Alper Mutlu, Emily J Vanderpool, Kendra P Rumbaugh, Stephen P Diggle, Ashleigh S Griffin
Antimicrobial resistance poses an escalating global threat, rendering traditional drug development approaches increasingly ineffective. Thus, novel alternatives to antibiotic-based therapies are needed. Exploiting pathogen cooperation as a strategy for combating resistant infections has been proposed but lacks experimental validation. Empirical findings demonstrate the successful invasion of cooperating populations by non-cooperating cheats, effectively reducing virulence in vitro and in vivo. The idea of harnessing cooperative behaviours for therapeutic benefit involves exploitation of the invasive capabilities of cheats to drive medically beneficial traits into infecting populations of cells. In this study, we employed Pseudomonas aeruginosa quorum sensing cheats to drive antibiotic sensitivity into both in vitro and in vivo resistant populations. We demonstrated the successful invasion of cheats, followed by increased antibiotic effectiveness against cheat-invaded populations, thereby establishing an experimental proof of principle for the potential application of the Trojan strategy in fighting resistant infections.
{"title":"Exploiting cooperative pathogen behaviour for enhanced antibiotic potency: A Trojan horse approach.","authors":"Alper Mutlu, Emily J Vanderpool, Kendra P Rumbaugh, Stephen P Diggle, Ashleigh S Griffin","doi":"10.1099/mic.0.001454","DOIUrl":"10.1099/mic.0.001454","url":null,"abstract":"<p><p>Antimicrobial resistance poses an escalating global threat, rendering traditional drug development approaches increasingly ineffective. Thus, novel alternatives to antibiotic-based therapies are needed. Exploiting pathogen cooperation as a strategy for combating resistant infections has been proposed but lacks experimental validation. Empirical findings demonstrate the successful invasion of cooperating populations by non-cooperating cheats, effectively reducing virulence <i>in vitro</i> and <i>in vivo</i>. The idea of harnessing cooperative behaviours for therapeutic benefit involves exploitation of the invasive capabilities of cheats to drive medically beneficial traits into infecting populations of cells. In this study, we employed <i>Pseudomonas aeruginosa</i> quorum sensing cheats to drive antibiotic sensitivity into both <i>in vitro</i> and <i>in vivo</i> resistant populations. We demonstrated the successful invasion of cheats, followed by increased antibiotic effectiveness against cheat-invaded populations, thereby establishing an experimental proof of principle for the potential application of the Trojan strategy in fighting resistant infections.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11084615/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140874938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrew L Woodruff, Judith Berman, Matthew Anderson
The genetic background between strains of a single species and within a single strain lineage can significantly impact the expression of biological traits. This genetic variation may also reshape epigenetic mechanisms of cell identity and environmental responses that are controlled by interconnected transcriptional networks and chromatin-modifying enzymes. Histone deacetylases, including sirtuins, are critical regulators of chromatin state and have been directly implicated in governing the phenotypic transition between the 'sterile' white state and the mating-competent opaque state in Candida albicans, a common fungal commensal and pathogen of humans. Here, we found that a previously ambiguous role for the sirtuin SIR2 in C. albicans phenotypic switching is likely linked to the genetic background of mutant strains produced in the RM lineage of SC5314. SIR2 mutants in a specific lineage of BWP17 displayed increased frequencies of switching to the opaque state compared to the wild-type. Loss of SIR2 in other SC5314-derived backgrounds, including newly constructed BWP17 sir2Δ/Δ mutants, failed to recapitulate the increased white-opaque switching frequencies observed in the original BWP17 sir2Δ/Δ mutant background. Whole-genome sequencing revealed the presence of multiple imbalanced chromosomes and large loss of heterozygosity tracts that likely interact with SIR2 to increase phenotypic switching in this BWP17 sir2Δ/Δ mutant lineage. These genomic changes are not found in other SC5314-derived sir2Δ/Δ mutants that do not display increased opaque cell formation. Thus, complex karyotypes can emerge during strain construction that modify mutant phenotypes and highlight the importance of validating strain background when interpreting phenotypes.
