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Marreddy RKR, Phelps GA, Churion K, Picker J, Powell R, Cherian PT, Bowling JJ, Stephan CC, Lee RE, Hurdle JG. Chemical genetic analysis of enoxolone inhibition of C. difficile toxin production reveals adenine deaminase and ATP synthase as anti-virulence targets. J Biol Chem 2024:107839. [PMID: 39343002 DOI: 10.1016/j.jbc.2024.107839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Revised: 09/06/2024] [Accepted: 09/20/2024] [Indexed: 10/01/2024] Open
Abstract
Toxins TcdA and TcdB are the main virulence factors of Clostridioides difficile, a leading cause of hospital-acquired diarrhea. Despite their importance, there is a significant knowledge gap of druggable targets for inhibiting toxin production. To address this, we screened non-antibiotic phytochemicals to identify potential chemical genetic probes to discover anti-virulence drug targets. This led to the identification of 18β-glycyrrhetinic acid (enoxolone), a licorice metabolite, as an inhibitor of TcdA and TcdB biosynthesis. Using affinity-based proteomics, potential targets were identified as ATP synthase subunit alpha (AtpA) and adenine deaminase (Ade, which catalyzes conversion of adenine to hypoxanthine in the purine salvage pathway). To validate these targets, a multi-faceted approach was adopted. Gene silencing of ade and atpA inhibited toxin biosynthesis, while SPR and ITC molecular interaction analyses revealed direct binding of enoxolone to Ade. Metabolomics demonstrated enoxolone induced the accumulation of adenosine, while depleting hypoxanthine and ATP in C. difficile. Transcriptomics further revealed enoxolone dysregulated phosphate uptake genes, which correlated with reduced cellular phosphate levels. These findings suggest that enoxolone's cellular action is multi-targeted. Accordingly, supplementation with both hypoxanthine and triethyl phosphate (TEP), a phosphate source, was required to fully restore toxin production in the presence of enoxolone. In conclusion, through the characterization of enoxolone, we identified promising anti-virulence targets that interfere with nucleotide salvage and ATP synthesis, which may also block toxin biosynthesis.
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Affiliation(s)
- Ravi K R Marreddy
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA
| | - Gregory A Phelps
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA; Graduate School of Biomedical Sciences, St. Jude Children's Research Hospital, Memphis TN, 38103 USA
| | - Kelly Churion
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA
| | - Jonathan Picker
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA
| | - Reid Powell
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA
| | - Philip T Cherian
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - John J Bowling
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Clifford C Stephan
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA
| | - Richard E Lee
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Julian G Hurdle
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA.
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2
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Peng Y, Moffat JG, DuPai C, Kofoed EM, Skippington E, Modrusan Z, Gloor SL, Clark K, Xu Y, Li S, Chen L, Liu X, Wu P, Harris SF, Wang S, Crawford TD, Li CS, Liu Z, Wai J, Tan MW. Differential effects of inosine monophosphate dehydrogenase (IMPDH/GuaB) inhibition in Acinetobacter baumannii and Escherichia coli. J Bacteriol 2024:e0010224. [PMID: 39235234 DOI: 10.1128/jb.00102-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 07/25/2024] [Indexed: 09/06/2024] Open
Abstract
Inosine 5'-monophosphate dehydrogenase (IMPDH), known as GuaB in bacteria, catalyzes the rate-limiting step in de novo guanine biosynthesis and is conserved from humans to bacteria. We developed a series of potent inhibitors that selectively target GuaB over its human homolog. Here, we show that these GuaB inhibitors are bactericidal, generate phenotypic signatures that are distinct from other antibiotics, and elicit different time-kill kinetics and regulatory responses in two important Gram-negative pathogens: Acinetobacter baumannii and Escherichia coli. Specifically, the GuaB inhibitor G6 rapidly kills A. baumannii but only kills E. coli after 24 h. After exposure to G6, the expression of genes involved in purine biosynthesis and stress responses change in opposite directions while siderophore biosynthesis is downregulated in both species. Our results suggest that different species respond to GuaB inhibition using distinct regulatory programs and possibly explain the different bactericidal kinetics upon GuaB inhibition. The comparison highlights opportunities for developing GuaB inhibitors as novel antibiotics.IMPORTANCEA. baumannii is a priority bacterial pathogen for which development of new antibiotics is urgently needed due to the emergence of multidrug resistance. We recently developed a series of specific inhibitors against GuaB, a bacterial inosine 5'-monophosphate dehydrogenase, and achieved sub-micromolar minimum inhibitory concentrations against A. baumannii. GuaB catalyzes the rate-limiting step of de novo guanine biosynthesis and is highly conserved across bacterial pathogens. This study shows that inhibition of GuaB induced a bacterial morphological profile distinct from that of other classes of antibiotics, highlighting a novel mechanism of action. Moreover, our transcriptomic analysis showed that regulation of de novo purine biosynthesis and stress responses of A. baumannii upon GuaB inhibition differed significantly from that of E. coli.
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Affiliation(s)
- Yutian Peng
- Department of Infectious Diseases, Genentech Inc., South San Francisco, California, USA
| | - John G Moffat
- Department of Biochemical and Cellular Pharmacology, Genentech Inc., South San Francisco, California, USA
| | - Cory DuPai
- Department of Bioinformatics, Genentech Inc., South San Francisco, California, USA
| | - Eric M Kofoed
- Department of Infectious Diseases, Genentech Inc., South San Francisco, California, USA
| | | | - Zora Modrusan
- Department of Proteomic and Genomic Technologies, Genentech Inc., South San Francisco, California, USA
| | - Susan L Gloor
- Department of Biochemical and Cellular Pharmacology, Genentech Inc., South San Francisco, California, USA
| | - Kevin Clark
- Department of Biochemical and Cellular Pharmacology, Genentech Inc., South San Francisco, California, USA
| | - Yiming Xu
- Department of Biochemical and Cellular Pharmacology, Genentech Inc., South San Francisco, California, USA
| | - Shuxuan Li
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Liuxi Chen
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Xingrong Liu
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Ping Wu
- Department of Structural Biology, Genentech Inc., South San Francisco, California, USA
| | - Seth F Harris
- Department of Structural Biology, Genentech Inc., South San Francisco, California, USA
| | - Shumei Wang
- Department of Discovery Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Terry D Crawford
- Department of Discovery Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Chun Sing Li
- WuXi AppTec Co., Ltd., Waigaoqiao Free Trade Zone, Shanghai, China
| | - Zhiguo Liu
- WuXi AppTec Co., Ltd., Waigaoqiao Free Trade Zone, Shanghai, China
| | - John Wai
- WuXi AppTec Co., Ltd., Waigaoqiao Free Trade Zone, Shanghai, China
| | - Man-Wah Tan
- Department of Infectious Diseases, Genentech Inc., South San Francisco, California, USA
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3
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Kofoed EM, Aliagas I, Crawford T, Mao J, Harris SF, Xu M, Wang S, Wu P, Ma F, Clark K, Sims J, Xu Y, Peng Y, Skippington E, Yang Y, Reeder J, Ubhayakar S, Baumgardner M, Yan Z, Chen J, Park S, Zhang H, Yen CW, Lorenzo M, Skelton N, Liang X, Chen L, Hoag B, Li CS, Liu Z, Wai J, Liu X, Liang J, Tan MW. Discovery of GuaB inhibitors with efficacy against Acinetobacter baumannii infection. mBio 2024:e0089724. [PMID: 39207111 DOI: 10.1128/mbio.00897-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Accepted: 07/25/2024] [Indexed: 09/04/2024] Open
Abstract
Guanine nucleotides are required for growth and viability of cells due to their structural role in DNA and RNA, and their regulatory roles in translation, signal transduction, and cell division. The natural antibiotic mycophenolic acid (MPA) targets the rate-limiting step in de novo guanine nucleotide biosynthesis executed by inosine-5´-monophosphate dehydrogenase (IMPDH). MPA is used clinically as an immunosuppressant, but whether in vivo inhibition of bacterial IMPDH (GuaB) is a valid antibacterial strategy is controversial. Here, we describe the discovery of extremely potent small molecule GuaB inhibitors (GuaBi) specific to pathogenic bacteria with a low frequency of on-target spontaneous resistance and bactericidal efficacy in vivo against Acinetobacter baumannii mouse models of infection. The spectrum of GuaBi activity includes multidrug-resistant pathogens that are a critical priority of new antibiotic development. Co-crystal structures of A. baumannii, Staphylococcus aureus, and Escherichia coli GuaB proteins bound to inhibitors show comparable binding modes of GuaBi across species and identifies key binding site residues that are predictive of whole-cell activity across both Gram-positive and Gram-negative clades of Bacteria. The clear in vivo efficacy of these small molecule GuaB inhibitors in a model of A. baumannii infection validates GuaB as an essential antibiotic target. IMPORTANCE The emergence of multidrug-resistant bacteria worldwide has renewed interest in discovering antibiotics with novel mechanism of action. For the first time ever, we demonstrate that pharmacological inhibition of de novo guanine biosynthesis is bactericidal in a mouse model of Acinetobacter baumannii infection. Structural analyses of novel inhibitors explain differences in biochemical and whole-cell activity across bacterial clades and underscore why this discovery may have broad translational impact on treatment of the most recalcitrant bacterial infections.
