1
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Watanabe N, Savchenko A. Molecular insights into the initiation step of the Rcs signaling pathway. Structure 2024:S0969-2126(24)00221-1. [PMID: 38964336 DOI: 10.1016/j.str.2024.06.003] [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: 12/07/2023] [Revised: 04/05/2024] [Accepted: 06/07/2024] [Indexed: 07/06/2024]
Abstract
The Rcs pathway is repressed by the inner membrane protein IgaA under non-stressed conditions. This repression is hypothesized to be relieved by the binding of the outer membrane-anchored RcsF to IgaA. However, the precise mechanism by which RcsF binding triggers the signaling remains unclear. Here, we present the 1.8 Å resolution crystal structure capturing the interaction between IgaA and RcsF. Our comparative structural analysis, examining both the bound and unbound states of the periplasmic domain of IgaA (IgaAp), highlights rotational flexibility within IgaAp. Conversely, the conformation of RcsF remains unchanged upon binding. Our in vivo and in vitro studies do not support the model of a stable complex involving RcsF, IgaAp, and RcsDp. Instead, we demonstrate that the elements beyond IgaAp play a role in the interaction between IgaA and RcsD. These findings collectively allow us to propose a potential mechanism for the signaling across the inner membrane through IgaA.
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Affiliation(s)
- Nobuhiko Watanabe
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada; Center for Structural Biology for Infectious Diseases (CSBID) Chicago, IL, USA
| | - Alexei Savchenko
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada; Center for Structural Biology for Infectious Diseases (CSBID) Chicago, IL, USA.
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2
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Buchholz KR, Reichelt M, Johnson MC, Robinson SJ, Smith PA, Rutherford ST, Quinn JG. Potent activity of polymyxin B is associated with long-lived super-stoichiometric accumulation mediated by weak-affinity binding to lipid A. Nat Commun 2024; 15:4733. [PMID: 38830951 PMCID: PMC11148078 DOI: 10.1038/s41467-024-49200-5] [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] [Received: 11/15/2022] [Accepted: 05/23/2024] [Indexed: 06/05/2024] Open
Abstract
Polymyxins are gram-negative antibiotics that target lipid A, the conserved membrane anchor of lipopolysaccharide in the outer membrane. Despite their clinical importance, the molecular mechanisms underpinning polymyxin activity remain unresolved. Here, we use surface plasmon resonance to kinetically interrogate interactions between polymyxins and lipid A and derive a phenomenological model. Our analyses suggest a lipid A-catalyzed, three-state mechanism for polymyxins: transient binding, membrane insertion, and super-stoichiometric cluster accumulation with a long residence time. Accumulation also occurs for brevicidine, another lipid A-targeting antibacterial molecule. Lipid A modifications that impart polymyxin resistance and a non-bactericidal polymyxin derivative exhibit binding that does not evolve into long-lived species. We propose that transient binding to lipid A permeabilizes the outer membrane and cluster accumulation enables the bactericidal activity of polymyxins. These findings could establish a blueprint for discovery of lipid A-targeting antibiotics and provide a generalizable approach to study interactions with the gram-negative outer membrane.
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Affiliation(s)
- Kerry R Buchholz
- Department of Infectious Diseases, Genentech, Inc., South San Francisco, CA, USA.
| | - Mike Reichelt
- Department of Pathology, Genentech, Inc., South San Francisco, CA, USA
| | - Matthew C Johnson
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA, USA
| | - Sarah J Robinson
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA, USA
| | - Peter A Smith
- Department of Infectious Diseases, Genentech, Inc., South San Francisco, CA, USA
- Revagenix, Inc., San Mateo, CA, USA
| | - Steven T Rutherford
- Department of Infectious Diseases, Genentech, Inc., South San Francisco, CA, USA.
| | - John G Quinn
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, CA, USA.
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3
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Kaur M, Mingeot-Leclercq MP. Maintenance of bacterial outer membrane lipid asymmetry: insight into MlaA. BMC Microbiol 2024; 24:186. [PMID: 38802775 PMCID: PMC11131202 DOI: 10.1186/s12866-023-03138-8] [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: 03/28/2023] [Accepted: 11/29/2023] [Indexed: 05/29/2024] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria acts as an effective barrier to protect against toxic compounds. By nature, the OM is asymmetric with the highly packed lipopolysaccharide (LPS) at the outer leaflet and glycerophospholipids at the inner leaflet. OM asymmetry is maintained by the Mla system, in which is responsible for the retrograde transport of glycerophospholipids from the OM to the inner membrane. This system is comprised of six Mla proteins, including MlaA, an OM lipoprotein involved in the removal of glycerophospholipids that are mis-localized at the outer leaflet of the OM. Interestingly, MlaA was initially identified - and called VacJ - based on its role in the intracellular spreading of Shigella flexneri.Many open questions remain with respect to the Mla system and the mechanism involved in the translocation of mislocated glycerophospholipids at the outer leaflet of the OM, by MlaA. After summarizing the current knowledge on MlaA, we focus on the impact of mlaA deletion on OM lipid composition and biophysical properties of the OM. How changes in OM lipid composition and biophysical properties can impact the generation of membrane vesicles and membrane permeability is discussed. Finally, we explore whether and how MlaA might be a candidate for improving the activity of antibiotics and as a vaccine candidate.Efforts dedicated to understanding the relationship between the OM lipid composition and the mechanical strength of the bacterial envelope and, in turn, how such properties act against external stress, are needed for the design of new targets or drugs for Gram-negative infections.
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Affiliation(s)
- M Kaur
- Louvain Drug Research Institute, Université catholique de Louvain, Unité de Pharmacologie cellulaire et moléculaire, B1.73.05; 73 Av E. Mounier, Brussels, 1200, Belgium
| | - M-P Mingeot-Leclercq
- Louvain Drug Research Institute, Université catholique de Louvain, Unité de Pharmacologie cellulaire et moléculaire, B1.73.05; 73 Av E. Mounier, Brussels, 1200, Belgium.
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4
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Shu S, Tsutsui Y, Nathawat R, Mi W. Dual function of LapB (YciM) in regulating Escherichia coli lipopolysaccharide synthesis. Proc Natl Acad Sci U S A 2024; 121:e2321510121. [PMID: 38635633 PMCID: PMC11046580 DOI: 10.1073/pnas.2321510121] [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: 12/06/2023] [Accepted: 03/21/2024] [Indexed: 04/20/2024] Open
Abstract
Levels of lipopolysaccharide (LPS), an essential glycolipid on the surface of most gram-negative bacteria, are tightly controlled-making LPS synthesis a promising target for developing new antibiotics. Escherichia coli adaptor protein LapB (YciM) plays an important role in regulating LPS synthesis by promoting degradation of LpxC, a deacetylase that catalyzes the first committed step in LPS synthesis. Under conditions where LPS is abundant, LapB recruits LpxC to the AAA+ protease FtsH for degradation. LapB achieves this by simultaneously interacting with FtsH through its transmembrane helix and LpxC through its cytoplasmic domain. Here, we describe a cryo-EM structure of the complex formed between LpxC and the cytoplasmic domain of LapB (LapBcyto). The structure reveals how LapB exploits both its tetratricopeptide repeat (TPR) motifs and rubredoxin domain to interact with LpxC. Through both in vitro and in vivo analysis, we show that mutations at the LapBcyto/LpxC interface prevent LpxC degradation. Unexpectedly, binding to LapBcyto also inhibits the enzymatic activity of LpxC through allosteric effects reminiscent of LpxC activation by MurA in Pseudomonas aeruginosa. Our findings argue that LapB regulates LPS synthesis in two steps: In the first step, LapB inhibits the activity of LpxC, and in the second step, it commits LpxC to degradation by FtsH.
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Affiliation(s)
- Sheng Shu
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT06520
| | - Yuko Tsutsui
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT06520
- Cancer Biology Institute, Yale University, West Haven, CT06516
| | - Rajkanwar Nathawat
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT06520
| | - Wei Mi
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT06520
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT06520
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5
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Janssens A, Nguyen VS, Cecil AJ, Van der Verren SE, Timmerman E, Deghelt M, Pak AJ, Collet JF, Impens F, Remaut H. SlyB encapsulates outer membrane proteins in stress-induced lipid nanodomains. Nature 2024; 626:617-625. [PMID: 38081298 DOI: 10.1038/s41586-023-06925-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 12/01/2023] [Indexed: 01/19/2024]
Abstract
The outer membrane in Gram-negative bacteria consists of an asymmetric phospholipid-lipopolysaccharide bilayer that is densely packed with outer-membrane β-barrel proteins (OMPs) and lipoproteins1. The architecture and composition of this bilayer is closely monitored and is essential to cell integrity and survival2-4. Here we find that SlyB, a lipoprotein in the PhoPQ stress regulon, forms stable stress-induced complexes with the outer-membrane proteome. SlyB comprises a 10 kDa periplasmic β-sandwich domain and a glycine zipper domain that forms a transmembrane α-helical hairpin with discrete phospholipid- and lipopolysaccharide-binding sites. After loss in lipid asymmetry, SlyB oligomerizes into ring-shaped transmembrane complexes that encapsulate β-barrel proteins into lipid nanodomains of variable size. We find that the formation of SlyB nanodomains is essential during lipopolysaccharide destabilization by antimicrobial peptides or acute cation shortage, conditions that result in a loss of OMPs and compromised outer-membrane barrier function in the absence of a functional SlyB. Our data reveal that SlyB is a compartmentalizing transmembrane guard protein that is involved in cell-envelope proteostasis and integrity, and suggest that SlyB represents a larger family of broadly conserved lipoproteins with 2TM glycine zipper domains with the ability to form lipid nanodomains.