{"title":"Strain background of <i>Candida albicans</i> interacts with <i>SIR2</i> to alter phenotypic switching.","authors":"Andrew L Woodruff, Judith Berman, Matthew Anderson","doi":"10.1099/mic.0.001444","DOIUrl":"10.1099/mic.0.001444","url":null,"abstract":"<p><p>The genetic background between strains of a single species and within a single strain lineage can significantly impact the expression of biological traits. This genetic variation may also reshape epigenetic mechanisms of cell identity and environmental responses that are controlled by interconnected transcriptional networks and chromatin-modifying enzymes. Histone deacetylases, including sirtuins, are critical regulators of chromatin state and have been directly implicated in governing the phenotypic transition between the 'sterile' white state and the mating-competent opaque state in <i>Candida albicans,</i> a common fungal commensal and pathogen of humans. Here, we found that a previously ambiguous role for the sirtuin <i>SIR2</i> in <i>C. albicans</i> phenotypic switching is likely linked to the genetic background of mutant strains produced in the RM lineage of SC5314. <i>SIR2</i> mutants in a specific lineage of BWP17 displayed increased frequencies of switching to the opaque state compared to the wild-type. Loss of <i>SIR2</i> in other SC5314-derived backgrounds, including newly constructed BWP17 <i>sir2</i>Δ/Δ mutants, failed to recapitulate the increased white-opaque switching frequencies observed in the original BWP17 <i>sir2</i>Δ/Δ mutant background. Whole-genome sequencing revealed the presence of multiple imbalanced chromosomes and large loss of heterozygosity tracts that likely interact with <i>SIR2</i> to increase phenotypic switching in this BWP17 <i>sir2</i>Δ/Δ mutant lineage. These genomic changes are not found in other SC5314-derived <i>sir2</i>Δ/Δ mutants that do not display increased opaque cell formation. Thus, complex karyotypes can emerge during strain construction that modify mutant phenotypes and highlight the importance of validating strain background when interpreting phenotypes.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10999749/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140040726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Stefano Freddi, Vaheesan Rajabal, Sasha G Tetu, Michael R Gillings, Anahit Penesyan
Integrons are genetic platforms that capture, rearrange and express mobile modules called gene cassettes. The best characterized gene cassettes encode antibiotic resistance, but the function of most integron gene cassettes remains unknown. Functional predictions suggest that many gene cassettes could encode proteins that facilitate interactions with other cells and with the extracellular environment. Because cell interactions are essential for biofilm stability, we sequenced gene cassettes from biofilms growing on the surface of the marine macroalgae Ulva australis and Sargassum linearifolium. Algal samples were obtained from coastal rock platforms around Sydney, Australia, using seawater as a control. We demonstrated that integrons in microbial biofilms did not sample genes randomly from the surrounding seawater, but harboured specific functions that potentially provided an adaptive advantage to both the bacterial cells in biofilm communities and their macroalgal host. Further, integron gene cassettes had a well-defined spatial distribution, suggesting that each bacterial biofilm acquired these genetic elements via sampling from a large but localized pool of gene cassettes. These findings suggest two forms of filtering: a selective acquisition of different integron-containing bacterial species into the distinct biofilms on Ulva and Sargassum surfaces, and a selective retention of unique populations of gene cassettes at each sampling location.