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Affiliation(s)
- Eric M Kofoed
- Department of Infectious Diseases, Genentech Inc., South San Francisco, California, USA
| | - Ignacio Aliagas
- Department of Discovery Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Terry Crawford
- Department of Medicinal Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Jialin Mao
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Seth F Harris
- Department of Structural Biology, Genentech Inc., South San Francisco, California, USA
| | - Min Xu
- Department of Translational Immunology, Genentech Inc., South San Francisco, California, USA
| | - Shumei Wang
- Department of Medicinal Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Ping Wu
- Department of Structural Biology, Genentech Inc., South San Francisco, California, USA
| | - Fang Ma
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Kevin Clark
- Department of Biochemistry and Cellular Pharmacology, Genentech Inc., South San Francisco, California, USA
| | - Jessica Sims
- Department of Developmental Sciences Safety Assessment, Genentech Inc., South San Francisco, California, USA
| | - Yiming Xu
- Department of Biochemistry and Cellular Pharmacology, Genentech Inc., South San Francisco, California, USA
| | - Yutian Peng
- Department of Infectious Diseases, Genentech Inc., South San Francisco, California, USA
| | | | - Ying Yang
- Department of Discovery Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Janina Reeder
- Department of Bioinformatics, Genentech Inc., South San Francisco, California, USA
| | - Savita Ubhayakar
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Matt Baumgardner
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Zhengyin Yan
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Jacob Chen
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Summer Park
- Department of Translational Immunology, Genentech Inc., South San Francisco, California, USA
| | - Hua Zhang
- Department of Translational Immunology, Genentech Inc., South San Francisco, California, USA
| | - Chun-Wan Yen
- Department of Small Molecule Pharmaceutical Science, Genentech Inc., South San Francisco, California, USA
| | - Maria Lorenzo
- Department of Protein Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Nicholas Skelton
- Department of Discovery Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Xiaorong Liang
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Liuxi Chen
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Bridget Hoag
- Department of Biochemistry and Cellular Pharmacology, Genentech Inc., South San Francisco, California, USA
| | | | | | - John Wai
- WuXi AppTec Co., Ltd., Shanghai, China
| | - Xingrong Liu
- Department of Drug Metabolism and Pharmacokinetics, Genentech Inc., South San Francisco, California, USA
| | - Jun Liang
- Department of Medicinal Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Man Wah Tan
- Department of Infectious Diseases, Genentech Inc., South San Francisco, California, USA
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4
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Reed P, Sorg M, Alwardt D, Serra L, Veiga H, Schäper S, Pinho MG. A CRISPRi-based genetic resource to study essential Staphylococcus aureus genes. mBio 2024; 15:e0277323. [PMID: 38054745 PMCID: PMC10870820 DOI: 10.1128/mbio.02773-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 10/19/2023] [Indexed: 12/07/2023] Open
Abstract
IMPORTANCE Staphylococcus aureus is an important clinical pathogen that causes a high number of antibiotic-resistant infections. The study of S. aureus biology, and particularly of the function of essential proteins, is of particular importance to develop new approaches to combat this pathogen. We have optimized a clustered regularly interspaced short palindromic repeat interference (CRISPRi) system that allows efficient targeting of essential S. aureus genes. Furthermore, we have used that system to construct a library comprising 261 strains, which allows the depletion of essential proteins encoded by 200 genes/operons. This library, which we have named Lisbon CRISPRi Mutant Library, should facilitate the study of S. aureus pathogenesis and biology.
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Affiliation(s)
- Patricia Reed
- Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Moritz Sorg
- Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Dominik Alwardt
- Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Lúcia Serra
- Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Helena Veiga
- Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Simon Schäper
- Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Mariana G. Pinho
- Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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5
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Pavlova N, Traykovska M, Penchovsky R. Targeting FMN, TPP, SAM-I, and glmS Riboswitches with Chimeric Antisense Oligonucleotides for Completely Rational Antibacterial Drug Development. Antibiotics (Basel) 2023; 12:1607. [PMID: 37998809 PMCID: PMC10668854 DOI: 10.3390/antibiotics12111607] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/05/2023] [Accepted: 11/07/2023] [Indexed: 11/25/2023] Open
Abstract
Antimicrobial drug resistance has emerged as a significant challenge in contemporary medicine due to the proliferation of numerous bacterial strains resistant to all existing antibiotics. Meanwhile, riboswitches have emerged as promising targets for discovering antibacterial drugs. Riboswitches are regulatory elements in certain bacterial mRNAs that can bind to specific molecules and control gene expression via transcriptional termination, prevention of translation, or mRNA destabilization. By targeting riboswitches, we aim to develop innovative strategies to combat antibiotic-resistant bacteria and enhance the efficacy of antibacterial treatments. This convergence of challenges and opportunities underscores the ongoing quest to revolutionize medical approaches against evolving bacterial threats. For the first time, this innovative review describes the rational design and applications of chimeric antisense oligonucleotides as antibacterial agents targeting four riboswitches selected based on genome-wide bioinformatic analyses. The antisense oligonucleotides are coupled with the cell-penetrating oligopeptide pVEC, which penetrates Gram-positive and Gram-negative bacteria and specifically targets glmS, FMN, TPP, and SAM-I riboswitches in Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli. The average antibiotic dosage of antisense oligonucleotides that inhibits 80% of bacterial growth is around 700 nM (4.5 μg/mL). Antisense oligonucleotides do not exhibit toxicity in human cell lines at this concentration. The results demonstrate that these riboswitches are suitable targets for antibacterial drug development using antisense oligonucleotide technology. The approach is fully rational because selecting suitable riboswitch targets and designing ASOs that target them are based on predefined criteria. The approach can be used to develop narrow or broad-spectrum antibiotics against multidrug-resistant bacterial strains for a short time. The approach is easily adaptive to new resistance using targeting NGS technology.
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Affiliation(s)
| | | | - Robert Penchovsky
- Laboratory of Synthetic Biology and Bioinformatics, Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Blvd., 1164 Sofia, Bulgaria
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6
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Li C, Yin L, He X, Jin Y, Zhu X, Wu R. Competition-cooperation mechanism between Escherichia coli and Staphylococcus aureus based on systems mapping. Front Microbiol 2023; 14:1192574. [PMID: 38029174 PMCID: PMC10657823 DOI: 10.3389/fmicb.2023.1192574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 10/23/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction Interspecies interactions are a crucial driving force of species evolution. The genes of each coexisting species play a pivotal role in shaping the structure and function within the community, but how to identify them at the genome-wide level has always been challenging. Methods In this study, we embed the Lotka-Volterra ordinary differential equations in the theory of community ecology into the systems mapping model, so that this model can not only describe how the quantitative trait loci (QTL) of a species directly affects its own phenotype, but also describe the QTL of the species how to indirectly affect the phenotype of its interacting species, and how QTL from different species affects community behavior through epistatic interactions. Results By designing and implementing a co-culture experiment for 100 pairs of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), we mapped 244 significant QTL combinations in the interaction process of the two bacteria using this model, including 69 QTLs from E. coli and 59 QTLs from S. aureus, respectively. Through gene annotation, we obtained 57 genes in E. coli, among which the genes with higher frequency were ypdC, nrfC, yphH, acrE, dcuS, rpnE, and ptsA, while we obtained 43 genes in S. aureus, among which the genes with higher frequency were ebh, SAOUHSC_00172, capF, gdpP, orfX, bsaA, and phnE1. Discussion By dividing the overall growth into independent growth and interactive growth, we could estimate how QTLs modulate interspecific competition and cooperation. Based on the quantitative genetic model, we can obtain the direct genetic effect, indirect genetic effect, and genome-genome epistatic effect related to interspecific interaction genes, and then further mine the hub genes in the QTL networks, which will be particularly useful for inferring and predicting the genetic mechanisms of community dynamics and evolution. Systems mapping can provide a tool for studying the mechanism of competition and cooperation among bacteria in co-culture, and this framework can lay the foundation for a more comprehensive and systematic study of species interactions.
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Affiliation(s)
- Caifeng Li
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
| | - Lixin Yin
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
| | - Xiaoqing He
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing, China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology, Laboratory of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Yi Jin
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing, China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology, Laboratory of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Xuli Zhu
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing, China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology, Laboratory of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Rongling Wu
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing, China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology, Laboratory of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
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7
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Millette G, Lacasse E, Binette R, Belley V, Chaumont LP, Ster C, Beaudry F, Boyapelly K, Boudreault PL, Malouin F. Rationally Designed Pyrimidine Compounds: Promising Novel Antibiotics for the Treatment of Staphylococcus aureus-Associated Bovine Mastitis. Antibiotics (Basel) 2023; 12:1344. [PMID: 37627764 PMCID: PMC10451377 DOI: 10.3390/antibiotics12081344] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/18/2023] [Accepted: 08/19/2023] [Indexed: 08/27/2023] Open
Abstract
Staphylococcus aureus is one of the major pathogens causing bovine mastitis, and antibiotic treatment is most often inefficient due to its virulence and antibiotic-resistance attributes. The development of new antibiotics for veterinary use should account for the One Health concept, in which humans, animals, and environmental wellbeing are all interconnected. S. aureus can infect cattle and humans alike and antibiotic resistance can impact both if the same classes of antibiotics are used. New effective antibiotic classes against S. aureus are thus needed in dairy farms. We previously described PC1 as a novel antibiotic, which binds the S. aureus guanine riboswitch and interrupts transcription of essential GMP synthesis genes. However, chemical instability of PC1 hindered its development, evaluation, and commercialization. Novel PC1 analogs with improved stability have now been rationally designed and synthesized, and their in vitro and in vivo activities have been evaluated. One of these novel compounds, PC206, remains stable in solution and demonstrates specific narrow-spectrum activity against S. aureus. It is active against biofilm-embedded S. aureus, its cytotoxicity profile is adequate, and in vivo tests in mice and cows show that it is effective and well tolerated. PC206 and structural analogs represent a promising new antibiotic class to treat S. aureus-induced bovine mastitis.