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Affiliation(s)
- Arne Janssens
- Structural and Molecular Microbiology, VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
- Department of Bioengineering Sciences, Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Van Son Nguyen
- Structural and Molecular Microbiology, VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
- Department of Bioengineering Sciences, Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Adam J Cecil
- Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, USA
| | - Sander E Van der Verren
- Structural and Molecular Microbiology, VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
- Department of Bioengineering Sciences, Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Evy Timmerman
- VIB Proteomics Core, Ghent, Belgium
- VIB-UGent Center for Medical Biotechnology, Ghent, Belgium
- Faculty of Medicine and Health Sciences, Department of Biochemistry, Ghent University, Ghent, Belgium
| | - Michaël Deghelt
- Walloon Excellence in Life Sciences and Biotechnology, WELBIO, Brussels, Belgium
- De Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Alexander J Pak
- Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, USA
- Quantitative Biosciences and Engineering, Colorado School of Mines, Golden, CO, USA
| | - Jean-François Collet
- Walloon Excellence in Life Sciences and Biotechnology, WELBIO, Brussels, Belgium
- De Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Francis Impens
- VIB Proteomics Core, Ghent, Belgium
- VIB-UGent Center for Medical Biotechnology, Ghent, Belgium
- Faculty of Medicine and Health Sciences, Department of Biochemistry, Ghent University, Ghent, Belgium
| | - Han Remaut
- Structural and Molecular Microbiology, VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium.
- Department of Bioengineering Sciences, Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.
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6
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Bogdanov M. Preparation of Uniformly Oriented Inverted Inner (Cytoplasmic) Membrane Vesicles from Gram-Negative Bacterial Cells. Methods Mol Biol 2024; 2715:159-180. [PMID: 37930527 PMCID: PMC10724710 DOI: 10.1007/978-1-0716-3445-5_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
The complex double-membrane organization of the envelope in Gram-negative bacteria places unique biosynthetic and topological constraints that can affect translocation of lipids and proteins synthesized on cytoplasm facing leaflet of cytoplasmic (inner) membrane (IM), across IM and between IM and outer membrane (OM). Uniformly oriented inside-out (ISO) vesicles became functional requisite for many biochemical reconstitution functional assays, vectorial proteomics, and vectorial lipidomics. Due to these demands, it is necessary to develop simple and reliable approaches for preparation of uniformly oriented IM membrane vesicles and validation of their sidedness. The uniformly ISO oriented membrane vesicles which have the cytoplasmic face of the membrane on the outside and the periplasmic side facing the sealed lumen can be obtained following intact cell disruption by a single passage through a French pressure cell (French press) at desired total pressure. Although high-pressure lysis leads to the formation of mostly inverted membrane vesicles (designated and abbreviated usually as ISO vesicles, everted or inverted membrane vesicles (IMVs)), inconclusive results are quite common. This uncertainty is due mainly by applying a different pressures, using either intact cells or spheroplasts and presence or absence of sucrose during rupture procedure. Many E. coli envelope fractionation techniques result in heterogeneity among isolated IM membrane vesicles. In part, this is due to difficulties in simple validation of sidedness of oriented membrane preparations of unknown sidedness. The sidedness of various preparations of membrane vesicles can be inferred from the orientation of residing uniformly oriented transmembrane protein. We outline the method in which the orientation of membrane vesicles can be verified by mapping of uniform or mixed topologies of essential protein E. coli protein leader peptidase (LepB) by advanced SCAM™. Although the protocol discussed in this chapter has been developed using Escherichia coli and Yersinia pseudotuberculosis, it can be directly adapted to other Gram-negative bacteria including pathogens.
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Affiliation(s)
- Mikhail Bogdanov
- Department of Biochemistry & Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, TX, USA.
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7
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Rashid A, Brusletto BS, Al-Obeidat F, Toufiq M, Benakatti G, Brierley J, Malik ZA, Hussain Z, Alkhazaimi H, Sharief J, Kadwa R, Sarpal A, Chaussabel D, Malik RA, Quraishi N, Khilnani P, Zaki SA, Nadeem R, Shaikh G, Al-Dubai A, Hafez W, Hussain A. A TRANSCRIPTOMIC APPRECIATION OF CHILDHOOD MENINGOCOCCAL AND POLYMICROBIAL SEPSIS FROM A PRO-INFLAMMATORY AND TRAJECTORIAL PERSPECTIVE, A ROLE FOR VASCULAR ENDOTHELIAL GROWTH FACTOR A AND B MODULATION? Shock 2023; 60:503-516. [PMID: 37553892 PMCID: PMC10581425 DOI: 10.1097/shk.0000000000002192] [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] [Received: 04/20/2023] [Revised: 05/12/2023] [Accepted: 07/19/2023] [Indexed: 08/10/2023]
Abstract
ABSTRACT This study investigated the temporal dynamics of childhood sepsis by analyzing gene expression changes associated with proinflammatory processes. Five datasets, including four meningococcal sepsis shock (MSS) datasets (two temporal and two longitudinal) and one polymicrobial sepsis dataset, were selected to track temporal changes in gene expression. Hierarchical clustering revealed three temporal phases: early, intermediate, and late, providing a framework for understanding sepsis progression. Principal component analysis supported the identification of gene expression trajectories. Differential gene analysis highlighted consistent upregulation of vascular endothelial growth factor A (VEGF-A) and nuclear factor κB1 (NFKB1), genes involved in inflammation, across the sepsis datasets. NFKB1 gene expression also showed temporal changes in the MSS datasets. In the postmortem dataset comparing MSS cases to controls, VEGF-A was upregulated and VEGF-B downregulated. Renal tissue exhibited higher VEGF-A expression compared with other tissues. Similar VEGF-A upregulation and VEGF-B downregulation patterns were observed in the cross-sectional MSS datasets and the polymicrobial sepsis dataset. Hexagonal plots confirmed VEGF-R (VEGF receptor)-VEGF-R2 signaling pathway enrichment in the MSS cross-sectional studies. The polymicrobial sepsis dataset also showed enrichment of the VEGF pathway in septic shock day 3 and sepsis day 3 samples compared with controls. These findings provide unique insights into the dynamic nature of sepsis from a transcriptomic perspective and suggest potential implications for biomarker development. Future research should focus on larger-scale temporal transcriptomic studies with appropriate control groups and validate the identified gene combination as a potential biomarker panel for sepsis.
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Affiliation(s)
- Asrar Rashid
- School of Computing, Edinburgh Napier University, Edinburgh, United Kingdom
- NMC Royal Hospital, Abu Dhabi, United Arab Emirates
| | - Berit S. Brusletto
- The Blood Cell Research Group, Department of Medical Biochemistry, Oslo University Hospital, Ullevål, Norway
| | - Feras Al-Obeidat
- College of Technological Innovation at Zayed University, Abu Dhabi, United Arab Emirates
| | - Mohammed Toufiq
- The Jackson Laboratory for Genomic Medicine Farmington, Connecticut, USA
| | - Govind Benakatti
- Medanta Gururam, Delhi, India
- Yas Clinic, Abu Dhabi, United Arab Emirates
| | - Joe Brierley
- Great Ormond Street Children's Hospital, London, United Kingdom
| | - Zainab A. Malik
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Zain Hussain
- Edinburgh Medical School, University go Edinburgh, Edinburgh, United Kingdom
| | | | | | - Raziya Kadwa
- NMC Royal Hospital, Abu Dhabi, United Arab Emirates
| | - Amrita Sarpal
- Sidra Medicine, Doha, Qatar
- Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Damien Chaussabel
- The Jackson Laboratory for Genomic Medicine Farmington, Connecticut, USA
| | - Rayaz A. Malik
- Weill Cornell Medicine-Qatar, Doha, Qatar
- Institute of Cardiovascular Science, University of Manchester, Manchester, United Kingdom
| | - Nasir Quraishi
- Centre for Spinal Studies & Surgery, Queen's Medical Centre, The University of Nottingham, Nottingham, United Kingdom
| | | | - Syed A. Zaki
- All India Institute of Medical Sciences, Hyderabad, India
| | | | - Guftar Shaikh
- Endocrinology, Royal Hospital for Children, Glasgow, United Kingdom
| | - Ahmed Al-Dubai
- School of Computing, Edinburgh Napier University, Edinburgh, United Kingdom
| | - Wael Hafez
- NMC Royal Hospital, Abu Dhabi, United Arab Emirates
- Medical Research Division, Department of Internal Medicine, The National Research Centre, Cairo, Egypt
| | - Amir Hussain
- School of Computing, Edinburgh Napier University, Edinburgh, United Kingdom
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8
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Bekale LA, Sharma D, Bacacao B, Chen J, Santa Maria PL. Eradication of Bacterial Persister Cells By Leveraging Their Low Metabolic Activity Using Adenosine Triphosphate Coated Gold Nanoclusters. NANO TODAY 2023; 51:101895. [PMID: 37575958 PMCID: PMC10421611 DOI: 10.1016/j.nantod.2023.101895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Bacteria first develop tolerance after antibiotic exposure; later genetic resistance emerges through the population of tolerant bacteria. Bacterial persister cells are the multidrug-tolerant subpopulation within an isogenic bacteria culture that maintains genetic susceptibility to antibiotics. Because of this link between antibiotic tolerance and resistance and the rise of antibiotic resistance, there is a pressing need to develop treatments to eradicate persister cells. Current anti persister cell strategies are based on the paradigm of "awakening" them from their low metabolic state before attempting eradication with traditional antibiotics. Herein, we demonstrate that the low metabolic activity of persister cells can be exploited for eradication over their metabolically active counterparts. We engineered gold nanoclusters coated with adenosine triphosphate (AuNC@ATP) as a benchmark nanocluster that kills persister cells over exponential growth bacterial cells and prove the feasibility of this new concept. Finally, using AuNC@ATP as a new research tool, we demonstrated that it is possible to prevent the emergence of antibiotic-resistant superbugs with an anti-persister compound. Eradicating persister cells with AuNC@ATP in an isogenic culture of bacteria stops the emergence of superbug bacteria mediated by the sub-lethal dose of conventional antibiotics. Our findings lay the groundwork for developing novel nano-antibiotics targeting persister cells, which promise to prevent the emergence of superbugs and prolong the lifespan of currently available antibiotics.