{"title":"Microbial biofilms on macroalgae harbour diverse integron gene cassettes.","authors":"Stefano Freddi, Vaheesan Rajabal, Sasha G Tetu, Michael R Gillings, Anahit Penesyan","doi":"10.1099/mic.0.001446","DOIUrl":"10.1099/mic.0.001446","url":null,"abstract":"<p><p>Integrons are genetic platforms that capture, rearrange and express mobile modules called gene cassettes. The best characterized gene cassettes encode antibiotic resistance, but the function of most integron gene cassettes remains unknown. Functional predictions suggest that many gene cassettes could encode proteins that facilitate interactions with other cells and with the extracellular environment. Because cell interactions are essential for biofilm stability, we sequenced gene cassettes from biofilms growing on the surface of the marine macroalgae <i>Ulva australis</i> and <i>Sargassum linearifolium</i>. Algal samples were obtained from coastal rock platforms around Sydney, Australia, using seawater as a control. We demonstrated that integrons in microbial biofilms did not sample genes randomly from the surrounding seawater, but harboured specific functions that potentially provided an adaptive advantage to both the bacterial cells in biofilm communities and their macroalgal host. Further, integron gene cassettes had a well-defined spatial distribution, suggesting that each bacterial biofilm acquired these genetic elements via sampling from a large but localized pool of gene cassettes. These findings suggest two forms of filtering: a selective acquisition of different integron-containing bacterial species into the distinct biofilms on <i>Ulva</i> and <i>Sargassum</i> surfaces, and a selective retention of unique populations of gene cassettes at each sampling location.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10963911/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140133109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yunhan Wu, Andrew Bell, Gavin H Thomas, David N Bolam, Frank Sargent, Nathalie Juge, Tracy Palmer, Emmanuele Severi
Sialic acid (Sia) transporters are critical to the capacity of host-associated bacteria to utilise Sia for growth and/or cell surface modification. While N-acetyl-neuraminic acid (Neu5Ac)-specific transporters have been studied extensively, little is known on transporters dedicated to anhydro-Sia forms such as 2,7-anhydro-Neu5Ac (2,7-AN) or 2,3-dehydro-2-deoxy-Neu5Ac (Neu5Ac2en). Here, we used a Sia-transport-null strain of Escherichia coli to investigate the function of members of anhydro-Sia transporter families previously identified by computational studies. First, we showed that the transporter NanG, from the Glycoside-Pentoside-Hexuronide:cation symporter family, is a specific 2,7-AN transporter, and identified by mutagenesis a crucial functional residue within the putative substrate-binding site. We then demonstrated that NanX transporters, of the Major Facilitator Superfamily, also only transport 2,7-AN and not Neu5Ac2en nor Neu5Ac. Finally, we provided evidence that SiaX transporters, of the Sodium-Solute Symporter superfamily, are promiscuous Neu5Ac/Neu5Ac2en transporters able to acquire either substrate equally well. The characterisation of anhydro-Sia transporters expands our current understanding of prokaryotic Sia metabolism within host-associated microbial communities.
唾液酸(Sia)转运体对于宿主相关细菌利用 Sia 进行生长和/或细胞表面修饰的能力至关重要。虽然对 N-乙酰神经氨酸(Neu5Ac)特异性转运体进行了广泛研究,但对 2,7-脱水-Neu5Ac(2,7-AN)或 2,3-脱水-2-脱氧-Neu5Ac(Neu5Ac2en)等脱水 Sia 形式专用转运体却知之甚少。在这里,我们利用一株 Sia 转运无效的大肠杆菌来研究之前通过计算研究发现的脱水-Sia 转运体家族成员的功能。首先,我们发现糖苷-戊糖苷-己糖醛酸:阳离子共转运体家族的转运体 NanG 是一种特异的 2,7-AN 转运体,并通过诱变确定了假定底物结合位点内的一个关键功能残基。然后,我们证明主要促进剂超家族的 NanX 转运体也只转运 2,7-AN 而不转运 Neu5Ac2en 或 Neu5Ac。最后,我们提供的证据表明,钠-溶质共转运超家族的 SiaX 转运体是 Neu5Ac/Neu5Ac2en 的杂交转运体,能够同样获取两种底物。无水 Sia 转运体的特征拓展了我们目前对宿主相关微生物群落中原核 Sia 代谢的了解。
