mSphere最新文献

{"title":"A nitrogenase-like enzyme is involved in the novel anaerobic assimilation pathway of a sulfonate, isethionate, in the photosynthetic bacterium <i>Rhodobacter capsulatus</i>.","authors":"Yoshiki Morimoto, Kazuma Uesaka, Yuichi Fujita, Haruki Yamamoto","doi":"10.1128/msphere.00498-24","DOIUrl":"10.1128/msphere.00498-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Prokaryotes contribute to the global sulfur cycle by using diverse sulfur compounds as sulfur sources or electron acceptors. In this study, we report that a nitrogenase-like enzyme (NFL) and a radical SAM enzyme (RSE) are involved in the novel anaerobic assimilation pathway of a sulfonate, isethionate, in the photosynthetic bacterium &lt;i&gt;Rhodobacter capsulatus&lt;/i&gt;. The &lt;i&gt;nflHDK&lt;/i&gt; genes for NFL are localized at a locus containing genes for known sulfonate metabolism in the genome. A gene &lt;i&gt;nflB&lt;/i&gt; encoding an RSE is present just upstream of &lt;i&gt;nflH&lt;/i&gt;, forming a small gene cluster &lt;i&gt;nflBHDK&lt;/i&gt;. Mutants lacking any &lt;i&gt;nflBHDK&lt;/i&gt; genes are incapable of growing with isethionate as the sole sulfur source under anaerobic photosynthetic conditions, indicating that all four NflBHDK proteins are essential for the isethionate assimilation pathway. Heterologous expression of the &lt;i&gt;islAB&lt;/i&gt; genes encoding a known isethionate lyase that degrades isethionate to sulfite and acetaldehyde restored the isethionate-dependent growth of a mutant lacking &lt;i&gt;nflDK&lt;/i&gt;, indicating that the enzyme encoding &lt;i&gt;nflBHDK&lt;/i&gt; is involved in an isethionate assimilation reaction to release sulfite. Furthermore, the heterologous expression of &lt;i&gt;nflBHDK&lt;/i&gt; and &lt;i&gt;ssuCAB&lt;/i&gt; encoding an isethionate transporter in the closely related species &lt;i&gt;R. sphaeroides&lt;/i&gt;, which does not have &lt;i&gt;nflBHDK&lt;/i&gt; and cannot grow with isethionate as the sole sulfur source, conferred isethionate-dependent growth ability to this species. We propose to rename &lt;i&gt;nflBHDK&lt;/i&gt; as &lt;i&gt;isrBHDK&lt;/i&gt; (&lt;u&gt;is&lt;/u&gt;ethionate &lt;u&gt;r&lt;/u&gt;eductase). The &lt;i&gt;isrBHDK&lt;/i&gt; genes are widely distributed among various prokaryote phyla. Discovery of the isethionate assimilation pathway by IsrBHDK provides a missing piece for the anaerobic sulfur cycle and for understanding the evolution of ancient sulfur metabolism.IMPORTANCENitrogenase is an important enzyme found in prokaryotes that reduces atmospheric nitrogen to ammonia and plays a fundamental role in the global nitrogen cycle. It has been noted that nitrogenase-like enzymes (NFLs), which share an evolutionary origin with nitrogenase, have evolved to catalyze diverse reactions such as chlorophyll biosynthesis (photosynthesis), coenzyme F&lt;sub&gt;430&lt;/sub&gt; biosynthesis (methanogenesis), and methionine biosynthesis. In this study, we discovered that an NFL with unknown function in the photosynthetic bacterium &lt;i&gt;Rhodobacter capsulatus&lt;/i&gt; is a novel isethionate reductase (Isr), which catalyzes the assimilatory degradation of isethionate, a sulfonate, releasing sulfite used as the sulfur source under anaerobic conditions. Isr is widely distributed among various bacterial phyla, including intestinal bacteria, and is presumed to play an important role in sulfur metabolism in anaerobic environments such as animal guts and microbial mats. This finding provides a clue for understanding ancient metabolism that evolved under anaerobic environments at the dawn of life.&lt;/p","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11423573/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142081024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Delivery of <i>Yersinia pestis</i> antigens via <i>Escherichia coli</i> outer membrane vesicles offered improved protection against plague.","authors":"Zehui Tong, Xiangting Zhang, Xiao Guo, Gengshan Wu, Shiyang Cao, Yuan Zhang, Xiangze Meng, Tong Wang, Yiqian Wang, Yajun Song, Ruifu Yang, Zongmin Du","doi":"10.1128/msphere.00330-24","DOIUrl":"10.1128/msphere.00330-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Outer membrane vesicles (OMVs) from Gram-negative bacteria can be used as a vaccine platform to deliver heterologous antigens. Here, the major protective antigens of &lt;i&gt;Yersinia pestis,&lt;/i&gt; F1 and LcrV, were fused either with the leader sequence