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Affiliation(s)
- Laurent A. Bekale
- Department of Otolaryngology, Head and Neck Surgery, Stanford University, 801 Welch Road Stanford, CA 94305-5739, USA
| | - Devesh Sharma
- Department of Otolaryngology, Head and Neck Surgery, Stanford University, 801 Welch Road Stanford, CA 94305-5739, USA
| | - Brian Bacacao
- Department of Otolaryngology, Head and Neck Surgery, Stanford University, 801 Welch Road Stanford, CA 94305-5739, USA
| | - Jing Chen
- Department of Otolaryngology, Head and Neck Surgery, Stanford University, 801 Welch Road Stanford, CA 94305-5739, USA
| | - Peter L. Santa Maria
- Department of Otolaryngology, Head and Neck Surgery, Stanford University, 801 Welch Road Stanford, CA 94305-5739, USA
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9
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Yang Y, Wu B, Li W, Han F. Molecular Characterization of Galectin-3 in Large Yellow Croaker Larimichthys crocea Functioning in Antibacterial Activity. Int J Mol Sci 2023; 24:11539. [PMID: 37511297 PMCID: PMC10380712 DOI: 10.3390/ijms241411539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 07/13/2023] [Accepted: 07/15/2023] [Indexed: 07/30/2023] Open
Abstract
Galectins are proteins that play a crucial role in the innate immune response against pathogenic microorganisms. Previous studies have suggested that Galectin-3 could be a candidate gene for antibacterial immunity in the large yellow croaker Larimichthys crocea. In this study, we cloned the Galectin-3 gene in the large yellow croaker, and named it LcGal-3. The deduced amino acid sequence of LcGal-3 contains a carbohydrate recognition domain with two conserved β-galactoside binding motifs. Quantitative reverse transcription PCR (qRT-PCR) analysis revealed that LcGal-3 was expressed in all the organs/tissues that were tested, with the highest expression level in the gill. In Larimichthys crocea kidney cell lines, LcGal-3 protein was distributed in both the cytoplasm and nucleus. Moreover, we found that the expression of LcGal-3 was significantly upregulated upon infection with Pseudomonas plecoglossicida, as demonstrated by qRT-PCR analyses. We also purified the LcGal-3 protein that was expressed in prokaryotes, and found that it has the ability to agglutinate large yellow croaker red blood cells in a Ca2+-independent manner. The agglutination activity of LcGal-3 was inhibited by lipopolysaccharides (LPS) in a concentration-dependent manner, as shown in the sugar inhibition test. Additionally, LcGal-3 exhibited agglutination and antibacterial activities against three Gram-negative bacteria, including P. plecoglossicida, Vibrio parahaemolyticus, and Vibrio harveyi. Furthermore, we studied the agglutination mechanism of the LcGal-3 protein using blood coagulation tests with LcGal-3 deletion and point mutation proteins. Our results indicate that LcGal-3 protein plays a critical role in the innate immunity of the large yellow croaker, providing a basis for further studies on the immune mechanism and disease-resistant breeding in L. crocea and other marine fish.
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Affiliation(s)
- Yao Yang
- Key Laboratory of Healthy Mariculture for the East China Sea, Minsistry of Agriculture and Rural Affairs Fujian Provincial Key Laboratory of Marine Fishery Resources and Eco-Environment, Jimei University, Xiamen 361021, China
| | - Baolan Wu
- Key Laboratory of Healthy Mariculture for the East China Sea, Minsistry of Agriculture and Rural Affairs Fujian Provincial Key Laboratory of Marine Fishery Resources and Eco-Environment, Jimei University, Xiamen 361021, China
| | - Wanbo Li
- Key Laboratory of Healthy Mariculture for the East China Sea, Minsistry of Agriculture and Rural Affairs Fujian Provincial Key Laboratory of Marine Fishery Resources and Eco-Environment, Jimei University, Xiamen 361021, China
| | - Fang Han
- Key Laboratory of Healthy Mariculture for the East China Sea, Minsistry of Agriculture and Rural Affairs Fujian Provincial Key Laboratory of Marine Fishery Resources and Eco-Environment, Jimei University, Xiamen 361021, China
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10
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Som N, Reddy M. Cross-talk between phospholipid synthesis and peptidoglycan expansion by a cell wall hydrolase. Proc Natl Acad Sci U S A 2023; 120:e2300784120. [PMID: 37276399 PMCID: PMC10268279 DOI: 10.1073/pnas.2300784120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 05/04/2023] [Indexed: 06/07/2023] Open
Abstract
The Gram-negative bacterial cell envelope is a complex multilayered structure comprising a bilayered phospholipid (PL) membrane that surrounds the cytoplasm (inner membrane or IM) and an asymmetric outer membrane (OM) with PLs in the inner leaflet and lipopolysaccharides in the outer leaflet. Between these two layers is the periplasmic space, which contains a highly cross-linked mesh-like glycan polymer, peptidoglycan (PG). During cell expansion, coordinated synthesis of each of these components is required to maintain the integrity of the cell envelope; however, it is currently not clear how such coordination is achieved. In this study, we show that a cross-link-specific PG hydrolase couples the expansion of PG sacculus with that of PL synthesis in the Gram-negative model bacterium, Escherichia coli. We find that unregulated activity of a PG hydrolytic enzyme, MepS is detrimental for growth of E. coli during fatty acid (FA)-limiting conditions. Further genetic and biochemical analyses revealed that cellular availability of FA or PL alters the post-translational stability of MepS by modulating the proteolytic activity of a periplasmic adaptor-protease complex, NlpI-Prc toward MepS. Our results indicate that loss of OM lipid asymmetry caused by alterations in PL abundance leads to the generation of a signal to the NlpI-Prc complex for the stabilization of MepS, which subsequently cleaves the cross-links to facilitate expansion of PG. In summary, our study shows the existence of a molecular cross-talk that enables coordinated expansion of the PG sacculus with that of membrane synthesis for balanced cell-envelope biogenesis.
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Affiliation(s)
- Nilanjan Som
- Centre for Cellular and Molecular Biology, Hyderabad, 500007Telangana, India
| | - Manjula Reddy
- Centre for Cellular and Molecular Biology, Hyderabad, 500007Telangana, India
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11
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Trotta KL, Hayes BM, Schneider JP, Wang J, Todor H, Rockefeller Grimes P, Zhao Z, Hatleberg WL, Silvis MR, Kim R, Koo BM, Basler M, Chou S. Lipopolysaccharide transport regulates bacterial sensitivity to a cell wall-degrading intermicrobial toxin. PLoS Pathog 2023; 19:e1011454. [PMID: 37363922 PMCID: PMC10328246 DOI: 10.1371/journal.ppat.1011454] [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: 05/02/2023] [Revised: 07/07/2023] [Accepted: 06/01/2023] [Indexed: 06/28/2023] Open
Abstract
Gram-negative bacteria can antagonize neighboring microbes using a type VI secretion system (T6SS) to deliver toxins that target different essential cellular features. Despite the conserved nature of these targets, T6SS potency can vary across recipient species. To understand the functional basis of intrinsic T6SS susceptibility, we screened for essential Escherichia coli (Eco) genes that affect its survival when antagonized by a cell wall-degrading T6SS toxin from Pseudomonas aeruginosa, Tae1. We revealed genes associated with both the cell wall and a separate layer of the cell envelope, lipopolysaccharide, that modulate Tae1 toxicity in vivo. Disruption of genes in early lipopolysaccharide biosynthesis provided Eco with novel resistance to Tae1, despite significant cell wall degradation. These data suggest that Tae1 toxicity is determined not only by direct substrate damage, but also by indirect cell envelope homeostasis activities. We also found that Tae1-resistant Eco exhibited reduced cell wall synthesis and overall slowed growth, suggesting that reactive cell envelope maintenance pathways could promote, not prevent, self-lysis. Together, our study reveals the complex functional underpinnings of susceptibility to Tae1 and T6SS which regulate the impact of toxin-substrate interactions in vivo.
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Affiliation(s)
- Kristine L. Trotta
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
| | - Beth M. Hayes
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
| | | | - Jing Wang
- Biozentrum, University of Basel, Basel, Switzerland
| | - Horia Todor
- Department of Cell and Tissue Biology, University of California–San Francisco, San Francisco, California, United States of America
| | - Patrick Rockefeller Grimes
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
| | - Ziyi Zhao
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
| | | | - Melanie R. Silvis
- Department of Cell and Tissue Biology, University of California–San Francisco, San Francisco, California, United States of America
| | - Rachel Kim
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
| | - Byoung Mo Koo
- Department of Cell and Tissue Biology, University of California–San Francisco, San Francisco, California, United States of America
| | - Marek Basler
- Biozentrum, University of Basel, Basel, Switzerland
| | - Seemay Chou
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
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12
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Oi KK, Moehle K, Schuster M, Zerbe O. Early Molecular Insights into Thanatin Analogues Binding to A. baumannii LptA. Molecules 2023; 28:4335. [PMID: 37298811 PMCID: PMC10254193 DOI: 10.3390/molecules28114335] [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: 05/04/2023] [Revised: 05/11/2023] [Accepted: 05/12/2023] [Indexed: 06/12/2023] Open
Abstract
The cationic antimicrobial ß-hairpin, thanatin, was recently developed into drug-like analogues active against carbapenem-resistant Enterobacteriaceae (CRE). The analogues represent new antibiotics with a novel mode of action targeting LptA in the periplasm and disrupting LPS transport. The compounds lose antimicrobial efficacy when the sequence identity to E. coli LptA falls below 70%. We wanted to test the thanatin analogues against LptA of a phylogenetic distant organism and investigate the molecular determinants of inactivity. Acinetobacter baumannii (A. baumannii) is a critical Gram-negative pathogen that has gained increasing attention for its multi-drug resistance and hospital burden. A. baumannii LptA shares 28% sequence identity with E. coli LptA and displays an intrinsic resistance to thanatin and thanatin analogues (MIC values > 32 µg/mL) through a mechanism not yet described. We investigated the inactivity further and discovered that these CRE-optimized derivatives can bind to LptA of A. baumannii in vitro, despite the high MIC values. Herein, we present a high-resolution structure of A. baumannii LptAm in complex with a thanatin derivative 7 and binding affinities of selected thanatin derivatives. Together, these data offer structural insights into why thanatin derivatives are inactive against A. baumannii LptA, despite binding events in vitro.
