mSphere最新文献

{"title":"Antibiotic tolerance due to restriction of cAMP-Crp regulation by mannitol, a non-glucose-family PTS carbon source.","authors":"Weiwei Zhu, Miaomiao Chen, Xue Zhang, Jie Su, Xinyang Zhang, Yuejuan Nong, Bowen Wang, Weihong Guo, Yunxin Xue, Dai Wang, Yiqun Liao, Jianjun Niu, Yuzhi Hong, Karl Drlica, Xilin Zhao","doi":"10.1128/msphere.00772-24","DOIUrl":"https://doi.org/10.1128/msphere.00772-24","url":null,"abstract":"<p><p>Enzyme-IIA (EIIA<sup>Glc</sup>, Crr) of the phosphotransferase system (PTS) connects the uptake of glucose-family sugars to the cAMP-Crp regulatory cascade; phosphorylated EIIA<sup>Glc</sup> enhances cAMP-Crp activity, which then contributes to the antibiotic-mediated accumulation of reactive oxygen species (ROS) and cell death. Defects in PTS cause antibiotic and disinfectant tolerance. We report that mannitol, a carbon source whose uptake does not use EIIA<sup>Glc</sup>, reduces antibiotic-mediated killing of <i>Escherichia coli</i> without affecting antibiotic minimal inhibitory concentration. Thus, mannitol promotes antibiotic tolerance. The tolerance pathway was defined by the loss of ciprofloxacin lethality from the deletion of <i>ptsI</i> (first gene in PTS), <i>mtlA</i> (mannitol-specific Enzyme-II), <i>cyaA</i> (cAMP synthase), and <i>crp</i> (cAMP receptor protein) but not <i>crr</i> (EIIA<sup>Glc</sup>). A <i>crp*</i> mutant, which encodes a constitutively active Crp that bypasses the need for cAMP activation, also decreased mannitol-mediated antibiotic tolerance, as did exogenous cAMP. Thus, inhibition of antibiotic lethality by mannitol involves both PTS-mediated mannitol uptake and suppression of cAMP-Crp action, independent of EIIA<sup>Glc</sup>. Mannitol suppressed the downstream antibiotic-mediated transcription of genes involved in NADH production and cellular respiration, expression of a superoxide reporter gene (<i>soxS</i>), and accumulation of antibiotic-mediated ROS. Similar phenomena were observed with mannose and sorbitol, demonstrating that non-glucose PTS carbon sources can cause antibiotic tolerance by a novel path that reduces the ROS-promoting activity of cAMP-Crp. The work emphasizes that antibiotic tolerance, which contributes to disease relapse and the need for prolonged antibiotic treatment, can result from commonly consumed carbohydrates. This finding, plus mutations that interfere specifically with antibiotic lethality, makes tolerance a high probability event.IMPORTANCEBacterial tolerance constitutes a significant threat to anti-infective therapy and potentially to the use of disinfectants. Deficiency mutations that reduce glucose uptake, central carbon metabolism, and cellular respiration confer antibiotic/disinfectant tolerance by reducing the accumulation of reactive metabolites, such as reactive oxygen species. We identified novel environmental generators of tolerance by showing that non-glucose carbohydrates, such as mannitol, mannose, and sorbitol, generate tolerance to multiple antibiotic classes. Finding that these sugars inhibit a universal, stress-mediated death pathway emphasizes the potential danger of compounds that block the lethal response to severe stress. Immediate practical importance derives from mannitol being a popular food sweetener, a treatment for glaucoma, and a dehydrating agent for treating cerebral edema, including cases caused by bacterial infection: antibiotic tolerance coul","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0077224"},"PeriodicalIF":3.7,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142676203","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":"Whole genome sequencing revealed high proportions of ST152 MRSA among clinical <i>Staphylococcus aureus</i> isolates from ten hospitals in Ghana.","authors":"Beverly Egyir, Christian Owusu-Nyantakyi, Alfred Bortey, Grebstad Rabbi Amuasi, Felicia Amoa Owusu, William Boateng, Hawawu Ahmed, Justice Kwesi Danso, Agnes Akosua Gyamaah Oclu, Quaneeta Mohktar, Georgina Tetteh-Ocloo, Harold Amegbletor, Kwabena Fosu, Francis Kwame Morgan Tetteh, Solomon Asante-Sefa, Oliver Nangkuu Deberu, Kennedy Mensah Osei, Joana Twasam, Sarkodie Kodom, Esther Gyinae, James Sampah, Nicholas Dzifa Dayie, Noah Obeng-Nkrumah, William Addo Mills-Pappoe, Gifty Boateng, Pernille Nilsson, Harriet Affran Bonful, Bright Adu, Rene S Hendriksen","doi":"10.1128/msphere.00446-24","DOIUrl":"https://doi.org/10.1128/msphere.00446-24","url":null,"abstract":"<p><p>Previous studies in Ghana indicated low prevalence of methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) and predominance of ST152 methicillin-susceptible <i>S. aureus</i> (MSSA) among clinical isolates. ST152 MRSA clones are associated with severe infections and epidemics. Using whole genome sequencing (WGS), 159 <i>S</i>. <i>aureus</i> isolated