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Adams JME, Moulding PB, El-Halfawy OM. Polyamine-Mediated Sensitization of Klebsiella pneumoniae to Macrolides through a Dual Mode of Action. ACS Infect Dis 2024; 10:2183-2195. [PMID: 38695481 DOI: 10.1021/acsinfecdis.4c00157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Chemicals bacteria encounter at the infection site could shape their stress and antibiotic responses; such effects are typically undetected under standard lab conditions. Polyamines are small molecules typically overproduced by the host during infection and have been shown to alter bacterial stress responses. We sought to determine the effect of polyamines on the antibiotic response of Klebsiella pneumoniae, a Gram-negative priority pathogen. Interestingly, putrescine and other natural polyamines sensitized K. pneumoniae to azithromycin, a macrolide protein translation inhibitor typically used for Gram-positive bacteria. This synergy was further potentiated in the physiological buffer, bicarbonate. Chemical genomic screens suggested a dual mechanism, whereby putrescine acts at the membrane and ribosome levels. Putrescine permeabilized the outer membrane of K. pneumoniae (NPN and β-lactamase assays) and the inner membrane (Escherichia coli β-galactosidase assays). Chemically and genetically perturbing membranes led to a loss of putrescine-azithromycin synergy. Putrescine also inhibited protein synthesis in an E. coli-derived cell-free protein expression assay simultaneously monitoring transcription and translation. Profiling the putrescine-azithromycin synergy against a combinatorial array of antibiotics targeting various ribosomal sites suggested that putrescine acts as tetracyclines targeting the 30S ribosomal acceptor site. Next, exploiting the natural polyamine-azithromycin synergy, we screened a polyamine analogue library for azithromycin adjuvants, discovering four azithromycin synergists with activity starting from the low micromolar range and mechanisms similar to putrescine. This work sheds light on the bacterial antibiotic responses under conditions more reflective of those at the infection site and provides a new strategy to extend the macrolide spectrum to drug-resistant K. pneumoniae.
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Affiliation(s)
- Joshua M E Adams
- Department of Chemistry and Biochemistry, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Peri B Moulding
- Department of Chemistry and Biochemistry, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Omar M El-Halfawy
- Department of Chemistry and Biochemistry, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
- Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University, Alexandria, 21521, Egypt
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2
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Chitboonthavisuk C, Martin C, Huss P, Peters JM, Anantharaman K, Raman S. Systematic genome-wide discovery of host factors governing bacteriophage infectivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.20.590424. [PMID: 38659955 PMCID: PMC11042327 DOI: 10.1101/2024.04.20.590424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Bacterial host factors regulate the infection cycle of bacteriophages. Except for some well-studied host factors (e.g., receptors or restriction-modification systems), the contribution of the rest of the host genome on phage infection remains poorly understood. We developed PHAGEPACK, a pooled assay that systematically and comprehensively measures each host-gene impact on phage fitness. PHAGEPACK combines CRISPR interference with phage packaging to link host perturbation to phage fitness during active infection. Using PHAGEPACK, we constructed a genome-wide map of genes impacting T7 phage fitness in permissive E. coli, revealing pathways previously unknown to affect phage packaging. When applied to the non-permissive E. coli O121, PHAGEPACK identified pathways leading to host resistance; their removal increased phage susceptibility up to a billion-fold. Bioinformatic analysis indicates phage genomes carry homologs or truncations of key host factors, potentially for fitness advantage. In summary, PHAGEPACK offers valuable insights into phage-host interactions, phage evolution, and bacterial resistance.
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3
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Gucwa K, Wons E, Wisniewska A, Jakalski M, Dubiak Z, Kozlowski LP, Mruk I. Lethal perturbation of an Escherichia coli regulatory network is triggered by a restriction-modification system's regulator and can be mitigated by excision of the cryptic prophage Rac. Nucleic Acids Res 2024; 52:2942-2960. [PMID: 38153127 PMCID: PMC11014345 DOI: 10.1093/nar/gkad1234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 12/08/2023] [Accepted: 12/13/2023] [Indexed: 12/29/2023] Open
Abstract
Bacterial gene regulatory networks orchestrate responses to environmental challenges. Horizontal gene transfer can bring in genes with regulatory potential, such as new transcription factors (TFs), and this can disrupt existing networks. Serious regulatory perturbations may even result in cell death. Here, we show the impact on Escherichia coli of importing a promiscuous TF that has adventitious transcriptional effects within the cryptic Rac prophage. A cascade of regulatory network perturbations occurred on a global level. The TF, a C regulatory protein, normally controls a Type II restriction-modification system, but in E. coli K-12 interferes with expression of the RacR repressor gene, resulting in de-repression of the normally-silent Rac ydaT gene. YdaT is a prophage-encoded TF with pleiotropic effects on E. coli physiology. In turn, YdaT alters expression of a variety of bacterial regulons normally controlled by the RcsA TF, resulting in deficient lipopolysaccharide biosynthesis and cell division. At the same time, insufficient RacR repressor results in Rac DNA excision, halting Rac gene expression due to loss of the replication-defective Rac prophage. Overall, Rac induction appears to counteract the lethal toxicity of YdaT. We show here that E. coli rewires its regulatory network, so as to minimize the adverse regulatory effects of the imported C TF. This complex set of interactions may reflect the ability of bacteria to protect themselves by having robust mechanisms to maintain their regulatory networks, and/or suggest that regulatory C proteins from mobile operons are under selection to manipulate their host's regulatory networks for their own benefit.
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Affiliation(s)
- Katarzyna Gucwa
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Ewa Wons
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Aleksandra Wisniewska
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Marcin Jakalski
- 3P-Medicine Laboratory, Medical University of Gdansk, Debinki 7, 80-211 Gdansk, Poland
| | - Zuzanna Dubiak
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Lukasz Pawel Kozlowski
- Institute of Informatics, Faculty of Mathematics, Informatics and Mechanics, University of Warsaw, Banacha 2, 02-097 Warsaw, Poland
| | - Iwona Mruk
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
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4
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VanOtterloo LM, Macias LA, Powers MJ, Brodbelt JS, Trent MS. Characterization of Acinetobacter baumannii core oligosaccharide synthesis reveals novel aspects of lipooligosaccharide assembly. mBio 2024; 15:e0301323. [PMID: 38349180 PMCID: PMC10936431 DOI: 10.1128/mbio.03013-23] [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: 11/06/2023] [Accepted: 01/12/2024] [Indexed: 03/14/2024] Open
Abstract
A fundamental feature of Gram-negative bacteria is their outer membrane that protects the cell against environmental stressors. This defense is predominantly due to its asymmetry, with glycerophospholipids located in the inner leaflet and lipopolysaccharide (LPS) or lipooligosaccharide (LOS) confined to the outer leaflet. LPS consists of a lipid A anchor, a core oligosaccharide, and a distal O-antigen while LOS lacks O-antigen. While LPS/LOS is typically essential for growth, this is not the case for Acinetobacter baumannii. Despite this unique property, the synthesis of the core oligosaccharide of A. baumannii LOS is not well-described. Here, we characterized the LOS chemotypes of A. baumannii strains with mutations in a predicted core oligosaccharide locus via tandem mass spectrometry. This allowed for an extensive identification of genes required for core assembly that can be exploited to generate precise structural LOS modifications in many A. baumannii strains. We further investigated two chemotypically identical yet phenotypically distinct mutants, ∆2903 and ∆lpsB, that exposed a possible link between LOS and the peptidoglycan cell wall-two cell envelope components whose coordination has not yet been described in A. baumannii. Selective reconstruction of the core oligosaccharide via expression of 2903 and LpsB revealed that these proteins rely on each other for the unusual tandem transfer of two residues, KdoIII and N-acetylglucosaminuronic acid. The data presented not only allow for better usage of A. baumannii as a tool to study outer membrane integrity but also provide further evidence for a novel mechanism of core oligosaccharide assembly. IMPORTANCE Acinetobacter baumannii is a multidrug-resistant pathogen that produces lipooligosaccharide (LOS), a glycolipid that confers protective asymmetry to the bacterial outer membrane. The core oligosaccharide is a ubiquitous component of LOS that typically follows a well-established model of synthesis. In addition to providing an extensive analysis of the genes involved in the synthesis of the core region, we demonstrate that this organism has evidently diverged from the long-held archetype of core synthesis. Moreover, our data suggest that A. baumannii LOS assembly is important for cell division and likely intersects with the synthesis of the peptidoglycan cell wall, another essential component of the Gram-negative cell envelope. This connection between LOS and cell wall synthesis provides an intriguing foundation for a unique method of outer membrane biogenesis and cell envelope coordination.
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Affiliation(s)
- Leah M. VanOtterloo
- Department of Microbiology, College of Art and Sciences, University of Georgia, Athens, Georgia, USA
| | - Luis A. Macias
- Department of Chemistry, University of Texas at Austin, Austin, Texas, USA
| | - Matthew J. Powers
- Department of Microbiology, College of Art and Sciences, University of Georgia, Athens, Georgia, USA
| | | | - M. Stephen Trent
- Department of Microbiology, College of Art and Sciences, University of Georgia, Athens, Georgia, USA
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
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5
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Xu Z, Ding Z, Shi L, Xie Y, Zhang Y, Wang Z, Liu Q. Coevolution between marine Aeromonas and phages reveals temporal trade-off patterns of phage resistance and host population fitness. THE ISME JOURNAL 2023; 17:2200-2209. [PMID: 37814126 PMCID: PMC10689771 DOI: 10.1038/s41396-023-01529-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 09/22/2023] [Accepted: 09/28/2023] [Indexed: 10/11/2023]
Abstract
Coevolution of bacteria and phages is an important host and parasite dynamic in marine ecosystems, contributing to the understanding of bacterial community diversity. On the time scale, questions remain concerning what is the difference between phage resistance patterns in marine bacteria and how advantageous mutations gradually accumulate during coevolution. In this study, marine Aeromonas was co-cultured with its phage for 180 days and their genetic and phenotypic dynamics were measured every 30 days. We identified 11 phage resistance genes and classified them into three categories: lipopolysaccharide (LPS), outer membrane protein (OMP), and two-component system (TCS). LPS shortening and OMP mutations are two distinct modes of complete phage resistance, while TCS mutants mediate incomplete resistance by repressing the transcription of phage genes. The co-mutation of LPS and OMP was a major mode for bacterial resistance at a low cost. The mutations led to significant reductions in the growth and virulence of bacterial populations during the first 60 days of coevolution, with subsequent leveling off. Our findings reveal the marine bacterial community dynamics and evolutionary trade-offs of phage resistance during coevolution, thus granting further understanding of the interaction of marine microbes.
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Affiliation(s)
- Zhenhe Xu
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai, 200237, China
| | - Zihan Ding
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai, 200237, China
| | - Lijia Shi
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai, 200237, China
| | - Yuzhen Xie
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai, 200237, China
| | - Yuanxing Zhang
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), 519000, Zhuhai, China
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai, 200237, China
| | - Zhuang Wang
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai, 200237, China.
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai, 200237, China.
| | - Qin Liu
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai, 200237, China.
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai, 200237, China.
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6
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Subbian S. Editorial: Innate immune evasion strategies during microbial infection. Front Cell Infect Microbiol 2023; 13:1332253. [PMID: 38029251 PMCID: PMC10668012 DOI: 10.3389/fcimb.2023.1332253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 11/03/2023] [Indexed: 12/01/2023] Open
Affiliation(s)
- Selvakumar Subbian
- Public Health Research Institute Center at New Jersey Medical School, Rutgers University, Newark, NJ, United States
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7
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Fujiki J, Nakamura K, Nakamura T, Iwano H. Fitness Trade-Offs between Phage and Antibiotic Sensitivity in Phage-Resistant Variants: Molecular Action and Insights into Clinical Applications for Phage Therapy. Int J Mol Sci 2023; 24:15628. [PMID: 37958612 PMCID: PMC10650657 DOI: 10.3390/ijms242115628] [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: 10/06/2023] [Revised: 10/23/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
In recent decades, phage therapy has been overshadowed by the widespread use of antibiotics in Western countries. However, it has been revitalized as a powerful approach due to the increasing prevalence of antimicrobial-resistant bacteria. Although bacterial resistance to phages has been reported in clinical cases, recent studies on the fitness trade-offs between phage and antibiotic resistance have revealed new avenues in the field of phage therapy. This strategy aims to restore the antibiotic susceptibility of antimicrobial-resistant bacteria, even if phage-resistant variants develop. Here, we summarize the basic virological properties of phages and their applications within the context of antimicrobial resistance. In addition, we review the occurrence of phage resistance in clinical cases, and examine fitness trade-offs between phage and antibiotic sensitivity, exploring the potential of an evolutionary fitness cost as a countermeasure against phage resistance in therapy. Finally, we discuss future strategies and directions for phage-based therapy from the aspect of fitness trade-offs. This approach is expected to provide robust options when combined with antibiotics in this era of phage 're'-discovery.