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Affiliation(s)
| | | | | | - Oliver Zerbe
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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13
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Purcell AB, Simpson BW, Trent MS. Impact of the cAMP-cAMP Receptor Protein Regulatory Complex on Lipopolysaccharide Modifications and Polymyxin B Resistance in Escherichia coli. J Bacteriol 2023; 205:e0006723. [PMID: 37070977 PMCID: PMC10210979 DOI: 10.1128/jb.00067-23] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 03/17/2023] [Indexed: 04/19/2023] Open
Abstract
Gram-negative bacteria have a unique cell surface that can be modified to maintain bacterial fitness in diverse environments. A well-defined example is the modification of the lipid A component of lipopolysaccharide (LPS), which promotes resistance to polymyxin antibiotics and antimicrobial peptides. In many organisms, such modifications include the addition of the amine-containing constituents 4-amino-4-deoxy-l-arabinose (l-Ara4N) and phosphoethanolamine (pEtN). Addition of pEtN is catalyzed by EptA, which uses phosphatidylethanolamine (PE) as its substrate donor, resulting in production of diacylglycerol (DAG). DAG is then quickly recycled into glycerophospholipid (GPL) synthesis by the DAG kinase A (DgkA) to produce phosphatidic acid, the major GPL precursor. Previously, we hypothesized that loss of DgkA recycling would be detrimental to the cell when LPS is heavily modified. Instead, we found that DAG accumulation inhibits EptA activity, preventing further degradation of PE, the predominant GPL of the cell. However, DAG inhibition of pEtN addition results in complete loss of polymyxin resistance. Here, we selected for suppressors to find a mechanism of resistance independent of DAG recycling or pEtN modification. Disrupting the gene encoding the adenylate cyclase, cyaA, fully restored antibiotic resistance without restoring DAG recycling or pEtN modification. Supporting this, disruptions of genes that reduce CyaA-derived cAMP formation (e.g., ptsI) or disruption of the cAMP receptor protein, Crp, also restored resistance. We found that loss of the cAMP-CRP regulatory complex was necessary for suppression and that resistance arises from a substantial increase in l-Ara4N-modified LPS, bypassing the need for pEtN modification. IMPORTANCE Gram-negative bacteria can alter the structure of their LPS to promote resistance to cationic antimicrobial peptides, including polymyxin antibiotics. Polymyxins are considered last-resort antibiotics for treatment against multidrug-resistant Gram-negative organisms. Here, we explore how changes in general metabolism and carbon catabolite repression pathways can alter LPS structure and influence polymyxin resistance.
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Affiliation(s)
- Alexandria B. Purcell
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - Brent W. Simpson
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - M. Stephen Trent
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
- Department of Microbiology, College of Arts and Sciences, University of Georgia, Athens, Georgia, USA
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14
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Trotta KL, Hayes BM, Schneider JP, Wang J, Todor H, Grimes PR, Zhao Z, Hatleberg WL, Silvis MR, Kim R, Koo BM, Basler M, Chou S. Lipopolysaccharide integrity primes bacterial sensitivity to a cell wall-degrading intermicrobial toxin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.524922. [PMID: 36747731 PMCID: PMC9900751 DOI: 10.1101/2023.01.20.524922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Gram-negative bacteria can antagonize neighboring microbes using a type VI secretion system (T6SS) to deliver toxins that target different essential cellular features. Despite the conserved nature of these targets, T6SS potency can vary across recipient species. To understand the molecular basis of intrinsic T6SS susceptibility, we screened for essential Escherichia coli genes that affect its survival when antagonized by a cell wall-degrading T6SS toxin from Pseudomonas aeruginosa , Tae1. We revealed genes associated with both the cell wall and a separate layer of the cell envelope, surface lipopolysaccharide, that modulate Tae1 toxicity in vivo . Disruption of lipopolysaccharide synthesis provided Escherichia coli (Eco) with novel resistance to Tae1, despite significant cell wall degradation. These data suggest that Tae1 toxicity is determined not only by direct substrate damage, but also by indirect cell envelope homeostasis activities. We also found that Tae1-resistant Eco exhibited reduced cell wall synthesis and overall slowed growth, suggesting that reactive cell envelope maintenance pathways could promote, not prevent, self-lysis. Together, our study highlights the consequences of co-regulating essential pathways on recipient fitness during interbacterial competition, and how antibacterial toxins leverage cellular vulnerabilities that are both direct and indirect to their specific targets in vivo .
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Affiliation(s)
- Kristine L Trotta
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
| | - Beth M Hayes
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
| | - Johannes P Schneider
- Focal Area Infection Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH - 4056 Basel, Switzerland
| | - Jing Wang
- Focal Area Infection Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH - 4056 Basel, Switzerland
| | - Horia Todor
- Department of Cell and Tissue Biology, University of California – San Francisco, San Francisco, CA, USA
| | - Patrick Rockefeller Grimes
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
| | - Ziyi Zhao
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
| | | | - Melanie R Silvis
- Department of Cell and Tissue Biology, University of California – San Francisco, San Francisco, CA, USA
| | - Rachel Kim
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
| | - Byoung Mo Koo
- Department of Cell and Tissue Biology, University of California – San Francisco, San Francisco, CA, USA
| | - Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH - 4056 Basel, Switzerland
| | - Seemay Chou
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
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15
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Surveying membrane landscapes: a new look at the bacterial cell surface. Nat Rev Microbiol 2023:10.1038/s41579-023-00862-w. [PMID: 36828896 DOI: 10.1038/s41579-023-00862-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2023] [Indexed: 02/26/2023]
Abstract
Recent studies applying advanced imaging techniques are changing the way we understand bacterial cell surfaces, bringing new knowledge on everything from single-cell heterogeneity in bacterial populations to their drug sensitivity and mechanisms of antimicrobial resistance. In both Gram-positive and Gram-negative bacteria, the outermost surface of the bacterial cell is being imaged at nanoscale; as a result, topographical maps of bacterial cell surfaces can be constructed, revealing distinct zones and specific features that might uniquely identify each cell in a population. Functionally defined assembly precincts for protein insertion into the membrane have been mapped at nanoscale, and equivalent lipid-assembly precincts are suggested from discrete lipopolysaccharide patches. As we review here, particularly for Gram-negative bacteria, the applications of various modalities of nanoscale imaging are reawakening our curiosity about what is conceptually a 3D cell surface landscape: what it looks like, how it is made and how it provides resilience to respond to environmental impacts.
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16
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Single-cell recordings reveal subpopulations that grow and generate resistance at bactericidal concentrations of antibiotics. Proc Natl Acad Sci U S A 2023; 120:e2221546120. [PMID: 36745803 PMCID: PMC9963259 DOI: 10.1073/pnas.2221546120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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17
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Lai L, Yang J, Sun W, Su X, Chen J, Chen X, Pei S. Design, synthesis and antibacterial evaluation of a novel class of tetrahydrobenzothiophene derivatives. RSC Med Chem 2023; 14:166-172. [PMID: 36760738 PMCID: PMC9890943 DOI: 10.1039/d2md00373b] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 11/09/2022] [Indexed: 12/11/2022] Open
Abstract
In this study, a new series of tetrahydrobenzothiophene derivatives have been designed. Newly designed molecules have been synthesized through a medicinal chemistry route, and their characterization was done by using NMR and HR-MS techniques. Biological evaluation of the synthesized compounds has been done on Gram-negative and Gram-positive bacteria. The marketed antibiotics such as ciprofloxacin and gentamicin were used as controls. The in vitro evaluation results have shown that most of the targeted compounds exhibit good potency in inhibiting the growth of bacteria, including E. coli (MIC: 0.64-19.92 μM), P. aeruginosa (MIC: 0.72-45.30 μM), Salmonella (MIC: 0.54-90.58 μM) and S. aureus (MIC: 1.11-99.92 μM). In particular, compound 3b showed excellent activity with an MIC value of 1.11 μM against E. coli, 1.00 μM against P. aeruginosa, 0.54 μM against Salmonella, and 1.11 μM against S. aureus. From the results, a promising lead compound was identified for future development.
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Affiliation(s)
- Lin Lai
- Key Laboratory of Industrial Fermentation Microorganism, Chongqing University of Science and Technology Chongqing 401331 China
| | - Jinhua Yang
- Key Laboratory of Industrial Fermentation Microorganism, Chongqing University of Science and Technology Chongqing 401331 China
| | - Wanlin Sun
- Key Laboratory of Industrial Fermentation Microorganism, Chongqing University of Science and Technology Chongqing 401331 China
| | - Xiaoyan Su
- Key Laboratory of Industrial Fermentation Microorganism, Chongqing University of Science and Technology Chongqing 401331 China
| | - Jun Chen
- Key Laboratory of Industrial Fermentation Microorganism, Chongqing University of Science and Technology Chongqing 401331 China
| | - Xinan Chen
- German Institute of Engineering, Chongqing College of Mobile Communtion Chongqing 401520 China
| | - Shuchen Pei
- Key Laboratory of Industrial Fermentation Microorganism, Chongqing University of Science and Technology Chongqing 401331 China
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18
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Möller AM, Brückner S, Tilg LJ, Kutscher B, Nowaczyk MM, Narberhaus F. LapB (YciM) orchestrates protein-protein interactions at the interface of lipopolysaccharide and phospholipid biosynthesis. Mol Microbiol 2023; 119:29-43. [PMID: 36464488 DOI: 10.1111/mmi.15005] [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: 09/29/2022] [Revised: 11/14/2022] [Accepted: 11/14/2022] [Indexed: 11/23/2022]
Abstract
The outer membrane (OM) of Gram-negative bacteria functions as an essential barrier and is characterized by an asymmetric bilayer with lipopolysaccharide (LPS) in the outer leaflet. The enzyme LpxC catalyzes the first committed step in LPS biosynthesis. It plays a critical role in maintaining the balance between LPS and phospholipids (PL), which are both derived from the same biosynthetic precursor. The essential inner membrane proteins YejM (PbgA, LapC), LapB (YciM), and the protease FtsH are known to account for optimal LpxC levels, but the mechanistic details are poorly understood. LapB is thought to be a bi-functional protein serving as an adaptor for FtsH-mediated turnover of LpxC and acting as a scaffold in the coordination of LPS biosynthesis. Here, we provide experimental evidence for the physical interaction of LapB with proteins at the biosynthetic node from where the LPS and PL biosynthesis pathways diverge. By a total of four in vivo and in vitro assays, we demonstrate protein-protein interactions between LapB and the LPS biosynthesis enzymes LpxA, LpxC, and LpxD, between LapB and YejM, the anti-adaptor protein regulating LapB activity, and between LapB and FabZ, the first PL biosynthesis enzyme. Moreover, we uncovered a new adaptor function of LapB in destabilizing not only LpxC but also LpxD. Overall, our study shows that LapB is a multi-functional protein that serves as a protein-protein interaction hub for key enzymes in LPS and PL biogenesis presumably by virtue of multiple tetratricopeptide repeat (TPR) motifs in its cytoplasmic C-terminal region.