{"title":"Characterisation of anhydro-sialic acid transporters from mucosa-associated bacteria.","authors":"Yunhan Wu, Andrew Bell, Gavin H Thomas, David N Bolam, Frank Sargent, Nathalie Juge, Tracy Palmer, Emmanuele Severi","doi":"10.1099/mic.0.001448","DOIUrl":"10.1099/mic.0.001448","url":null,"abstract":"<p><p>Sialic acid (Sia) transporters are critical to the capacity of host-associated bacteria to utilise Sia for growth and/or cell surface modification. While N-acetyl-neuraminic acid (Neu5Ac)-specific transporters have been studied extensively, little is known on transporters dedicated to anhydro-Sia forms such as 2,7-anhydro-Neu5Ac (2,7-AN) or 2,3-dehydro-2-deoxy-Neu5Ac (Neu5Ac2en). Here, we used a Sia-transport-null strain of <i>Escherichia coli</i> to investigate the function of members of anhydro-Sia transporter families previously identified by computational studies. First, we showed that the transporter NanG, from the Glycoside-Pentoside-Hexuronide:cation symporter family, is a specific 2,7-AN transporter, and identified by mutagenesis a crucial functional residue within the putative substrate-binding site. We then demonstrated that NanX transporters, of the Major Facilitator Superfamily, also only transport 2,7-AN and not Neu5Ac2en nor Neu5Ac. Finally, we provided evidence that SiaX transporters, of the Sodium-Solute Symporter superfamily, are promiscuous Neu5Ac/Neu5Ac2en transporters able to acquire either substrate equally well. The characterisation of anhydro-Sia transporters expands our current understanding of prokaryotic Sia metabolism within host-associated microbial communities.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10955332/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140133108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marco Chávez-Tinoco, Luis F García-Ortega, Eugenio Mancera
Candida maltosa is closely related to important pathogenic Candida species, especially C. tropicalis and C. albicans, but it has been rarely isolated from humans. For this reason, through comparative studies, it could be a powerful model to understand the genetic underpinnings of the pathogenicity of Candida species. Here, we generated a cohesive assembly of the C. maltosa genome and developed genetic engineering tools that will facilitate studying this species at a molecular level. We used a combination of short and long-read sequencing to build a polished genomic draft composed of 14 Mbp, 45 contigs and close to 5700 genes. This assembly represents a substantial improvement from the currently available sequences that are composed of thousands of contigs. Genomic comparison with C. albicans and C. tropicalis revealed a substantial reduction in the total number of genes in C. maltosa. However, gene loss seems not to be associated to the avirulence of this species given that most genes that have been previously associated with pathogenicity were also present in C. maltosa. To be able to edit the genome of C. maltosa we generated a set of triple auxotrophic strains so that gene deletions can be performed similarly to what has been routinely done in pathogenic Candida species. As a proof of concept, we generated gene knockouts of EFG1, a gene that encodes a transcription factor that is essential for filamentation and biofilm formation in C. albicans and C. tropicalis. Characterization of these mutants showed that Efg1 also plays a role in biofilm formation and filamentous growth in C. maltosa, but it seems to be a repressor of filamentation in this species. The genome assembly and auxotrophic mutants developed here are a key step forward to start using C. maltosa for comparative and evolutionary studies at a molecular level.
