomes of host-pathogen interactions. This review summarizes the mechanisms underlying classic NET formation and their crosstalk with the immune system, offering novel insights aimed at balancing the anti-microbial function with their potential inflammatory risks.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":"16 5","pages":"e0018925"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077121/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143991724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fecal microbiota transplants (FMT) of three distinct human communities to germ-free mice exacerbated inflammation and decreased lung function in their offspring.","authors":"Ivon A Moya Uribe, Hinako Terauchi, Julia A Bell, Alexander Zanetti, Sanket Jantre, Marianne Huebner, S Hasan Arshad, Susan L Ewart, Linda S Mansfield","doi":"10.1128/mbio.03764-24","DOIUrl":"10.1128/mbio.03764-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Despite explosive rise in allergies, little is known about early life gut microbiota effects on postnatal respiratory function. We hypothesized that &lt;i&gt;Enterobacteriaceae&lt;/i&gt;-dominant gut microbiota from eczemic infants increases Type 2 inflammation and decreases lung function in transplanted mice, while &lt;i&gt;Bacteroidaceae&lt;/i&gt;-dominant gut microbiota from non-eczemic infants is protective. Fecal microbiota transplants (FMT) from eczemic infants \"Infant A\" and non-eczemic infants \"Infant B\" were successfully transplanted into germ-free C57BL/6 mice, passing to offspring unchanged. Infant A and B, Adult C-human-derived (positive control), and Mouse (negative control) microbiotas all in C57BL/6 mice were tested for effects on airway function in nonallergic (phosphate-buffered saline [PBS]) and allergic (house dust mite [HDM]) conditions. Baseline lung mechanics in mice with human microbiotas (&lt;sup&gt;HU&lt;/sup&gt;microbiota) were significantly impaired compared to Mouse microbiota controls (&lt;sup&gt;MO&lt;/sup&gt;microbiota) with or without HDM; respiratory system resistance (Rrs) was increased (&lt;i&gt;P&lt;/i&gt; &lt; 0.05-&lt;i&gt;P&lt;/i&gt; &lt; 0.01), and respiratory system compliance (Crs) was decreased (&lt;i&gt;P&lt;/i&gt; &lt; 0.05-&lt;i&gt;P&lt;/i&gt; &lt; 0.01). &lt;sup&gt;HU&lt;/sup&gt;Microbiota mice showed a statistically significant impairment compared to &lt;sup&gt;MO&lt;/sup&gt;microbiota mice in lung parameters Rrs, Ers, Rn, and G at baseline, and at multiple methacholine (MCh) doses with baseline removed. Impairment manifested as increased small airway resistance and tissue resistance. HDM significantly elevated IL-4, eosinophils, lung inflammation, and mucus cell metaplasia, and decreased macrophages and lung function (&lt;i&gt;P&lt;/i&gt; &lt; 0.05) in mice of all microbiotas, yet each &lt;sup&gt;HU&lt;/sup&gt;microbiota produced distinct features. Infant B and Adult C mice had elevated basal levels of total IgE compared to &lt;sup&gt;MO&lt;/sup&gt;microbiota and Infant A mice (&lt;i&gt;P&lt;/i&gt; &lt; 0.05). In &lt;sup&gt;HU&lt;/sup&gt;microbiota mice given HDM, only Adult C had elevated IL-5 and IL-13 (&lt;i&gt;P&lt;/i&gt; &lt; 0.05), only Adult C and Infant B mice had elevated neutrophils (&lt;i&gt;P&lt;/i&gt; &lt; 0.05), and only Infant A had elevated lymphocytes (&lt;i&gt;P&lt;/i&gt; &lt; 0.01).&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Importance: &lt;/strong&gt;Fecal microbiota transplants (FMT) of three distinct human communities to germ-free mice exacerbated inflammation and decreased lung function in their offspring. Taxa formerly described to induce an allergic response (agonists) and pro-inflammatory taxa were abundant in &lt;sup&gt;HU&lt;/sup&gt;microbiotas compared to &lt;sup&gt;MO&lt;/sup&gt;microbiota controls, while taxa formerly described to reduce allergic responses (antagonists) and anti-inflammatory taxa were numerous in &lt;sup&gt;MO&lt;/sup&gt;microbiotas and low in &lt;sup&gt;HU&lt;/sup&gt;microbiotas. Thus, we largely rejected our hypotheses because data supported multiple pro-inflammatory allergy agonists functioning in a community-wide fashion to impair lung function in the absence of antagonistic anti-inflammatory taxa. Structure of &lt;sup&gt;HU&lt;/sup&gt;microbiotas played a key role in dete","PeriodicalId":18315,"journal":{"name":"mBio","volume":"16 5","pages":"e0376424"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077122/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144008388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural and mechanistic bases for resistance of the M66I capsid variant to lenacapavir.","authors":"Lorenzo Briganti, Arun S Annamalai, Stephanie M Bester, Guochao Wei, Jonathan R Andino-Moncada, Satya P Singh, Alex B Kleinpeter, Meghna Tripathi, Binh Nguyen, Rajalingam Radhakrishnan, Parmit K Singh, Juliet Greenwood, Lauren I Schope, Reed Haney, Szu-Wei Huang, Eric O Freed, Alan N Engelman, Ashwanth C Francis, Mamuka Kvaratskhelia","doi":"10.1128/mbio.03613-24","DOIUrl":"10.1128/mbio.03613-24","url":null,"abstract":"<p><p>Lenacapavir (LEN) is the first-in-class viral capsid protein (CA) targeting antiretroviral for treating multi-drug-resistant HIV-1 infection. Clinical trials and cell culture experiments have identified resistance-associated mutations (RAMs) in the vicinity of the hydrophobic CA pocket targeted by LEN. The M66I substitution conferred by far the highest level of resistance to the inhibitor compared to other RAMs. Here we investigated structural and mechanistic