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Affiliation(s)
- Jumpei Fujiki
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu 069-8501, Japan
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Keisuke Nakamura
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu 069-8501, Japan
| | - Tomohiro Nakamura
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu 069-8501, Japan
- Phage Therapy Institute, Waseda University, Tokyo 169-8050, Japan
- Research Center for Drug and Vaccine Development, National Institute of Infectious Diseases, Tokyo 208-0011, Japan
- Department of Veterinary Medicine, Azabu University, Sagamihara 252-5201, Japan
| | - Hidetomo Iwano
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu 069-8501, Japan
- Phage Therapy Institute, Waseda University, Tokyo 169-8050, Japan
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8
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Panteleev PV, Safronova VN, Kruglikov RN, Bolosov IA, Ovchinnikova TV. Genomic Insights into Bacterial Resistance to Proline-Rich Antimicrobial Peptide Bac7. MEMBRANES 2023; 13:438. [PMID: 37103865 PMCID: PMC10145973 DOI: 10.3390/membranes13040438] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/10/2023] [Accepted: 04/16/2023] [Indexed: 06/19/2023]
Abstract
Proline-rich antimicrobial peptides (PrAMPs) having a potent antimicrobial activity and a modest toxicity toward mammalian cells attract much attention as new templates for the development of antibiotic drugs. However, a comprehensive understanding of mechanisms of bacterial resistance development to PrAMPs is necessary before their clinical application. In this study, development of the resistance to the proline-rich bovine cathelicidin Bac71-22 derivative was characterized in the multidrug-resistant Escherichia coli clinical isolate causing the urinary tract infection. Three Bac71-22-resistant strains with ≥16-fold increase in minimal inhibitory concentrations (MICs) were selected by serially passaging after four-week experimental evolution. It was shown that in salt-containing medium, the resistance was mediated by inactivation of the SbmA transporter. The absence of salt in the selection media affected both dynamics and main molecular targets under selective pressure: a point mutation leading to the amino acid substitution N159H in the WaaP kinase responsible for heptose I phosphorylation in the LPS structure was also found. This mutation led to a phenotype with a decreased susceptibility to both the Bac71-22 and polymyxin B. Screening of antimicrobial activities with the use of a wide panel of known AMPs, including the human cathelicidin LL-37 and conventional antibiotics, against selected strains indicated no significant cross-resistance effects.
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9
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Laffargue T, Moulis C, Remaud-Simeon M. Phosphorylated polysaccharides: Applications, natural abundance, and new-to-nature structures generated by chemical and enzymatic functionalization. Biotechnol Adv 2023; 65:108140. [PMID: 36958536 DOI: 10.1016/j.biotechadv.2023.108140] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/14/2023] [Accepted: 03/18/2023] [Indexed: 03/25/2023]
Abstract
Polysaccharides are foreseen as serious candidates for the future generation of polymers, as they are biosourced and biodegradable materials. Their functionalisation is an attractive way to modify their properties, thereby increasing their range of applications. Introduction of phosphate groups in polysaccharide chains for the stimulation of the immune system was first described in the nineteen seventies. Since then, the use of phosphorylated polysaccharides has been proposed in various domains, such as healthcare, water treatment, cosmetic, biomaterials, etc. These alternative usages capitalize on newly acquired physico-chemical or biological properties, leading to materials as diverse as flame-resistant agents or drug delivery systems. Phosphorylated polysaccharides are found in Nature and need to be extracted to assess their biological potential. However, they are not abundant, often present complex backbones hard to characterize, and most of them have a low phosphate content. These drawbacks have pushed forward the development of chemical phosphorylation employing a wide variety of phosphorylating agents to obtain polysaccharides with a large range of phosphate content. Chemical phosphorylation requires the use of harsh conditions and toxic, petroleum-based solvents, which hinders their exploitation in the food and health industry. Over the last 20 years, although enzymes are regiospecific catalysts that work in aqueous and mild conditions, enzymatic phosphorylation has been little investigated. To date, only three families of enzymes have been used for the in vitro phosphorylation of polysaccharides. Considering the number of unresolved metabolic pathways leading to phosphorylated polysaccharides, the huge diversity of kinase sequences, and the recent progress in protein engineering one can envision native and engineered kinases as promising tools for polysaccharide phosphorylation.
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Affiliation(s)
- Thibaud Laffargue
- Biotechnology Institute (TBI), Université de Toulouse, CNRS, INRAE, INSA, 135, Avenue de Rangueil, CEDEX 04, F-31077 Toulouse, France
| | - Claire Moulis
- Biotechnology Institute (TBI), Université de Toulouse, CNRS, INRAE, INSA, 135, Avenue de Rangueil, CEDEX 04, F-31077 Toulouse, France
| | - Magali Remaud-Simeon
- Biotechnology Institute (TBI), Université de Toulouse, CNRS, INRAE, INSA, 135, Avenue de Rangueil, CEDEX 04, F-31077 Toulouse, France.
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10
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Wang Q, Kim H, Halvorsen TM, Chen S, Hayes CS, Buie CR. Leveraging microfluidic dielectrophoresis to distinguish compositional variations of lipopolysaccharide in E. coli. Front Bioeng Biotechnol 2023; 11:991784. [PMID: 36873367 PMCID: PMC9979706 DOI: 10.3389/fbioe.2023.991784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 02/03/2023] [Indexed: 02/18/2023] Open
Abstract
Lipopolysaccharide (LPS) is the unique feature that composes the outer leaflet of the Gram-negative bacterial cell envelope. Variations in LPS structures affect a number of physiological processes, including outer membrane permeability, antimicrobial resistance, recognition by the host immune system, biofilm formation, and interbacterial competition. Rapid characterization of LPS properties is crucial for studying the relationship between these LPS structural changes and bacterial physiology. However, current assessments of LPS structures require LPS extraction and purification followed by cumbersome proteomic analysis. This paper demonstrates one of the first high-throughput and non-invasive strategies to directly distinguish Escherichia coli with different LPS structures. Using a combination of three-dimensional insulator-based dielectrophoresis (3DiDEP) and cell tracking in a linear electrokinetics assay, we elucidate the effect of structural changes in E. coli LPS oligosaccharides on electrokinetic mobility and polarizability. We show that our platform is sufficiently sensitive to detect LPS structural variations at the molecular level. To correlate electrokinetic properties of LPS with the outer membrane permeability, we further examined effects of LPS structural variations on bacterial susceptibility to colistin, an antibiotic known to disrupt the outer membrane by targeting LPS. Our results suggest that microfluidic electrokinetic platforms employing 3DiDEP can be a useful tool for isolating and selecting bacteria based on their LPS glycoforms. Future iterations of these platforms could be leveraged for rapid profiling of pathogens based on their surface LPS structural identity.
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Affiliation(s)
- Qianru Wang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Hyungseok Kim
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Tiffany M. Halvorsen
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Sijie Chen
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Christopher S. Hayes
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Cullen R. Buie
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
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11
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McGee LW, Barhoush Y, Shima R, Hennessy M. Phage-resistant mutations impact bacteria susceptibility to future phage infections and antibiotic response. Ecol Evol 2023; 13:e9712. [PMID: 36620417 PMCID: PMC9817185 DOI: 10.1002/ece3.9712] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 11/16/2022] [Accepted: 12/16/2022] [Indexed: 01/09/2023] Open
Abstract
Bacteriophage (phage) therapy in combination with antibiotic treatment serves as a potential strategy to overcome the continued rise in antibiotic resistance across bacterial pathogens. Understanding the impacts of evolutionary and ecological processes to the phage-antibiotic-resistance dynamic could advance the development of such combinatorial therapy. We tested whether the acquisition of mutations conferring phage resistance may have antagonistically pleiotropic consequences for antibiotic resistance. First, to determine the robustness of phage resistance across different phage strains, we infected resistant Escherichia coli cultures with phage that were not previously encountered. We found that phage-resistant E. coli mutants that gained resistance to a single phage strain maintain resistance to other phages with overlapping adsorption methods. Mutations underlying the phage-resistant phenotype affects lipopolysaccharide (LPS) structure and/or synthesis. Because LPS is implicated in both phage infection and antibiotic response, we then determined whether phage-resistant trade-offs exist when challenged with different classes of antibiotics. We found that only 1 out of the 4 phage-resistant E. coli mutants yielded trade-offs between phage and antibiotic resistance. Surprisingly, when challenged with novobiocin, we uncovered evidence of synergistic pleiotropy for some mutants allowing for greater antibiotic resistance, even though antibiotic resistance was never selected for. Our results highlight the importance of understanding the role of selective pressures and pleiotropic interactions in the bacterial response to phage-antibiotic combinatorial therapy.
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Affiliation(s)
| | - Yazid Barhoush
- Biology DepartmentEarlham CollegeRichmondIndianaUSA
- Department of Epidemiology and BiostatisticsDrexel UniversityPhiladelphiaPennsylvaniaUSA
| | - Rafaella Shima
- Biology DepartmentEarlham CollegeRichmondIndianaUSA
- Department of Physiology and Institute of Diabetes, Obesity, and Metabolism, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
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12
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Choi E, Huh A, Hwang J. Novel rRNA transcriptional activity of NhaR revealed by its growth recovery for the bipA-deleted Escherichia coli at low temperature. Front Mol Biosci 2023; 10:1175889. [PMID: 37152896 PMCID: PMC10157491 DOI: 10.3389/fmolb.2023.1175889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 04/12/2023] [Indexed: 05/09/2023] Open
Abstract
The BipA protein is a universally conserved GTPase in bacterial species and is structurally similar to translational GTPases. Despite its wide distribution, BipA is dispensable for growth under optimal growth conditions but is required under stress conditions. In particular, bipA-deleted cells (ESC19) have been shown to display a variety of phenotypic changes in ribosome assembly, capsule production, lipopolysaccharide (LPS) synthesis, biofilm formation, and motility at low temperature, suggesting its global regulatory roles in cold adaptation. Here, through genomic library screening, we found a suppressor clone containing nhaR, which encodes a Na+-responsive LysR-type transcriptional regulator and whose gene product partially restored the growth of strain ESC19 at 20°C. The suppressed cells showed slightly reduced capsule production and improved biofilm-forming ability at 20°C, whereas the defects in the LPS core and swimming motility were not restored but aggravated by overexpression of nhaR. Notably, the overexpression partially alleviated the defects in 50S ribosomal subunit assembly and rRNA processing of ESC19 cells by enhancing the overall transcription of rRNA. Electrophoretic mobility shift assay revealed the association of NhaR with the promoter of seven rrn operons, suggesting that NhaR directly regulates rRNA transcription in ESC19 at 20°C. The suppressive effects of NhaR on ribosomes, capsules, and LPS were dependent on its DNA-binding activity, implying that NhaR might be a transcriptional factor involved in regulating these genes at 20°C. Furthermore, we found that BipA may be involved in adaptation to salt stress, designating BipA as a global stress-responsive regulator, as the deletion of bipA led to growth defects at 37°C and high Na+ concentrations without ribosomal defects.