{"title":"Genetic modification of <i>Candida maltosa</i>, a non-pathogenic CTG species, reveals <i>EFG1</i> function.","authors":"Marco Chávez-Tinoco, Luis F García-Ortega, Eugenio Mancera","doi":"10.1099/mic.0.001447","DOIUrl":"10.1099/mic.0.001447","url":null,"abstract":"<p><p><i>Candida maltosa</i> is closely related to important pathogenic <i>Candida</i> species, especially <i>C. tropicalis</i> and <i>C. albicans,</i> but it has been rarely isolated from humans. For this reason, through comparative studies, it could be a powerful model to understand the genetic underpinnings of the pathogenicity of <i>Candida</i> species. Here, we generated a cohesive assembly of the <i>C. maltosa</i> genome and developed genetic engineering tools that will facilitate studying this species at a molecular level. We used a combination of short and long-read sequencing to build a polished genomic draft composed of 14 Mbp, 45 contigs and close to 5700 genes. This assembly represents a substantial improvement from the currently available sequences that are composed of thousands of contigs. Genomic comparison with <i>C. albicans</i> and <i>C. tropicalis</i> revealed a substantial reduction in the total number of genes in <i>C. maltosa</i>. However, gene loss seems not to be associated to the avirulence of this species given that most genes that have been previously associated with pathogenicity were also present in <i>C. maltosa</i>. To be able to edit the genome of <i>C. maltosa</i> we generated a set of triple auxotrophic strains so that gene deletions can be performed similarly to what has been routinely done in pathogenic <i>Candida</i> species. As a proof of concept, we generated gene knockouts of <i>EFG1,</i> a gene that encodes a transcription factor that is essential for filamentation and biofilm formation in <i>C. albicans</i> and <i>C. tropicalis</i>. Characterization of these mutants showed that Efg1 also plays a role in biofilm formation and filamentous growth in <i>C. maltosa</i>, but it seems to be a repressor of filamentation in this species. The genome assembly and auxotrophic mutants developed here are a key step forward to start using <i>C. maltosa</i> for comparative and evolutionary studies at a molecular level.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10999747/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140060995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jonas Devos, Patrick Van Dijck, Wouter Van Genechten
Fluorescent proteins (FPs) have always been a crucial part of molecular research in life sciences, including the research into the human fungal pathogen Candida albicans, but have obvious shortcomings such as their relatively large size and long maturation time. However, the next generation of FPs overcome these issues and rely on the binding of a fluorogen for the protein to become fluorescently active. This generation of FPs includes the improved version of Fluorescence activating and Absorption Shifting Tag (iFAST). The binding between the fluorogen and the iFAST protein is reversible, thus resulting in reversible fluorescence. The fluorogens of iFAST are analogues of 4-hydroxylbenzylidene-rhodanine (HBR). These HBR analogues differ in spectral properties depending on functional group substitutions, which gives the iFAST system flexibility in terms of absorbance and emission maxima. In this work we describe and illustrate the application of iFAST as a protein tag and its reversible multi-colour characteristics in C. albicans.
{"title":"A multi-colour fluorogenic tag and its application in <i>Candida albicans</i>.","authors":"Jonas Devos, Patrick Van Dijck, Wouter Van Genechten","doi":"10.1099/mic.0.001451","DOIUrl":"10.1099/mic.0.001451","url":null,"abstract":"<p><p>Fluorescent proteins (FPs) have always been a crucial part of molecular research in life sciences, including the research into the human fungal pathogen <i>Candida albicans,</i> but have obvious shortcomings such as their relatively large size and long maturation time. However, the next generation of FPs overcome these issues and rely on the binding of a fluorogen for the protein to become fluorescently active. This generation of FPs includes the improved version of Fluorescence activating and Absorption Shifting Tag (iFAST). The binding between the fluorogen and the iFAST protein is reversible, thus resulting in reversible fluorescence. The fluorogens of iFAST are analogues of 4-hydroxylbenzylidene-rhodanine (HBR). These HBR analogues differ in spectral properties depending on functional group substitutions, which gives the iFAST system flexibility in terms of absorbance and emission maxima. In this work we describe and illustrate the application of iFAST as a protein tag and its reversible multi-colour characteristics in <i>C. albicans</i>.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10995450/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140295125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lipopolysaccharide (LPS) is a fundamental tripartite glycolipid found on the surface of nearly all Gram-negative bacteria. It acts as a protective shield for the bacterial cell and is a potent agonist of the innate immune system. This primer serves to introduce the basic properties of LPS, its function in bacterial physiology and pathogenicity, and its use as a therapeutic target.