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Affiliation(s)
- Guillaume Millette
- Department of Biology, Institute of Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (E.L.); (C.S.)
| | - Evelyne Lacasse
- Department of Biology, Institute of Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (E.L.); (C.S.)
| | - Renaud Binette
- Department of Chemistry, Institute of Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada;
| | - Véronique Belley
- Department of Biology, Institute of Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (E.L.); (C.S.)
| | - Louis-Philippe Chaumont
- Department of Biology, Institute of Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (E.L.); (C.S.)
| | - Céline Ster
- Department of Biology, Institute of Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (E.L.); (C.S.)
| | - Francis Beaudry
- Department of Veterinary Biomedicine, Institute of Veterinary Medicine, University of Montreal, St-Hyacinthe, QC J2S 2M2, Canada;
| | - Kumaraswamy Boyapelly
- Department of Pharmacology and Physiology, Institute of Medicine and Health Sciences, Sherbrooke University, Sherbrooke, QC J1H 5N4, Canada
| | - Pierre-Luc Boudreault
- Department of Pharmacology and Physiology, Institute of Medicine and Health Sciences, Sherbrooke University, Sherbrooke, QC J1H 5N4, Canada
| | - François Malouin
- Department of Biology, Institute of Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (E.L.); (C.S.)
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8
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Esser A, Mayer G. Characterization of the glmS Ribozymes from Listeria Monocytogenes and Clostridium Difficile. Chemistry 2023; 29:e202202376. [PMID: 36194523 PMCID: PMC10099748 DOI: 10.1002/chem.202202376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Indexed: 11/23/2022]
Abstract
The glmS ribozyme regulates the expression of the essential GlmS enzyme being involved in cell wall biosynthesis. While >450 variants of the glmS ribozyme were identified by in silico approaches and homology searches, only a few have yet been experimentally investigated. Herein, we validate and characterize the glmS ribozymes of the human pathogens Clostridium difficile and Listeria monocytogenes. Both ribozymes, as their previous characterized homologs rely on glucosamine-6-phosphate as co-factor and the presence of divalent cations for exerting the cleavage reaction. The observed EC50 values in turn were found to be in the submicromolar range, at least an order of magnitude lower than observed for glmS ribozymes from other bacteria. The glmS ribozyme of L. monocytogenes was further shown to bear unique properties. It discriminates between co-factors very stringently and other than the glmS ribozyme of C. difficile retains activity at low temperatures. This finding illustrates that albeit being highly conserved, glmS ribozymes have unique characteristics.
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Affiliation(s)
- Anna Esser
- Life & Medical Sciences Institute, University of Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
| | - Günter Mayer
- Life & Medical Sciences Institute, University of Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany.,Center of Aptamer Research & Development, University of Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
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9
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Giarimoglou N, Kouvela A, Maniatis A, Papakyriakou A, Zhang J, Stamatopoulou V, Stathopoulos C. A Riboswitch-Driven Era of New Antibacterials. Antibiotics (Basel) 2022; 11:antibiotics11091243. [PMID: 36140022 PMCID: PMC9495366 DOI: 10.3390/antibiotics11091243] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/01/2022] [Accepted: 09/08/2022] [Indexed: 11/26/2022] Open
Abstract
Riboswitches are structured non-coding RNAs found in the 5′ UTR of important genes for bacterial metabolism, virulence and survival. Upon the binding of specific ligands that can vary from simple ions to complex molecules such as nucleotides and tRNAs, riboswitches change their local and global mRNA conformations to affect downstream transcription or translation. Due to their dynamic nature and central regulatory role in bacterial metabolism, riboswitches have been exploited as novel RNA-based targets for the development of new generation antibacterials that can overcome drug-resistance problems. During recent years, several important riboswitch structures from many bacterial representatives, including several prominent human pathogens, have shown that riboswitches are ideal RNA targets for new compounds that can interfere with their structure and function, exhibiting much reduced resistance over time. Most interestingly, mainstream antibiotics that target the ribosome have been shown to effectively modulate the regulatory behavior and capacity of several riboswitches, both in vivo and in vitro, emphasizing the need for more in-depth studies and biological evaluation of new antibiotics. Herein, we summarize the currently known compounds that target several main riboswitches and discuss the role of mainstream antibiotics as modulators of T-box riboswitches, in the dawn of an era of novel inhibitors that target important bacterial regulatory RNAs.
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Affiliation(s)
- Nikoleta Giarimoglou
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Adamantia Kouvela
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Alexandros Maniatis
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Athanasios Papakyriakou
- Institute of Biosciences & Applications, National Centre for Scientific Research “Demokritos”, Ag. Paraskevi, 15341 Athens, Greece
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | | | - Constantinos Stathopoulos
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
- Correspondence: ; Tel.: +30-2610-997932
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10
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Liu K, Abouelhassan Y, Zhang Y, Jin S, Huigens Iii RW. Transcript Profiling of Nitroxoline-Treated Biofilms Shows Rapid Up-regulation of Iron Acquisition Gene Clusters. ACS Infect Dis 2022; 8:1594-1605. [PMID: 35830188 PMCID: PMC10549994 DOI: 10.1021/acsinfecdis.2c00206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bacterial biofilms are surface-attached communities of slow- or non-replicating cells embedded within a protective matrix of biomolecules. Unlike free-floating planktonic bacteria, biofilms are innately tolerant to conventional antibiotics and are prevalent in recurring and chronic infections. Nitroxoline, a broad-spectrum biofilm-eradicating agent, was used to probe biofilm viability. Transcript profiling (RNA-seq) showed that 452 of 2594 genes (17.4%) in methicillin-resistant Staphylococcus aureus (MRSA) biofilms were differentially expressed after a 2 h treatment of nitroxoline. WoPPER analysis and time-course validation (RT-qPCR) revealed that gene clusters involved in iron acquisition (sbn, isd, MW2101, MW0695, fhu, and feo) were rapidly up-regulated following nitroxoline treatment, which is indicative of iron starvation in MRSA biofilms. In addition, genes related to oligopeptide transporters and riboflavin biosynthesis were found to be up-regulated, while genes related to carotenoid biosynthesis and nitrate assimilation were down-regulated. RT-qPCR experiments revealed that iron uptake transcripts were also up-regulated in established Staphylococcus epidermidis and Acinetobacter baumannii biofilms following nitroxoline treatment. Overall, we show RNA-seq to be an ideal platform to define cellular pathways critical for biofilm survival, in addition to demonstrating the need these bacterial communities have for iron.
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Affiliation(s)
- Ke Liu
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Yasmeen Abouelhassan
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Yanping Zhang
- Interdisciplinary Center for Biotechnology Research (ICBR), Gene Expression and Genotyping, University of Florida, Gainesville, Florida 32610, United States
| | - Shouguang Jin
- Department of Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville, Florida 32610, United States
| | - Robert W Huigens Iii
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
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11
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Impact of the Stringent Stress Response on the Expression of Methicillin Resistance in Staphylococcaceae Strains Carrying mecA, mecA1 and mecC. Antibiotics (Basel) 2022; 11:antibiotics11020255. [PMID: 35203858 PMCID: PMC8868139 DOI: 10.3390/antibiotics11020255] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 02/09/2022] [Accepted: 02/14/2022] [Indexed: 02/05/2023] Open
Abstract
The acquisition of the resistance determinant mecA by Staphylococcus aureus is of major clinical importance, since it confers a resistant phenotype to virtually the entire large family of structurally diverse β-lactam antibiotics. While the common resistance determinant mecA is essential, the optimal expression of the resistance phenotype also requires additional factors. Previous studies showed that the great majority of clinical isolates of methicillin-resistant S. aureus (MRSA) have a heterogeneous resistant phenotype, and we observed that strains carrying methicillin genetic determinants other than mecA also produce similar heterogeneous phenotypes. All these strains were able to express high and homogeneous levels of oxacillin resistance when sub-inhibitory concentrations of mupirocin, an effector of the stringent stress response, were added to growth media. Our studies show that the gene gmk, involved in guanine metabolism, was one of the first genes to exhibit mutations in homoresistant (H*R) derivatives obtained through serial passages (with increasing concentrations of oxacillin) of the prototype mecC-carrying MRSA strain LGA251. All these observations led us to propose that a common molecular mechanism for the establishment of high and homogeneous oxacillin resistance must be present among isolates carrying different methicillin resistance determinants. In this work, we tested this hypothesis using whole-genome sequencing (WGS) to compare isogenic populations differing only in their degrees of oxacillin resistance and carrying various methicillin genetic determinants
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12
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Díaz Calvo T, Tejera N, McNamara I, Langridge GC, Wain J, Poolman M, Singh D. Genome-Scale Metabolic Modelling Approach to Understand the Metabolism of the Opportunistic Human Pathogen Staphylococcus epidermidis RP62A. Metabolites 2022; 12:metabo12020136. [PMID: 35208211 PMCID: PMC8874387 DOI: 10.3390/metabo12020136] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/18/2022] [Accepted: 01/29/2022] [Indexed: 02/01/2023] Open
Abstract
Staphylococcus epidermidis is a common commensal of collagen-rich regions of the body, such as the skin, but also represents a threat to patients with medical implants (joints and heart), and to preterm babies. Far less studied than Staphylococcus aureus, the mechanisms behind this increasingly recognised pathogenicity are yet to be fully understood. Improving our knowledge of the metabolic processes that allow S. epidermidis to colonise different body sites is key to defining its pathogenic potential. Thus, we have constructed a fully curated, genome-scale metabolic model for S. epidermidis RP62A, and investigated its metabolic properties with a focus on substrate auxotrophies and its utilisation for energy and biomass production. Our results show that, although glucose is available in the medium, only a small portion of it enters the glycolytic pathways, whils most is utilised for the production of biofilm, storage and the structural components of biomass. Amino acids, proline, valine, alanine, glutamate and arginine, are preferred sources of energy and biomass production. In contrast to previous studies, we have shown that this strain has no real substrate auxotrophies, although removal of proline from the media has the highest impact on the model and the experimental growth characteristics. Further study is needed to determine the significance of proline, an abundant amino acid in collagen, in S. epidermidis colonisation.