or the transmembrane domain of the outer membrane protein A (OmpA), resulting in chimeric proteins OmpA-ls-F1V and OmpA&lt;sub&gt;46-159&lt;/sub&gt;-F1V, respectively. We show that OmpA-ls-F1V and OmpA&lt;sub&gt;46-159&lt;/sub&gt;-F1V can be successfully delivered into the lumen and membrane of the OMVs of &lt;i&gt;Escherichia coli,&lt;/i&gt; respectively. Mutation of &lt;i&gt;ompA&lt;/i&gt; but not &lt;i&gt;tolR&lt;/i&gt; in &lt;i&gt;E. coli&lt;/i&gt; enhanced the delivery efficiency of OmpA-ls-F1V into OMVs. The OmpA-ls-F1V protein comprises up to 20% of the total protein in OMVs derived from the &lt;i&gt;ompA&lt;/i&gt; mutant (OMV&lt;sub&gt;dA&lt;/sub&gt;-ALS-F1V), a proportion significantly higher than the 1% observed for OmpA&lt;sub&gt;46-159&lt;/sub&gt;-F1V in OMVs produced by an &lt;i&gt;ompA&lt;/i&gt; mutant that expresses OmpA46-159-F1V, referred to as OMV&lt;sub&gt;dA&lt;/sub&gt;-LATM5-F1V. Intramuscular (&lt;i&gt;i.m&lt;/i&gt;.) immunization of mice with OMV&lt;sub&gt;dA&lt;/sub&gt;-ALS-F1V induced significantly higher levels of serum anti-LcrV and anti-F1 IgG, and provided higher efficacy in protection against subcutaneous (&lt;i&gt;s.c.&lt;/i&gt;) &lt;i&gt;Y. pestis&lt;/i&gt; infection compared to OMV&lt;sub&gt;dA&lt;/sub&gt;-LATM5-F1V and the purified recombinant F1V (rF1V) protein adsorbed to aluminum hydroxide. The three-dose &lt;i&gt;i.m&lt;/i&gt;. immunization with OMV&lt;sub&gt;dA&lt;/sub&gt;-ALS-F1V, administered at 14-day intervals, provides complete protection to mice against &lt;i&gt;s.c.&lt;/i&gt; infection with 130 LD&lt;sub&gt;50&lt;/sub&gt; of &lt;i&gt;Y. pestis&lt;/i&gt; 201 and conferred 80% against intranasal (&lt;i&gt;i.n&lt;/i&gt;.) challenge with 11.4 LD&lt;sub&gt;50&lt;/sub&gt; of &lt;i&gt;Y. pestis&lt;/i&gt; 201. Taken together, our findings indicate that the engineered OMVs containing F1V fused with the leader sequence of OmpA provide significantly higher protection than rF1V against both &lt;i&gt;s.c&lt;/i&gt;. and &lt;i&gt;i.n&lt;/i&gt;. infection of &lt;i&gt;Y. pestis&lt;/i&gt; and more balanced Th1/Th2 responses.IMPORTANCEThe two major protective antigens of &lt;i&gt;Y. pestis&lt;/i&gt;, LcrV and F1, have demonstrated the ability to elicit systemic and local mucosal immune responses as subunit vaccines. However, these vaccines have failed to provide adequate protection against pneumonic plague in African green monkeys. Here, &lt;i&gt;Y. pestis&lt;/i&gt; F1 and LcrV antigens were successfully incorporated into the lumen and the surface of the outer membrane vesicles (OMVs) of &lt;i&gt;E. coli&lt;/i&gt; by fusion either with the leader sequence or the transmembrane domain of OmpA. We compared the humoral immune response elicited by these OMV formulations and their protective efficacy in mice against &lt;i&gt;Y. pestis&lt;/i&gt;. Our results demonstrate that the plague OMV vaccine candidates can induce robust protective immunity against both &lt;i&gt;s.c&lt;/i&gt;. and &lt;i&gt;i.n. Y. pestis&lt;/i&gt; infections, surpassing the effectiveness of rF1V. In addition, immunization with OMVs generated a relatively balanced Th1/Th2 immune response compared ","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11423571/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142000420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 transplant allows transmission of the gut microbiota in honey bees.","authors":"Amélie Cabirol, Audam Chhun, Joanito Liberti, Lucie Kesner, Nicolas Neuschwander, Yolanda Schaerli, Philipp Engel","doi":"10.1128/msphere.00262-24","DOIUrl":"10.1128/msphere.00262-24","url":null,"abstract":"<p><p>The study of the fecal microbiota is crucial for unraveling the pathways through which gut symbionts are acquired and transmitted. While stable gut microbial communities are essential for honey bee health, their modes of acquisition and transmission are yet to be confirmed. The gut of honey bees is colonized by symbiotic bacteria within 5 days after emergence from their wax cells as adults. Few studies have suggested that bees could be colonized in part via contact with fecal matter in the hive. However, the composition of the fecal microbiota is still unknown. It is particularly unclear whether all bacterial species can be found viable in the feces and can therefore be transmitted to newborn nestmates. Using 16S rRNA gene amplicon sequencing, we revealed that the composition of the honey bee fecal microbiota is strikingly similar to the microbiota of entire guts. We found that fecal transplantation resulted in gut microbial communities similar to those obtained from feeding gut homogenates. Our study shows that fecal sampling and transplantation are viable tools for the non-invasive analysis of bacterial community composition and host-microbe interactions. It also implies that contact of young bees with fecal matter in the hive is a plausible route for gut microbiota acquisition.