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Affiliation(s)
- Eunsil Choi
- Department of Microbiology, Pusan National University, Busan, Republic of Korea
- Microbiological Resource Research Institute, Pusan National University, Busan, Republic of Korea
| | - Ahhyun Huh
- Department of Microbiology, Pusan National University, Busan, Republic of Korea
| | - Jihwan Hwang
- Department of Microbiology, Pusan National University, Busan, Republic of Korea
- Microbiological Resource Research Institute, Pusan National University, Busan, Republic of Korea
- *Correspondence: Jihwan Hwang,
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13
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Identification of novel genes involved in the biofilm formation process of Avian Pathogenic Escherichia coli (APEC). PLoS One 2022; 17:e0279206. [PMID: 36534660 PMCID: PMC9762606 DOI: 10.1371/journal.pone.0279206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 12/01/2022] [Indexed: 12/23/2022] Open
Abstract
Avian pathogenic Escherichia coli (APEC) is the etiological agent of avian colibacillosis, a leading cause of economic loss to the poultry industry worldwide. APEC causes disease using a diverse repertoire of virulence factors and has the ability to form biofilms, which contributes to the survival and persistence of APEC in harsh environments. The objective of this study was to identify genes most widespread and important in APEC that contribute to APEC biofilm formation. Using the characterized APEC O18 as the template strain, a total of 15,660 mutants were randomly generated using signature tagged mutagenesis and evaluated for decreased biofilm formation ability using the crystal violet assay. Biofilm deficient mutants were sequenced, and a total of 547 putative biofilm formation genes were identified. Thirty of these genes were analyzed by PCR for prevalence among 109 APEC isolates and 104 avian fecal E. coli (AFEC) isolates, resulting in nine genes with significantly greater prevalence in APEC than AFEC. The expression of these genes was evaluated in the wild-type APEC O18 strain using quantitative real-time PCR (qPCR) in both the exponential growth phase and the mature biofilm phase. To investigate the role of these genes in biofilm formation, isogenic mutants were constructed and evaluated for their biofilm production and planktonic growth abilities. Four of the mutants (rfaY, rfaI, and two uncharacterized genes) displayed significantly decreased biofilm formation, and of those four, one (rfaI) displayed significantly decreased growth compared to the wild type. Overall, this study identified novel genes that may be important in APEC and its biofilm formation. The data generated from this study will benefit further investigation into the mechanisms of APEC biofilm formation.
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Genomic features of in vitro selected mutants of Escherichia coli with decreased susceptibility to tigecycline. J Glob Antimicrob Resist 2022; 31:32-37. [PMID: 35933109 DOI: 10.1016/j.jgar.2022.07.023] [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: 03/18/2022] [Revised: 07/27/2022] [Accepted: 07/31/2022] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVES The increase in multidrug-resistant bacteria has reached an alarming rate globally, making it necessary to understand the underlying mechanisms mediating resistance in order to discover new therapeutics. Tigecycline (TGC) is a last-resort antimicrobial agent for the treatment of serious infections caused by extensively drug-resistant Enterobacteriaceae. METHODS The TGC-resistant Escherichia coli mutants were obtained by exposing three different TGC-susceptible isolates belonging to ST131 (n = 2) and ST405 (n = 1) to increasing concentrations of TGC. The genetic alterations associated with reduced susceptibility to TGC were identified using whole genome sequencing. The fitness cost of TGC resistance acquisition, as well as incidence of cross-resistance, was also investigated. RESULTS The TGC minimum inhibitory concentrations (MICs) of in vitro selected mutants were elevated 8 to 32 times compared with ancestral strains. Inactivating mutations (frameshift and nonsense) or amino acid substitutions were identified in genes encoding proteins with diverse functions, including AcrAB efflux pump or its regulators (lon and marR), Lipopolysaccharides (LPS) inner core biosynthesis enzymes (waaQ and eptB), ribosomal S9 protein (rpsI), and RNA polymerase β subunit. In most cases (but not all), acquisition of TGC resistance was associated with a fitness cost. While TGC resistance development was associated with cross-resistance to other members of the tetracycline family and chloramphenicol, hypersensitivity to nitrofurantoin was identified among heptose III-less LPS mutants. CONCLUSION TGC resistance among the studied mutants was found to be multifactorial with extrusion by efflux transports being the most common mechanism. The LPS inner core biosynthesis pathway, as well as ribosomal S9 protein, could be additional targets for TGC resistance.
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Ifrid E, Ouertatani-Sakouhi H, Jauslin T, Kicka S, Chiriano G, Harrison CF, Hilbi H, Scapozza L, Soldati T, Cosson P. 5-ethyl-2'-deoxyuridine fragilizes Klebsiella pneumoniae outer wall and facilitates intracellular killing by phagocytic cells. PLoS One 2022; 17:e0269093. [PMID: 36315510 PMCID: PMC9621411 DOI: 10.1371/journal.pone.0269093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 05/14/2022] [Indexed: 01/24/2023] Open
Abstract
Klebsiella pneumoniae is the causative agent of a variety of severe infections. Many K. pneumoniae strains are resistant to multiple antibiotics, and this situation creates a need for new antibacterial molecules. K. pneumoniae pathogenicity relies largely on its ability to escape phagocytosis and intracellular killing by phagocytic cells. Interfering with these escape mechanisms may allow to decrease bacterial virulence and to combat infections. In this study, we used Dictyostelium discoideum as a model phagocyte to screen a collection of 1,099 chemical compounds. Phg1A KO D. discoideum cells cannot feed upon K. pneumoniae bacteria, unless bacteria bear mutations decreasing their virulence. We identified 3 non-antibiotic compounds that restored growth of phg1A KO cells on K. pneumoniae, and we characterized the mode of action of one of them, 5-ethyl-2'-deoxyuridine (K2). K2-treated bacteria were more rapidly killed in D. discoideum phagosomes than non-treated bacteria. They were more sensitive to polymyxin and their outer membrane was more accessible to a hydrophobic fluorescent probe. These results suggest that K2 acts by rendering the membrane of K. pneumoniae accessible to antibacterial effectors. K2 was effective on three different K. pneumoniae strains, and acted at concentrations as low as 3 μM. K2 has previously been used to treat viral infections but its precise molecular mechanism of action in K. pneumoniae remains to be determined.
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Affiliation(s)
- Estelle Ifrid
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Centre Médical Universitaire, Geneva, Switzerland
| | - Hajer Ouertatani-Sakouhi
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Centre Médical Universitaire, Geneva, Switzerland
| | - Tania Jauslin
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Centre Médical Universitaire, Geneva, Switzerland
| | - Sebastien Kicka
- Department of Biochemistry, Faculty of Science, University of Geneva, Geneva, Switzerland
| | - Gianpaolo Chiriano
- Pharmaceutical Biochemistry, School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland
| | - Christopher F. Harrison
- Max von Pettenkofer Institute, Department of Medicine, Ludwig-Maximilians University Munich, Munich, Germany
| | - Hubert Hilbi
- Institute of Medical Microbiology, Department of Medicine, University of Zürich, Zürich, Switzerland
| | - Leonardo Scapozza
- Pharmaceutical Biochemistry, School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland
| | - Thierry Soldati
- Department of Biochemistry, Faculty of Science, University of Geneva, Geneva, Switzerland
| | - Pierre Cosson
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Centre Médical Universitaire, Geneva, Switzerland
- * E-mail:
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Jiang X, Chu C, Wang Z, Gu J, Hong Y, Li Q, Jiao X. Preclinical evaluation of OMVs as potential vaccine candidates against Salmonella enterica serovar Enteritidis infection. Front Cell Infect Microbiol 2022; 12:1037607. [DOI: 10.3389/fcimb.2022.1037607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 10/17/2022] [Indexed: 11/13/2022] Open
Abstract
Salmonella enterica serovar Enteritidis is the most prevalent serotype that causes human infections worldwide. Consumption of S. Enteritidis-contaminated animal foods is a major source of human infections; however, eradicating bacteria from animals remains difficult. Therefore, it is necessary to develop new measures to prevent and control salmonellosis. Here, we used the outer-membrane vesicles (OMVs) of S. Enteritidis and assessed their protective efficacy and immune response in mice. Deletion of tolR in S. Enteritidis increased the production and size of OMVs compared to those in the wild type (WT) and ΔrfaQ strains. Intramuscular immunization with OMVs conferred greater protection than intraperitoneal and intranasal immunization. Moreover, OMVs extracted from both WT and ΔtolR strains provided an 83.3% protective rate in mice challenged with S. Enteritidis, which was higher than that provided by OMVs extracted from the ΔrfaQ strain. However, compared with OMVs from the ΔtolR strain, OMVs from WT and ΔrfaQ strains rapidly eradicated S. Enteritidis colonizing the liver, spleen, ileum, and cecum of BALB/c mice after immunization. Immunization with OMVs from each of the three strains induced humoral immune responses and showed no side effects on the growth of mice. Our study revealed that OMVs from various S. Enteritidis strains could be developed for use as subunit vaccine candidates against nontyphoidal Salmonella infections in mammals.
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17
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Maleš M, Zoranić L. Simulation Study of the Effect of Antimicrobial Peptide Associations on the Mechanism of Action with Bacterial and Eukaryotic Membranes. MEMBRANES 2022; 12:891. [PMID: 36135911 PMCID: PMC9502835 DOI: 10.3390/membranes12090891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/06/2022] [Accepted: 09/09/2022] [Indexed: 06/16/2023]
Abstract
Antimicrobial peptides (AMPs) can be directed to specific membranes based on differences in lipid composition. In this study, we performed atomistic and coarse-grained simulations of different numbers of the designed AMP adepantin-1 with a eukaryotic membrane, cytoplasmic Gram-positive and Gram-negative membranes, and an outer Gram-negative membrane. At the core of adepantin-1's behavior is its amphipathic α-helical structure, which was implemented in its design. The amphipathic structure promotes rapid self-association of peptide in water or upon binding to bacterial membranes. Aggregates initially make contact with the membrane via positively charged residues, but with insertion, the hydrophobic residues are exposed to the membrane's hydrophobic core. This adaptation alters the aggregate's stability, causing the peptides to diffuse in the polar region of the membrane, mostly remaining as a single peptide or pairing up to form an antiparallel dimer. Thus, the aggregate's proposed role is to aid in positioning the peptide into a favorable conformation for insertion. Simulations revealed the molecular basics of adepantin-1 binding to various membranes, and highlighted peptide aggregation as an important factor. These findings contribute to the development of novel anti-infective agents to combat the rapidly growing problem of bacterial resistance to antibiotics.
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Affiliation(s)
- Matko Maleš
- Faculty of Maritime Studies, University of Split, 21000 Split, Croatia
| | - Larisa Zoranić
- Department of Physics, Faculty of Science, University of Split, 21000 Split, Croatia
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18
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Abstract
Urinary tract infection (UTI) is among the most common infections treated worldwide each year and is caused primarily by uropathogenic Escherichia coli (UPEC). Rising rates of antibiotic resistance among uropathogens have spurred a consideration of alternative treatment strategies, such as bacteriophage (phage) therapy; however, phage-bacterial interactions within the urinary environment are poorly defined. Here, we assess the activity of two phages, namely, HP3 and ES17, against clinical UPEC isolates using in vitro and in vivo models of UTI. In both bacteriologic medium and pooled human urine, we identified phage resistance arising within the first 6 to 8 h of coincubation. Whole-genome sequencing revealed that UPEC strains resistant to HP3 and ES17 harbored mutations in genes involved in lipopolysaccharide (LPS) biosynthesis. Phage-resistant strains displayed several in vitro phenotypes, including alterations to adherence to and invasion of human bladder epithelial HTB-9 cells and increased biofilm formation in some isolates. Interestingly, these phage-resistant UPEC isolates demonstrated reduced growth in pooled human urine, which could be partially rescued by nutrient supplementation and were more sensitive to several outer membrane-targeting antibiotics than parental strains. Additionally, phage-resistant UPEC isolates were attenuated in bladder colonization in a murine UTI model. In total, our findings suggest that while resistance to phages, such as HP3 and ES17, may arise readily in the urinary environment, phage resistance is accompanied by fitness costs which may render UPEC more susceptible to host immunity or antibiotics. IMPORTANCE UTI is one of the most common causes of outpatient antibiotic use, and rising antibiotic resistance threatens the ability to control UTI unless alternative treatments are developed. Bacteriophage (phage) therapy is gaining renewed interest; however, much like with antibiotics, bacteria can readily become resistant to phages. For successful UTI treatment, we must predict how bacteria will evade killing by phage and identify the downstream consequences of phage resistance during bacterial infection. In our current study, we found that while phage-resistant bacteria quickly emerged in vitro, these bacteria were less capable of growing in human urine and colonizing the murine bladder. These results suggest that phage therapy poses a viable UTI treatment if phage resistance confers fitness costs for the uropathogen. These results have implications for developing cocktails of phage with multiple different bacterial targets, of which each is evaded only at the cost of bacterial fitness.
