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Wang H, Ishchenko A, Skudlarek J, Shen P, Dzhekieva L, Painter RE, Chen YT, Bukhtiyarova M, Leithead A, Tracy R, Babaoglu K, Bahnck-Teets C, Buevich A, Cabalu TD, Labroli M, Lange H, Lei Y, Li W, Liu J, Mann PA, Meng T, Mitchell HJ, Mulhearn J, Scapin G, Sha D, Shaw AW, Si Q, Tong L, Wu C, Wu Z, Xiao JC, Xu M, Zhang LK, McKenney D, Miller RR, Black TA, Cooke A, Balibar CJ, Klein DJ, Raheem I, Walker SS. Cerastecins inhibit membrane lipooligosaccharide transport in drug-resistant Acinetobacter baumannii. Nat Microbiol 2024; 9:1244-1255. [PMID: 38649414 DOI: 10.1038/s41564-024-01667-0] [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: 11/22/2023] [Accepted: 03/06/2024] [Indexed: 04/25/2024]
Abstract
Carbapenem-resistant Acinetobacter baumannii infections have limited treatment options. Synthesis, transport and placement of lipopolysaccharide or lipooligosaccharide (LOS) in the outer membrane of Gram-negative bacteria are important for bacterial virulence and survival. Here we describe the cerastecins, inhibitors of the A. baumannii transporter MsbA, an LOS flippase. These molecules are potent and bactericidal against A. baumannii, including clinical carbapenem-resistant Acinetobacter baumannii isolates. Using cryo-electron microscopy and biochemical analysis, we show that the cerastecins adopt a serpentine configuration in the central vault of the MsbA dimer, stalling the enzyme and uncoupling ATP hydrolysis from substrate flipping. A derivative with optimized potency and pharmacokinetic properties showed efficacy in murine models of bloodstream or pulmonary A. baumannii infection. While resistance development is inevitable, targeting a clinically unexploited mechanism avoids existing antibiotic resistance mechanisms. Although clinical validation of LOS transport remains undetermined, the cerastecins may open a path to narrow-spectrum treatment modalities for important nosocomial infections.
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Affiliation(s)
- Hao Wang
- Merck & Co., Inc., West Point, PA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Ying Lei
- Merck & Co., Inc., West Point, PA, USA
| | - Wei Li
- Merck & Co., Inc., West Point, PA, USA
| | - Jian Liu
- Merck & Co., Inc., West Point, PA, USA
| | | | - Tao Meng
- Merck & Co., Inc., Rahway, NJ, USA
| | | | | | | | - Deyou Sha
- Merck & Co., Inc., West Point, PA, USA
| | | | - Qian Si
- Merck & Co., Inc., West Point, PA, USA
| | - Ling Tong
- Merck & Co., Inc., West Point, PA, USA
| | | | - Zhe Wu
- Merck & Co., Inc., West Point, PA, USA
| | | | - Min Xu
- Merck & Co., Inc., West Point, PA, USA
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2
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Yoon Y, Song S. Structural Insights into the Lipopolysaccharide Transport (Lpt) System as a Novel Antibiotic Target. J Microbiol 2024; 62:261-275. [PMID: 38816673 DOI: 10.1007/s12275-024-00137-w] [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: 03/19/2024] [Revised: 04/15/2024] [Accepted: 04/15/2024] [Indexed: 06/01/2024]
Abstract
Lipopolysaccharide (LPS) is a critical component of the extracellular leaflet within the bacterial outer membrane, forming an effective physical barrier against environmental threats in Gram-negative bacteria. After LPS is synthesized and matured in the bacterial cytoplasm and the inner membrane (IM), LPS is inserted into the outer membrane (OM) through the ATP-driven LPS transport (Lpt) pathway, which is an energy-intensive process. A trans-envelope complex that contains seven Lpt proteins (LptA-LptG) is crucial for extracting LPS from the IM and transporting it across the periplasm to the OM. The last step in LPS transport involves the mediation of the LptDE complex, facilitating the insertion of LPS into the outer leaflet of the OM. As the Lpt system plays an essential role in maintaining the impermeability of the OM via LPS decoration, the interactions between these interconnected subunits, which are meticulously regulated, may be potential targets for the development of new antibiotics to combat multidrug-resistant Gram-negative bacteria. In this review, we aimed to provide an overview of current research concerning the structural interactions within the Lpt system and their implications to clarify the function and regulation of LPS transport in the overall process of OM biogenesis. Additionally, we explored studies on the development of therapeutic inhibitors of LPS transport, the factors that limit success, and future prospects.