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Affiliation(s)
- Teresa Díaz Calvo
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK;
| | - Noemi Tejera
- Microbes in the Food Chain, Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (N.T.); (G.C.L.); (J.W.)
| | - Iain McNamara
- Norwich Medical School, University of East Anglia, Norwich NR4 7UQ, UK;
- Department of Orthopaedics and Trauma, Norfolk and Norwich University Hospital NHS Foundation Trust, Norwich NR4 7UY, UK
| | - Gemma C. Langridge
- Microbes in the Food Chain, Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (N.T.); (G.C.L.); (J.W.)
| | - John Wain
- Microbes in the Food Chain, Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (N.T.); (G.C.L.); (J.W.)
- Norwich Medical School, University of East Anglia, Norwich NR4 7UQ, UK;
| | - Mark Poolman
- Cell System Modelling Group, Oxford Brookes University, Oxford OX3 OBP, UK;
| | - Dipali Singh
- Microbes in the Food Chain, Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (N.T.); (G.C.L.); (J.W.)
- Correspondence:
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13
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Goncheva MI, Chin D, Heinrichs DE. Nucleotide biosynthesis: the base of bacterial pathogenesis. Trends Microbiol 2022; 30:793-804. [PMID: 35074276 DOI: 10.1016/j.tim.2021.12.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 01/08/2023]
Abstract
Most free-living organisms require the synthesis and/or acquisition of purines and pyrimidines, which form the basis of nucleotides, to survive. In most bacteria, the nucleotides are synthesized de novo and the products are used in many cell functions, including DNA replication, energy storage, and as signaling molecules. Due to their central role in the metabolism of bacteria, both nucleotide biosynthesis pathways have strong links with the virulence of opportunistic and bona fide bacterial pathogens. Recent findings have established a new, shared link in the control of nucleotide biosynthesis and the production of virulence factors. Furthermore, targeting of these pathways forms the basis of interspecies competition and can provide an open source for new antimicrobial compounds. Here, we highlight the contribution of nucleotide biosynthesis to bacterial pathogenesis in a plethora of different diseases and speculate on how they can be targeted by intervention strategies.
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Affiliation(s)
- Mariya I Goncheva
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada N6A 5C1
| | - Denny Chin
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada N6A 5C1
| | - David E Heinrichs
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada N6A 5C1.
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14
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Proteomic analysis of hexahydro-β-acids/hydroxypropyl-β-cyclodextrin inhibit Listeria monocytogenes. Appl Microbiol Biotechnol 2022; 106:755-771. [DOI: 10.1007/s00253-022-11764-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 12/28/2021] [Accepted: 01/05/2022] [Indexed: 01/12/2023]
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15
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Braverman J, Monk IR, Ge C, Westall GP, Stinear TP, Wakim LM. Staphylococcus aureus specific lung resident memory CD4 + Th1 cells attenuate the severity of influenza virus induced secondary bacterial pneumonia. Mucosal Immunol 2022; 15:783-796. [PMID: 35637249 PMCID: PMC9148937 DOI: 10.1038/s41385-022-00529-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 03/25/2022] [Accepted: 05/03/2022] [Indexed: 02/04/2023]
Abstract
Staphylococcus aureus is a major cause of severe pulmonary infections. The evolution of multi-drug resistant strains limits antibiotic treatment options. To date, all candidate vaccines tested have failed, highlighting the need for an increased understanding of the immunological requirements for effective S. aureus immunity. Using an S. aureus strain engineered to express a trackable CD4+ T cell epitope and a murine model of S. aureus pneumonia, we show strategies that lodge Th1 polarised bacterium specific CD4+ tissue resident memory T cells (Trm) in the lung can significantly attenuate the severity of S. aureus pneumonia. This contrasts natural infection of mice that fails to lodge CD4+ Trm cells along the respiratory tract or provide protection against re-infection, despite initially generating Th17 bacterium specific CD4+ T cell responses. Interestingly, lack of CD4+ Trm formation after natural infection in mice appears to be reflected in humans, where the frequency of S. aureus reactive CD4+ Trm cells in lung tissue is also low. Our findings reveal the protective capacity of S. aureus specific respiratory tract CD4+ Th1 polarised Trm cells and highlight the potential for targeting these cells in vaccines that aim to prevent the development of S. aureus pneumonia.
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Affiliation(s)
- Jessica Braverman
- grid.1008.90000 0001 2179 088XDepartment of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000 Australia
| | - Ian R. Monk
- grid.1008.90000 0001 2179 088XDepartment of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000 Australia
| | - Chenghao Ge
- grid.1008.90000 0001 2179 088XDepartment of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000 Australia ,grid.12527.330000 0001 0662 3178School of Medicine, Tsinghua University, Beijing, China
| | - Glen P. Westall
- grid.1002.30000 0004 1936 7857Lung Transplant Service, Alfred Hospital, Melbourne, Victoria, Australia; Department of Medicine, Monash University, Melbourne, VIC Australia
| | - Timothy P. Stinear
- grid.1008.90000 0001 2179 088XDepartment of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000 Australia
| | - Linda M. Wakim
- grid.1008.90000 0001 2179 088XDepartment of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000 Australia
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16
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Modi G, Marqus GM, Vippila MR, Gollapalli DR, Kim Y, Manna AC, Chacko S, Maltseva N, Wang X, Cullinane RT, Zhang Y, Kotler JLM, Kuzmic P, Zhang M, Lawson AP, Joachimiak A, Cheung A, Snider BB, Rothstein DM, Cuny GD, Hedstrom L. The Enzymatic Activity of Inosine 5'-Monophosphate Dehydrogenase May Not Be a Vulnerable Target for Staphylococcus aureus Infections. ACS Infect Dis 2021; 7:3062-3076. [PMID: 34590817 DOI: 10.1021/acsinfecdis.1c00342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many bacterial pathogens, including Staphylococcus aureus, require inosine 5'-monophosphate dehydrogenase (IMPDH) for infection, making this enzyme a promising new target for antibiotics. Although potent selective inhibitors of bacterial IMPDHs have been reported, relatively few have displayed antibacterial activity. Here we use structure-informed design to obtain inhibitors of S. aureus IMPDH (SaIMPDH) that have potent antibacterial activity (minimal inhibitory concentrations less than 2 μM) and low cytotoxicity in mammalian cells. The physicochemical properties of the most active compounds were within typical Lipinski/Veber space, suggesting that polarity is not a general requirement for achieving antibacterial activity. Five compounds failed to display activity in mouse models of septicemia and abscess infection. Inhibitor-resistant S. aureus strains readily emerged in vitro. Resistance resulted from substitutions in the cofactor/inhibitor binding site of SaIMPDH, confirming on-target antibacterial activity. These mutations decreased the binding of all inhibitors tested, but also decreased catalytic activity. Nonetheless, the resistant strains had comparable virulence to wild-type bacteria. Surprisingly, strains expressing catalytically inactive SaIMPDH displayed only a mild virulence defect. Collectively these observations question the vulnerability of the enzymatic activity of SaIMPDH as a target for the treatment of S. aureus infections, suggesting other functions of this protein may be responsible for its role in infection.
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Affiliation(s)
- Gyan Modi
- Department of Biology, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Gary M. Marqus
- Graduate Program in Chemistry, Brandeis University, Waltham Massachusetts 02453, United States
| | - Mohana Rao Vippila
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Health Building 2, 4849 Calhoun Rd., Houston, Texas 77204, United States
| | | | - Youngchang Kim
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, Illinois 60667, United States
- The Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Adhar C. Manna
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755, United States
| | - Shibin Chacko
- Department of Biology, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Natalia Maltseva
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, Illinois 60667, United States
- The Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Xingyou Wang
- Graduate Program in Chemistry, Brandeis University, Waltham Massachusetts 02453, United States
| | - Ryan T. Cullinane
- Department of Biochemistry, Brandeis University, Massachusetts 02453, United States
| | - Yubo Zhang
- Department of Biochemistry, Brandeis University, Massachusetts 02453, United States
| | - Judy L. M. Kotler
- Graduate Program in Biochemistry and Biophysics, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Petr Kuzmic
- BioKin Ltd., Watertown, Massachusetts 02472, United States
| | - Minjia Zhang
- Department of Biology, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Ann P. Lawson
- Department of Biology, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Andrzej Joachimiak
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, Illinois 60667, United States
- The Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60367, United States
| | - Ambrose Cheung
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755, United States
| | - Barry B. Snider
- Department of Chemistry, Brandeis University, Waltham, Massachusetts 02453, United States
| | - David M. Rothstein
- David Rothstein Consulting, LLC, Lexington, Massachusetts 02421, United States
| | - Gregory D. Cuny
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Health Building 2, 4849 Calhoun Rd., Houston, Texas 77204, United States
| | - Lizbeth Hedstrom
- Department of Biology, Brandeis University, Waltham, Massachusetts 02453, United States
- Department of Chemistry, Brandeis University, Waltham, Massachusetts 02453, United States
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17
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Smith-Peter E, Séguin DL, St-Pierre É, Sekulovic O, Jeanneau S, Tremblay-Tétreault C, Lamontagne AM, Jacques PÉ, Lafontaine DA, Fortier LC. Inactivation of the riboswitch-controlled GMP synthase GuaA in Clostridioides difficile is associated with severe growth defects and poor infectivity in a mouse model of infection. RNA Biol 2021; 18:699-710. [PMID: 34612173 DOI: 10.1080/15476286.2021.1978768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Clostridioides difficile is the main cause of nosocomial antibiotic-associated diarrhoea. There is a need for new antimicrobials to tackle this pathogen. Guanine riboswitches have been proposed as promising new antimicrobial targets, but experimental evidence of their importance in C. difficile is missing. The genome of C. difficile encodes four distinct guanine riboswitches, each controlling a single gene involved in purine metabolism and transport. One of them controls the expression of guaA, encoding a guanosine monophosphate (GMP) synthase. Here, using in-line probing and GusA reporter assays, we show that these riboswitches are functional in C. difficile and cause premature transcription termination upon binding of guanine. All riboswitches exhibit a high affinity for guanine characterized by Kd values in the low nanomolar range. Xanthine and guanosine also bind the guanine riboswitches, although with less affinity. Inactivating the GMP synthase (guaA) in C. difficile strain 630 led to cell death in minimal growth conditions, but not in rich medium. Importantly, the capacity of a guaA mutant to colonize the mouse gut was significantly reduced. Together, these results demonstrate the importance of de novo GMP biosynthesis in C. difficile during infection, suggesting that targeting guanine riboswitches with analogues could be a viable therapeutic strategy.