{"title":"Microbial Primer: Lipopolysaccharide - a remarkable component of the Gram-negative bacterial surface.","authors":"Leah M VanOtterloo, M Stephen Trent","doi":"10.1099/mic.0.001439","DOIUrl":"10.1099/mic.0.001439","url":null,"abstract":"<p><p>Lipopolysaccharide (LPS) is a fundamental tripartite glycolipid found on the surface of nearly all Gram-negative bacteria. It acts as a protective shield for the bacterial cell and is a potent agonist of the innate immune system. This primer serves to introduce the basic properties of LPS, its function in bacterial physiology and pathogenicity, and its use as a therapeutic target.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10999752/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140050845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ashley M Alexander, Justin M Luu, Vishnu Raghuram, Giulia Bottacin, Simon van Vliet, Timothy D Read, Joanna B Goldberg
When cultured together under standard laboratory conditions Pseudomonas aeruginosa has been shown to be an effective inhibitor of Staphylococcus aureus. However, P. aeruginosa and S. aureus are commonly observed in coinfections of individuals with cystic fibrosis (CF) and in chronic wounds. Previous work from our group revealed that S. aureus isolates from CF infections are able to persist in the presence of P. aeruginosa strain PAO1 with a range of tolerances with some isolates being eliminated entirely and others maintaining large populations. In this study, we designed a serial transfer, evolution experiment to identify mutations that allow S. aureus to survive in the presence of P. aeruginosa. Using S. aureus USA300 JE2 as our ancestral strain, populations of S. aureus were repeatedly cocultured with fresh P. aeruginosa PAO1. After eight coculture periods, S. aureus populations that survived better in the presence of PAO1 were observed. We found two independent mutations in the highly conserved S. aureus aspartate transporter, gltT, that were unique to evolved P. aeruginosa-tolerant isolates. Subsequent phenotypic testing demonstrated that gltT mutants have reduced uptake of glutamate and outcompeted wild-type S. aureus when glutamate was absent from chemically defined media. These findings together demonstrate that the presence of P. aeruginosa exerts selective pressure on S. aureus to alter its uptake and metabolism of key amino acids when the two are cultured together.
{"title":"Experimentally evolved <i>Staphylococcus aureus</i> shows increased survival in the presence of <i>Pseudomonas aeruginosa</i> by acquiring mutations in the amino acid transporter, GltT.","authors":"Ashley M Alexander, Justin M Luu, Vishnu Raghuram, Giulia Bottacin, Simon van Vliet, Timothy D Read, Joanna B Goldberg","doi":"10.1099/mic.0.001445","DOIUrl":"10.1099/mic.0.001445","url":null,"abstract":"<p><p>When cultured together under standard laboratory conditions <i>Pseudomonas aeruginosa</i> has been shown to be an effective inhibitor of <i>Staphylococcus aureus</i>. However, <i>P. aeruginosa</i> and <i>S. aureus</i> are commonly observed in coinfections of individuals with cystic fibrosis (CF) and in chronic wounds. Previous work from our group revealed that <i>S. aureus</i> isolates from CF infections are able to persist in the presence of <i>P. aeruginosa</i> strain PAO1 with a range of tolerances with some isolates being eliminated entirely and others maintaining large populations. In this study, we designed a serial transfer, evolution experiment to identify mutations that allow <i>S. aureus</i> to survive in the presence of <i>P. aeruginosa</i>. Using <i>S. aureus</i> USA300 JE2 as our ancestral strain, populations of <i>S. aureus</i> were repeatedly cocultured with fresh <i>P. aeruginosa</i> PAO1. After eight coculture periods, <i>S. aureus</i> populations that survived better in the presence of PAO1 were observed. We found two independent mutations in the highly conserved <i>S. aureus</i> aspartate transporter, <i>gltT</i>, that were unique to evolved <i>P. aeruginosa</i>-tolerant isolates. Subsequent phenotypic testing demonstrated that <i>gltT</i> mutants have reduced uptake of glutamate and outcompeted wild-type <i>S. aureus</i> when glutamate was absent from chemically defined media. These findings together demonstrate that the presence of <i>P. aeruginosa</i> exerts selective pressure on <i>S. aureus</i> to alter its uptake and metabolism of key amino acids when the two are cultured together.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10999751/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139998104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
María Antonia Molina-Henares, María Isabel Ramos-González, Serena Rinaldo, Manuel Espinosa-Urgel
Different bacteria change their life styles in response to specific amino acids. In Pseudomonas putida (now alloputida) KT2440, arginine acts both as an environmental and a metabolic indicator that modulates the turnover of the intracellular second messenger c-di-GMP, and expression of biofilm-related genes. The transcriptional regulator ArgR, belonging to the AraC/XylS family, is key for the physiological reprogramming in response to arginine, as it controls transport and metabolism of the amino acid. To further expand our knowledge on the roles of ArgR, a global transcriptomic analysis of KT2440 and a null argR mutant growing in the presence of arginine was carried out. Results indicate that this transcriptional regulator influences a variety of cellular functions beyond arginine metabolism and transport, thus widening its regulatory role. ArgR acts as positive or negative modulator of the expression of several metabolic routes and transport systems, respiratory chain and stress response elements, as well as biofilm-related functions. The partial overlap between the ArgR regulon and those corresponding to the global regulators RoxR and ANR is also discussed.