</p><p><strong>Importance: </strong>Honey bees are crucial pollinators for many crops and wildflowers. They are also powerful models for studying microbiome-host interactions. However, current methods rely on gut tissue disruption to analyze microbiota composition and use gut homogenates to inoculate microbiota-deprived bees. Here, we provide two new and non-invasive approaches that will open doors to longitudinal studies: fecal sampling and transplantation. Furthermore, our findings provide insights into gut microbiota transmission in social insects by showing that ingestion of fecal matter can result in gut microbiota acquisition.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11423570/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142000421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Requirement of a Wnt5A-microbiota axis in the maintenance of gut B-cell repertoire and protection from infection.","authors":"Soham Sengupta, Malini Sen","doi":"10.1128/msphere.00204-24","DOIUrl":"10.1128/msphere.00204-24","url":null,"abstract":"<p><p>We investigated the influence of a Wnt5A-gut microbiota axis on gut B-cell repertoire and protection from infection, having previously demonstrated that Wnt5A in association with gut commensals helps shape gut T-cell repertoire. Accordingly, Wnt5A heterozygous mice, which express less than wild-type level of Wnt5A, and their isolated Peyer's patches (PPs) were studied in comparison with the wild-type counterparts. The percentages of IgM- and IgA-expressing B cells were quite similar in the PP of both sets of mice. However, the PP of the Wnt5A heterozygous mice harbored significantly higher than wild-type levels of microbiota-bound B cell-secreted IgA, indicating the prevalence of a microbial population therein, which is significantly altered from that of wild-type. Additionally, the percentage of PP IgG1-expressing B cells was appreciably depressed in the Wnt5A heterozygous mice in comparison to wild-type. Wnt5A heterozygous mice, furthermore, exhibited notably higher than the wild-type levels of morbidity and mortality following infection with <i>Salmonella typhimurium</i>, a common gut pathogen. Differences in morbidity/mortality correlated with considerable disparity between the PP-B-cell repertoires of the <i>Salmonella</i>-infected Wnt5A heterozygous and wild-type mice, in which the percentage of IgG1-expressing B1b cells in the PP of heterozygous mice remains significantly low as compared to wild-type. Overall, these results suggest that a gut Wnt5A-microbiota axis is intrinsically associated with the maintenance of gut B-cell repertoire and protection from infection.IMPORTANCEAlthough it is well accepted that B cells and microbiota are required for protection from infection and preservation of gut health, a lot remains unknown about how the optimum B-cell repertoire and microbiota are maintained in the gut. The importance of this study lies in the fact that it unveils a potential role of a growth factor termed Wnt5A in the safeguarding of the gut B-cell population and microbiota, thereby protecting the gut from the deleterious effect of infections by common pathogens. Documentation of the involvement of a Wnt5A-microbiota axis in the shaping of a protective gut B-cell repertoire, furthermore, opens up new avenues of investigations for understanding gut disorders related to microbial dysbiosis and B-cell homeostasis that, till date, are considered incurable.