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19
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Marciano DC, Wang C, Hsu TK, Bourquard T, Atri B, Nehring RB, Abel NS, Bowling EA, Chen TJ, Lurie PD, Katsonis P, Rosenberg SM, Herman C, Lichtarge O. Evolutionary action of mutations reveals antimicrobial resistance genes in Escherichia coli. Nat Commun 2022; 13:3189. [PMID: 35680894 PMCID: PMC9184624 DOI: 10.1038/s41467-022-30889-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 05/24/2022] [Indexed: 11/08/2022] Open
Abstract
Since antibiotic development lags, we search for potential drug targets through directed evolution experiments. A challenge is that many resistance genes hide in a noisy mutational background as mutator clones emerge in the adaptive population. Here, to overcome this noise, we quantify the impact of mutations through evolutionary action (EA). After sequencing ciprofloxacin or colistin resistance strains grown under different mutational regimes, we find that an elevated sum of the evolutionary action of mutations in a gene identifies known resistance drivers. This EA integration approach also suggests new antibiotic resistance genes which are then shown to provide a fitness advantage in competition experiments. Moreover, EA integration analysis of clinical and environmental isolates of antibiotic resistant of E. coli identifies gene drivers of resistance where a standard approach fails. Together these results inform the genetic basis of de novo colistin resistance and support the robust discovery of phenotype-driving genes via the evolutionary action of genetic perturbations in fitness landscapes.
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Affiliation(s)
- David C Marciano
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
| | - Chen Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Teng-Kuei Hsu
- The Verna and Marrs McLean Department of Biochemistry & Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Thomas Bourquard
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Benu Atri
- Structural and Computational Biology & Molecular Biophysics Program, Baylor College of Medicine, Houston, TX, 77030, USA
- Clara Analytics Inc., 451 El Camino Real #201, Santa Clara, CA, 95050, USA
| | - Ralf B Nehring
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- The Verna and Marrs McLean Department of Biochemistry & Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, 77030, USA
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Nicholas S Abel
- Department of Pharmacology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Elizabeth A Bowling
- The Verna and Marrs McLean Department of Biochemistry & Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Taylor J Chen
- Integrative Molecular & Biomedical Biosciences Program, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Pamela D Lurie
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Panagiotis Katsonis
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Susan M Rosenberg
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- The Verna and Marrs McLean Department of Biochemistry & Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, 77030, USA
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, 77030, USA
- Integrative Molecular & Biomedical Biosciences Program, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Christophe Herman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, 77030, USA
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Olivier Lichtarge
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
- Structural and Computational Biology & Molecular Biophysics Program, Baylor College of Medicine, Houston, TX, 77030, USA.
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, 77030, USA.
- Computational and Integrative Biomedical Research Center, Baylor College of Medicine, Houston, TX, 77030, USA.
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Valvano MA. Remodelling of the Gram-negative bacterial Kdo 2-lipid A and its functional implications. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35394417 DOI: 10.1099/mic.0.001159] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The lipopolysaccharide (LPS) is a characteristic molecule of the outer leaflet of the Gram-negative bacterial outer membrane, which consists of lipid A, core oligosaccharide, and O antigen. The lipid A is embedded in outer membrane and provides an efficient permeability barrier, which is particularly important to reduce the permeability of antibiotics, toxic cationic metals, and antimicrobial peptides. LPS, an important modulator of innate immune responses ranging from localized inflammation to disseminated sepsis, displays a high level of structural and functional heterogeneity, which arise due to regulated differences in the acylation of the lipid A and the incorporation of non-stoichiometric modifications in lipid A and the core oligosaccharide. This review focuses on the current mechanistic understanding of the synthesis and assembly of the lipid A molecule and its most salient non-stoichiometric modifications.
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Affiliation(s)
- Miguel A Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7BL, UK
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21
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Wang Z, Fan F, Wang J, Wang L, Hu H, Wang C, Wang X. Engineering Escherichia coli to produce Bordetella pertussis oligosaccharide with multiple trisaccharide units. Metab Eng 2021; 69:147-162. [PMID: 34863939 DOI: 10.1016/j.ymben.2021.11.013] [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: 08/19/2021] [Revised: 11/18/2021] [Accepted: 11/30/2021] [Indexed: 11/25/2022]
Abstract
The immunogenicity of the pertussis vaccine can be significantly improved by adding Bordetella pertussis oligosaccharide with multiple trisaccharide units. The more trisaccharide units there are, the better the efficiency of the immune response induction. However, natural B. pertussis oligosaccharides usually contain only a single terminal trisaccharide unit. In addition, B. pertussis is pathogenic, and there are potential safety hazards when preparing oligosaccharides from B. pertussis. In this study, Escherichia coli MG1655 was engineered to produce B. pertussis oligosaccharides containing multiple trisaccharide units. Fifty-nine genes relevant to the biosynthesis of the O-antigen and core oligosaccharide of lipopolysaccharide, enterobacterial common antigen, and colanic acid were deleted in MG1655, resulting in strain MDCO020. Then, 25 genes relevant to the biosynthesis of the oligosaccharide antigen in B. pertussis and 3 genes relevant to the repeating trisaccharide unit in Pseudomonas aeruginosa PAO1 were overexpressed in MDCO020, resulting in the recombinant E. coli MDCO020/pWpBpD5. The production of B. pertussis oligosaccharide with multiple trisaccharide units by MDCO020/pWpBpD5 was confirmed by SDS-PAGE and 1H NMR analyses, and its immune response-stimulating activity was confirmed by using rabbit anti-pertussis serum.
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Affiliation(s)
- Zhen Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Fengfeng Fan
- Suzhou Microvac Biotech Co., Ltd., Suzhou, 215021, China
| | - Jianli Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Liangjia Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Hao Hu
- Suzhou Microvac Biotech Co., Ltd., Suzhou, 215021, China
| | - Chenhui Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
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22
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Lipidation of Class IV CdiA Effector Proteins Promotes Target Cell Recognition during Contact-Dependent Growth Inhibition. mBio 2021; 12:e0253021. [PMID: 34634941 PMCID: PMC8510554 DOI: 10.1128/mbio.02530-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Contact-dependent growth inhibition (CDI) systems enable the direct transfer of protein toxins between competing Gram-negative bacteria. CDI+ strains produce cell surface CdiA effector proteins that bind specific receptors on neighboring bacteria to initiate toxin delivery. Three classes of CdiA effectors that recognize different outer membrane protein receptors have been characterized in Escherichia coli to date. Here, we describe a fourth effector class that uses the lipopolysaccharide (LPS) core as a receptor to identify target bacteria. Selection for CDI-resistant target cells yielded waaF and waaP “deep-rough” mutants, which are unable to synthesize the full LPS core. The CDI resistance phenotypes of other waa mutants suggest that phosphorylated inner-core heptose residues form a critical CdiA recognition epitope. Class IV cdi loci also encode putative lysyl acyltransferases (CdiC) that are homologous to enzymes that lipidate repeats-in-toxin (RTX) cytolysins. We found that catalytically active CdiC is required for full target cell killing activity, and we provide evidence that the acyltransferase appends 3-hydroxydecanoate to a specific Lys residue within the CdiA receptor-binding domain. We propose that the lipid moiety inserts into the hydrophobic leaflet of lipid A to anchor CdiA interactions with the core oligosaccharide. Thus, LPS-binding CDI systems appear to have co-opted an RTX toxin-activating acyltransferase to increase the affinity of CdiA effectors for the target cell outer membrane.
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23
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Georgieva M, Heinonen T, Vitale A, Hargraves S, Causevic S, Pillonel T, Eberl L, Widmann C, Jacquier N. Bacterial surface properties influence the activity of the TAT-RasGAP 317-326 antimicrobial peptide. iScience 2021; 24:102923. [PMID: 34430812 PMCID: PMC8365389 DOI: 10.1016/j.isci.2021.102923] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/05/2021] [Accepted: 07/27/2021] [Indexed: 12/13/2022] Open
Abstract
Antibiotic resistance is an increasing threat for public health, underscoring the need for new antibacterial agents. Antimicrobial peptides (AMPs) represent an alternative to classical antibiotics. TAT-RasGAP317-326 is a recently described AMP effective against a broad range of bacteria, but little is known about the conditions that may influence its activity. Using RNA-sequencing and screening of mutant libraries, we show that Escherichia coli and Pseudomonas aeruginosa respond to TAT-RasGAP317-326 by regulating metabolic and stress response pathways, possibly implicating two-component systems. Our results also indicate that bacterial surface properties, in particular integrity of the lipopolysaccharide layer, influence peptide binding and entry. Finally, we found differences between bacterial species with respect to their rate of resistance emergence against this peptide. Our findings provide the basis for future investigation on the mode of action of TAT-RasGAP317-326, which may help developing antimicrobial treatments based on this peptide.
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Affiliation(s)
- Maria Georgieva
- Department of Biomedical Sciences, University of Lausanne, Lausanne 1005, Switzerland
| | - Tytti Heinonen
- Institute of Microbiology, Lausanne University Hospital and University of Lausanne, Lausanne 1011, Switzerland
| | - Alessandra Vitale
- Department of Plant and Microbial Biology, University of Zurich, Zurich 8008, Switzerland
| | - Simone Hargraves
- Institute of Microbiology, Lausanne University Hospital and University of Lausanne, Lausanne 1011, Switzerland
| | - Senka Causevic
- Institute of Microbiology, Lausanne University Hospital and University of Lausanne, Lausanne 1011, Switzerland
| | - Trestan Pillonel
- Institute of Microbiology, Lausanne University Hospital and University of Lausanne, Lausanne 1011, Switzerland
| | - Leo Eberl
- Department of Plant and Microbial Biology, University of Zurich, Zurich 8008, Switzerland
| | - Christian Widmann
- Department of Biomedical Sciences, University of Lausanne, Lausanne 1005, Switzerland
- Corresponding author
| | - Nicolas Jacquier
- Institute of Microbiology, Lausanne University Hospital and University of Lausanne, Lausanne 1011, Switzerland
- Corresponding author
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Di Lorenzo F, Duda KA, Lanzetta R, Silipo A, De Castro C, Molinaro A. A Journey from Structure to Function of Bacterial Lipopolysaccharides. Chem Rev 2021; 122:15767-15821. [PMID: 34286971 DOI: 10.1021/acs.chemrev.0c01321] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Lipopolysaccharide (LPS) is a crucial constituent of the outer membrane of most Gram-negative bacteria, playing a fundamental role in the protection of bacteria from environmental stress factors, in drug resistance, in pathogenesis, and in symbiosis. During the last decades, LPS has been thoroughly dissected, and massive information on this fascinating biomolecule is now available. In this Review, we will give the reader a third millennium update of the current knowledge of LPS with key information on the inherent peculiar carbohydrate chemistry due to often puzzling sugar residues that are uniquely found on it. Then, we will drive the reader through the complex and multifarious immunological outcomes that any given LPS can raise, which is strictly dependent on its chemical structure. Further, we will argue about issues that still remain unresolved and that would represent the immediate future of LPS research. It is critical to address these points to complete our notions on LPS chemistry, functions, and roles, in turn leading to innovative ways to manipulate the processes involving such a still controversial and intriguing biomolecule.
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Affiliation(s)
- Flaviana Di Lorenzo
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy
| | - Katarzyna A Duda
- Research Center Borstel Leibniz Lung Center, Parkallee 4a, 23845 Borstel, Germany
| | - Rosa Lanzetta
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy
| | - Alba Silipo
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy
| | - Cristina De Castro
- Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Department of Agricultural Sciences, University of Naples Federico II, Via Università 96, 80055 Portici, Naples, Italy
| | - Antonio Molinaro
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Department of Chemistry, School of Science, Osaka University, 1-1 Osaka University Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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The expanding world of protein kinase-like families in bacteria: forty families and counting. Biochem Soc Trans 2021; 48:1337-1352. [PMID: 32677675 DOI: 10.1042/bst20190712] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/24/2020] [Accepted: 06/29/2020] [Indexed: 12/14/2022]
Abstract
The protein kinase-like clan/superfamily is a large group of regulatory, signaling and biosynthetic enzymes that were historically regarded as typically eukaryotic proteins, although bacterial members have also been known for a long time. In this review, we explore the diversity of bacterial protein kinase like families, and discuss functional versatility of these enzymes, both the ones acting within the bacterial cell, and those acting within eukaryotic cells as effectors during infection. We focus on novel bacterial kinase-like families discovered in the last five years. A bioinformatics perspective is held here, hence sequence and structure comparison overview is presented, and also a comparison of genomic neighbourhoods of the families. We perform a phylum-level census of the families. Also, we discuss apparent pseudokinases that turned out to perform alternative catalytic functions by repurposing their atypical kinase-like active sites. We also highlight some 'unpopular' kinase-like families that await characterisation.