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Affiliation(s)
- Erich Smith-Peter
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université De Sherbrooke, Sherbrooke, Quebec, Canada.,Department of Biology, Faculty of Science, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - David Lalonde Séguin
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Émilie St-Pierre
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Ognjen Sekulovic
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Simon Jeanneau
- Department of Biology, Faculty of Science, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | | | - Anne-Marie Lamontagne
- Department of Biology, Faculty of Science, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Pierre-Étienne Jacques
- Department of Biology, Faculty of Science, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Daniel A Lafontaine
- Department of Biology, Faculty of Science, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Louis-Charles Fortier
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université De Sherbrooke, Sherbrooke, Quebec, Canada
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18
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Mutations in a Membrane Permease or hpt Lead to 6-Thioguanine Resistance in Staphylococcus aureus. Antimicrob Agents Chemother 2021; 65:e0076021. [PMID: 34125595 DOI: 10.1128/aac.00760-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
We recently discovered that 6-thioguanine (6-TG) is an antivirulence compound that is produced by a number of coagulase-negative staphylococci. In Staphylococcus aureus, it inhibits de novo purine biosynthesis and ribosomal protein expression, thus inhibiting growth and abrogating toxin production. Mechanisms by which S. aureus may develop resistance to this compound are currently unknown. Here, we show that 6-TG-resistant S. aureus mutants emerge spontaneously when the bacteria are subjected to high concentrations of 6-TG in vitro. Whole-genome sequencing of these mutants revealed frameshift and missense mutations in a xanthine-uracil permease family protein (stgP [six thioguanine permease]) and single nucleotide polymorphisms in hypoxanthine phosphoribosyltransferase (hpt). These mutations engender S. aureus the ability to resist both the growth inhibitory and toxin downregulation effects of 6-TG. While prophylactic administration of 6-TG ameliorates necrotic lesions in subcutaneous infection of mice with methicillin-resistant S. aureus (MRSA) strain USA300 LAC, the drug did not reduce lesion size formed by the 6-TG-resistant strains. These findings identify mechanisms of 6-TG resistance, and this information can be leveraged to inform strategies to slow the evolution of resistance.
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19
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Xu J, Li Q, Zhang J, Li X, Sun T. In Silico Structural and Functional Analysis of Cold Shock Proteins in Pseudomonas fluorescens PF08 from Marine Fish. J Food Prot 2021; 84:1446-1454. [PMID: 33852731 DOI: 10.4315/jfp-21-044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/08/2021] [Indexed: 12/18/2022]
Abstract
ABSTRACT Pseudomonas fluorescens is a specific spoilage microorganism of refrigerated marine fish, and is highly adapted to low temperature. Cold shock proteins (CSPs) play an important role in cold adaptation of bacteria. In this study, CSP genes were identified from the genome of P. fluorescens PF08 by search of the conserved domain of CSPs with HMMER software, and the CSP physicochemical properties, structures, and functions were analyzed through bioinformatics. Five typical CSPs were identified in the P. fluorescens PF08 genome (PfCSPs). All five PfCSPs are small hydrophilic acidic proteins with a molecular mass of ca. 7.4 kDa. They are located in the cytoplasm and are nonsecretory and nontransmembrane proteins. Multiple sequence alignment analysis indicated that the CSPs are highly conserved between species, especially in DNA-binding sites and RNA-binding motifs that can bind to single-stranded DNA and RNA. The five PfCSPs clustered with CspD from Escherichia coli and Salmonella Typhimurium, which suggests a close homology and high functional similarity among the five PfCSPs and CspD. The secondary and tertiary structures of the PfCSPs are in accordance with the characteristics of the CSP family, and ligand binding sites with higher likelihood were found in PfCSPs. The five PfCSPs were predicted to interact with some of the same proteins that are involved in virulence, stress responses (including to low temperature), cell growth, ribosome assembly, and RNA degradation. The results provide further elucidation of the function of CSPs in adaptation to low temperatures by P. fluorescens. HIGHLIGHTS
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Affiliation(s)
- Jinxiu Xu
- College of Food Science and Engineering, Bohai University, National & Local Joint Engineering Research Center of Storage, Processing and Safety Control Technology for Fresh Agricultural and Aquatic Products, Jinzhou, Liaoning 121013, People's Republic of China
| | - Qiuying Li
- College of Food Science and Engineering, Bohai University, National & Local Joint Engineering Research Center of Storage, Processing and Safety Control Technology for Fresh Agricultural and Aquatic Products, Jinzhou, Liaoning 121013, People's Republic of China
| | - Jingyang Zhang
- College of Food Science and Engineering, Bohai University, National & Local Joint Engineering Research Center of Storage, Processing and Safety Control Technology for Fresh Agricultural and Aquatic Products, Jinzhou, Liaoning 121013, People's Republic of China
| | - Xuepeng Li
- College of Food Science and Engineering, Bohai University, National & Local Joint Engineering Research Center of Storage, Processing and Safety Control Technology for Fresh Agricultural and Aquatic Products, Jinzhou, Liaoning 121013, People's Republic of China
| | - Tong Sun
- College of Food Science and Engineering, Bohai University, National & Local Joint Engineering Research Center of Storage, Processing and Safety Control Technology for Fresh Agricultural and Aquatic Products, Jinzhou, Liaoning 121013, People's Republic of China
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20
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Conserved bacterial de novo guanine biosynthesis pathway enables microbial survival and colonization in the environmental niche of the urinary tract. ISME JOURNAL 2021; 15:2158-2162. [PMID: 33649549 DOI: 10.1038/s41396-021-00934-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/08/2021] [Indexed: 02/08/2023]
Abstract
In bacteria, guaA encodes guanosine monophosphate synthetase that confers an ability to biosynthesize guanine nucleotides de novo. This enables bacterial colonization in different environments and, while guaA is widely distributed among Bacteroidetes and Firmicutes, its contribution to the inhabitation of the human microbiome by commensal bacteria is unclear. We studied Streptococcus as a commensal urogenital tract bacterium and opportunistic pathogen, and explored the role of guaA in bacterial survival and colonization of urine. Analysis of guaA-deficient Streptococcus revealed guanine utilization is essential for bacterial colonization of this niche. The genomic location of guaA in other commensals of the human urogenital tract revealed substantial cross-phyla diversity and organizational structures of guaA that are divergent across phyla. Essentiality of guaA for Streptococcus colonization in the urinary tract establishes that purine biosynthesis is a critical element of the ability of this bacterium to survive and colonize in the host as part of the resident human microbiome.
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Panchal V, Brenk R. Riboswitches as Drug Targets for Antibiotics. Antibiotics (Basel) 2021; 10:45. [PMID: 33466288 PMCID: PMC7824784 DOI: 10.3390/antibiotics10010045] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/21/2020] [Accepted: 12/29/2020] [Indexed: 12/13/2022] Open
Abstract
Riboswitches reside in the untranslated region of RNA and regulate genes involved in the biosynthesis of essential metabolites through binding of small molecules. Since their discovery at the beginning of this century, riboswitches have been regarded as potential antibacterial targets. Using fragment screening, high-throughput screening and rational ligand design guided by X-ray crystallography, lead compounds against various riboswitches have been identified. Here, we review the current status and suitability of the thiamine pyrophosphate (TPP), flavin mononucleotide (FMN), glmS, guanine, and other riboswitches as antibacterial targets and discuss them in a biological context. Further, we highlight challenges in riboswitch drug discovery and emphasis the need to develop riboswitch specific high-throughput screening methods.
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Affiliation(s)
- Vipul Panchal
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5020 Bergen, Norway
| | - Ruth Brenk
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5020 Bergen, Norway
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22
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Revealing 29 sets of independently modulated genes in Staphylococcus aureus, their regulators, and role in key physiological response. Proc Natl Acad Sci U S A 2020; 117:17228-17239. [PMID: 32616573 PMCID: PMC7382225 DOI: 10.1073/pnas.2008413117] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Staphylococcus aureus infections impose an immense burden on the healthcare system. To establish a successful infection in a hostile host environment, S. aureus must coordinate its gene expression to respond to a wide array of challenges. This balancing act is largely orchestrated by the transcriptional regulatory network. Here, we present a model of 29 independently modulated sets of genes that form the basis for a segment of the transcriptional regulatory network in clinical USA300 strains of S. aureus. Using this model, we demonstrate the concerted role of various cellular systems (e.g., metabolism, virulence, and stress response) underlying key physiological responses, including response during blood infection. The ability of Staphylococcus aureus to infect many different tissue sites is enabled, in part, by its transcriptional regulatory network (TRN) that coordinates its gene expression to respond to different environments. We elucidated the organization and activity of this TRN by applying independent component analysis to a compendium of 108 RNA-sequencing expression profiles from two S. aureus clinical strains (TCH1516 and LAC). ICA decomposed the S. aureus transcriptome into 29 independently modulated sets of genes (i-modulons) that revealed: 1) High confidence associations between 21 i-modulons and known regulators; 2) an association between an i-modulon and σS, whose regulatory role was previously undefined; 3) the regulatory organization of 65 virulence factors in the form of three i-modulons associated with AgrR, SaeR, and Vim-3; 4) the roles of three key transcription factors (CodY, Fur, and CcpA) in coordinating the metabolic and regulatory networks; and 5) a low-dimensional representation, involving the function of few transcription factors of changes in gene expression between two laboratory media (RPMI, cation adjust Mueller Hinton broth) and two physiological media (blood and serum). This representation of the TRN covers 842 genes representing 76% of the variance in gene expression that provides a quantitative reconstruction of transcriptional modules in S. aureus, and a platform enabling its full elucidation.