from clinical sources (wound, blood, urine, ear, abscess, umbilical cord, eye, vaginal samples, and others) from 10 hospitals across Ghana were investigated. <i>mecA</i> (gene for methicillin resistance) was detected in 38% of the isolates. Panton-Valentine leucocidin toxin (PVL) gene occurred in 65% isolates, with 84% of the MRSA's harboring the PVL gene. ST152 was the major clone, with 74% harboring the <i>mecA</i> gene. Other MRSA clones detected were ST5, ST5204, ST852, and ST1. MSSA clones included ST3249, ST152, ST5, ST1, and ST8. Twenty-three genes encoding resistance to 12 antimicrobial classes were observed with <i>blaZ</i> (97%) being the most prevalent. Other predominant resistance genes included <i>tetK</i> (46%), <i>cat</i> (42%), and <i>dfrG</i> (36%) encoding resistance for tetracyclines, phenicols, and diaminopyrimidine, respectively. Virulence genes for enterotoxins, biofilms, toxic-shock-syndrome toxins, hemolysins<i>,</i> and leukotoxins were also detected. Phylogenetic analysis revealed a shift in the dominant clone from MSSA ST152 to MRSA ST152 over the past decade. The study provides valuable insights into the genomic content of <i>S. aureus</i> from clinical sources in Ghana. The finding of ST152 MRSA in high numbers suggests a shifting epidemiological landscape of these pathogens and continuous surveillance using robust tools like WGS is needed to monitor the rise and spread of these epidemic clones in the country.IMPORTANCESince its emergence in 1959, MRSA has been a significant public health concern, causing infections in both clinical and community settings. Patients with MRSA-related infections experience higher mortality rates due to its ability to evade antimicrobials and immune defenses. In Ghana, understanding the molecular epidemiology of MRSA has been hindered by the lack of appropriate laboratory infrastructure and the limited capacity for molecular data analysis. This study, the largest genomic study of <i>S. aureus</i> in Ghana, addresses this gap by utilizing whole genome sequencing to examine the diversity of circulating <i>S. aureus</i> strains from 10 hospitals. Our findings highlight the predominance of pandemic clones, particularly ST152, and the notable transition of ST152 MSSA to ST152 MRSA over the past decade. The findings from this study supports AMR surveillance efforts in Ghana and emphasize the importance of implementing genomic surveillance using WGS to comprehensively monitor the rise and spread of multi-drug-resitant organisms such as MRSA in the country.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0044624"},"PeriodicalIF":3.7,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142676210","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":"CRISPR-Cas9-based approaches for genetic analysis and epistatic interaction studies in <i>Coxiella burnetii</i>.","authors":"Samuel Steiner, Craig R Roy","doi":"10.1128/msphere.00523-24","DOIUrl":"10.1128/msphere.00523-24","url":null,"abstract":"<p><p><i>Coxiella burnetii</i> is an obligate intracellular bacterial pathogen that replicates to high numbers in an acidified lysosome-derived vacuole. Intracellular replication requires the Dot/Icm type IVB secretion system, which translocates over 100 different effector proteins into the host cell. Screens employing random transposon mutagenesis have identified several <i>C. burnetii</i> effectors that play an important role in intracellular replication; however, the difficulty in conducting directed mutagenesis has been a barrier to the systematic analysis of effector mutants and to the construction of double mutants to assess epistatic interactions between effectors. Here, two CRISPR-Cas9 technology-based approaches were developed to study <i>C. burnetii</i> phenotypes resulting from targeted gene disruptions. CRISPRi was used to silence gene expression and demonstrated that silencing of effectors or Dot/Icm system components resulted in phenotypes similar to those of transposon insertion mutants. A CRISPR-Cas9-mediated cytosine base editing protocol was developed to generate targeted loss-of-function mutants through the introduction of premature stop codons into <i>C. burnetii</i> genes. Cytosine base editing successfully generated double mutants in a single step. A double mutant deficient in both <i>cig57</i> and <i>cig2</i> had a robust and additive intracellular replication defect when compared to either single mutant, which is consistent with Cig57 and Cig2 functioning in independent pathways that both contribute to a vacuole that supports <i>C. burnetii</i> replication. Thus, CRISPR-Cas9-based technologies expand the genetic toolbox for <i>C. burnetii</i> and will facilitate genetic studies aimed at investigating the mechanisms this pathogen uses to replicate inside host cells.