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11423572/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141976220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic evidence for a regulated cysteine protease catalytic triad in LegA7, a <i>Legionella pneumophila</i> protein that impinges on a stress response pathway.","authors":"Dar Hershkovitz, Emy J Chen, Alexander W Ensminger, Aisling S Dugan, Kaleigh T Conway, Alex C Joyce, Gil Segal, Ralph R Isberg","doi":"10.1128/msphere.00222-24","DOIUrl":"10.1128/msphere.00222-24","url":null,"abstract":"<p><p><i>Legionella pneumophila</i> grows within membrane-bound vacuoles in phylogenetically diverse hosts. Intracellular growth requires the function of the Icm/Dot type-IVb secretion system, which translocates more than 300 proteins into host cells. A screen was performed to identify <i>L. pneumophila</i> proteins that stimulate mitogen-activated protein kinase (MAPK) activation, using Icm/Dot translocated proteins ectopically expressed in mammalian cells. In parallel, a second screen was performed to identify <i>L. pneumophila</i> proteins expressed in yeast that cause growth inhibition in MAPK pathway-stimulatory high-osmolarity medium. LegA7 was shared in both screens, a protein predicted to be a member of the bacterial cysteine protease family that has five carboxyl-terminal ankyrin repeats. Three conserved residues in the predicted catalytic triad of LegA7 were mutated. These mutations abolished the ability of LegA7 to inhibit yeast growth. To identify other residues important for LegA7 function, a generalizable selection strategy in yeast was devised to isolate mutants that have lost function and no longer cause growth inhibition on a high-osmolarity medium. Mutations were isolated in the two carboxyl-terminal ankyrin repeats, as well as an inter-domain region located between the cysteine protease domain and the ankyrin repeats. These mutations were predicted by AlphaFold modeling to localize to the face opposite from the catalytic site, arguing that they interfere with the positive regulation of the catalytic activity. Based on our data, we present a model in which LegA7 harbors a cysteine protease domain with an inter-domain and two carboxyl-terminal ankyrin repeat regions that modulate the function of the catalytic domain.</p><p><strong>Importance: </strong><i>Legionella pneumophila</i> grows in a membrane-bound compartment in macrophages during disease. Construction of the compartment requires a dedicated secretion system that translocates virulence proteins into host cells. One of these proteins, LegA7, is shown to activate a stress response pathway in host cells called the mitogen-activated protein kinase (MAPK) pathway. The effects on the mammalian MAPK pathway were reconstructed in yeast, allowing the development of a strategy to identify the role of individual domains of LegA7. A domain similar to cysteine proteases is demonstrated to be critical for impinging on the MAPK pathway, and the catalytic activity of this domain is required for targeting this path. In addition, a conserved series of repeats, called ankyrin repeats, controls this activity. Data are provided that argue the interaction of the ankyrin repeats with unknown targets probably results in activation of the cysteine protease domain.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11423584/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142018102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of glycogen metabolism in <i>Clostridioides difficile</i> virulence.","authors":"Md Kamrul Hasan, Marjorie Pizzarro-Guajardo, Javier Sanchez, Revathi Govind","doi":"10.1128/msphere.00310-24","DOIUrl":"10.1128/msphere.00310-24","url":null,"abstract":"<p><p>Glycogen plays a vital role as an energy reserve in various bacterial and fungal species. <i>Clostridioides difficile</i> possesses a glycogen metabolism operon that contains genes for both glycogen synthesis and utilization. In our investigation, we focused on understanding the significance of glycogen metabolism in the physiology and pathogenesis of <i>C. difficile</i>. To explore this, we engineered a <i>C. difficile</i> JIR8094 strain lacking glycogen synthesis capability by introducing a group II intron into the <i>glgC</i> gene, the operon's first component. Quantification of intracellular glycogen levels validated the impact of this modification. Interestingly, the mutant strain exhibited a 1.5-fold increase in toxin production compared with the parental strain, without significant changes in the sporulation rate. Our analysis also revealed that wild-type <i>C. difficile</i> spores contained glycogen, whereas spores from the mutant strain lacking stored glycogen showed increased sensitivity to physical and chemical treatments and had a shorter storage life. By suppressing <i>glgP</i> expression, the gene coding for glycogen-phosphorylase, via CRISPRi, we demonstrated that glycogen accumulation but not the utilization is needed for spore resilience in <i>C. difficile</i>. Transmission