{"title":"Gene expression reprogramming of <i>Pseudomonas alloputida</i> in response to arginine through the transcriptional regulator ArgR.","authors":"María Antonia Molina-Henares, María Isabel Ramos-González, Serena Rinaldo, Manuel Espinosa-Urgel","doi":"10.1099/mic.0.001449","DOIUrl":"10.1099/mic.0.001449","url":null,"abstract":"<p><p>Different bacteria change their life styles in response to specific amino acids. In <i>Pseudomonas putida</i> (now <i>alloputida</i>) KT2440, arginine acts both as an environmental and a metabolic indicator that modulates the turnover of the intracellular second messenger c-di-GMP, and expression of biofilm-related genes. The transcriptional regulator ArgR, belonging to the AraC/XylS family, is key for the physiological reprogramming in response to arginine, as it controls transport and metabolism of the amino acid. To further expand our knowledge on the roles of ArgR, a global transcriptomic analysis of KT2440 and a null <i>argR</i> mutant growing in the presence of arginine was carried out. Results indicate that this transcriptional regulator influences a variety of cellular functions beyond arginine metabolism and transport, thus widening its regulatory role. ArgR acts as positive or negative modulator of the expression of several metabolic routes and transport systems, respiratory chain and stress response elements, as well as biofilm-related functions. The partial overlap between the ArgR regulon and those corresponding to the global regulators RoxR and ANR is also discussed.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10963909/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140177408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P B Leung, X M Matanza, B Roche, K P Ha, H C Cheung, S Appleyard, T Collins, O Flanagan, B S Marteyn, A Clements
The mammalian colon is one of the most densely populated habitats currently recognised, with 1011-1013 commensal bacteria per gram of colonic contents. Enteric pathogens must compete with the resident intestinal microbiota to cause infection. Among these enteric pathogens are Shigella species which cause approximately 125 million infections annually, of which over 90 % are caused by Shigella flexneri and Shigella sonnei. Shigella sonnei was previously reported to use a Type VI Secretion System (T6SS) to outcompete E. coli and S. flexneri in in vitro and in vivo experiments. S. sonnei strains have also been reported to harbour colicinogenic plasmids, which are an alternative anti-bacterial mechanism that could provide a competitive advantage against the intestinal microbiota. We sought to determine the contribution of both T6SS and colicins to the anti-bacterial killing activity of S. sonnei. We reveal that whilst the T6SS operon is present in S. sonnei, there is evidence of functional degradation of the system through SNPs, indels and IS within key components of the system. We created strains with synthetically inducible T6SS operons but were still unable to demonstrate anti-bacterial activity of the T6SS. We demonstrate that the anti-bacterial activity observed in our in vitro assays was due to colicin activity. We show that S. sonnei no longer displayed anti-bacterial activity against bacteria that were resistant to colicins, and removal of the colicin plasmid from S. sonnei abrogated anti-bacterial activity of S. sonnei. We propose that the anti-bacterial activity demonstrated by colicins may be sufficient for niche competition by S. sonnei within the gastrointestinal environment.