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Affiliation(s)
- Yurim Yoon
- Infectious Diseases Therapeutic Research Center, Korea Research Institute of Chemical Technology, Daejeon, 34114, Republic of Korea
| | - Saemee Song
- Infectious Diseases Therapeutic Research Center, Korea Research Institute of Chemical Technology, Daejeon, 34114, Republic of Korea.
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3
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VanOtterloo LM, Macias LA, Powers MJ, Brodbelt JS, Trent MS. Characterization of Acinetobacter baumannii core oligosaccharide synthesis reveals novel aspects of lipooligosaccharide assembly. mBio 2024; 15:e0301323. [PMID: 38349180 PMCID: PMC10936431 DOI: 10.1128/mbio.03013-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 01/12/2024] [Indexed: 03/14/2024] Open
Abstract
A fundamental feature of Gram-negative bacteria is their outer membrane that protects the cell against environmental stressors. This defense is predominantly due to its asymmetry, with glycerophospholipids located in the inner leaflet and lipopolysaccharide (LPS) or lipooligosaccharide (LOS) confined to the outer leaflet. LPS consists of a lipid A anchor, a core oligosaccharide, and a distal O-antigen while LOS lacks O-antigen. While LPS/LOS is typically essential for growth, this is not the case for Acinetobacter baumannii. Despite this unique property, the synthesis of the core oligosaccharide of A. baumannii LOS is not well-described. Here, we characterized the LOS chemotypes of A. baumannii strains with mutations in a predicted core oligosaccharide locus via tandem mass spectrometry. This allowed for an extensive identification of genes required for core assembly that can be exploited to generate precise structural LOS modifications in many A. baumannii strains. We further investigated two chemotypically identical yet phenotypically distinct mutants, ∆2903 and ∆lpsB, that exposed a possible link between LOS and the peptidoglycan cell wall-two cell envelope components whose coordination has not yet been described in A. baumannii. Selective reconstruction of the core oligosaccharide via expression of 2903 and LpsB revealed that these proteins rely on each other for the unusual tandem transfer of two residues, KdoIII and N-acetylglucosaminuronic acid. The data presented not only allow for better usage of A. baumannii as a tool to study outer membrane integrity but also provide further evidence for a novel mechanism of core oligosaccharide assembly. IMPORTANCE Acinetobacter baumannii is a multidrug-resistant pathogen that produces lipooligosaccharide (LOS), a glycolipid that confers protective asymmetry to the bacterial outer membrane. The core oligosaccharide is a ubiquitous component of LOS that typically follows a well-established model of synthesis. In addition to providing an extensive analysis of the genes involved in the synthesis of the core region, we demonstrate that this organism has evidently diverged from the long-held archetype of core synthesis. Moreover, our data suggest that A. baumannii LOS assembly is important for cell division and likely intersects with the synthesis of the peptidoglycan cell wall, another essential component of the Gram-negative cell envelope. This connection between LOS and cell wall synthesis provides an intriguing foundation for a unique method of outer membrane biogenesis and cell envelope coordination.