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Affiliation(s)
| | - Simon Brückner
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
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19
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Yang Z, Song M, Li X, Zhang Q, Shen J, Zhu K. Synergy of outer membrane disruptor SLAP-S25 with hydrophobic antibiotics against Gram-negative pathogens. J Antimicrob Chemother 2022; 78:263-271. [PMID: 36385317 DOI: 10.1093/jac/dkac387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 10/26/2022] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVES An effective strategy for combating MDR Gram-negative pathogens can greatly reduce the cost and shorten the antibiotic development progress. Here, we investigated the synergistic activity of outer membrane disruptor SLAP-S25 in combination with hydrophobic antibiotics (LogP > 2, including novobiocin, erythromycin, clindamycin and rifampicin) against MDR Gram-negative pathogens. METHODS Five representative Gram-negative bacteria were selected as model strains to analyse the synergistic combination of SLAP-S25 and hydrophobic antibiotics. Carbapenem-resistant hypervirulent Klebsiella pneumoniae CRHvKP4 was used to investigate the synergistic mechanism. The in vivo synergistically therapeutic activity of SLAP-S25 and hydrophobic antibiotics was measured in the mouse peritonitis/sepsis model infected with K. pneumoniae CRHvKP4. RESULTS SLAP-S25 disrupted the outer membrane by removing LPS from Gram-negative bacteria, facilitating the entry of hydrophobic antibiotics to kill MDR Gram-negative pathogens. Moreover, the combination of SLAP-S25 and rifampicin exhibited promising therapeutic effects in the mouse infection model infected with K. pneumoniae CRHvKP4. CONCLUSIONS Our findings provide a potential therapeutic strategy to combine SLAP-S25 with hydrophobic antibiotics for combating MDR Gram-negative pathogens.
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Affiliation(s)
- Zhiqiang Yang
- Department of Basic Veterinary Medicine, Key Laboratory of Traditional Chinese Veterinary Medicine Biology, Ministry of Agriculture and Rural Affairs, College of VeterinaryMedicine, China Agricultural University, Beijing 100193, China
| | - Meirong Song
- Department of Basic Veterinary Medicine, Key Laboratory of Traditional Chinese Veterinary Medicine Biology, Ministry of Agriculture and Rural Affairs, College of VeterinaryMedicine, China Agricultural University, Beijing 100193, China
| | - Xiaoyu Li
- Department of Basic Veterinary Medicine, Key Laboratory of Traditional Chinese Veterinary Medicine Biology, Ministry of Agriculture and Rural Affairs, College of VeterinaryMedicine, China Agricultural University, Beijing 100193, China
| | - Qi Zhang
- Department of Basic Veterinary Medicine, Key Laboratory of Traditional Chinese Veterinary Medicine Biology, Ministry of Agriculture and Rural Affairs, College of VeterinaryMedicine, China Agricultural University, Beijing 100193, China
| | - Jianzhong Shen
- Department of Basic Veterinary Medicine, Key Laboratory of Traditional Chinese Veterinary Medicine Biology, Ministry of Agriculture and Rural Affairs, College of VeterinaryMedicine, China Agricultural University, Beijing 100193, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Kui Zhu
- Department of Basic Veterinary Medicine, Key Laboratory of Traditional Chinese Veterinary Medicine Biology, Ministry of Agriculture and Rural Affairs, College of VeterinaryMedicine, China Agricultural University, Beijing 100193, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
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20
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Huang Z, Chen Y, Yang C, Ma B, Guo S, Zhang J, Chen N, Umar T, Yin B, Deng G. Enhanced expression of miR-26a ameliorates lipopolysaccharide-induced endometritis by targeting MAP3K8 to inactivate MAPK signaling pathway. J Reprod Immunol 2022; 154:103751. [PMID: 36252394 DOI: 10.1016/j.jri.2022.103751] [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: 08/10/2022] [Revised: 09/08/2022] [Accepted: 09/16/2022] [Indexed: 12/14/2022]
Abstract
Endometritis is a severe postpartum inflammatory disease that puts cows' reproductive health at risk and causes the dairy industry to suffer significant financial losses. The present study aimed to investigate the regulatory role of miR‑26a in LPS‑induced bovine endometrial epithelial cells (bEECs) and the implication for endometritis. Here, we found inflammatory cell infiltration and destruction of endometrial structure in cow uterus, and dramatic increase in myeloperoxidase (MPO) activity and upregulation of pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6) in endometritis. Meanwhile, miR-26a was down-regulated, but MAP3K8 was increased in the uterine tissue of endometritis. Similarly, the expression of miR-26a was significantly decreased in LPS-stimulated bEECs, while MAP3K8 was risen. In addition, we further verified that MAP3K8 was a target of miR-26a by dual-luciferase reporter assay. Under LPS stress, over-expressing miR-26a markedly decreased MAP3K8 expression levels, along with the reduced expression of inflammatory factors, such as IL-1β, TNF-α and IL-6, whereas this effect was countered by the inhibition of miR-26a. Furthermore, we demonstrated that miR-26a overexpression prevented the MAPK pathway from being activated by targeting MAP3K8. Then we carried out experiments in LPS-stimulated mice uterus to expound that MAP3K8 was essential in endometritis development, which further confirmed the reliability of the above results. In conclusion, overexpression of miR-26a effectively inhibited the expression of MAP3K8 in LPS-induced bEECs and thereby partially suppressed the activation of MAPK signaling pathway. miR-26a and MAP3K8 may be a promising biomarker and therapeutic target for dairy cow endometritis.
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Affiliation(s)
- Zhi Huang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Yu Chen
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Cheng Yang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Bin Ma
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Shuai Guo
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Jinxin Zhang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Nuoer Chen
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Talha Umar
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Baoyi Yin
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Ganzhen Deng
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
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21
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Liston SD, Ovchinnikova OG, Kimber MS, Whitfield C. A dedicated C-6 β-hydroxyacyltransferase required for biosynthesis of the glycolipid anchor for Vi antigen capsule in typhoidal Salmonella. J Biol Chem 2022; 298:102520. [PMID: 36152747 DOI: 10.1016/j.jbc.2022.102520] [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: 08/02/2022] [Revised: 09/15/2022] [Accepted: 09/16/2022] [Indexed: 11/17/2022] Open
Abstract
Vi antigen is an extracellular polysaccharide produced by Salmonella enterica Typhi, Citrobacter freundii, and some soil bacteria belonging to the Burkholderiales. In Salmonella Typhi, Vi-antigen capsule protects the bacterium against host defenses, and the glycan is used in a current glycoconjugate vaccine to protect against typhoid. Vi antigen is a glycolipid assembled in the cytoplasm and translocated to the cell surface by an export complex driven by an ABC transporter. In Salmonella Typhi, efficient export and cell-surface retention of the capsule layer depend on a reducing terminal acylated-HexNAc moiety. Although the precise structure and biosynthesis of the acylated terminus has not been resolved, it distinguishes Vi antigen from other known glycolipid substrates for bacterial ABC transporters. The genetic locus for Vi antigen-biosynthesis encodes a single acyltransferase candidate (VexE), which is implicated in the acylation process. Here, we determined the structure of the VexE in vitro reaction product by mass spectrometry and nuclear magnetic resonance spectroscopy, to reveal that VexE catalyzes β-hydroxyacyl-ACP dependent acylation of the activated sugar precursor, uridine-5'-diphospho-N-acetylglucosamine (UDP-GlcNAc), at C-6 to form UDP-6-O-[β-hydroxymyristoyl]-α-d-GlcNAc. VexE belongs to the lysophosphatidyl acyltransferase (LPLAT) family, and comparison of an Alphafold VexE model to solved LPLAT structures, together with modeling enzyme:substrate complexes, led us to predict an enzyme mechanism. This study provides new insight into Vi terminal structure, offers a new model substrate to investigate the mechanism of glycolipid ABC transporters, and adds biochemical understanding for a novel reaction used in synthesis of an important bacterial virulence factor.
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Affiliation(s)
- S D Liston
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - O G Ovchinnikova
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - M S Kimber
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - C Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.