</p><p><strong>Importance: </strong>Understanding the genetic mechanisms that enable <i>C. burnetii</i> to replicate in mammalian host cells has been hampered by the difficulty in making directed mutations. Here, a reliable and efficient system for generating targeted loss-of-function mutations in <i>C. burnetii</i> using a CRISPR-Cas9-assisted base editing approach is described. This technology was applied to make double mutants in <i>C. burnetii</i> that enabled the genetic analysis of two genes that play independent roles in promoting the formation of vacuoles that support intracellular replication. This advance will accelerate the discovery of mechanisms important for <i>C. burnetii</i> host infection and disease.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0052324"},"PeriodicalIF":3.7,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142668534","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":"Erratum for Longley et al., \"Signatures of Mollicutes-related endobacteria in publicly available Mucoromycota genomes\".","authors":"Reid Longley, Aaron J Robinson, Olivia A Asher, Earl Middlebrook, Gregory Bonito, Patrick S G Chain","doi":"10.1128/msphere.00881-24","DOIUrl":"https://doi.org/10.1128/msphere.00881-24","url":null,"abstract":"","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0088124"},"PeriodicalIF":3.7,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142648473","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":"Similarities and distinctions in the activation of the <i>Candida glabrata</i> Pdr1 regulatory pathway by azole and non-azole drugs.","authors":"Thomas P Conway, Bao Gia Vu, Sarah R Beattie, Damian J Krysan, W Scott Moye-Rowley","doi":"10.1128/msphere.00792-24","DOIUrl":"10.1128/msphere.00792-24","url":null,"abstract":"<p><p>Incidences of fluconazole (FLC) resistance among <i>Candida glabrata</i> clinical isolates are a growing issue in clinics. The pleiotropic drug response network in <i>C. glabrata</i> confers azole resistance and is defined primarily by the Zn₂Cys₆ zinc cluster-containing transcription factor Pdr1 and target genes such as <i>CDR1</i>, which encodes an ATP-binding cassette transporter protein thought to act as an FLC efflux pump. Mutations in the <i>PDR1</i> gene that render the transcription factor hyperactive are the most common cause of fluconazole resistance among clinical isolates. The phenothiazine class drug fluphenazine and a molecular derivative, CWHM-974, which both exhibit antifungal properties, have been shown to induce the expression of Cdr1 in <i>Candida</i> spp. We have used a firefly luciferase reporter gene driven by the <i>CDR1</i> promoter to demonstrate two distinct patterns of <i>CDR1</i> promoter activation kinetics: gradual promoter activation kinetics that occur in response to ergosterol limitations imposed by exposure to azole and polyene class antifungals and a robust and rapid <i>CDR1</i> induction occurring in response to the stress imposed by fluphenazines. We can attribute these different patterns of <i>CDR1</i> induction as proceeding through the promoter region of this gene since this is the only segment of the gene included in the luciferase reporter construct. Genetic analysis indicates that the signaling pathways responsible for phenothiazine and azole induction of <i>CDR1</i> overlap but are not identical. The short time course of phenothiazine induction suggests that these compounds may act more directly on the Pdr1 protein to stimulate its activity.</p><p><strong>Importance: </strong><i>Candida glabrata</i> has emerged as the second-leading cause of candidiasis due, in part, to its ability to acquire high-level resistance to azole drugs, a major class of antifungal that acts to block the biosynthesis of the fungal sterol ergosterol. The presence of azole drugs causes the induction of a variety of genes involved in controlling susceptibility to this drug class, including drug transporters and ergosterol biosynthetic genes such as ERG11. We found that the presence of azole drugs leads to an induction of genes encoding drug transporters and ERG11, while exposure of <i>C. glabrata</i> cells to antifungals of the phenothiazine class of drugs caused a much faster and larger induction of drug transporters but not ERG11. Coupled with further genetic analyses of the effects of azole and phenothiazine drugs, our data indicate that these compounds are sensed and responded to differentially in the yeast cell.