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Affiliation(s)
- Leah M. VanOtterloo
- Department of Microbiology, College of Art and Sciences, University of Georgia, Athens, Georgia, USA
| | - Luis A. Macias
- Department of Chemistry, University of Texas at Austin, Austin, Texas, USA
| | - Matthew J. Powers
- Department of Microbiology, College of Art and Sciences, University of Georgia, Athens, Georgia, USA
| | | | - M. Stephen Trent
- Department of Microbiology, College of Art and Sciences, University of Georgia, Athens, Georgia, USA
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
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4
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Zahid A, Wilson JC, Grice ID, Peak IR. Otitis media: recent advances in otitis media vaccine development and model systems. Front Microbiol 2024; 15:1345027. [PMID: 38328427 PMCID: PMC10847372 DOI: 10.3389/fmicb.2024.1345027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 01/08/2024] [Indexed: 02/09/2024] Open
Abstract
Otitis media is an inflammatory disorder of the middle ear caused by airways-associated bacterial or viral infections. It is one of the most common childhood infections as globally more than 80% of children are diagnosed with acute otitis media by 3 years of age and it is a common reason for doctor's visits, antibiotics prescriptions, and surgery among children. Otitis media is a multifactorial disease with various genetic, immunologic, infectious, and environmental factors predisposing children to develop ear infections. Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are the most common culprits responsible for acute otitis media. Despite the massive global disease burden, the pathogenesis of otitis media is still unclear and requires extensive future research. Antibiotics are the preferred treatment to cure middle ear infections, however, the antimicrobial resistance rate of common middle ear pathogens has increased considerably over the years. At present, pneumococcal and influenza vaccines are administered as a preventive measure against otitis media, nevertheless, these vaccines are only beneficial in preventing carriage and/or disease caused by vaccine serotypes. Otitis media caused by non-vaccine serotype pneumococci, non-typeable H. influenza, and M. catarrhalis remain an important healthcare burden. The development of multi-species vaccines is an arduous process but is required to reduce the global burden of this disease. Many novel vaccines against S. pneumoniae, non-typeable H. influenza, and M. catarrhalis are in preclinical trials. It is anticipated that these vaccines will lower the disease burden and provide better protection against otitis media. To study disease pathology the rat, mouse, and chinchilla are commonly used to induce experimental acute otitis media to test new therapeutics, including antibiotics and vaccines. Each of these models has its advantages and disadvantages, yet there is still a need to develop an improved animal model providing a better correlated mechanistic understanding of human middle ear infections, thereby underpinning the development of more effective otitis media therapeutics. This review provides an updated summary of current vaccines against otitis media, various animal models of otitis media, their limitations, and some future insights in this field providing a springboard in the development of new animal models and novel vaccines for otitis media.
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Affiliation(s)
- Ayesha Zahid
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
| | - Jennifer C. Wilson
- School of Pharmacy and Medical Science, Griffith University, Gold Coast, QLD, Australia
| | - I. Darren Grice
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
- School of Pharmacy and Medical Science, Griffith University, Gold Coast, QLD, Australia
| | - Ian R. Peak
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
- School of Pharmacy and Medical Science, Griffith University, Gold Coast, QLD, Australia
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5
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Shi J, Cheng J, Liu S, Zhu Y, Zhu M. Acinetobacter baumannii: an evolving and cunning opponent. Front Microbiol 2024; 15:1332108. [PMID: 38318341 PMCID: PMC10838990 DOI: 10.3389/fmicb.2024.1332108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 01/08/2024] [Indexed: 02/07/2024] Open
Abstract
Acinetobacter baumannii is one of the most common multidrug-resistant pathogens causing nosocomial infections. The prevalence of multidrug-resistant A. baumannii infections is increasing because of several factors, including unregulated antibiotic use. A. baumannii drug resistance rate is high; in particular, its resistance rates for tigecycline and polymyxin-the drugs of last resort for extensively drug-resistant A. baumannii-has been increasing annually. Patients with a severe infection of extensively antibiotic-resistant A. baumannii demonstrate a high mortality rate along with a poor prognosis, which makes treating them challenging. Through carbapenem enzyme production and other relevant mechanisms, A. baumannii has rapidly acquired a strong resistance to carbapenem antibiotics-once considered a class of strong antibacterials for A. baumannii infection treatment. Therefore, understanding the resistance mechanism of A. baumannii is particularly crucial. This review summarizes mechanisms underlying common antimicrobial resistance in A. baumannii, particularly those underlying tigecycline and polymyxin resistance. This review will serve as a reference for reasonable antibiotic use at clinics, as well as new antibiotic development.