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22
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Pellizza L, Bialer MG, Sieira R, Aran M. MliR, a novel MerR-like regulator of iron homeostasis, impacts metabolism, membrane remodeling, and cell adhesion in the marine Bacteroidetes Bizionia argentinensis. Front Microbiol 2022; 13:987756. [PMID: 36118216 PMCID: PMC9478572 DOI: 10.3389/fmicb.2022.987756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
The MerR family is a group of transcriptional activators with conserved N-terminal helix-turn-helix DNA binding domains and variable C-terminal effector binding regions. In most MerR proteins the effector binding domain (EBD) contains a cysteine center suited for metal binding and mediates the response to environmental stimuli, such as oxidative stress, heavy metals or antibiotics. We here present a novel transcriptional regulator classified in the MerR superfamily that lacks an EBD domain and has neither conserved metal binding sites nor cysteine residues. This regulator from the psychrotolerant bacteria Bizionia argentinensis JUB59 is involved in iron homeostasis and was named MliR (MerR-like iron responsive Regulator). In silico analysis revealed that homologs of the MliR protein are widely distributed among different bacterial species. Deletion of the mliR gene led to decreased cell growth, increased cell adhesion and filamentation. Genome-wide transcriptomic analysis showed that genes associated with iron homeostasis were downregulated in mliR-deletion mutant. Through nuclear magnetic resonance-based metabolomics, ICP-MS, fluorescence microscopy and biochemical analysis we evaluated metabolic and phenotypic changes associated with mliR deletion. This work provides the first evidence of a MerR-family regulator involved in iron homeostasis and contributes to expanding our current knowledge on relevant metabolic pathways and cell remodeling mechanisms underlying in the adaptive response to iron availability in bacteria.
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23
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Jangir PK, Yang Q, Shaw LP, Caballero JD, Ogunlana L, Wheatley R, Walsh T, MacLean RC. Pre-existing chromosomal polymorphisms in pathogenic E. coli potentiate the evolution of resistance to a last-resort antibiotic. eLife 2022; 11:78834. [PMID: 35943060 PMCID: PMC9363117 DOI: 10.7554/elife.78834] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 07/22/2022] [Indexed: 12/17/2022] Open
Abstract
Bacterial pathogens show high levels of chromosomal genetic diversity, but the influence of this diversity on the evolution of antibiotic resistance by plasmid acquisition remains unclear. Here, we address this problem in the context of colistin, a 'last line of defence' antibiotic. Using experimental evolution, we show that a plasmid carrying the MCR-1 colistin resistance gene dramatically increases the ability of Escherichia coli to evolve high-level colistin resistance by acquiring mutations in lpxC, an essential chromosomal gene involved in lipopolysaccharide biosynthesis. Crucially, lpxC mutations increase colistin resistance in the presence of the MCR-1 gene, but decrease the resistance of wild-type cells, revealing positive sign epistasis for antibiotic resistance between the chromosomal mutations and a mobile resistance gene. Analysis of public genomic datasets shows that lpxC polymorphisms are common in pathogenic E. coli, including those carrying MCR-1, highlighting the clinical relevance of this interaction. Importantly, lpxC diversity is high in pathogenic E. coli from regions with no history of MCR-1 acquisition, suggesting that pre-existing lpxC polymorphisms potentiated the evolution of high-level colistin resistance by MCR-1 acquisition. More broadly, these findings highlight the importance of standing genetic variation and plasmid/chromosomal interactions in the evolutionary dynamics of antibiotic resistance.
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Affiliation(s)
- Pramod K Jangir
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - Qiue Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry UniversityFuzhouChina
| | - Liam P Shaw
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | | | - Lois Ogunlana
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - Rachel Wheatley
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - Timothy Walsh
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - R Craig MacLean
- Department of Zoology, University of OxfordOxfordUnited Kingdom
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Shu S, Mi W. Regulatory mechanisms of lipopolysaccharide synthesis in Escherichia coli. Nat Commun 2022; 13:4576. [PMID: 35931690 PMCID: PMC9356133 DOI: 10.1038/s41467-022-32277-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 07/25/2022] [Indexed: 11/09/2022] Open
Abstract
Lipopolysaccharide (LPS) is an essential glycolipid and forms a protective permeability barrier for most Gram-negative bacteria. In E. coli, LPS levels are under feedback control, achieved by FtsH-mediated degradation of LpxC, which catalyzes the first committed step in LPS synthesis. FtsH is a membrane-bound AAA+ protease, and its protease activity toward LpxC is regulated by essential membrane proteins LapB and YejM. However, the regulatory mechanisms are elusive. We establish an in vitro assay to analyze the kinetics of LpxC degradation and demonstrate that LapB is an adaptor protein that utilizes its transmembrane helix to interact with FtsH and its cytoplasmic domains to recruit LpxC. Our YejM/LapB complex structure reveals that YejM is an anti-adaptor protein, competing with FtsH for LapB to inhibit LpxC degradation. Structural analysis unravels that LapB and LPS have overlapping binding sites in YejM. Thus, LPS levels control formation of the YejM/LapB complex to determine LpxC protein levels.
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Affiliation(s)
- Sheng Shu
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Wei Mi
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, 06520, USA. .,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA.
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Regulated Expression of lpxC Allows for Reduction of Endotoxicity in Bordetella pertussis. Int J Mol Sci 2022; 23:ijms23148027. [PMID: 35887374 PMCID: PMC9324023 DOI: 10.3390/ijms23148027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/16/2022] [Accepted: 07/17/2022] [Indexed: 02/05/2023] Open
Abstract
The Gram-negative bacterium Bordetella pertussis is the causative agent of a respiratory infection known as whooping cough. Previously developed whole-cell pertussis vaccines were effective, but appeared to be too reactogenic mainly due to the presence of lipopolysaccharide (LPS, also known as endotoxin) in the outer membrane (OM). Here, we investigated the possibility of reducing endotoxicity by modulating the LPS levels. The promoter of the lpxC gene, which encodes the first committed enzyme in LPS biosynthesis, was replaced by an isopropyl β-D-1-thiogalactopyranoside (IPTG)-inducible promoter. The IPTG was essential for growth, even when the construct was moved into a strain that should allow for the replacement of LPS in the outer leaflet of the OM with phospholipids by defective phospholipid transporter Mla and OM phospholipase A. LpxC depletion in the absence of IPTG resulted in morphological changes of the cells and in overproduction of outer-membrane vesicles (OMVs). The reduced amounts of LPS in whole-cell preparations and in isolated OMVs of LpxC-depleted cells resulted in lower activation of Toll-like receptor 4 in HEK-Blue reporter cells. We suggest that, besides lipid A engineering, also a reduction in LPS synthesis is an attractive strategy for the production of either whole-cell- or OMV-based vaccines, with reduced reactogenicity for B. pertussis and other Gram-negative bacteria.
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26
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Sun L, Zhang Y, Cai T, Li X, Li N, Xie Z, Yang F, You X. CrrAB regulates PagP-mediated glycerophosphoglycerol palmitoylation in the outer membrane of Klebsiella pneumoniae. J Lipid Res 2022; 63:100251. [PMID: 35841948 PMCID: PMC9403492 DOI: 10.1016/j.jlr.2022.100251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 06/28/2022] [Accepted: 06/29/2022] [Indexed: 11/29/2022] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria is an evolving antibiotic barrier composed of a glycerophospholipid (GP) inner leaflet and a lipopolysaccharide (LPS) outer leaflet. The two-component regulatory system CrrAB has only recently been reported to confer high-level polymyxin resistance and virulence in Klebsiella pneumoniae. Mutations in crrB have been shown to lead to the modification of the lipid A moiety of LPS through CrrAB activation. However, functions of CrrAB activation in the regulation of other lipids are unclear. Work here demonstrates CrrAB activation not only stimulates LPS modification, but also regulates synthesis of acyl-glycerophosphoglycerols (acyl-PGs), a lipid species with undefined functions and biosynthesis. Among all possible modulators of acyl-PG identified from proteomic data, we found expression of lipid A palmitoyltransferase (PagP) was significantly up-regulated in the crrB mutant. Furthermore, comparative lipidomics showed that most of the increasing acyl-PG activated by CrrAB was decreased after pagP knockout with CRISPR-Cas9. These results suggest that PagP also transfers a palmitate chain from GPs to PGs, generating acyl-PGs. Further investigation revealed that PagP mainly regulates the GP contents within the OM, leading to an increased ratio of acyl-PG to PG species, and improving OM hydrophobicity, which may contribute to resistance against certain cationic antimicrobial peptides (CAMP) resistance upon LPS modification. Taken together, this work suggests that CrrAB regulates the outer membrane GP contents of K. pneumoniae through upregulation of PagP, which functions along with LPS to form an outer membrane barrier critical for bacterial survival.
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Affiliation(s)
- Lang Sun
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Youwen Zhang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Tanxi Cai
- Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, University of Chinese Academy of Sciences, Beijing, China
| | - Xue Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Na Li
- Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, University of Chinese Academy of Sciences, Beijing, China
| | - Zhensheng Xie
- Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, University of Chinese Academy of Sciences, Beijing, China
| | - Fuquan Yang
- Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, University of Chinese Academy of Sciences, Beijing, China.