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Chen S, Chen S, Wang J, Zhan Y, Wang Z, Fang Y, Wang X. Characterization of a gene cluster containing four genes relevant to biosynthesis of inner core of lipopolysaccharide in Cronobacter sakazakii. Biotechnol Appl Biochem 2021; 69:1080-1093. [PMID: 33928676 DOI: 10.1002/bab.2179] [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] [Received: 01/27/2021] [Accepted: 04/20/2021] [Indexed: 11/08/2022]
Abstract
Many genes in the biosynthetic pathway of lipopolysaccharide in Cronobacter sakazakii have not been identified. In this study, we demonstrate that an operon containing four genes ESA_RS18945, ESA_RS18950, ESA_RS18955, and ESA_RS18960 is responsible for L-glycero-D-mannoheptose addition on the inner core of lipopolysaccharide in C. sakazakii. The proteins encoded by these four genes are homologous to E. coli WaaQ, WaaC, WaaF, and WaaD. Lipopolysaccharide from the deletion mutants of ESA_RS18945, ESA_RS18950, ESA_RS18955, and ESA_RS18960 (named as △RS18945, △RS18950, △RS18955 and △RS18960, respectively) were analyzed by SDS-PAGE. △RS18945 synthesized lipopolysaccharide with similar length to the wildtype BAA-894, whereas △RS18950, △RS18955, and △RS18960 synthesized much shorter lipopolysaccharide. This suggests that the enzyme encoded by ESA_RS18945 might function as E. coli WaaQ on the sidechain of lipopolysaccharide. When E. coli WaaC, WaaF, and WaaD were overexpressed in △RS18950, △RS18955, and △RS18960, respectively, the full length of lipopolysaccharide was recovered. Mass spectrometry analysis indicates that △RS18950 and △RS18960 only synthesized Kdo2 -lipid A, confirming that enzymes encoded by ESA_RS18950 and ESA_RS18960 have similar functions to E. coli WaaC and WaaD, respectively. Hep-Kdo2 -lipid A with a phosphoethanolamine was produced in △RS18955, suggesting that the enzyme encoded by ESA_RS18955 has similar function to E. coli WaaF.
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Affiliation(s)
- Shanshan Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Si Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Jianli Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, China
| | - Yi Zhan
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Zhen Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Yu Fang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
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Wang J, Ma W, Wang X. Insights into the structure of Escherichia coli outer membrane as the target for engineering microbial cell factories. Microb Cell Fact 2021; 20:73. [PMID: 33743682 PMCID: PMC7980664 DOI: 10.1186/s12934-021-01565-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/12/2021] [Indexed: 12/16/2022] Open
Abstract
Escherichia coli is generally used as model bacteria to define microbial cell factories for many products and to investigate regulation mechanisms. E. coli exhibits phospholipids, lipopolysaccharides, colanic acid, flagella and type I fimbriae on the outer membrane which is a self-protective barrier and closely related to cellular morphology, growth, phenotypes and stress adaptation. However, these outer membrane associated molecules could also lead to potential contamination and insecurity for fermentation products and consume lots of nutrients and energy sources. Therefore, understanding critical insights of these membrane associated molecules is necessary for building better microbial producers. Here the biosynthesis, function, influences, and current membrane engineering applications of these outer membrane associated molecules were reviewed from the perspective of synthetic biology, and the potential and effective engineering strategies on the outer membrane to improve fermentation features for microbial cell factories were suggested.
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Affiliation(s)
- Jianli Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,International Joint Laboratory On Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Wenjian Ma
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China. .,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
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28
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Guo Z, Tang Y, Tang W, Chen Y. Heptose-containing bacterial natural products: structures, bioactivities, and biosyntheses. Nat Prod Rep 2021; 38:1887-1909. [PMID: 33704304 DOI: 10.1039/d0np00075b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Covering: up to 2020Glycosylated natural products hold great potential as drugs for the treatment of human and animal diseases. Heptoses, known as seven-carbon-chain-containing sugars, are a group of saccharides that are rarely observed in natural products. Based on the structures of the heptoses, the heptose-containing natural products can be divided into four groups, characterized by heptofuranose, highly-reduced heptopyranose, d-heptopyranose, and l-heptopyranose. Many of them possess remarkable biological properties, including antibacterial, antifungal, antitumor, and pain relief activities, thereby attracting great interest in biosynthesis and chemical synthesis studies to understand their construction mechanisms and structure-activity relationships. In this review, we summarize the structural properties, biological activities, and recent progress in the biosynthesis of bacterial natural products featuring seven-carbon-chain-containing sugars. The biosynthetic origins of the heptose moieties are emphasized.
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Affiliation(s)
- Zhengyan Guo
- State Key Laboratory of Microbial Resources, CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China. and University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Yue Tang
- State Key Laboratory of Microbial Resources, CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China. and University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Wei Tang
- State Key Laboratory of Microbial Resources, CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China. and University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Yihua Chen
- State Key Laboratory of Microbial Resources, CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China. and University of Chinese Academy of Sciences, 100049 Beijing, China
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29
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Palmieri E, Arato V, Oldrini D, Ricchetti B, Aruta MG, Pansegrau W, Marchi S, Giusti F, Ferlenghi I, Rossi O, Alfini R, Giannelli C, Gasperini G, Necchi F, Micoli F. Stability of Outer Membrane Vesicles-Based Vaccines, Identifying the Most Appropriate Methods to Detect Changes in Vaccine Potency. Vaccines (Basel) 2021; 9:229. [PMID: 33800727 PMCID: PMC7998687 DOI: 10.3390/vaccines9030229] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/01/2021] [Accepted: 03/02/2021] [Indexed: 01/15/2023] Open
Abstract
Ensuring the stability of vaccines is crucial to successfully performing global immunization programs. Outer Membrane Vesicles (OMV) are receiving great attention as vaccine platforms. OMV are complex molecules and few data have been collected so far on their stability. OMV produced by bacteria, genetically modified to increase their spontaneous release, simplifying their production, are also known as Generalized Modules for Membrane Antigens (GMMA). We have performed accelerated stability studies on GMMA from different pathogens and verified the ability of physico-chemical and immunological methods to detect possible changes. High-temperature conditions (100 °C for 40 min) did not affect GMMA stability and immunogenicity in mice, in contrast to the effect of milder temperatures for a longer period of time (37 °C or 50 °C for 4 weeks). We identified critical quality attributes to monitor during stability assessment that could impact vaccine efficacy. In particular, specific recognition of antigens by monoclonal antibodies through competitive ELISA assays may replace in vivo tests for the potency assessment of GMMA-based vaccines.
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Affiliation(s)
- Elena Palmieri
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
| | - Vanessa Arato
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
| | - Davide Oldrini
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
| | - Beatrice Ricchetti
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
| | - Maria Grazia Aruta
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
| | - Werner Pansegrau
- GSK, Via Fiorentina 1, 53100 Siena, Italy; (W.P.); (S.M.); (F.G.); (I.F.)
| | - Sara Marchi
- GSK, Via Fiorentina 1, 53100 Siena, Italy; (W.P.); (S.M.); (F.G.); (I.F.)
| | - Fabiola Giusti
- GSK, Via Fiorentina 1, 53100 Siena, Italy; (W.P.); (S.M.); (F.G.); (I.F.)
| | - Ilaria Ferlenghi
- GSK, Via Fiorentina 1, 53100 Siena, Italy; (W.P.); (S.M.); (F.G.); (I.F.)
| | - Omar Rossi
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
| | - Renzo Alfini
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
| | - Carlo Giannelli
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
| | - Gianmarco Gasperini
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
| | - Francesca Necchi
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
| | - Francesca Micoli
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Via Fiorentina 1, 53100 Siena, Italy; (E.P.); (V.A.); (D.O.); (B.R.); (M.G.A.); (O.R.); (R.A.); (C.G.); (G.G.); (F.N.)
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30
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Lundstedt EA, Simpson BW, Ruiz N. Lipopolysaccharide transport involves long-range coupling between cytoplasmic and periplasmic domains of the LptB 2FGC extractor. J Bacteriol 2020; 203:JB.00618-20. [PMID: 33361195 PMCID: PMC8095461 DOI: 10.1128/jb.00618-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 12/18/2020] [Indexed: 01/04/2023] Open
Abstract
The cell surface of the Gram-negative cell envelope contains lipopolysaccharide (LPS) molecules, which form a permeability barrier against hydrophobic antibiotics. The LPS transport (Lpt) machine composed of LptB2FGCADE forms a proteinaceous trans-envelope bridge that allows for the rapid and specific transport of newly synthesized LPS from the inner membrane (IM) to the outer membrane (OM). This transport is powered from the IM by the ATP-binding cassette transporter LptB2FGC. The ATP-driven cycling between closed- and open-dimer states of the ATPase LptB2 is coupled to the extraction of LPS by the transmembrane domains LptFG. However, the mechanism by which LPS moves from a substrate-binding cavity formed by LptFG at the IM to the first component of the periplasmic bridge, the periplasmic β-jellyroll domain of LptF, is poorly understood. To better understand how LptB2FGC functions in Escherichia coli, we searched for suppressors of a defective LptB variant. We found that defects in LptB2 can be suppressed by both structural modifications to the core oligosaccharide of LPS and changes in various regions of LptFG, including a periplasmic loop in LptF that connects the substrate-binding cavity in LptFG to the periplasmic β-jellyroll domain of LptF. These novel suppressors suggest that interactions between the core oligosaccharide of LPS and periplasmic regions in the transporter influence the rate of LPS extraction by LptB2FGC. Together, our genetic data reveal a path for the bi-directional coupling between LptB2 and LptFG that extends from the cytoplasm to the entrance to the periplasmic bridge of the transporter.IMPORTANCEGram-negative bacteria are intrinsically resistant to many antibiotics due to the presence of lipopolysaccharide (LPS) at their cell surface. LPS is transported from its site of synthesis at the inner membrane to the outer membrane by the Lpt machine. Lpt proteins form a transporter that spans the entire envelope and is thought to function similarly to a PEZ candy dispenser. This trans-envelope machine is powered by the cytoplasmic LptB ATPase through a poorly understood mechanism. Using genetic analyses in Escherichia coli, we found that LPS transport involves long-ranging bi-directional coupling across cellular compartments between cytoplasmic LptB and periplasmic regions of the Lpt transporter. This knowledge could be exploited in developing antimicrobials that overcome the permeability barrier imposed by LPS.
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Affiliation(s)
- Emily A Lundstedt
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Brent W Simpson
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Natividad Ruiz
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
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31
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Rcs Phosphorelay Responses to Truncated Lipopolysaccharide-Induced Cell Envelope Stress in Yersinia enterocolitica. Molecules 2020; 25:molecules25235718. [PMID: 33287412 PMCID: PMC7730088 DOI: 10.3390/molecules25235718] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/28/2020] [Accepted: 11/30/2020] [Indexed: 01/22/2023] Open
Abstract
Lipopolysaccharide (LPS) is the major component of the outer membrane of Gram-negative bacteria, and its integrity is monitored by various stress response systems. Although the Rcs system is involved in the envelope stress response and regulates genes controlling numerous bacterial cell functions of Yersinia enterocolitica, whether it can sense the truncated LPS in Y. enterocolitica remains unclear. In this study, the deletion of the Y. enterocolitica waaF gene truncated the structure of LPS and produced a deep rough LPS. The truncated LPS increased the cell surface hydrophobicity and outer membrane permeability, generating cell envelope stress. The truncated LPS also directly exposed the smooth outer membrane to the external environment and attenuated the resistance to adverse conditions, such as impaired survival under polymyxin B and sodium dodecyl sulfate (SDS) exposure. Further phenotypic experiment and gene expression analysis indicated that the truncated LPS was correlated with the activation of the Rcs phosphorelay, thereby repressing cell motility and biofilm formation. Our findings highlight the importance of LPS integrity in maintaining membrane function and broaden the understanding of Rcs phosphorelay signaling in response to cell envelope stress, thus opening new avenues to develop effective antimicrobial agents for combating Y. enterocolitica infections.