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0079224"},"PeriodicalIF":3.7,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142648474","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":"Astragalus polysaccharide enhances maternal mucosal immunity against PEDV.","authors":"Jianli Tang, Shuaiyong Wang, Jianmei Tang, Jinming Li","doi":"10.1128/msphere.00777-24","DOIUrl":"https://doi.org/10.1128/msphere.00777-24","url":null,"abstract":"<p><p>Porcine epidemic diarrhea virus (PEDV), the major causative pathogen of porcine epidemic diarrhea, poses a severe threat to the swine industry, particularly affecting neonatal piglets. Maternal milk-derived IgA antibody is crucial for protecting piglets from PEDV infection. Despite the effectiveness of current intramuscularly administered PEDV vaccines in inducing strong systemic immune responses, their ability to generate high levels of maternal milk IgA is limited. This study explores the potential of Astragalus polysaccharide (APS) to enhance PEDV vaccine efficacy, specifically focusing on maternal milk IgA levels. We first evaluated anti-PEDV antibody levels in the blood and colostrum of sows vaccinated with PEDV or subjected to feedback feeding. Our results indicated that while vaccination induced robust serum PEDV-specific IgG and IgA, milk IgA levels were lower compared to the feedback group. To address this limitation, APS was administered orally to sows before PEDV vaccination. APS supplementation significantly increased both serum and milk PEDV-specific IgA levels and enhanced cellular immune responses, as evidenced by elevated cytokine levels. Further analysis demonstrated that APS improved intestinal immune function and homeostasis in piglets. Overall, APS supplementation proved to be an effective immune booster, enhancing PEDV vaccine-induced mucosal immunity and providing a promising strategy for improving maternal immunity and piglet protection against PEDV.</p><p><strong>Importance: </strong>This study highlights the limitations of current porcine epidemic diarrhea virus (PEDV) vaccines in inducing sufficient maternal milk IgA, which is crucial for protecting neonatal piglets. By supplementing Astragalus polysaccharide (APS) into the vaccination regimen, we demonstrated a significant enhancement in milk PEDV-specific IgA levels, as well as improved cellular immune responses. APS also bolstered intestinal immune function and homeostasis in piglets. These findings suggest that APS supplementation could serve as an immune booster to enhance maternal immunity, offering a promising approach to better protect piglets against PEDV.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0077724"},"PeriodicalIF":3.7,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142624646","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":"Exploring the genomic basis of Mpox virus-host transmission and pathogenesis.","authors":"Brayden Young, Stephanie N Seifert, Crystal Lawson, Heather Koehler","doi":"10.1128/msphere.00576-24","DOIUrl":"https://doi.org/10.1128/msphere.00576-24","url":null,"abstract":"<p><p>Mpox disease, caused by the monkeypox virus (MPXV), was recently classified as a public health emergency of international concern due to its high lethality and pandemic potential. MPXV is a zoonotic disease that emerged and is primarily spread by small rodents. Historically, it was considered mainly zoonotic and not likely to sustain human-to-human transmission. However, the worldwide outbreak of Clade IIb MPXV from 2020 to 2022 and ongoing Clade I MPXV epidemics in the Democratic Republic of the Congo and surrounding areas are a warning that human-adapted MPXVs will continually arise. Understanding the viral genetic determinants of host range, pathogenesis, and immune evasion is imperative for developing control strategies and predicting the future of Mpox. Here, we delve into the MPXV genome to detail genes involved in host immune evasion strategies for this zoonotic rodent-borne and human-circulating virus. We compare MPXV gene content to related Orthopoxviruses, which have narrow host ranges, to identify potential genes involved in species-specific pathogenesis and host tropism. In addition, we cover the key virulence factor differences that distinguish the MPXV clade lineages. Finally, we dissect how genomic reduction of Orthopoxviruses, through various molecular mechanisms, is contributing to the generation of novel MPXV lineages with increased human adaptation. This review aims to highlight gene content that defines the MPXV species, MPXV clades, and novel MPXV lineages that have culminated in this virus being elevated to a public health emergency of national concern.