| | - Xuefu You
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
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27
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Lakey BD, Myers KS, Alberge F, Mettert EL, Kiley PJ, Noguera DR, Donohue TJ. The essential Rhodobacter sphaeroides CenKR two-component system regulates cell division and envelope biosynthesis. PLoS Genet 2022; 18:e1010270. [PMID: 35767559 PMCID: PMC9275681 DOI: 10.1371/journal.pgen.1010270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 07/12/2022] [Accepted: 05/20/2022] [Indexed: 12/13/2022] Open
Abstract
Bacterial two-component systems (TCSs) often function through the detection of an extracytoplasmic stimulus and the transduction of a signal by a transmembrane sensory histidine kinase. This kinase then initiates a series of reversible phosphorylation modifications to regulate the activity of a cognate, cytoplasmic response regulator as a transcription factor. Several TCSs have been implicated in the regulation of cell cycle dynamics, cell envelope integrity, or cell wall development in Escherichia coli and other well-studied Gram-negative model organisms. However, many α-proteobacteria lack homologs to these regulators, so an understanding of how α-proteobacteria orchestrate extracytoplasmic events is lacking. In this work we identify an essential TCS, CenKR (Cell envelope Kinase and Regulator), in the α-proteobacterium Rhodobacter sphaeroides and show that modulation of its activity results in major morphological changes. Using genetic and biochemical approaches, we dissect the requirements for the phosphotransfer event between CenK and CenR, use this information to manipulate the activity of this TCS in vivo, and identify genes that are directly and indirectly controlled by CenKR in Rb. sphaeroides. Combining ChIP-seq and RNA-seq, we show that the CenKR TCS plays a direct role in maintenance of the cell envelope, regulates the expression of subunits of the Tol-Pal outer membrane division complex, and indirectly modulates the expression of peptidoglycan biosynthetic genes. CenKR represents the first TCS reported to directly control the expression of Tol-Pal machinery genes in Gram-negative bacteria, and we predict that homologs of this TCS serve a similar function in other closely related organisms. We propose that Rb. sphaeroides genes of unknown function that are directly regulated by CenKR play unknown roles in cell envelope biosynthesis, assembly, and/or remodeling in this and other α-proteobacteria. The bacterial cell envelope is home to an array of important functions including energy conservation, motility, influx/efflux of nutrients and toxins, modulation of cell morphology and division, cell-cell interaction, and biofilm formation. Consequently, it is a major target of antibiotics and antimicrobial agents that inhibit these essential processes. Key to the recognition of environmental stressors or stimuli are bacterial TCSs, however systems that monitor or directly regulate cell envelope assembly and homeostasis are not widely conserved amongst bacteria. Here, we use Rhodobacter sphaeroides as a model to investigate the function of the CenKR TCS in this and other α-proteobacteria. We show that this essential TCS plays a key role in maintenance of the cell envelope through the regulation of outer membrane integrity and division, cell wall remodeling and homeostasis, and an alternate sigma factor that controls global cellular stress response. We provide evidence that this TCS and its function is widely conserved in α-proteobacteria and identify genes of unknown function as candidates for the study of cell envelope assembly in this and related bacteria.
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Affiliation(s)
- Bryan D. Lakey
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Kevin S. Myers
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - François Alberge
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Erin L. Mettert
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Patricia J. Kiley
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Daniel R. Noguera
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Timothy J. Donohue
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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28
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Isolation and Characterization of a Novel Temperate Escherichia coli Bacteriophage, Kapi1, Which Modifies the O-Antigen and Contributes to the Competitiveness of Its Host during Colonization of the Murine Gastrointestinal Tract. mBio 2022; 13:e0208521. [PMID: 35073745 PMCID: PMC8787464 DOI: 10.1128/mbio.02085-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In this study, we describe the isolation and characterization of novel bacteriophage vB_EcoP_Kapi1 (Kapi1) isolated from a strain of commensal Escherichia coli inhabiting the gastrointestinal tract of healthy mice. We show that Kapi1 is a temperate phage integrated into tRNA argW of strain MP1 and describe its genome annotation and structure. Kapi1 shows limited homology to other characterized prophages but is most similar to the seroconverting phages of Shigella flexneri and clusters taxonomically with P22-like phages. The receptor for Kapi1 is the lipopolysaccharide O-antigen, and we further show that Kapi1 alters the structure of its host's O-antigen in multiple ways. Kapi1 displays unstable lysogeny, and we find that the lysogenic state is more stable during growth in simulated intestinal fluid. Furthermore, Kapi1 lysogens have a competitive advantage over their nonlysogenic counterparts both in vitro and in vivo, suggesting a role for Kapi1 during colonization. We thus report the use of MP1 and Kapi1 as a model system to explore the molecular mechanisms of mammalian colonization by E. coli to ask what the role(s) of prophages in this context might be. IMPORTANCE Although research exploring the microbiome has exploded in recent years, our understanding of the viral component of the microbiome is lagging far behind our understanding of the bacterial component. The vast majority of intestinal bacteria carry prophages integrated into their chromosomes, but most of these bacteriophages remain uncharacterized and unexplored. Here, we isolate and characterize a novel temperate bacteriophage infecting a commensal strain of Escherichia coli. We aim to explore the interactions between bacteriophages and their hosts in the context of the gastrointestinal tract, asking what role(s) temperate bacteriophages may play in growth and survival of bacteria in the gut. Understanding the fundamental biology of gut commensal bacteria can inform the development of novel antimicrobial or probiotic strategies for intestinal infections.
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Ledger EVK, Sabnis A, Edwards AM. Polymyxin and lipopeptide antibiotics: membrane-targeting drugs of last resort. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35118938 PMCID: PMC8941995 DOI: 10.1099/mic.0.001136] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The polymyxin and lipopeptide classes of antibiotics are membrane-targeting drugs of last resort used to treat infections caused by multi-drug-resistant pathogens. Despite similar structures, these two antibiotic classes have distinct modes of action and clinical uses. The polymyxins target lipopolysaccharide in the membranes of most Gram-negative species and are often used to treat infections caused by carbapenem-resistant species such as Escherichia coli, Acinetobacter baumannii and Pseudomonas aeruginosa. By contrast, the lipopeptide daptomycin requires membrane phosphatidylglycerol for activity and is only used to treat infections caused by drug-resistant Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. However, despite having distinct targets, both antibiotic classes cause membrane disruption, are potently bactericidal in vitro and share similarities in resistance mechanisms. Furthermore, there are concerns about the efficacy of these antibiotics, and there is increasing interest in using both polymyxins and daptomycin in combination therapies to improve patient outcomes. In this review article, we will explore what is known about these distinct but structurally similar classes of antibiotics, discuss recent advances in the field and highlight remaining gaps in our knowledge.
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Affiliation(s)
- Elizabeth V K Ledger
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
| | - Akshay Sabnis
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
| | - Andrew M Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
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30
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Tanaka M, Kohchi C, Inagawa H, Ikemoto T, Hara-Chikuma M. Effect of topical application of lipopolysaccharide on contact hypersensitivity. Biochem Biophys Res Commun 2022; 586:100-106. [PMID: 34837833 DOI: 10.1016/j.bbrc.2021.11.045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 11/11/2021] [Indexed: 11/02/2022]
Abstract
Lipopolysaccharide (LPS) is the principal component of the outer membrane of gram-negative bacteria. The prior oral administration of LPS attenuates inflammatory responses, such as intestinal injury and atopic dermatitis, in mouse models; however, the underlying mechanism remains unclear. Here, we examined the effect of topical LPS application on allergic contact dermatitis and its mechanism of action using a murine contact hypersensitivity (CHS) model. Prolonged LPS application to the skin significantly suppressed 2,4-dinitrofluorobenzene (DNFB)-induced CHS. LPS application to the skin also reduced the phagocytosis of fluorescein isothiocyanate (FITC)-dextran by Langerhans and dendritic cells. Cutaneous cell migration into the skin-draining lymph nodes (LNs) induced by FITC painting was reduced by LPS application. During the CHS response, DNFB application induced T-cell proliferation and inflammatory cytokine production in skin-draining LNs, whereas prolonged LPS application inhibited DNFB-induced T-cell growth and interferon gamma production, indicating suppression of DNFB-induced sensitization. These results suggest that prolonged LPS application suppressed DNFB-induced sensitization and subsequently CHS response. Our findings imply that topical application of LPS may prevent allergic dermatitis such as CHS.
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Affiliation(s)
- Manami Tanaka
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinano-machi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Chie Kohchi
- Macrophi Inc., 2217-6 Hayashi-cho, Takamatsu-shi, Kagawa-ken, 761-0301, Japan
| | - Hiroyuki Inagawa
- Macrophi Inc., 2217-6 Hayashi-cho, Takamatsu-shi, Kagawa-ken, 761-0301, Japan
| | - Takeshi Ikemoto
- Kyowa Co., Ltd., 1-22-2 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Mariko Hara-Chikuma
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinano-machi, Shinjuku-ku, Tokyo, 160-8582, Japan.
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31
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Fiorentino F, Bolla JR. Mass Spectrometry Analysis of Dynamics and Interactions of the LPS Translocon LptDE. Methods Mol Biol 2022; 2548:109-128. [PMID: 36151495 DOI: 10.1007/978-1-0716-2581-1_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The presence of lipopolysaccharide (LPS) in the outer leaflet of the outer membrane (OM) is essential for Gram-negative bacteria OM barrier function and for maintaining its cell integrity. As such, comprehensive information about its biosynthesis and translocation represents a successful strategy for the development of antibacterial drugs. LPS is a complex glycolipid, and probing its interactions with LPS transport (Lpt) proteins has been extremely challenging. However, mass spectrometry (MS) techniques have recently catalyzed tremendous advancements in the characterization of LPS transport (Lpt) proteins and probed associated conformational dynamics upon substrate binding. Here, we describe the application of MS methods to study the dynamics of LPS translocon LptDE in the presence of natural substrates and inhibitors.
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Affiliation(s)
- Francesco Fiorentino
- Department of Drug Chemistry and Technologies, Sapienza University of Rome, Rome, Italy
| | - Jani R Bolla
- The Kavli Institute for Nanoscience Discovery, Oxford, UK.
- Department of Plant Sciences, University of Oxford, Oxford, UK.
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Checkpoints That Regulate Balanced Biosynthesis of Lipopolysaccharide and Its Essentiality in Escherichia coli. Int J Mol Sci 2021; 23:ijms23010189. [PMID: 35008618 PMCID: PMC8745692 DOI: 10.3390/ijms23010189] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/17/2021] [Accepted: 12/22/2021] [Indexed: 12/17/2022] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria, such as Escherichia coli, is essential for their viability. Lipopolysaccharide (LPS) constitutes the major component of OM, providing the permeability barrier, and a tight balance exists between LPS and phospholipids amounts as both of these essential components use a common metabolic precursor. Hence, checkpoints are in place, right from the regulation of the first committed step in LPS biosynthesis mediated by LpxC through its turnover by FtsH and HslUV proteases in coordination with LPS assembly factors LapB and LapC. After the synthesis of LPS on the inner leaflet of the inner membrane (IM), LPS is flipped by the IM-located essential ATP-dependent transporter to the periplasmic face of IM, where it is picked up by the LPS transport complex spanning all three components of the cell envelope for its delivery to OM. MsbA exerts its intrinsic hydrocarbon ruler function as another checkpoint to transport hexa-acylated LPS as compared to underacylated LPS. Additional checkpoints in LPS assembly are: LapB-assisted coupling of LPS synthesis and translocation; cardiolipin presence when LPS is underacylated; the recruitment of RfaH transcriptional factor ensuring the transcription of LPS core biosynthetic genes; and the regulated incorporation of non-stoichiometric modifications, controlled by the stress-responsive RpoE sigma factor, small RNAs and two-component systems.