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32
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Choi E, Jeon H, Oh C, Hwang J. Elucidation of a Novel Role of YebC in Surface Polysaccharides Regulation of Escherichia coli bipA-Deletion. Front Microbiol 2020; 11:597515. [PMID: 33240252 PMCID: PMC7682190 DOI: 10.3389/fmicb.2020.597515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 10/23/2020] [Indexed: 12/19/2022] Open
Abstract
The BipA (BPI-inducible protein A) protein is ubiquitously conserved in various bacterial species and belongs to the translational GTPase family. Interestingly, the function of Escherichia coli BipA is not essential for cell growth under normal growth conditions. However, cultivation of bipA-deleted cells at 20°C leads to cold-sensitive growth defect and several phenotypic changes in ribosome assembly, capsule production, and motility, suggesting its global regulatory roles. Previously, our genomic library screening revealed that the overexpressed ribosomal protein (r-protein) L20 partially suppressed cold-sensitive growth defect by resolving the ribosomal abnormality in bipA-deleted cells at low temperature. Here, we explored another genomic library clone containing yebC, which encodes a predicted transcriptional factor that is not directly associated with ribosome biogenesis. Interestingly, overexpression of yebC in bipA-deleted cells diminished capsule synthesis and partially restored lipopolysaccharide (LPS) core maturation at a low temperature without resolving defects in ribosome assembly or motility, indicating that YebC may be specifically involved in the regulation of exopolysaccharide and LPS core synthesis. In this study, we collectively investigated the impacts of bipA-deletion on E. coli capsule, LPS, biofilm formation, and motility and revealed novel roles of YebC in extracellular polysaccharide production and LPS core synthesis at low temperature using this mutant strain. Furthermore, our findings suggest that ribosomal defects as well as increased capsule synthesis, and changes in LPS composition may contribute independently to the cold-sensitivity of bipA-deleted cells, implying multiple regulatory roles of BipA.
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Affiliation(s)
- Eunsil Choi
- Microbiological Resource Research Institute, Pusan National University, Busan, South Korea.,Department of Microbiology, Pusan National University, Busan, South Korea
| | - Hyerin Jeon
- Microbiological Resource Research Institute, Pusan National University, Busan, South Korea
| | - Changmin Oh
- Microbiological Resource Research Institute, Pusan National University, Busan, South Korea
| | - Jihwan Hwang
- Microbiological Resource Research Institute, Pusan National University, Busan, South Korea.,Department of Microbiology, Pusan National University, Busan, South Korea
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33
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Nakkarach A, Foo HL, Song AAL, Nitisinprasert S, Withayagiat U. Promising discovery of beneficial Escherichia coli in the human gut. 3 Biotech 2020; 10:296. [PMID: 32550113 DOI: 10.1007/s13205-020-02289-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 06/01/2020] [Indexed: 01/03/2023] Open
Abstract
Ingested dietary fibres are hydrolysed by colon microbiota to produce energy-providing short-chain fatty acids (SCFA) that stimulate anti-inflammatory effects. SCFA-producing bacteria were screened from bacteria isolated from human faeces using bromothymol blue as an acid indicator and gas chromatography for SCFA profiling. The beneficial functions (antagonistic activity, haemolytic activities, antibiotic susceptibility, mucus adherent percentage and toxin gene detection) were evaluated for the top five SCFA-producing bacteria isolated from three healthy volunteers that identified as Escherichia coli strains. They produced acetic, propionic, isobutyric, butyric, isovaleric, valeric and caproic acids at average concentrations of 15.9, 1.8, 1.1, 1.9, 1.8, 2.7 and 3.4 mM, respectively. The SCFA production by E. coli strains was rapidly increased during the first 8 h of incubation and gradually decreased after 16 h of incubation. All E. coli strains showed acid and bile tolerance, resulting in a survival rate greater than 70% with no haemolytic activity, mucus adherence greater than 40% and susceptibility to conventional antibiotics. Hence, the selected E. coli strains exhibited promising probiotic properties with neither enterotoxin nor LPS producibility was detected. The present results confirm the existence of friendly and harmless E. coli strains in human microbiota as potential probiotics.
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Affiliation(s)
- Atchareeya Nakkarach
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
- Department of Bioprocess, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
| | - Hooi Ling Foo
- Department of Bioprocess, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
- Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
| | - Adelene Ai-Lian Song
- Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
| | - Sunee Nitisinprasert
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
| | - Ulaiwan Withayagiat
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
- Fermentation Technology Research Center, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
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Colanic acid biosynthesis in Escherichia coli is dependent on lipopolysaccharide structure and glucose availability. Microbiol Res 2020; 239:126527. [PMID: 32590169 DOI: 10.1016/j.micres.2020.126527] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 06/06/2020] [Accepted: 06/06/2020] [Indexed: 01/31/2023]
Abstract
Lipopolysaccharide and colanic acid are important forms of exopolysaccharides located on the cell surface of Escherichia coli, but their interrelation with the cell stress response is not well understood. In this study, nine mutant strains with different structures of lipopolysaccharide were constructed from E. coli MG1655 by deletion of a single gene or multiple genes. All mutant strains did not produce colanic acid when grown in LB medium, but six of them could produce colanic acid when grown either in M9 medium in which glucose is the sole carbon source or in LB medium supplemented with glucose. The results indicate that colanic acid production in E. coli is dependent on both lipopolysaccharide structure and glucose availability. However, transcriptional analysis showed that 20 genes related to the colanic acid biosynthesis and the key gene rcsA in the Rcs system were all transcriptionally up-regulated in all of the nine mutant strains no matter they were grown in M9 or LB medium. This suggests that the availability of some nucleotide-sugar precursors shared by the biosynthesis of lipopolysaccharide and colanic acid might play a major role in colanic acid production in E. coli. Lipopolysaccharide pathway might have a huge priority to colanic acid pathway to use the common precursors; therefore, the colanic acid is not produced in MG1655 and the nine mutants when grown in LB medium. In the six mutant strains that can produce colanic acid in the glucose rich media, the common precursors might be abundant because they were not needed for synthesizing the mutant lipopolysaccharide.
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Genome-wide screens reveal Escherichia coli genes required for growth of T1-like phage LL5 and V5-like phage LL12. Sci Rep 2020; 10:8058. [PMID: 32415154 PMCID: PMC7229145 DOI: 10.1038/s41598-020-64981-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 04/17/2020] [Indexed: 01/08/2023] Open
Abstract
The host factor requirements of phages and mechanisms of mutational phage insensitivity must be characterized for rational design of phage cocktails. To characterize host dependencies of two novel Escherichia coli phages, the T1-like siphophage LL5 and the V5-like myophage LL12, forward genetic screens were conducted against the Keio collection, a library of single non-essential gene deletions in E. coli str. BW25113. These screens and subsequent experiments identified genes required by phages LL5 and LL12. E. coli mutants deficient in heptose II and the phosphoryl substituent of heptose I of the inner core lipopolysaccharide (LPS) were unable to propagate phage LL5, as were mutants deficient in the outer membrane protein TolC. Mutants lacking glucose I of the LPS outer core failed to propagate LL12. Two additional genes encoding cytoplasmic chaperones, PpiB and SecB, were found to be required for efficient propagation of phage LL5, but not LL12. This screening approach may be useful for identifying host factors dependencies of phages, which would provide valuable information for their potential use as therapeutics and for phage engineering.
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Kapach G, Nuri R, Schmidt C, Danin A, Ferrera S, Savidor A, Gerlach RG, Shai Y. Loss of the Periplasmic Chaperone Skp and Mutations in the Efflux Pump AcrAB-TolC Play a Role in Acquired Resistance to Antimicrobial Peptides in Salmonella typhimurium. Front Microbiol 2020; 11:189. [PMID: 32210923 PMCID: PMC7075815 DOI: 10.3389/fmicb.2020.00189] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/27/2020] [Indexed: 01/01/2023] Open
Abstract
Bacterial resistance to antibiotics is a major concern worldwide, leading to an extensive search for alternative drugs. Promising candidates are antimicrobial peptides (AMPs), innate immunity molecules, shown to be highly efficient against multidrug resistant bacteria. Therefore, it is essential to study bacterial resistance mechanisms against them. For that purpose, we used experimental evolution, and isolated a Salmonella enterica serovar typhimurium-resistant line to the AMP 4DK5L7. This AMP displayed promising features including widespread activity against Gram-negative bacteria and protection from proteolytic degradation. However, the resistance that evolved in the isolated strain was particularly high. Whole genome sequencing revealed that five spontaneous mutations had evolved. Of these, three are novel in the context of acquired AMP resistance. Two mutations are related to the AcrAB-TolC multidrug efflux pump. One occurred in AcrB, the substrate-binding domain of the system, and the second in RamR, a transcriptional regulator of the system. Together, the mutations increased the minimal inhibitory concentration (MIC) by twofold toward this AMP. Moreover, the mutation in AcrB induced hypersusceptibility toward ampicillin and colistin. The last mutation occurred in Skp, a periplasmic chaperone that participates in the biogenesis of outer membrane proteins (OMPs). This mutation increased the MIC by twofold to 4DK5L7 and by fourfold to another AMP, seg5D. Proteomic analysis revealed that the mutation abolished Skp expression, reduced OMP abundance, and increased DegP levels. DegP, a protease that was reported to have an additional chaperone activity, escorts OMPs through the periplasm along with Skp, but is also associated with AMP resistance. In conclusion, our data demonstrate that both loss of Skp and manipulation of the AcrAB-TolC system are alternative strategies of AMP acquired resistance in Salmonella typhimurium and might represent a common mechanism in other Gram-negative bacteria.
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Affiliation(s)
- Gal Kapach
- Departmant of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Reut Nuri
- Departmant of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | | | - Adi Danin
- Departmant of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Shir Ferrera
- Departmant of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Alon Savidor
- de Botton Institute for Protein Profiling, The Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Roman G Gerlach
- Project Group 5, Robert Koch Institute, Wernigerode, Germany
| | - Yechiel Shai
- Departmant of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
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Klobucar K, French S, Côté JP, Howes JR, Brown ED. Genetic and Chemical-Genetic Interactions Map Biogenesis and Permeability Determinants of the Outer Membrane of Escherichia coli. mBio 2020; 11:e00161-20. [PMID: 32156814 PMCID: PMC7064757 DOI: 10.1128/mbio.00161-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 01/29/2020] [Indexed: 02/08/2023] Open
Abstract
Gram-negative bacteria are intrinsically resistant to many antibiotics due to their outer membrane barrier. Although the outer membrane has been studied for decades, there is much to uncover about the biology and permeability of this complex structure. Investigating synthetic genetic interactions can reveal a great deal of information about genetic function and pathway interconnectivity. Here, we performed synthetic genetic arrays (SGAs) in Escherichia coli by crossing a subset of gene deletion strains implicated in outer membrane permeability with nonessential gene and small RNA (sRNA) deletion collections. Some 155,400 double-deletion strains were grown on rich microbiological medium with and without subinhibitory concentrations of two antibiotics excluded by the outer membrane, vancomycin and rifampin, to probe both genetic interactions and permeability. The genetic interactions of interest were synthetic sick or lethal (SSL) gene deletions that were detrimental to the cell in combination but had a negligible impact on viability individually. On average, there were ∼30, ∼36, and ∼40 SSL interactions per gene under no-drug, rifampin, and vancomycin conditions, respectively; however, many of these involved frequent interactors. Our data sets have been compiled into an interactive database called the Outer Membrane Interaction (OMI) Explorer, where genetic interactions can be searched, visualized across the genome, compared between conditions, and enriched for gene ontology (GO) terms. A set of SSL interactions revealed connectivity and permeability links between enterobacterial common antigen (ECA) and lipopolysaccharide (LPS) of the outer membrane. This data set provides a novel platform to generate hypotheses about outer membrane biology and permeability.IMPORTANCE Gram-negative bacteria are a major concern for public health, particularly due to the rise of antibiotic resistance. It is important to understand the biology and permeability of the outer membrane of these bacteria in order to increase the efficacy of antibiotics that have difficulty penetrating this structure. Here, we studied the genetic interactions of a subset of outer membrane-related gene deletions in the model Gram-negative bacterium E. coli We systematically combined these mutants with 3,985 nonessential gene and small RNA deletion mutations in the genome. We examined the viability of these double-deletion strains and probed their permeability characteristics using two antibiotics that have difficulty crossing the outer membrane barrier. An understanding of the genetic basis for outer membrane integrity can assist in the development of new antibiotics with favorable permeability properties and the discovery of compounds capable of increasing outer membrane permeability to enhance the activity of existing antibiotics.