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Ge C, Monk IR, Monard SC, Bedford JG, Braverman J, Stinear TP, Wakim LM. Neutrophils play an ongoing role in preventing bacterial pneumonia by blocking the dissemination of
Staphylococcus aureus
from the upper to the lower airways. Immunol Cell Biol 2020; 98:577-594. [DOI: 10.1111/imcb.12343] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 04/22/2020] [Accepted: 04/22/2020] [Indexed: 12/13/2022]
Affiliation(s)
- Chenghao Ge
- Department of Microbiology and Immunology The University of Melbourne Peter Doherty Institute for Infection and Immunity Melbourne VIC 3000 Australia
- School of Medicine Tsinghua University Beijing China
| | - Ian R Monk
- Department of Microbiology and Immunology The University of Melbourne Peter Doherty Institute for Infection and Immunity Melbourne VIC 3000 Australia
| | - Sarah C Monard
- Department of Microbiology and Immunology The University of Melbourne Peter Doherty Institute for Infection and Immunity Melbourne VIC 3000 Australia
| | - James G Bedford
- Department of Microbiology and Immunology The University of Melbourne Peter Doherty Institute for Infection and Immunity Melbourne VIC 3000 Australia
| | - Jessica Braverman
- Department of Microbiology and Immunology The University of Melbourne Peter Doherty Institute for Infection and Immunity Melbourne VIC 3000 Australia
| | - Timothy P Stinear
- Department of Microbiology and Immunology The University of Melbourne Peter Doherty Institute for Infection and Immunity Melbourne VIC 3000 Australia
| | - Linda M Wakim
- Department of Microbiology and Immunology The University of Melbourne Peter Doherty Institute for Infection and Immunity Melbourne VIC 3000 Australia
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Host nutrient milieu drives an essential role for aspartate biosynthesis during invasive Staphylococcus aureus infection. Proc Natl Acad Sci U S A 2020; 117:12394-12401. [PMID: 32414924 PMCID: PMC7275739 DOI: 10.1073/pnas.1922211117] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Staphylococcus aureus can infect a diverse array of host environments. The broad tissue tropism of S. aureus requires metabolic flexibility to utilize the variety of nutrient sources found within target organ systems. In this work, we conducted a systematic analysis of the central metabolic pathways required for S. aureus survival during bone infection, one of the most frequent sites of invasive staphylococcal disease. We show that S. aureus requires aspartate biosynthesis to survive during bone infection, despite possessing an aspartate transporter, due to inhibition of aspartate utilization by the amino acid glutamate. Our results reveal a crucial role for inflammation-associated shifts in the host nutrient milieu for determining the metabolic pathways utilized by S. aureus during invasive infection. The bacterial pathogen Staphylococcus aureus is capable of infecting a broad spectrum of host tissues, in part due to flexibility of metabolic programs. S. aureus, like all organisms, requires essential biosynthetic intermediates to synthesize macromolecules. We therefore sought to determine the metabolic pathways contributing to synthesis of essential precursors during invasive S. aureus infection. We focused specifically on staphylococcal infection of bone, one of the most common sites of invasive S. aureus infection and a unique environment characterized by dynamic substrate accessibility, infection-induced hypoxia, and a metabolic profile skewed toward aerobic glycolysis. Using a murine model of osteomyelitis, we examined survival of S. aureus mutants deficient in central metabolic pathways, including glycolysis, gluconeogenesis, the tricarboxylic acid (TCA) cycle, and amino acid synthesis/catabolism. Despite the high glycolytic demand of skeletal cells, we discovered that S. aureus requires glycolysis for survival in bone. Furthermore, the TCA cycle is dispensable for survival during osteomyelitis, and S. aureus instead has a critical need for anaplerosis. Bacterial synthesis of aspartate in particular is absolutely essential for staphylococcal survival in bone, despite the presence of an aspartate transporter, which we identified as GltT and confirmed biochemically. This dependence on endogenous aspartate synthesis derives from the presence of excess glutamate in infected tissue, which inhibits aspartate acquisition by S. aureus. Together, these data elucidate the metabolic pathways required for staphylococcal infection within bone and demonstrate that the host nutrient milieu can determine essentiality of bacterial nutrient biosynthesis pathways despite the presence of dedicated transporters.
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Nan J, Zhang S, Zhan P, Jiang L. Evaluation of Bronopol and Disulfiram as Potential Candidatus Liberibacter asiaticus Inosine 5'-Monophosphate Dehydrogenase Inhibitors by Using Molecular Docking and Enzyme Kinetic. Molecules 2020; 25:E2313. [PMID: 32423116 PMCID: PMC7287799 DOI: 10.3390/molecules25102313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 04/30/2020] [Accepted: 05/11/2020] [Indexed: 12/12/2022] Open
Abstract
Citrus huanglongbing (HLB) is a destructive disease that causes significant damage to many citrus producing areas worldwide. To date, no strategy against this disease has been established. Inosine 5'-monophosphate dehydrogenase (IMPDH) plays crucial roles in the de novo synthesis of guanine nucleotides. This enzyme is used as a potential target to treat bacterial infection. In this study, the crystal structure of a deletion mutant of CLas IMPDHΔ98-201 in the apo form was determined. Eight known bioactive compounds were used as ligands for molecular docking. The results showed that bronopol and disulfiram bound to CLas IMPDHΔ98-201 with high affinity. These compounds were tested for their inhibition against CLas IMPDHΔ98-201 activity. Bronopol and disulfiram showed high inhibition at nanomolar concentrations, and bronopol was found to be the most potent molecule (Ki = 234 nM). The Ki value of disulfiram was 616 nM. These results suggest that bronopol and disulfiram can be considered potential candidate agents for the development of CLas inhibitors.
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Affiliation(s)
- Jing Nan
- College of Horticulture and Forestry, Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, Wuhan 430070, China; (J.N.); (P.Z.)
| | - Shaoran Zhang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China;
| | - Ping Zhan
- College of Horticulture and Forestry, Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, Wuhan 430070, China; (J.N.); (P.Z.)
| | - Ling Jiang
- College of Horticulture and Forestry, Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, Wuhan 430070, China; (J.N.); (P.Z.)
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De Novo Purine Biosynthesis Is Required for Intracellular Growth of Staphylococcus aureus and for the Hypervirulence Phenotype of a purR Mutant. Infect Immun 2020; 88:IAI.00104-20. [PMID: 32094249 PMCID: PMC7171247 DOI: 10.1128/iai.00104-20] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 02/20/2020] [Indexed: 02/07/2023] Open
Abstract
Staphylococcus aureus is a noted human and animal pathogen. Despite decades of research on this important bacterium, there are still many unanswered questions regarding the pathogenic mechanisms it uses to infect the mammalian host. This can be attributed to it possessing a plethora of virulence factors and complex virulence factor and metabolic regulation. PurR, the purine biosynthesis regulator, was recently also shown to regulate virulence factors in S. aureus, and mutations in purR result in derepression of fibronectin binding proteins (FnBPs) and extracellular toxins, required for a so-called hypervirulent phenotype. Staphylococcus aureus is a noted human and animal pathogen. Despite decades of research on this important bacterium, there are still many unanswered questions regarding the pathogenic mechanisms it uses to infect the mammalian host. This can be attributed to it possessing a plethora of virulence factors and complex virulence factor and metabolic regulation. PurR, the purine biosynthesis regulator, was recently also shown to regulate virulence factors in S. aureus, and mutations in purR result in derepression of fibronectin binding proteins (FnBPs) and extracellular toxins, required for a so-called hypervirulent phenotype. Here, we show that hypervirulent strains containing purR mutations can be attenuated with the addition of purine biosynthesis mutations, implicating the necessity for de novo purine biosynthesis in this phenotype and indicating that S. aureus in the mammalian host experiences purine limitation. Using cell culture, we showed that while purR mutants are not altered in epithelial cell binding, compared to that of wild-type (WT) S. aureus, purR mutants have enhanced invasion of these nonprofessional phagocytes, consistent with the requirement of FnBPs for invasion of these cells. This correlates with purR mutants having increased transcription of fnb genes, resulting in higher levels of surface-exposed FnBPs to promote invasion. These data provide important contributions to our understanding of how the pathogenesis of S. aureus is affected by sensing of purine levels during infection of the mammalian host.