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33
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Conserved tandem arginines for PbgA/YejM allow Salmonella Typhimurium to regulate LpxC and control lipopolysaccharide biogenesis during infection. Infect Immun 2021; 90:e0049021. [PMID: 34780276 DOI: 10.1128/iai.00490-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterobacteriaceae use the periplasmic domain of the conserved inner membrane protein, PbgA/YejM, to regulate lipopolysaccharide (LPS) biogenesis. Salmonella enterica serovar Typhimurium (S. Typhimurium) relies on PbgA to cause systemic disease in mice and this involves functional interactions with LapB/YciM, FtsH, and LpxC. Escherichia coli PbgA interacts with LapB, an adaptor for the FtsH protease, via the transmembrane segments. LapB and FtsH control proteolysis of LpxC, the rate-limiting LPS biosynthesis enzyme. Lipid A-core, the hydrophobic anchor of LPS molecules, co-crystallizes with PbgA and interacts with residues in the basic region. The model predicts that PbgA-LapB detects periplasmic LPS molecules and prompts FtsH to degrade LpxC. However, the key residues and critical interactions are not defined. We establish that S. Typhimurium uses PbgA to regulate LpxC and define the contribution of two pairs of arginines within the basic region. PbgA R215 R216 form contacts with lipid A-core in the structure and R231 R232 exist in an adjacent alpha helix. PbgA R215 R216 are necessary for S. Typhimurium to regulate LpxC, control lipid-A core biogenesis, promote survival in macrophages, and enhance virulence in mice. In contrast, PbgA R231 R232 are not necessary to regulate LpxC or to control lipid A-core levels, nor are they necessary to promote survival in macrophages or mice. However, residues R231 R232 are critical for infection lethality, and the persistent infection phenotype requires mouse Toll-like receptor four, which detects lipid A. Therefore, S. Typhimurium relies on PbgA's tandem arginines for multiple interconnected mechanisms of LPS regulation that enhance pathogenesis.
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Humphrey M, Larrouy-Maumus GJ, Furniss RCD, Mavridou DAI, Sabnis A, Edwards AM. Colistin resistance in Escherichia coli confers protection of the cytoplasmic but not outer membrane from the polymyxin antibiotic. MICROBIOLOGY-SGM 2021; 167. [PMID: 34723787 PMCID: PMC8743629 DOI: 10.1099/mic.0.001104] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Colistin is a polymyxin antibiotic of last resort for the treatment of infections caused by multi-drug-resistant Gram-negative bacteria. By targeting lipopolysaccharide (LPS), the antibiotic disrupts both the outer and cytoplasmic membranes, leading to bacterial death and lysis. Colistin resistance in Escherichia coli occurs via mutations in the chromosome or the acquisition of mobilized colistin-resistance (mcr) genes. Both these colistin-resistance mechanisms result in chemical modifications to the LPS, with positively charged moieties added at the cytoplasmic membrane before the LPS is transported to the outer membrane. We have previously shown that MCR-1-mediated LPS modification protects the cytoplasmic but not the outer membrane from damage caused by colistin, enabling bacterial survival. However, it remains unclear whether this observation extends to colistin resistance conferred by other mcr genes, or resistance due to chromosomal mutations. Using a panel of clinical E. coli that had acquired mcr −1, –1.5, −2, –3, −3.2 or −5, or had acquired polymyxin resistance independently of mcr genes, we found that almost all isolates were susceptible to colistin-mediated permeabilization of the outer, but not cytoplasmic, membrane. Furthermore, we showed that permeabilization of the outer membrane of colistin-resistant isolates by the polymyxin is in turn sufficient to sensitize bacteria to the antibiotic rifampicin, which normally cannot cross the LPS monolayer. These findings demonstrate that colistin resistance in these E. coli isolates is due to protection of the cytoplasmic but not outer membrane from colistin-mediated damage, regardless of the mechanism of resistance.
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Affiliation(s)
- Madeleine Humphrey
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2AZ, UK.,Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4AX, UK
| | - Gerald J Larrouy-Maumus
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2AZ, UK
| | - R Christopher D Furniss
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden
| | - Despoina A I Mavridou
- Department of Molecular Biosciences, University of Texas at Austin, Austin, 78712, Texas, USA
| | - Akshay Sabnis
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2AZ, UK
| | - Andrew M Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2AZ, UK
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35
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Wang Z, Qin Q, Zheng Y, Li F, Zhao Y, Chen GQ. Engineering the permeability of Halomonas bluephagenesis enhanced its chassis properties. Metab Eng 2021; 67:53-66. [PMID: 34098101 DOI: 10.1016/j.ymben.2021.05.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/26/2021] [Accepted: 05/31/2021] [Indexed: 12/24/2022]
Abstract
Bacterial outer membrane (OM), an asymmetric lipid bilayer functioning as a self-protective barrier with reduced permeability for Gram-negative bacteria, yet wasting nutrients and energy to synthesize, has not been studied for its effect on bioproduction. Here we construct several OM-defected halophile Halomonas bluephagenesis strains to investigate the effects of OM on bioproduction. We achieve enhanced chassis properties of H. bluephagenesis based on positive cellular properties among several OM-defected strains. The OM-defected H. bluephagenesis WZY09 demonstrates better adaptation to lower salinity, increasing 28%, 30% and 12% on dry cell mass (DCM), poly(3-hydroxybutyrate) (PHB) accumulation and glucose to PHB conversion rate, respectively, including enlarged cell sizes and 21-folds reduced endotoxin. Interestingly, a poly(3-hydroxybutyrate-co-21mol%4-hydroxybutyrate) (P(3HB-co-21mol%4HB)) is produced by H. bluephagenesis WZY09 derivate WZY249, increasing 60% and 260% on polyhydroxyalkanoate (PHA) production and 4HB content, respectively. Furthermore, increased electroporation efficiency, more sensitive isopropyl β-D-1-thio-galactopyranoside (IPTG) induction, better oxygen uptake, enhanced antibiotics sensitivity and ectoine secretion due to better membrane permeability are observed if OM defected, demonstrating significant OM defection impacts for further metabolic engineering, synthetic biology studies and industrial applications.
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Affiliation(s)
- Ziyu Wang
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Qin Qin
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yifei Zheng
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Fajin Li
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yiqing Zhao
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Guo-Qiang Chen
- School of Life Sciences, Tsinghua University, Beijing, 100084, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China; MOE Key Lab of Industrial Biocatalysis, Dept Chemical Engineering, Tsinghua University, Beijing, 100084, China.
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Saha S, Lach SR, Konovalova A. Homeostasis of the Gram-negative cell envelope. Curr Opin Microbiol 2021; 61:99-106. [PMID: 33901778 DOI: 10.1016/j.mib.2021.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/23/2021] [Accepted: 03/25/2021] [Indexed: 01/08/2023]
Abstract
The Gram-negative bacterial cell envelope is a complex structure and its homeostasis is essential for bacterial survival. Envelope stress responses (ESRs) are signal transduction pathways that monitor the fidelity of envelope assembly during normal growth and also detect and repair envelope damage caused by external assaults, including immune factors, protein toxins, and antibiotics. In this review, we focus on three best-studied ESRs and discuss the mechanisms by which ESRs detect various perturbations of envelope assembly and integrity and regulate envelope remodeling to promote bacterial survival. We will highlight the complex relationship of ESRs with envelope biogenesis pathways and discuss some of the challenges in this field on the road to mapping the global regulatory network of envelope homeostasis.
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Affiliation(s)
- Shreya Saha
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), 6431 Fannin Street, Houston, TX, 77030, USA
| | - Sarah R Lach
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), 6431 Fannin Street, Houston, TX, 77030, USA; MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, 6767 Bertner Avenue, Houston, TX, 77030, USA
| | - Anna Konovalova
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), 6431 Fannin Street, Houston, TX, 77030, USA.
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Troudi A, Pagès JM, Brunel JM. Chemical Highlights Supporting the Role of Lipid A in Efficient Biological Adaptation of Gram-Negative Bacteria to External Stresses. J Med Chem 2021; 64:1816-1834. [PMID: 33538159 DOI: 10.1021/acs.jmedchem.0c02185] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The outer membrane (OM) of Gram-negative bacteria provides an efficient barrier against external noxious compounds such as antimicrobial agents. Associated with drug target modification, it contributes to the overall failure of chemotherapy. In the complex OM architecture, Lipid A plays an essential role by anchoring the lipopolysaccharide in the membrane and ensuring the spatial organization between lipids, proteins, and sugars. Currently, the targets of almost all antibiotics are intracellularly located and require translocation across membranes. We report herein an integrated view of Lipid A synthesis, membrane assembly, a structure comparison at the molecular structure level of numerous Gram-negative bacterial species, as well as its recent use as a target for original antibacterial molecules. This review paves the way for a new vision of a key membrane component that acts during bacterial adaptation to environmental stresses and for the development of new weapons against microbial resistance to usual antibiotics.
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Affiliation(s)
- Azza Troudi
- UMR-MD1, U1261, Aix Marseille Université, INSERM, SSA, MCT, 13385 Marseille, France.,Laboratory of Microorganisms and Active Biomolecules, Department of Biology, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis 1008, Tunisia
| | - Jean Marie Pagès
- UMR-MD1, U1261, Aix Marseille Université, INSERM, SSA, MCT, 13385 Marseille, France
| | - Jean Michel Brunel
- UMR-MD1, U1261, Aix Marseille Université, INSERM, SSA, MCT, 13385 Marseille, France
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Bishop RE. Phospholipid transporter shifts into reverse. Nat Struct Mol Biol 2020; 28:8-10. [PMID: 33361785 DOI: 10.1038/s41594-020-00546-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Russell E Bishop
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada.
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