electron microscopy analysis revealed a significantly lower core/cortex ratio in <i>glgC</i> mutant strain spores. In hamster challenge experiments, both the parental and <i>glgC</i> mutant strains colonized hosts similarly; however, the mutant strain failed to induce infection relapse after antibiotic treatment cessation. These findings highlight the importance of glycogen metabolism in <i>C. difficile</i> spore resilience and suggest its role in disease relapse.IMPORTANCEThis study on the role of glycogen metabolism in <i>Clostridioides difficile</i> highlights its critical involvement in the pathogen's energy management, its pathogenicity, and its resilience. Our results also revealed that glycogen presence in spores is pivotal for their structural integrity and resistance to adverse conditions, which is essential for their longevity and infectivity. Importantly, the inability of the mutant strain to cause infection relapse in hamsters post-antibiotic treatment pinpoints a potential target for therapeutic interventions, highlighting the importance of glycogen in disease dynamics. This research thus significantly advances our understanding of <i>C. difficile</i> physiology and pathogenesis, offering new avenues for combating its persistence and recurrence.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11423593/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142073373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface hydrophilicity promotes bacterial twitching motility.","authors":"Megan T O'Hara, Tori M Shimozono, Keane J Dye, David Harris, Zhaomin Yang","doi":"10.1128/msphere.00390-24","DOIUrl":"10.1128/msphere.00390-24","url":null,"abstract":"<p><p>Twitching motility is a form of bacterial surface translocation powered by the type IV pilus (T4P). It is frequently analyzed by interstitial colony expansion between agar and the polystyrene surfaces of petri dishes. In such assays, the twitching motility of <i>Acinetobacter nosocomialis</i> was observed with MacConkey but not Luria-Bertani (LB) agar media. One difference between these two media is the presence of bile salts as a selective agent in MacConkey but not in LB. Here, we demonstrate that the addition of bile salts to LB allowed <i>A. nosocomialis</i> to display twitching. Similarly, bile salts enhanced the twitching of <i>Acinetobacter baumannii</i> and <i>Pseudomonas aeruginosa</i> in LB. These observations suggest that there is a common mechanism, whereby bile salts enhance bacterial twitching and promote interstitial colony expansion. Bile salts disrupt lipid membranes and apply envelope stress as detergents. Surprisingly, their stimulatory effect on twitching appears not to be related to a bacterial physiological response to stressors. Rather, it is due to their ability to alter the physicochemical properties of a twitching surface. We observed that while other detergents promoted twitching like bile salts, stresses applied by antibiotics, including the outer membrane-targeting polymyxin B, did not enhance twitching motility. More importantly, bacteria displayed increased twitching on hydrophilic surfaces such as those of glass and tissue culture-treated polystyrene plastics, and bile salts no longer stimulated twitching on these surfaces. Together, our results show that altering the hydrophilicity of a twitching surface significantly impacts T4P functionality.</p><p><strong>Importance: </strong>The bacterial type IV pilus (T4P) is a critical virulence factor for many medically important pathogens, some of which are prioritized by the World Health Organization for their high levels of antibiotic resistance. The T4P is known to propel bacterial twitching motility, the analysis of which provides a convenient assay for T4P functionality. Here, we show that bile salts and other detergents augment the twitching of multiple bacterial pathogens. We identified the underlying mechanism as the alteration of surface hydrophilicity by detergents. Consequently, hydrophilic surfaces like those of glass or plasma-treated polystyrene promote bacterial twitching, bypassing the requirement for detergents. The implication is that surface properties, such as those of tissues and medical implants, significantly impact the functionality of bacterial T4P as a virulence determinant. This offers valuable insights for developing countermeasures against the colonization and infection by bacterial pathogens of critical importance to human health on a global scale.