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0057624"},"PeriodicalIF":3.7,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142624648","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":"Recombinant chimeric horsepox virus (TNX-801) is attenuated relative to vaccinia virus strains in both <i>in vitro</i> and <i>in vivo</i> models.","authors":"Stephanie V Trefry, Mayanka Awasthi, Christy N Raney, Amy L Cregger, Chase A Gonzales, Brittney L Layton, Robert N Enamorado, Nelson A Martinez, Deborah S Gohegan, Masoudeh Masoud-Bahnamiri, Jennifer Y Cho, Dawn M Myscofski, Tinoush Moulaei, Natasza E Ziółkowska, Scott J Goebel, Seth Lederman, Sina Bavari, Farooq Nasar","doi":"10.1128/msphere.00265-24","DOIUrl":"https://doi.org/10.1128/msphere.00265-24","url":null,"abstract":"<p><p>Recombinant chimeric horsepox virus (TNX-801) is a preclinical vaccine in development against mpox and smallpox. In this report, we investigated the potential phenotypic differences in <i>in vitro</i> and <i>in vivo</i> models between TNX-801 and older vaccinia virus (VACV)-based vaccine strains (VACV-Lis and VACV-NYCBH) used in the eradication of smallpox as well as VACV-WR, VACV-IHD, and MVA. TNX-801 displayed a small plaque phenotype (~1-2 mm) in BSC-40 and Vero-E6 cells. Multi-step replication kinetics in immortalized nonhuman primate cell lines, and human primary cells from dermal and respiratory tracts yielded >10- to 100-fold lower infectious titers than the VACV strains. In addition, the infectious particle-to-genome copy ratio data suggests that TNX-801 genome packaging is ~10- to 100-fold less efficient than the VACV strains and the potential mechanism of TNX-801 attenuation is at the packaging/egress stage. Lastly, the susceptibility to VACV and TNX-801 infection of three new immunocompromised murine models (C56BL/6 <i>Ifnar</i>^-/-, C56BL/6 <i>Ifngr</i>^-/-, and C56BL/6 <i>Ifnar</i>^-/-/<i>Ifngr</i>^-/-) was investigated. VACV strains were able to produce severe disease including decrease in body weight and temperature, as well as lethality in murine models via the intraperitoneal or intranasal routes. In contrast to VACV strains, TNX-801 was unable to produce any disease in murine models. These data demonstrate that TNX-801 is >10- to 1,000-fold more attenuated compared to older VACV-based smallpox vaccine strains in human primary cell lines and immunocompromised mice.</p><p><strong>Importance: </strong>Variola and monkeypox viruses are medically important pathogens that can cause fatal human disease. The two FDA-approved vaccines, ACAM-2000 and JYNNEOS, have important advantages and disadvantages. ACAM-2000 offers durable immunity; however, it has high adverse event rates. In contrast, JYNNEOS has a safer profile but requires two doses 4-weeks apart to achieve comparable immunity. Consequently, there is a need for vaccines offering durable immunity via single immunization with minimal adverse events. TNX-801 is a preclinical stage vaccine that can stimulate potent immunity via a single dose and provides protection against lethal mpox disease in the nonhuman primate model. Here, we show that TNX-801 is >10- to 1,000-fold attenuated in <i>in vitro</i> and <i>in vivo</i> models including human primary cells and immunocompromised murine models than vaccine strains utilized in smallpox eradication. The natural attenuation of TNX-801 and its ability to induce protective immunity via a single vaccination are promising and warrants further development.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0026524"},"PeriodicalIF":3.7,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142624746","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":"Comparative genomics of obligate predatory bacteria belonging to phylum <i>Bdellovibrionota</i> highlights distribution and predicted functions of lineage-specific protein families.","authors":"Sidney C Davis, Joseph Cerra, Laura E Williams","doi":"10.1128/msphere.00680-24","DOIUrl":"https://doi.org/10.1128/msphere.00680-24","url":null,"abstract":"<p><p>Comparative genomics of predatory bacteria is important to understand their ecology and evolution and explore their potential to treat drug-resistant infections. We compared chromosomes of 18 obligate predators from phylum <i>Bdellovibrionota</i> (16 intraperiplasmic, two epibiotic) and 15 non-predatory bacteria. Phylogenetics of conserved single-copy genes and analysis of genome-wide average amino acid identity provide evidence for at least five <i>Bdellovibrio</i> species and support recent reclassifications of predatory taxa. To define shared and differential genome content, we grouped predicted protein sequences into gene clusters based on sequence similarity. Few gene clusters are shared by all 33 bacteria or all 18 predatory bacteria; however, we identified gene clusters conserved within lineages, such as intraperiplasmic <i>Bdellovibrio</i>, and not found in other bacteria. Many of these are predicted to function in cell envelope biogenesis, signal transduction, and other roles important for predatory lifestyles. Among intraperiplasmic <i>Bdellovibrio</i>, we detected high abundance of gene clusters predicted to encode transglycosylases, endopeptidases, and lysozymes, and we identified six gene clusters (amidase, L,D-transpeptidase, four transglycosylases) with