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Affiliation(s)
- Jingchao Shi
- Open Laboratory Medicine, Hangzhou Xixi Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
- Department of Clinical Laboratory, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua, China
- Graduate School, Zhejiang Chinese Medical University, Hangzhou, China
| | - Jianghao Cheng
- Open Laboratory Medicine, Hangzhou Xixi Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
| | - Shourong Liu
- Department of Infectious Disease, Hangzhou Xixi Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
| | - Yufeng Zhu
- Open Laboratory Medicine, Hangzhou Xixi Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
| | - Mingli Zhu
- Open Laboratory Medicine, Hangzhou Xixi Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
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6
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Storek KM, Sun D, Rutherford ST. Inhibitors targeting BamA in gram-negative bacteria. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119609. [PMID: 37852326 DOI: 10.1016/j.bbamcr.2023.119609] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/08/2023] [Accepted: 09/19/2023] [Indexed: 10/20/2023]
Abstract
Antibiotic resistance has led to an increase in the number of patient hospitalizations and deaths. The situation for gram-negative bacteria is especially dire as the last new class of antibiotics active against these bacteria was introduced to the clinic over 60 years ago, thus there is an immediate unmet need for new antibiotic classes able to overcome resistance. The outer membrane, a unique and essential structure in gram-negative bacteria, contains multiple potential antibacterial targets including BamA, an outer membrane protein that folds and inserts transmembrane β-barrel proteins. BamA is essential and conserved, and its outer membrane location eliminates a barrier that molecules must overcome to access this target. Recently, antibacterial small molecules, natural products, peptides, and antibodies that inhibit BamA activity have been reported, validating the druggability of this target and generating potential leads for antibiotic development. This review will describe these BamA inhibitors, highlight their key attributes, and identify challenges with this potential target.
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Affiliation(s)
- Kelly M Storek
- Department of Infectious Diseases, Genentech Inc., South San Francisco, CA, USA
| | - Dawei Sun
- Department of Structural Biology, Genentech Inc., South San Francisco, CA, USA
| | - Steven T Rutherford
- Department of Infectious Diseases, Genentech Inc., South San Francisco, CA, USA.
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7
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Zhang D, Jiang Y, Dong Y, Fu L, Zhuang L, Wu K, Dou X, Xu B, Wang C, Gong J. siRNA targeting Atp5a1 gene encoding ATPase α, the ligand of Peg fimbriae, reduced Salmonella Enteritidis adhesion. Avian Pathol 2023; 52:412-419. [PMID: 37526573 DOI: 10.1080/03079457.2023.2243842] [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: 04/26/2023] [Revised: 07/20/2023] [Accepted: 07/31/2023] [Indexed: 08/02/2023]
Abstract
Salmonella enterica serovar Enteritidis (S. Enteritidis) is a zoonotic pathogen that can infect both humans and animals. Among the 13 types of fimbrial operons in S. Enteritidis, the highly conserved Peg fimbriae play a crucial role in the adhesion and invasion of S. Enteritidis into host cells but are not well studied. In this study, we identified the ATP synthase subunit alpha (ATPase α) as a ligand of Peg fimbriae using ligand blotting and mass spectrometry techniques. We confirmed the in vitro binding of ATPase α to the purified adhesion protein (PegD). Furthermore, we used siRNA to suppress the expression of ATPase α gene Atp5a1 in Leghorn male hepatoma (LMH) cells, which resulted in a significant reduction in the adhesion rate of S. Enteritidis to the cells (P < 0.05). The findings in this study provide insight into the mechanism of S. Enteritidis infection through Peg fimbriae and highlight the importance of ATPase α in the adhesion process.RESEARCH HIGHLIGHTS Ligand blotting was performed to screen the ligand of S. Enteritidis Peg fimbriae.Binding assay confirmed that ATPase α is the ligand of the Peg fimbriae.siRNA targeting ATPase α gene (Atp5a1) significantly reduced S. Enteritidis adhesion.