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Affiliation(s)
- Kristina Klobucar
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Shawn French
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Jean-Philippe Côté
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - James R Howes
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Eric D Brown
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
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Komazin G, Maybin M, Woodard RW, Scior T, Schwudke D, Schombel U, Gisch N, Mamat U, Meredith TC. Substrate structure-activity relationship reveals a limited lipopolysaccharide chemotype range for intestinal alkaline phosphatase. J Biol Chem 2019; 294:19405-19423. [PMID: 31704704 DOI: 10.1074/jbc.ra119.010836] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 10/31/2019] [Indexed: 12/21/2022] Open
Abstract
Lipopolysaccharide (LPS) from the Gram-negative bacterial outer membrane potently activates the human innate immune system. LPS is recognized by the Toll-like receptor 4/myeloid differentiation factor-2 (TLR4/MD2) complex, leading to the release of pro-inflammatory cytokines. Alkaline phosphatase (AP) is currently being investigated as an anti-inflammatory agent for detoxifying LPS through dephosphorylating lipid A, thus providing a potential treatment for managing both acute (sepsis) and chronic (metabolic endotoxemia) pathologies wherein aberrant TLR4/MD2 activation has been implicated. Endogenous LPS preparations are chemically heterogeneous, and little is known regarding the LPS chemotype substrate range of AP. Here, we investigated the activity of AP on a panel of structurally defined LPS chemotypes isolated from Escherichia coli and demonstrate that calf intestinal AP (cIAP) has only minimal activity against unmodified enteric LPS chemotypes. Pi was only released from a subset of LPS chemotypes harboring spontaneously labile phosphoethanolamine (PEtN) modifications connected through phosphoanhydride bonds. We demonstrate that the spontaneously hydrolyzed O-phosphorylethanolamine is the actual substrate for AP. We found that the 1- and 4'-lipid A phosphate groups critical in TLR4/MD2 signaling become susceptible to hydrolysis only after de-O-acylation of ester linked primary acyl chains on lipid A. Furthermore, PEtN modifications on lipid A specifically enhanced hTLR4 agonist activity of underacylated LPS preparations. Computational binding models are proposed to explain the limitation of AP substrate specificity imposed by the acylation state of lipid A, and the mechanism of PEtN in enhancing hTLR4/MD2 signaling.
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Affiliation(s)
- Gloria Komazin
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Michael Maybin
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Ronald W Woodard
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Thomas Scior
- Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Puebla 72000, Mexico
| | - Dominik Schwudke
- Bioanalytical Chemistry, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Ursula Schombel
- Bioanalytical Chemistry, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Nicolas Gisch
- Bioanalytical Chemistry, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Uwe Mamat
- Cellular Microbiology, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Timothy C Meredith
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
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Liu G, Olsen JE, Thomsen LE. Identification of Genes Essential for Antibiotic-Induced Up-Regulation of Plasmid-Transfer-Genes in Cephalosporin Resistant Escherichia coli. Front Microbiol 2019; 10:2203. [PMID: 31616400 PMCID: PMC6768964 DOI: 10.3389/fmicb.2019.02203] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 09/09/2019] [Indexed: 12/14/2022] Open
Abstract
Bacterial conjugation is one of the most important mechanisms for spread of antibiotic resistance among bacteria. We have previously demonstrated that cefotaxime (CTX) exposure up-regulates expression of Type-IV conjugation transfer genes, and that this leads to increased transfer of a bla CTX-M- 1 encoding IncI1 resistance plasmid pTF2 in Escherichia coli. To elucidate the underlying mechanisms, a search for genes that are essential for the up-regulated expression of the transfer (tra) genes in the presence of CTX was undertaken. We constructed a reporter gene-fusion strain MG1655/pTF2 ΔtraF:lacZ where the promoter region of the traF-gene of the plasmid pTF2 was fused with a lacZ on the native plasmid. Random mutagenesis mediated by Tn5 transposon was carried out in the strain, and seven genes (rfaH, yhiN, waaP, waaQ, gnd, pgl, and ISEcp1) were identified where insertion prevented CTX-induced up regulation of traF. Site-specific mutagenesis was carried out, and for all seven mutants, gene deletions abolished the CTX induced up-regulation of traF, and the increased conjugation transfer of the plasmid in the presence of CTX was no longer observed. In addition, the deletion of the genes also abolished CTX induced expression of the bla CTX-M- 1 gene. Our results suggested that through CTX induced induction of the identified genes, bla CTX-M- 1 expression increased, which led to up-regulation of traF and plasmid transfer. These data reveal that a number of chromosomally encoded genes contribute to the antibiotic induced up-regulation of the conjugation machinery of plasmids, and such genes may be future targets to prevent antibiotic induced spread of resistance plasmids.
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Affiliation(s)
- Gang Liu
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - John Elmerdahl Olsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Line Elnif Thomsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Moore JP, Li H, Engmann ML, Bischof KM, Kunka KS, Harris ME, Tancredi AC, Ditmars FS, Basting PJ, George NS, Bhagwat AA, Slonczewski JL. Inverted Regulation of Multidrug Efflux Pumps, Acid Resistance, and Porins in Benzoate-Evolved Escherichia coli K-12. Appl Environ Microbiol 2019; 85:e00966-19. [PMID: 31175192 PMCID: PMC6677852 DOI: 10.1128/aem.00966-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 05/30/2019] [Indexed: 01/23/2023] Open
Abstract
Benzoic acid, a partial uncoupler of the proton motive force (PMF), selects for sensitivity to chloramphenicol and tetracycline during the experimental evolution of Escherichia coli K-12. Transcriptomes of E. coli isolates evolved with benzoate showed the reversal of benzoate-dependent regulation, including the downregulation of multidrug efflux pump genes, the gene for the Gad acid resistance regulon, the nitrate reductase genes narHJ, and the gene for the acid-consuming hydrogenase Hyd-3. However, the benzoate-evolved strains had increased expression of OmpF and other large-hole porins that admit fermentable substrates and antibiotics. Candidate genes identified from benzoate-evolved strains were tested for their roles in benzoate tolerance and in chloramphenicol sensitivity. Benzoate or salicylate tolerance was increased by deletion of the Gad activator ariR or of the acid fitness island from slp to the end of the gadX gene encoding Gad regulators and the multidrug pump genes mdtEF Benzoate tolerance was also increased by deletion of multidrug component gene emrA, RpoS posttranscriptional regulator gene cspC, adenosine deaminase gene add, hydrogenase gene hyc (Hyd-3), and the RNA chaperone/DNA-binding regulator gene hfq Chloramphenicol resistance was decreased by mutations in genes for global regulators, such as RNA polymerase alpha subunit gene rpoA, the Mar activator gene rob, and hfq Deletion of lipopolysaccharide biosynthetic kinase gene rfaY decreased the rate of growth in chloramphenicol. Isolates from experimental evolution with benzoate had many mutations affecting aromatic biosynthesis and catabolism, such as aroF (encoding tyrosine biosynthesis) and apt (encoding adenine phosphoribosyltransferase). Overall, benzoate or salicylate exposure selects for the loss of multidrug efflux pumps and of hydrogenases that generate a futile cycle of PMF and upregulates porins that admit fermentable nutrients and antibiotics.IMPORTANCE Benzoic acid is a common food preservative, and salicylic acid (2-hydroxybenzoic acid) is the active form of aspirin. At high concentrations, benzoic acid conducts a proton across the membrane, depleting the proton motive force. In the absence of antibiotics, benzoate exposure selects against proton-driven multidrug efflux pumps and upregulates porins that admit fermentable substrates but that also allow the entry of antibiotics. Thus, evolution with benzoate and related molecules, such as salicylates, requires a trade-off for antibiotic sensitivity, a trade-off that could help define a stable gut microbiome. Benzoate and salicylate are naturally occurring plant signal molecules that may modulate the microbiomes of plants and animal digestive tracts so as to favor fermenters and exclude drug-resistant pathogens.
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Affiliation(s)
- Jeremy P Moore
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | - Haofan Li
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | | | | | - Karina S Kunka
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | - Mary E Harris
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | | | | | | | - Nadja S George
- Environmental Microbiology and Food Safety Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Beltsville, Maryland, USA
| | - Arvind A Bhagwat
- Environmental Microbiology and Food Safety Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Beltsville, Maryland, USA
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41
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Isolation, Characterisation and Complete Genome Sequence of a Tequatrovirus Phage, Escherichia phage KIT03, Which Simultaneously Infects Escherichia coli O157:H7 and Salmonella enterica. Curr Microbiol 2019; 76:1130-1137. [DOI: 10.1007/s00284-019-01738-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 07/03/2019] [Indexed: 12/24/2022]
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Abstract
The cell envelope is the first line of defense between a bacterium and the world-at-large. Often, the initial steps that determine the outcome of chemical warfare, bacteriophage infections, and battles with other bacteria or the immune system greatly depend on the structure and composition of the bacterial cell surface. One of the most studied bacterial surface molecules is the glycolipid known as lipopolysaccharide (LPS), which is produced by most Gram-negative bacteria. Much of the initial attention LPS received in the early 1900s was owed to its ability to stimulate the immune system, for which the glycolipid was commonly known as endotoxin. It was later discovered that LPS also creates a permeability barrier at the cell surface and is a main contributor to the innate resistance that Gram-negative bacteria display against many antimicrobials. Not surprisingly, these important properties of LPS have driven a vast and still prolific body of literature for more than a hundred years. LPS research has also led to pioneering studies in bacterial envelope biogenesis and physiology, mostly using Escherichia coli and Salmonella as model systems. In this review, we will focus on the fundamental knowledge we have gained from studies of the complex structure of the LPS molecule and the biochemical pathways for its synthesis, as well as the transport of LPS across the bacterial envelope and its assembly at the cell surface.
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Klein G, Raina S. Regulated Assembly of LPS, Its Structural Alterations and Cellular Response to LPS Defects. Int J Mol Sci 2019; 20:ijms20020356. [PMID: 30654491 PMCID: PMC6358824 DOI: 10.3390/ijms20020356] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/11/2019] [Accepted: 01/13/2019] [Indexed: 12/21/2022] Open
Abstract
Distinguishing feature of the outer membrane (OM) of Gram-negative bacteria is its asymmetry due to the presence of lipopolysaccharide (LPS) in the outer leaflet of the OM and phospholipids in the inner leaflet. Recent studies have revealed the existence of regulatory controls that ensure a balanced biosynthesis of LPS and phospholipids, both of which are essential for bacterial viability. LPS provides the essential permeability barrier function and act as a major virulence determinant. In Escherichia coli, more than 100 genes are required for LPS synthesis, its assembly at inner leaflet of the inner membrane (IM), extraction from the IM, translocation to the OM, and in its structural alterations in response to various environmental and stress signals. Although LPS are highly heterogeneous, they share common structural elements defining their most conserved hydrophobic lipid A part to which a core polysaccharide is attached, which is further extended in smooth bacteria by O-antigen. Defects or any imbalance in LPS biosynthesis cause major cellular defects, which elicit envelope responsive signal transduction controlled by RpoE sigma factor and two-component systems (TCS). RpoE regulon members and specific TCSs, including their non-coding arm, regulate incorporation of non-stoichiometric modifications of LPS, contributing to LPS heterogeneity and impacting antibiotic resistance.
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Affiliation(s)
- Gracjana Klein
- Unit of Bacterial Genetics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland.
| | - Satish Raina
- Unit of Bacterial Genetics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland.
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Peterson JH, Hussain S, Bernstein HD. Identification of a novel post-insertion step in the assembly of a bacterial outer membrane protein. Mol Microbiol 2018; 110:143-159. [PMID: 30107065 DOI: 10.1111/mmi.14102] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2018] [Indexed: 01/09/2023]
Abstract
Although the barrel assembly machinery (Bam) complex has been shown to facilitate the insertion of β barrel proteins into the bacterial outer membrane (OM), the stage at which β barrels fold is unknown. Here, we describe insights into β barrel assembly that emerged from an analysis of a member of the autotransporter family of OM proteins (EspP) in Escherichia coli. EspP contains an extracellular 'passenger' domain that is translocated across the OM and then released from the covalently linked β barrel domain in an intra-barrel cleavage reaction. We found that the mutation of an unusual lipid-exposed lysine residue impairs a previously unidentified late folding step that follows both the membrane insertion of the β barrel domain and the secretion of the passenger domain but that precedes proteolytic maturation. Our results demonstrate that β barrel assembly can be completed at a post-insertion stage and raise the possibility that interactions with membrane lipids can promote folding in vivo. Furthermore, by showing that the passenger domain is secreted before the β barrel domain is fully assembled, our results also provide evidence against the long-standing hypothesis that autotransporters are autonomous protein secretion systems.