evidence of recent gene duplication and gene family expansion. Focusing on peptidoglycan metabolism, we defined a suite of gene clusters that include peptidoglycan-degrading and -modifying enzymes and occur only in predatory bacteria, suggesting these proteins may have evolved activities specific to predation. Our analyses highlight key genome content differences between obligate predatory bacteria and non-predatory relatives and identify gene clusters that may encode enzymes adapted to predatory lifestyles. These lineage-specific proteins are strong candidates for functional characterization to clarify their role in predation.IMPORTANCEEvolution of predation as a bacterial lifestyle involves selective pressure on and adaptation of enzymes that contribute to killing and digestion of prey bacteria, in some cases from within the prey itself. Such enzymes are a hallmark of obligate predatory bacteria belonging to phylum <i>Bdellovibrionota</i>, which includes the well-studied predator <i>Bdellovibrio</i>. By comparing protein sequences of obligate predatory bacteria and their non-predatory relatives, we define key genome content differences that distinguish bacterial predators and identify lineage-specific enzymes that may have evolved unique activities due to selective pressures related to a predatory lifestyle. In addition to providing insights into the ecology and evolution of predatory bacteria, comparative genomics studies, like this, can inform efforts to develop predatory bacteria and/or their enzymes as potential biocontrol agents to combat drug-resistant bacterial infections.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0068024"},"PeriodicalIF":3.7,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142624647","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":"MecA in <i>Streptococcus mutans</i> is a multi-functional protein.","authors":"Kassapa Ellepola, Robert C Shields, Jessica K Kajfasz, Hua Zhang, Jose A Lemos, Hui Wu, Zezhang T Wen","doi":"10.1128/msphere.00308-24","DOIUrl":"https://doi.org/10.1128/msphere.00308-24","url":null,"abstract":"<p><p>Our recent studies have shown that deficiency of MecA in <i>Streptococcus mutans</i> significantly affects cell division, growth, and biofilm formation. In this study, an <i>in vitro</i> mixed-species model, proteomics, and affinity pull-down assays were used to further characterize the MecA-mediated regulation in <i>S. mutans</i>. The results showed that compared with the wild type, UA159, the <i>mecA</i> mutant significantly reduced its production of glucans and weakened its ability to facilitate mixed-species biofilm formation. Relative to the wild type, the <i>mecA</i> mutant also displayed unique characteristics, including colony morphology, growth rate, and biofilm formation that did not fully resemble any of the <i>clpP, clpX, clpE, clpCE,</i> and <i>clpC</i> individual or combinational mutants. Deletion of <i>mecA</i> was shown to result in alteration of >337 proteins, including down expression of GtfBC&D and adhesin P1. More than 277 proteins were differentially expressed in response to <i>clpP</i> deletion, including increased expression of GtfB. By cross-referencing the two proteomes, a distinctive set of proteins was found to be altered in the <i>mecA</i> mutant, indicating a ClpP-independent role of MecA in the regulation of <i>S. mutans</i>. When analyzed using affinity pull-down, ClpC, ClpX, ClpE, and CcpA were among the members identified in the MecA-associated complex. Further analysis using a bacterial two-hybrid system confirmed CcpA, ClpX, and ClpE as members of the MecA interactome. These results further suggest that MecA in <i>S. mutans</i> is more than an adapter of the Clp-proteolytic machinery, although the mechanism that underlies the Clp-independent regulation and its impact on <i>S. mutans</i> pathophysiology await further investigation.</p><p><strong>Importance: </strong>MecA is known as an adaptor protein that works in concerto with ATPase ClpC and protease ClpP in the regulated proteolysis machinery. The results presented here provide further evidence that MecA in <i>S. mutans</i>, a keystone cariogenic bacterium, plays a significant role in its ability to facilitate mixed-species biofilm formation, a trait critical to its cariogenicity. Proteomics analysis, along with affinity pull-down and bacterial two-hybrid system, further confirm that MecA can also regulate <i>S. mutans</i> physiology and biofilm formation through pathways independent of the Clp proteolytic machinery, although how it functions independently of Clp awaits further investigation.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0030824"},"PeriodicalIF":3.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142624693","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}