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27
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Wang W, Cui J, Zhao Y, Ye C, Zhou S, Guo X, Zhang C, Li J, Wu D. A label-free approach to detect cell viability/cytotoxicity based on intracellular xanthine/guanine by electrochemical method. J Pharmacol Toxicol Methods 2019; 100:106625. [PMID: 31445082 DOI: 10.1016/j.vascn.2019.106625] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/04/2019] [Accepted: 08/14/2019] [Indexed: 12/29/2022]
Abstract
INTRODUCTION Cell viability and cytotoxicity is one of the most important toxicology indicators. In this study, an electrochemical method for detecting cell viability and cytotoxicity was discussed with the intracellular small molecule metabolite purines as indexes. METHODS The electrochemical behaviors of Balb/c 3T3, CHO, PC-12 and V79 cell suspensions were studies by cyclic voltammetry, and cell viability and cytotoxicity of four cell lines were compared by electrochemical, cell counting, 3-(4,5-dimethyl-2-Thiazyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) and trypan blue exclusion methods. RESULTS Four cell lines all showed an oxidation peak derived from mixture of xanthine and guanine at about 0.7 V. Using intracellular xanthine and guanine as index, the electrochemical method could not only describe the cell growth curves of four cell lines, but also reflect the changes of cell viability at various phases of the cell growth prior to the counting method. Compared with MTT, cell counting and trypan blue staining methods, the electrochemical method could detect the cytotoxicity of carcinogen earlier and more sensitively. DISCUSSION The electrochemical method could track the change of intracellular xanthine and guanine contents, and used it as index to detect cell viability and cytotoxicity at the molecular level without markers, showing greater advantages over the method with apparent cell proliferation as the endpoint.
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Affiliation(s)
- Wenqiang Wang
- College of Pharmacy, Jiamusi University, Heilongjiang 154007, China
| | - Jiwen Cui
- College of Pharmacy, Jiamusi University, Heilongjiang 154007, China
| | - Yanli Zhao
- College of Pharmacy, Jiamusi University, Heilongjiang 154007, China
| | - Cai Ye
- College of Pharmacy, Jiamusi University, Heilongjiang 154007, China
| | - Shi Zhou
- College of Pharmacy, Jiamusi University, Heilongjiang 154007, China
| | - Xiaoling Guo
- College of Pharmacy, Jiamusi University, Heilongjiang 154007, China
| | - Chunbin Zhang
- Department of Biology, The Basic Medical College, Jiamusi University, Heilongjiang 154007, China.
| | - Jinlian Li
- College of Pharmacy, Jiamusi University, Heilongjiang 154007, China.
| | - Dongmei Wu
- College of Pharmacy, Jiamusi University, Heilongjiang 154007, China.
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Guanine Limitation Results in CodY-Dependent and -Independent Alteration of Staphylococcus aureus Physiology and Gene Expression. J Bacteriol 2018; 200:JB.00136-18. [PMID: 29712876 DOI: 10.1128/jb.00136-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 04/25/2018] [Indexed: 02/03/2023] Open
Abstract
In Staphylococcus aureus, the global transcriptional regulator CodY modulates the expression of hundreds of genes in response to the availability of GTP and the branched-chain amino acids isoleucine, leucine, and valine (ILV). CodY DNA-binding activity is high when GTP and ILV are abundant. When GTP and ILV are limited, CodY's affinity for DNA drops, altering expression of CodY-regulated targets. In this work, we investigated the impact of guanine nucleotides (GNs) on S. aureus physiology and CodY activity by constructing a guaA null mutant (ΔguaA strain). De novo biosynthesis of guanine monophosphate is abolished due to the guaA mutation; thus, the mutant cells require exogenous guanosine for growth. We also found that CodY activity was reduced when we knocked out guaA, activating the Agr two-component system and increasing secreted protease activity. Notably, in a rich, complex medium, we detected an increase in alternative sigma factor B activity in the ΔguaA mutant, which results in a 5-fold increase in production of the antioxidant pigment staphyloxanthin. Under biologically relevant flow conditions, ΔguaA cells failed to form robust biofilms when limited for guanine or guanosine. Transcriptome sequencing (RNA-Seq) analysis of the S. aureus transcriptome during growth in guanosine-limited chemostats revealed substantial CodY-dependent and -independent alterations of gene expression profiles. Importantly, these changes increase production of proteases and δ-toxin, suggesting that S. aureus exhibits a more invasive lifestyle when limited for guanosine. Further, gene products upregulated under GN limitation, including those necessary for lipoic acid biosynthesis and sugar transport, may prove to be useful drug targets for treating Gram-positive infections.IMPORTANCE Staphylococcus aureus infections impose a serious economic burden on health care facilities and patients because of the emergence of strains resistant to last-line antibiotics. Understanding the physiological processes governing fitness and virulence of S. aureus in response to environmental cues is critical for developing efficient diagnostics and treatments. De novo purine biosynthesis is essential for both fitness and virulence in S. aureus since inhibiting production cripples S. aureus's ability to cause infection. Here, we corroborate these findings and show that blocking guanine nucleotide synthesis severely affects S. aureus fitness by altering metabolic and virulence gene expression. Characterizing pathways and gene products upregulated in response to guanine limitation can aid in the development of novel adjuvant strategies to combat S. aureus infections.
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Yan LH, Le Roux A, Boyapelly K, Lamontagne AM, Archambault MA, Picard-Jean F, Lalonde-Seguin D, St-Pierre E, Najmanovich RJ, Fortier LC, Lafontaine D, Marsault É. Purine analogs targeting the guanine riboswitch as potential antibiotics against Clostridioides difficile. Eur J Med Chem 2017; 143:755-768. [PMID: 29220796 DOI: 10.1016/j.ejmech.2017.11.079] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 11/22/2017] [Accepted: 11/27/2017] [Indexed: 12/14/2022]
Abstract
Riboswitches recently emerged as possible targets for the development of alternative antimicrobial approaches. Guanine-sensing riboswitches in the bacterial pathogen Clostridioides difficile (formerly known as Clostridium difficile) constitute potential targets based on their involvement in the regulation of basal metabolic control of purine compounds. In this study, we deciphered the structure-activity relationship of several guanine derivatives on the guanine riboswitch and determined their antimicrobial activity. We describe the synthesis of purine analogs modified in ring B as well as positions 2 and 6. Their biological activity was determined by measuring their affinity for the C. difficile guanine riboswitch and their inhibitory effect on bacterial growth, including a counter-screen to discriminate against riboswitch-independent antibacterial effects. Altogether, our results suggest that improvements in riboswitch binding affinity in vitro do not necessarily translate into improved antibacterial activity in bacteria, despite the fact that some structure-activity relationship was observed at least with respect to binding affinity.
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Affiliation(s)
- Lok-Hang Yan
- Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada; Department of Pharmacology-Physiology, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada
| | - Antoine Le Roux
- Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada; Department of Pharmacology-Physiology, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada
| | - Kumaraswamy Boyapelly
- Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada; Department of Pharmacology-Physiology, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada
| | - Anne-Marie Lamontagne
- Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada; Department of Biology, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada
| | - Marie-Ann Archambault
- Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada; Department of Biology, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada
| | - Frédéric Picard-Jean
- Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada; Department of Biology, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada
| | - David Lalonde-Seguin
- Department of Microbiology and Infectious Diseases, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada
| | - Emilie St-Pierre
- Department of Microbiology and Infectious Diseases, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada
| | - Rafael J Najmanovich
- Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada; Department of Biochemistry, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada
| | - Louis-Charles Fortier
- Department of Microbiology and Infectious Diseases, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada.
| | - Daniel Lafontaine
- Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada; Department of Biology, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada.
| | - Éric Marsault
- Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada; Department of Pharmacology-Physiology, Université de Sherbrooke, 3001, 12e av nord, Sherbrooke, Québec, J1H 5N4, Canada.
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Host-derived fatty acids activate type VII secretion in Staphylococcus aureus. Proc Natl Acad Sci U S A 2017; 114:11223-11228. [PMID: 28973946 DOI: 10.1073/pnas.1700627114] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The type VII secretion system (T7SS) of Staphylococcus aureus is a multiprotein complex dedicated to the export of several virulence factors during host infection. This virulence pathway plays a key role in promoting bacterial survival and the long-term persistence of staphylococcal abscess communities. The expression of the T7SS is activated by bacterial interaction with host tissues including blood serum, nasal secretions, and pulmonary surfactant. In this work we identify the major stimulatory factors as host-specific cis-unsaturated fatty acids. Increased T7SS expression requires host fatty acid incorporation into bacterial biosynthetic pathways by the Saureus fatty acid kinase (FAK) complex, and FakA is required for virulence. The incorporated cis-unsaturated fatty acids decrease Saureus membrane fluidity, and these altered membrane dynamics are partially responsible for T7SS activation. These data define a molecular mechanism by which Saureus cells sense the host environment and implement appropriate virulence pathways.
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31
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Krajewski SS, Isoz I, Johansson J. Antibacterial and antivirulence effect of 6-N-hydroxylaminopurine in Listeria monocytogenes. Nucleic Acids Res 2017; 45:1914-1924. [PMID: 28062853 PMCID: PMC5389569 DOI: 10.1093/nar/gkw1308] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 12/20/2016] [Indexed: 01/07/2023] Open
Abstract
The emerging development of antibiotic resistant bacteria calls for novel types of antibacterial agents. In this work we examined the putative antibacterial effect of purine analogs in Listeria monocytogenes. We show that, among several tested purine analogs, only 6-N-hydroxylaminopurine (6-N-HAP) reduces the viability of the Gram-positive pathogen Listeria monocytogenes. As in Bacillus subtilis, 6-N-HAP terminates expression at guanine riboswitches in L. monocytogenes hence preventing expression of their downstream genes. However, we show that the bacteriocidal effect of the compound was unlinked to the terminated expression at the guanine riboswitches. When further examining the antimicrobial effect, we observed that 6-N-HAP acts as a potent mutagen in L. monocytogenes, by increasing the mutation rate and inducing the SOS-response. Also, addition of 6-N-HAP decreased virulence gene expression by reducing both the levels and activity of the virulence regulator PrfA.