bases for how the M66I change affects LEN binding to CA and viral replication. The high-resolution X-ray structure of the CA(M66I) hexamer revealed that the β-branched side chain of Ile66 induces steric hindrance specifically to LEN, thereby markedly reducing the inhibitor binding affinity. By contrast, the M66I substitution did not affect the binding of Phe-Gly (FG)-motif-containing cellular cofactors CPSF6, NUP153, or SEC24C, which engage the same hydrophobic pocket of CA. In cell culture, the M66I variant did not acquire compensatory mutations. Analysis of viral replication intermediates revealed that HIV-1_{(M66I CA)} predominantly formed correctly matured viral cores, which were more stable than their wild-type counterparts. The mutant cores stably bound to the nuclear envelope but failed to penetrate inside the nucleus. Furthermore, the M66I substitution markedly altered HIV-1 integration targeting. Taken together, our findings elucidate mechanistic insights into how the M66I change confers remarkable resistance to LEN and affects HIV-1 replication. Moreover, our structural findings provide a powerful means for future medicinal chemistry efforts to rationally develop second-generation inhibitors with a higher barrier to resistance.IMPORTANCELenacapavir (LEN) is a highly potent and long-acting antiretroviral that works by a unique mechanism of targeting the viral capsid protein. The inhibitor is used in combination with other antiretrovirals to treat multi-drug-resistant HIV-1 infection in heavily treatment-experienced adults. Furthermore, LEN is in clinical trials for preexposure prophylaxis (PrEP) with interim results indicating 100% efficacy to prevent HIV-1 infections. However, one notable shortcoming is a relatively low barrier of viral resistance to LEN. Clinical trials and cell culture experiments identified emergent resistance mutations near the inhibitor binding site on capsid. The M66I variant was the most prevalent capsid substitution identified in patients receiving LEN to treat multi-drug-resistant HIV-1 infections. The studies described here elucidate the underlying mechanism by which the M66I substitution confers a marked resistance to the inhibitor. Furthermore, our structural findings will aid future efforts to develop the next generation of capsid inhibitors with enhanced barriers to resistance.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":"16 5","pages":"e0361324"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077090/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144018127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cryo-EM reveals a double oligomeric ring scaffold of the CHIKV nsP3 peptide in complex with the NTF2L domain of host G3BP1.","authors":"Yuanzhi Liu, Jie Wang, Yinze Han, Xiaoyan Xia, Rui Zeng, Xinyu Fan, Bo Zhang, Kaituo Wang, Jian Lei","doi":"10.1128/mbio.03967-24","DOIUrl":"10.1128/mbio.03967-24","url":null,"abstract":"<p><p>Chikungunya virus (CHIKV) poses a severe threat to global public health. The interaction between CHIKV nsP3 and host G3BP1 is critical for viral replication. However, the exact structural mechanism of the nsP3-G3BP1 interaction is scarce. Here, we report a cryo-electron microscopy structure of an octameric-heterotrimer formed by CHIKV nsP3 peptide (designated as CHIKV-43) in complex with the nuclear translocation factor 2-like (NTF2L) domain of G3BP1. The overall structure presents a double-layer ring scaffold. Two FGDF motifs and two alpha helices of CHIKV-43 are essential to bind NTF2L. Particularly, the secondary alpha helix plays key roles in forming the CHIKV-43-NTF2L high-order oligomer. We next analyzed the detailed interactions between CHIKV-43 and the NTF2L domain. The different binding patterns of NTF2L with its various partners were described as well. Subsequently, we demonstrated that the CHIKV-43 peptide is a crucial factor for nsP3 co-localization with G3BP1, reducing stress granule formation and interfering with interferon production. Overall, our findings present the structural and functional mechanisms on CHIKV nsP3 modulating host G3BP1 and provide a potential antiviral target based on the protein-protein interaction interface.</p><p><strong>Importance: </strong>Chikungunya virus (CHIKV) is an arbovirus responsible for causing fever, headache, and severe joint pain in humans, with widespread outbreaks affecting millions worldwide. The CHIKV nsP3 is a key protein that interacts with multiple host proteins. In this study, we present the cryo-electron microscopy structure of a high-order oligomer formed by the CHIKV nsP3 peptide and the nuclear translocation factor 2-like (NTF2L) domain of host protein G3BP1, revealing a completely novel interaction model. The detailed interactions within this oligomer were illustrated. We also analyzed the binding patterns of the NTF2L domain of G3BP1 with its various partners, providing essential insights for the development of peptide-mimetic inhibitors targeting nsP3 and/or G3BP1. Furthermore, our data indicate that the nsP3-G3BP1 interaction reduces stress granule formation and antagonizes interferon production. Overall, this study provides new knowledge on CHIKV biology and suggests a potential target for developing antiviral therapeutics.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":"16 5","pages":"e0396724"},"PeriodicalIF":5.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077208/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144025010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}