哺乳动物结肠是目前公认的菌群最密集的栖息地之一,每克结肠内容物中有 1011-1013 个共生细菌。肠道病原体必须与常驻肠道微生物群竞争才能引起感染。在这些肠道病原体中,志贺氏菌每年造成约 1.25 亿例感染,其中 90% 以上是由柔性志贺氏菌和松内志贺氏菌引起的。此前有报道称,在体外和体内实验中,子内志贺氏菌利用 VI 型分泌系统(T6SS)战胜了大肠杆菌和柔嫩志贺氏菌。也有报道称 S. sonnei 菌株携带致大肠杆菌素质粒,这是一种替代性抗菌机制,可提供对肠道微生物群的竞争优势。我们试图确定 T6SS 和大肠杆菌素对 S. sonnei 抗菌杀菌活性的贡献。我们发现,虽然在宋内氏杆菌中存在 T6SS 操作子,但有证据表明,通过 SNPs、吲哚和该系统关键部件中的 IS,该系统的功能已经退化。我们创建了具有合成诱导 T6SS 操作子的菌株,但仍无法证明 T6SS 的抗菌活性。我们证明,在体外实验中观察到的抗菌活性是由大肠杆菌素活性引起的。我们发现,宋内氏菌不再对对大肠杆菌素有抗性的细菌具有抗菌活性,而且从宋内氏菌中移除大肠杆菌素质粒也会削弱宋内氏菌的抗菌活性。我们认为,大肠杆菌素所表现出的抗菌活性可能足以使儿子弧菌在胃肠道环境中进行生态位竞争。
{"title":"<i>Shigella sonnei</i> utilises colicins during inter-bacterial competition.","authors":"P B Leung, X M Matanza, B Roche, K P Ha, H C Cheung, S Appleyard, T Collins, O Flanagan, B S Marteyn, A Clements","doi":"10.1099/mic.0.001434","DOIUrl":"10.1099/mic.0.001434","url":null,"abstract":"<p><p>The mammalian colon is one of the most densely populated habitats currently recognised, with 10<sup>11</sup>-10<sup>13</sup> commensal bacteria per gram of colonic contents. Enteric pathogens must compete with the resident intestinal microbiota to cause infection. Among these enteric pathogens are <i>Shigella</i> species which cause approximately 125 million infections annually, of which over 90 % are caused by <i>Shigella flexneri</i> and <i>Shigella sonnei. Shigella sonnei</i> was previously reported to use a Type VI Secretion System (T6SS) to outcompete <i>E. coli</i> and <i>S. flexneri</i> in <i>in vitro</i> and <i>in vivo</i> experiments. <i>S. sonnei</i> strains have also been reported to harbour colicinogenic plasmids, which are an alternative anti-bacterial mechanism that could provide a competitive advantage against the intestinal microbiota. We sought to determine the contribution of both T6SS and colicins to the anti-bacterial killing activity of <i>S. sonnei</i>. We reveal that whilst the T6SS operon is present in <i>S. sonnei,</i> there is evidence of functional degradation of the system through SNPs, indels and IS within key components of the system. We created strains with synthetically inducible T6SS operons but were still unable to demonstrate anti-bacterial activity of the T6SS. We demonstrate that the anti-bacterial activity observed in our <i>in vitro</i> assays was due to colicin activity. We show that <i>S. sonnei</i> no longer displayed anti-bacterial activity against bacteria that were resistant to colicins, and removal of the colicin plasmid from <i>S. sonnei</i> abrogated anti-bacterial activity of <i>S. sonnei</i>. We propose that the anti-bacterial activity demonstrated by colicins may be sufficient for niche competition by <i>S. sonnei</i> within the gastrointestinal environment.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924462/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139906758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}