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Affiliation(s)
- Stefanie Sandra Krajewski
- Department of Molecular Biology, Umeå University, 90187 Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 90187 Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, 90187 Umeå, Sweden
| | - Isabelle Isoz
- Department of Molecular Biology, Umeå University, 90187 Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 90187 Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, 90187 Umeå, Sweden
| | - Jörgen Johansson
- Department of Molecular Biology, Umeå University, 90187 Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 90187 Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, 90187 Umeå, Sweden
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Benzoxazoles, Phthalazinones, and Arylurea-Based Compounds with IMP Dehydrogenase-Independent Antibacterial Activity against Francisella tularensis. Antimicrob Agents Chemother 2017; 61:AAC.00939-17. [PMID: 28739786 DOI: 10.1128/aac.00939-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 07/07/2017] [Indexed: 01/06/2023] Open
Abstract
Francisella tularensis is the causative agent of tularemia and a potential biowarfare agent. The virulence of F. tularensis is decreased by deletion of guaB, the gene encoding IMP dehydrogenase (IMPDH), suggesting that this enzyme is a target for antibacterial design. Here we report that F. tularensis growth is blocked by inhibitors of bacterial IMPDHs. Seventeen compounds from two different frameworks, designated the D and Q series, display antibacterial activities with MICs of <1 μM. These compounds are also active against intracellular infections. Surprisingly, antibacterial activity does not correlate with IMPDH inhibition. In addition, the presence of guanine does not affect the antibacterial activity of most compounds, nor does the deletion of guaB These observations suggest that antibacterial activity derives from inhibition of another target(s). Moreover, D compounds display antibacterial activity only against F. tularensis, suggesting the presence of a unique target or uptake mechanism. A ΔguaB mutant resistant to compound D73 contained a missense mutation (Gly45Cys) in nuoB, which encodes a subunit of bacterial complex I. Overexpression of the nuoB mutant conferred resistance to D73 in both wild-type and ΔguaB strains. This strain was not resistant to Q compounds, suggesting that a different off-target mechanism operates for these compounds. Several Q compounds are also effective against Mycobacterium tuberculosis, in which a second target has also been implicated, in addition to IMPDH. The fortuitous presence of multiple targets with overlapping structure-activity relationships presents an intriguing opportunity for the development of robust antibiotics that may avoid the emergence of resistance.
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Abstract
Riboswitches are cis-acting gene regulatory elements and constitute potential targets for new antibiotics. Recent studies in this field have started to explore these targets for drug discovery. New ligands found by fragment screening, design of analogs of the natural ligands or serendipitously by phenotypic screening have shown antibacterial effects in cell assays against a range of bacteria strains and in animal models. In this review, we highlight the most advanced drug design work of riboswitch ligands and discuss the challenges in the field with respect to the development of antibiotics with a new mechanism of action.
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An in vivo high-throughput screening for riboswitch ligands using a reverse reporter gene system. Sci Rep 2017; 7:7732. [PMID: 28798404 PMCID: PMC5552694 DOI: 10.1038/s41598-017-07870-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 07/04/2017] [Indexed: 11/08/2022] Open
Abstract
Riboswitches are bacterial RNA elements that regulate gene expression in response to metabolite or ion abundance and are considered as potential drug targets. In recent years a number of methods to find non-natural riboswitch ligands have been described. Here we report a high-throughput in vivo screening system that allows identifying OFF-riboswitch modulators in a 384 well bioluminescence assay format. We use a reverse reporter gene setup in Bacillus subtilis, consisting of a primary screening assay, a secondary assay as well as counter assays to detect compounds in a library of 1,280 molecules that act on the guanine-responsive xpt riboswitch from B. anthracis. With this in vivo high-throughput approach we identified several hit compounds and could validate the impact of one of them on riboswitch-mediated gene regulation, albeit this might not be due to direct binding to the riboswitch. However, our data demonstrate the capability of our screening assay for bigger high-throughput screening campaigns. Furthermore, the screening system described here can not only be generally employed to detect non-natural ligands or compounds influencing riboswitches acting as genetic OFF switches, but it can also be used to investigate natural ligands of orphan OFF-riboswitches.
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Ignatov D, Johansson J. RNA-mediated signal perception in pathogenic bacteria. WILEY INTERDISCIPLINARY REVIEWS-RNA 2017; 8. [PMID: 28792118 DOI: 10.1002/wrna.1429] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 05/11/2017] [Accepted: 05/11/2017] [Indexed: 11/09/2022]
Abstract
Bacterial pathogens encounter several different environments during an infection, many of them possibly being detrimental. In order to sense its surroundings and adjust the gene expression accordingly, different regulatory schemes are undertaken. With these, the bacterium appropriately can differentiate between various environmental cues to express the correct virulence factor at the appropriate time and place. An attractive regulator device is RNA, which has an outstanding ability to alter its structure in response to external stimuli, such as metabolite concentration or alterations in temperature, to control its downstream gene expression. This review will describe the function of riboswitches and thermometers, with a particular emphasis on regulatory RNAs being important for bacterial pathogenicity. WIREs RNA 2017, 8:e1429. doi: 10.1002/wrna.1429 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Dmitriy Ignatov
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden.,Department of Molecular Biology, Umeå University, Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Jörgen Johansson
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden.,Department of Molecular Biology, Umeå University, Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
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Influence of IS 256 on Genome Variability and Formation of Small-Colony Variants in Staphylococcus aureus. Antimicrob Agents Chemother 2017; 61:AAC.00144-17. [PMID: 28584147 DOI: 10.1128/aac.00144-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 05/30/2017] [Indexed: 12/12/2022] Open
Abstract
Staphylococcus aureus has acquired resistance to nearly all antibiotics used in clinical practice. Whereas some resistance mechanisms are conferred by uptake of resistance genes, others evolve by mutation. In this study, IS256 has been shown to play a role, e.g., in S. aureus strains displaying intermediate resistance to vancomycin (VISA). To characterize the IS256 insertion sites in the genomes of two closely related sequence type 247 (ST247) VISA strains, all insertions were mapped in both VISA and a susceptible control strain. The results showed that the three ST247 strains contained the highest number so far of IS256 insertions for all sequenced S. aureus strains. Furthermore, in contrast to the case with the other IS elements in these genomes, the IS256 insertion sites were not identical in the closely related strains, indicating a high transposition frequency of IS256 When IS256 was introduced into a laboratory strain which was then cultured in the presence of antibiotics, it was possible to isolate small-colony variants (SCVs) that possessed IS256 insertions in guaA and hemY that displayed increased resistance to vancomycin and aminoglycosides, respectively. For these clones, a very rapid reversion to the wild type that resembled the fast reversion of clinical SCVs was observed. The reversion was caused by excision of IS256 in a small number of fast-growing clones that quickly outcompeted the SCVs in broth cultures. In conclusion, the presence of IS256 confers a strong genomic plasticity that is useful for adaptation to antibiotic stress.
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McCown PJ, Corbino KA, Stav S, Sherlock ME, Breaker RR. Riboswitch diversity and distribution. RNA (NEW YORK, N.Y.) 2017; 23:995-1011. [PMID: 28396576 PMCID: PMC5473149 DOI: 10.1261/rna.061234.117] [Citation(s) in RCA: 317] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 04/04/2017] [Indexed: 05/04/2023]
Abstract
Riboswitches are commonly used by bacteria to detect a variety of metabolites and ions to regulate gene expression. To date, nearly 40 different classes of riboswitches have been discovered, experimentally validated, and modeled at atomic resolution in complex with their cognate ligands. The research findings produced since the first riboswitch validation reports in 2002 reveal that these noncoding RNA domains exploit many different structural features to create binding pockets that are extremely selective for their target ligands. Some riboswitch classes are very common and are present in bacteria from nearly all lineages, whereas others are exceedingly rare and appear in only a few species whose DNA has been sequenced. Presented herein are the consensus sequences, structural models, and phylogenetic distributions for all validated riboswitch classes. Based on our findings, we predict that there are potentially many thousands of distinct bacterial riboswitch classes remaining to be discovered, but that the rarity of individual undiscovered classes will make it increasingly difficult to find additional examples of this RNA-based sensory and gene control mechanism.
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Affiliation(s)
- Phillip J McCown
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Keith A Corbino
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Shira Stav
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Madeline E Sherlock
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Ronald R Breaker
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8103, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103, USA
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Kirchner M, Schneider S. Gene expression control by Bacillus anthracis purine riboswitches. RNA (NEW YORK, N.Y.) 2017; 23:762-769. [PMID: 28209633 PMCID: PMC5393184 DOI: 10.1261/rna.058792.116] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 02/12/2017] [Indexed: 06/06/2023]
Abstract
In all kingdoms of life, cellular replication relies on the presence of nucleosides and nucleotides, the building blocks of nucleic acids and the main source of energy. In bacteria, the availability of metabolites sometimes directly regulates the expression of enzymes and proteins involved in purine salvage, biosynthesis, and uptake through riboswitches. Riboswitches are located in bacterial mRNAs and can control gene expression by conformational changes in response to ligand binding. We have established an inverse reporter gene system in Bacillus subtilis that allows us to monitor riboswitch-controlled gene expression. We used it to investigate the activity of five potential purine riboswitches from Bacillus anthracis in response to different purines and pyrimidines. Furthermore, in vitro studies on the aptamer domains of the riboswitches reveal their variation in guanine binding affinity ranging from namomolar to micromolar. These data do not only provide insight into metabolite sensing but can also aid in engineering artificial cell regulatory systems.
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Affiliation(s)
- Marion Kirchner
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, 85748 Garching, Germany
| | - Sabine Schneider
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, 85748 Garching, Germany
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