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Affiliation(s)
- Janine H Peterson
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0538, USA
| | - Sunyia Hussain
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0538, USA
| | - Harris D Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0538, USA
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45
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Ebbensgaard A, Mordhorst H, Aarestrup FM, Hansen EB. The Role of Outer Membrane Proteins and Lipopolysaccharides for the Sensitivity of Escherichia coli to Antimicrobial Peptides. Front Microbiol 2018; 9:2153. [PMID: 30245684 PMCID: PMC6137088 DOI: 10.3389/fmicb.2018.02153] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 08/22/2018] [Indexed: 01/20/2023] Open
Abstract
Bacterial resistance to classical antibiotics is emerging worldwide. The number of infections caused by multidrug resistant bacteria is increasing and becoming a serious threat for human health globally. In particular, Gram-negative pathogens including multidrug resistant Escherichia coli are of serious concern being resistant to the currently available antibiotics. All Gram-negative bacteria are enclosed by an outer membrane which acts as an additional protection barrier preventing the entry of toxic compounds including antibiotics and antimicrobial peptides (AMPs). In this study we report that the outer membrane component lipopolysaccharide (LPS) plays a crucial role for the antimicrobial susceptibility of E. coli BW25113 against the cationic AMPs Cap18, Cap11, Cap11-1-18m2, melittin, indolicidin, cecropin P1, cecropin B, and the polypeptide antibiotic colistin, whereas the outer membrane protease OmpT and the lipoprotein Lpp only play a minor role for the susceptibility against cationic AMPs. Increased susceptibility toward cationic AMPs was found for LPS deficient mutants of E. coli BW25113 harboring deletions in any of the genes required for the inner part of core-oligosaccharide of the LPS, waaC, waaE, waaF, waaG, and gmhA. In addition, our study demonstrates that the antimicrobial activity of Cap18, Cap11, Cap11-1-18m2, cecropin B, and cecropin P1 is not only dependent on the inner part of the core oligosaccharide, but also on the outer part and its sugar composition. Finally, we demonstrated that the antimicrobial activity of selected Cap18 derivatives harboring amino acid substitutions in the hydrophobic interface, are non-active against wild-type E. coli ATCC29522. By deleting waaC, waaE, waaF, or waaG the antimicrobial activity of the non-active derivatives can be partially or fully restored, suggesting a very close interplay between the LPS core oligosaccharide and the specific Cap18 derivative. Summarizing, this study implicates that the nature of the outer membrane component LPS has a big impact on the antimicrobial activity of cationic AMPs against E. coli. In particular, the inner as well as the outer part of the core oligosaccharide are important elements determining the antimicrobial susceptibility of E. coli against cationic AMPs.
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Affiliation(s)
- Anna Ebbensgaard
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark.,Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Hanne Mordhorst
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Frank M Aarestrup
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Egon B Hansen
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
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Comparative study of Salmonella enterica serovar Enteritidis genes expressed within avian and murine macrophages via selective capture of transcribed sequences (SCOTS). Appl Microbiol Biotechnol 2018; 102:6567-6579. [PMID: 29799087 DOI: 10.1007/s00253-018-9067-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 04/26/2018] [Accepted: 05/01/2018] [Indexed: 10/16/2022]
Abstract
Salmonella enterica serovar Enteritidis (SE) is a communicable zoonotic bacterium. Macrophages are essential for Salmonella survival, transmission, and infection. In this study, selective capture of transcribed sequences (SCOTS) was used to screen genes preferentially expressed by SE during contact with macrophages from different hosts. We found 57 predicted genes and 52 genes expressed by SE during interaction with avian HD-11 and murine RAW264.7 cells, respectively. These expressed genes were involved in virulence, metabolism, stress response, transport, regulation, and other functions. Although genes related to survival or metabolic pathways were needed during SE infection, different gene expression profiles of SE occurred in the two macrophage cell lines. qRT-PCR results confirmed that most screened genes were upregulated during infection in contrast to the observation during in vitro cultivation, with different expression levels in infected avian macrophages at 2-h and 7-h post-infection. In addition, in vitro and in vivo competition assays confirmed that SEN3610 (a putative deoR family regulator) and rfaQ (related to LPS synthesis) were closely related to SE virulence in both mice and chickens. Three putative transcriptional regulators, SEN2967, SEN4299, and rtcR, were related to SE colonization in mice, while the ycaM mutation caused decreased infection and survival of SE in HD-11 cells without influencing virulence in mice or chicken. Genes showing differential expression between SE-infected avian and murine macrophages indicate specific pathogen adaptation to enable infection of various hosts.
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47
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Mulla RS, Beecroft MS, Pal R, Aguilar JA, Pitarch-Jarque J, García-España E, Lurie-Luke E, Sharples GJ, Gareth Williams JA. On the Antibacterial Activity of Azacarboxylate Ligands: Lowered Metal Ion Affinities for Bis-amide Derivatives of EDTA do not mean Reduced Activity. Chemistry 2018; 24:7137-7148. [PMID: 29570870 DOI: 10.1002/chem.201800026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Indexed: 12/23/2022]
Abstract
EDTA is widely used as an inhibitor of bacterial growth, affecting the uptake and control of metal ions by microorganisms. We describe the synthesis and characterisation of two symmetrical bis-amide derivatives of EDTA, featuring glycyl or pyridyl substituents: AmGly2 and AmPy2 . Metal ion affinities (logK) have been evaluated for a range of metals (Mg2+ , Ca2+ , Fe3+ , Mn2+ , Zn2+ ), revealing less avid binding compared to EDTA. The solid-state structures of AmGly2 and of its Mg2+ complex have been determined crystallographically. The latter shows an unusual 7-coordinate, capped octahedral Mg2+ centre. The antibacterial activities of the two ligands and of EDTA have been evaluated against a range of health-relevant bacterial species, three Gram negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) and a Gram positive (Staphylococcus aureus). The AmPy2 ligand is the only one that displays a significant inhibitory effect against K. pneumoniae, but is less effective against the other organisms. AmGly2 exhibits a more powerful inhibitory effect against E. coli at lower concentrations than EDTA (<3 mm) or AmPy2 , but loses its efficacy at higher concentrations. The growth inhibition of EDTA and AmGly2 on mutant E. coli strains with defects in outer-membrane lipopolysaccharide (LPS) structures has been assessed to provide insight into the unexpected behaviour. Taken together, the results contradict the assumption of a simple link between metal ion affinity and antimicrobial efficacy.
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Affiliation(s)
| | | | - Robert Pal
- Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Juan A Aguilar
- Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Javier Pitarch-Jarque
- Instituto de Ciencia Molecular, Universidad de Valencia, C/ Catedrático José Beltrán 2, 46980, Paterna, Valencia, Spain
| | - Enrique García-España
- Instituto de Ciencia Molecular, Universidad de Valencia, C/ Catedrático José Beltrán 2, 46980, Paterna, Valencia, Spain
| | - Elena Lurie-Luke
- Procter and Gamble Technical Centres Limited, Rusham Park, Whitehall Lane, Egham, Surrey, TW20 9NW, UK
| | - Gary J Sharples
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK
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Agrawal A, Weisshaar JC. Effects of alterations of the E. coli lipopolysaccharide layer on membrane permeabilization events induced by Cecropin A. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1470-1479. [PMID: 29684333 DOI: 10.1016/j.bbamem.2018.04.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 04/12/2018] [Accepted: 04/18/2018] [Indexed: 11/24/2022]
Abstract
The outermost layer of Gram negative bacteria is composed of a lipopolysaccharide (LPS) network that forms a dense protective hydrophilic barrier against entry of hydrophobic drugs. At low μM concentrations, a large family of cationic polypeptides known as antimicrobial peptides (AMPs) are able to penetrate the LPS layer and permeabilize the outer membrane (OM) and the cytoplasmic membrane (CM), causing cell death. Cecropin A is a well-studied cationic AMP from moth. Here a battery of time-resolved, single-cell microscopy experiments explores how deletion of sugar layers and/or phosphoryl negative charges from the core oligosaccharide layer (core OS) of K12 E. coli alters the timing of OM and CM permeabilization induced by Cecropin A. Deletion of sugar layers, or phosphoryl charges, or both from the core OS shortens the time to the onset of OM permeabilization to periplasmic GFP and also the lag time between OM permeabilization and CM permeabilization. Meanwhile, the 12-h minimum inhibitory concentration (MIC) changes only twofold with core OS alterations. The results suggest a two-step model in which the core oligosaccharide layers act as a kinetic barrier to penetration of Cecropin A to the lipid A outer leaflet of the OM. Once a threshold concentration has built up at the lipid A leaflet, nucleation occurs and the OM is locally permeabilized to GFP and, by inference, to Cecropin A. Whenever Cecropin A permeabilizes the OM, CM permeabilization always follows, and cell growth subsequently halts and never recovers on the 45 min observation timescale.
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Affiliation(s)
- Anurag Agrawal
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | - James C Weisshaar
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
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Abstract
The outer membrane (OM) bilayer of Gram-negative bacteria is biologically unique in its asymmetrical organization of lipids, with an inner leaflet composed of glycerophospholipids (PLs) and a surface-exposed outer leaflet composed of lipopolysaccharide (LPS). This lipid organization is integral to the OM’s barrier properties. Perturbations of the outer leaflet by antimicrobial peptides or defects in LPS biosynthesis or transport to the OM cause a compensatory flipping of PLs to the outer leaflet. As a result, lipid asymmetry is disrupted and OM integrity is compromised. Recently, we identified an Escherichia coli mutant that exhibits aberrant accumulation of surface PLs accompanied by a cellular increase in LPS production. Remarkably, the observed hyperproduction of LPS is PldA dependent. Here we provide evidence that the fatty acids generated by PldA at the OM are transported into the cytoplasm and simultaneously activated by thioesterification to coenzyme A (CoA) by FadD. The acyl-CoAs produced ultimately inhibit LpxC degradation by FtsH. The increased levels of LpxC, the enzyme that catalyzes the first committed step in LPS biosynthesis, increases the amount of LPS produced. Our data suggest that PldA acts as a sensor for lipid asymmetry in the OM. PldA protects the OM barrier by both degrading mislocalized PLs and generating lipid second messengers that enable long-distance signaling that prompts the cell to restore homeostasis at a distant organelle. The outer membrane of Gram-negative bacteria is an effective permeability barrier that protects the cell from toxic agents, including antibiotics. Barrier defects are often manifested by phospholipids present in the outer leaflet of this membrane that take up space normally occupied by lipopolysaccharide. We have discovered a signaling mechanism that operates across the entire cell envelope used by the cell to detect these outer membrane defects. A phospholipase, PldA, that functions to degrade these mislocalized phospholipids has a second, equally important function as a sensor. The fatty acids produced by hydrolysis of the phospholipids act as second messengers to signal the cell that more lipopolysaccharide is needed. These fatty acids diffuse across the periplasm and are transported into the cytoplasm by a process that attaches coenzyme A. The acyl-CoA molecule produces signals to inhibit the degradation of the critical enzyme LpxC by the ATP-dependent protease FtsH, increasing lipopolysaccharide production.
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Sekyere JO, Asante J. Emerging mechanisms of antimicrobial resistance in bacteria and fungi: advances in the era of genomics. Future Microbiol 2018; 13:241-262. [PMID: 29319341 DOI: 10.2217/fmb-2017-0172] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Bacteria and fungi continue to develop new ways to adapt and survive the lethal or biostatic effects of antimicrobials through myriad mechanisms. Novel antibiotic resistance genes such as lsa(C), erm(44), VCC-1, mcr-1, mcr-2, mcr-3, mcr-4, bla KLUC-3 and bla KLUC-4 were discovered through comparative genomics and further functional studies. As well, mutations in genes that hitherto were unknown to confer resistance to antimicrobials, such as trm, PP2C, rpsJ, HSC82, FKS2 and Rv2887, were shown by genomics and transcomplementation assays to mediate antimicrobial resistance in Acinetobacter baumannii, Staphylococcus aureus, Enterococcus faecium, Saccharomyces cerevisae, Candida glabrata and Mycobacterium tuberculosis, respectively. Thus, genomics, transcriptomics and metagenomics, coupled with functional studies are the future of antimicrobial resistance research and novel drug discovery or design.
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Affiliation(s)
- John Osei Sekyere
- Faculty of Pharmacy & Pharmaceutical Sciences, Kwame Nkrumah University of Science & Technology, Kumasi, Ghana
| | - Jonathan Asante
- Faculty of Pharmacy & Pharmaceutical Sciences, Kwame Nkrumah University of Science & Technology, Kumasi, Ghana
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