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11423576/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142080954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of organic compounds on the stability of influenza A virus in deposited 1-μL droplets.","authors":"Aline Schaub, Shannon C David, Irina Glas, Liviana K Klein, Kalliopi Violaki, Céline Terrettaz, Ghislain Motos, Nir Bluvshtein, Beiping Luo, Marie Pohl, Walter Hugentobler, Athanasios Nenes, Ulrich K Krieger, Thomas Peter, Silke Stertz, Tamar Kohn","doi":"10.1128/msphere.00414-24","DOIUrl":"10.1128/msphere.00414-24","url":null,"abstract":"<p><p>The composition of respiratory fluids influences the stability of viruses in exhaled aerosol particles and droplets, though the role of respiratory organics in modulating virus stability remains poorly understood. This study investigates the effect of organic compounds on the stability of influenza A virus (IAV) in deposited droplets. We compare the infectivity loss of IAV at different relative humidities (RHs) over the course of 1 h in 1-µL droplets consisting of phosphate-buffered saline (without organics), synthetic lung fluid, or nasal mucus (both containing organics). We show that IAV stability increases with increasing organic:salt ratios. Among the various organic species, proteins are identified as the most protective component, with smaller proteins stabilizing IAV more efficiently at the same mass concentration. Organics act by both increasing the efflorescence RH and shortening the drying period until efflorescence at a given RH. This research advances our mechanistic understanding of how organics stabilize exhaled viruses and thus influence their inactivation in respiratory droplets.</p><p><strong>Importance: </strong>This study investigates how the composition of respiratory fluids affects the stability of viruses in exhaled droplets. Understanding virus stability in droplets is important as it impacts how viruses spread and how we can combat them. We focus on influenza A virus (IAV) and investigate how different organic compounds found in lung fluid and nasal mucus protect the virus from inactivation. We demonstrate that the ratio of organics to salt in the fluid is an indicator of IAV stability. Among organics, small proteins are particularly effective at protecting IAV. Their effect is in part explained by the proteins' influence on the crystallization of salts in the droplets, thereby shielding the viruses from prolonged exposure to harmful salt concentrations. Understanding these mechanisms helps us grasp how viruses sustain their infectivity over time in respiratory droplets, contributing to efforts in controlling infectious diseases.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11423574/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142018103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling the mystery of Tacaribe virus","authors":"Tony Schountz1Department of Microbiology, Immunology and Pathology, Center for Vector-borne Infectious Diseases, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USAMichael J. Imperiale","doi":"10.1128/msphere.00605-24","DOIUrl":"https://doi.org/10.1128/msphere.00605-24","url":null,"abstract":"mSphere, Ahead of Print. <br/>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in growth, lanthanide binding, and gene expression in Pseudomonas alloputida KT2440 in response to light and heavy lanthanides","authors":"Linda GorniakSarah Luise BuckaBayan NasrJialan CaoSteffen HellmannThorsten SchäferMartin WestermannJulia BechwarCarl-Eric Wegner1Institute of Biodiversity, Aquatic Geomicrobiology, Friedrich Schiller University Jena, Jena, Germany2Department of Physical Chemistry and Microreaction Technology, Institute for Chemistry and Biotechnique, Technische Universität Ilmenau, Ilmenau, Germany3Institute of Geosciences, Applied Geology, Friedrich Schiller University Jena, Jena, Germany4International Max Planck Research School for Global Biogeochemical Cycles, Department of Biogeochemical Processes, Max Planck Institute for Biogeochemistry, Jena, Germany5Electron Microscopy Center, Jena University Hospital, Jena, Germany6Bioinorganic Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, GermanyCraig D. Ellermeier","doi":"10.1128/msphere.00685-24","DOIUrl":"https://doi.org/10.1128/msphere.00685-24","url":null,"abstract":"mSphere, Ahead of Print. <br/>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}