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Affiliation(s)
- Di Zhang
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, People's Republic of China
| | - Yi Jiang
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, People's Republic of China
| | - Yongyi Dong
- Jiangsu Animal Disease Prevention and Control Center, Nanjing, People's Republic of China
| | - Lixia Fu
- College of Animal Science and Technology, Yangzhou University, Yangzhou, People's Republic of China
| | - Linlin Zhuang
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, People's Republic of China
| | - Kun Wu
- Jiangsu Animal Disease Prevention and Control Center, Nanjing, People's Republic of China
| | - Xinhong Dou
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, People's Republic of China
| | - Bu Xu
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, People's Republic of China
| | - Chengming Wang
- Department of Pathobiology, Auburn University College of Veterinary Medicine, Auburn, AL, USA
| | - Jiansen Gong
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, People's Republic of China
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8
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Dhakephalkar T, Stukey G, Guan Z, Carman GM, Klein EA. Characterization of an evolutionarily distinct bacterial ceramide kinase from Caulobacter crescentus. J Biol Chem 2023:104894. [PMID: 37286040 PMCID: PMC10331486 DOI: 10.1016/j.jbc.2023.104894] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 05/27/2023] [Accepted: 06/01/2023] [Indexed: 06/09/2023] Open
Abstract
A common feature among nearly all Gram-negative bacteria is the requirement for lipopolysaccharide (LPS) in the outer leaflet of the outer membrane. LPS provides structural integrity to the bacterial membrane which aids bacteria in maintaining their shape and acts as a barrier from environmental stress and harmful substances such as detergents and antibiotics. Recent work has demonstrated that Caulobacter crescentus can survive without LPS due to the presence of the anionic sphingolipid ceramide-phosphoglycerate. Based on genetic evidence, we predicted that protein CpgB functions as a ceramide kinase and performs the first step in generating the phosphoglycerate head group. Here, we characterized the kinase activity of recombinantly expressed CpgB and demonstrated that it can phosphorylate ceramide to form ceramide 1-phosphate. The pH optimum for CpgB was 7.5, and the enzyme required Mg2+ as a cofactor. Mn2+, but not other divalent cations, could substitute for Mg2+. Under these conditions, the enzyme exhibited typical Michaelis-Menten kinetics with respect to NBD-C6-ceramide (Km,app=19.2 ± 5.5 μM; Vmax,app=2590 ± 230 pmol/min/mg enzyme) and ATP (Km,app=0.29 ± 0.07 mM; Vmax,app=10100 ± 996 pmol/min/mg enzyme). Phylogenetic analysis of CpgB revealed that CpgB belongs to a new class of ceramide kinases which is distinct from its eukaryotic counterpart; furthermore, the pharmacological inhibitor of human ceramide kinase (NVP-231) had no effect on CpgB. The characterization of a new bacterial ceramide kinase opens avenues for understanding the structure and function of the various microbial phosphorylated sphingolipids.
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Affiliation(s)
| | - Geordan Stukey
- Department of Food Science, Rutgers University, New Brunswick, NJ 08901, USA; Rutgers Center for Lipid Research, New Jersey Institute for Food Nutrition and Health, Rutgers University, New Brunswick, NJ 08901, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - George M Carman
- Department of Food Science, Rutgers University, New Brunswick, NJ 08901, USA; Rutgers Center for Lipid Research, New Jersey Institute for Food Nutrition and Health, Rutgers University, New Brunswick, NJ 08901, USA
| | - Eric A Klein
- Biology Department, Rutgers University-Camden, Camden, NJ 08102, USA; Department of Food Science, Rutgers University, New Brunswick, NJ 08901, USA; Rutgers Center for Lipid Research, New Jersey Institute for Food Nutrition and Health, Rutgers University, New Brunswick, NJ 08901, USA; Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ 08102, USA.
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9
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Dhakephalkar T, Stukey G, Guan Z, Carman GM, Klein EA. Characterization of an evolutionarily distinct bacterial ceramide kinase from Caulobacter crescentus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.01.538943. [PMID: 37205603 PMCID: PMC10187206 DOI: 10.1101/2023.05.01.538943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A common feature among nearly all Gram-negative bacteria is the requirement for lipopolysaccharide (LPS) in the outer leaflet of the outer membrane. LPS provides structural integrity to the bacterial membrane which aids bacteria in maintaining their shape and acts as a barrier from environmental stress and harmful substances such as detergents and antibiotics. Recent work has demonstrated that Caulobacter crescentus can survive without LPS due to the presence of the anionic sphingolipid ceramide-phosphoglycerate. Based on genetic evidence, we predicted that protein CpgB functions as a ceramide kinase and performs the first step in generating the phosphoglycerate head group. Here, we characterized the kinase activity of recombinantly expressed CpgB and demonstrated that it can phosphorylate ceramide to form ceramide 1-phosphate. The pH optimum for CpgB was 7.5, and the enzyme required Mg 2+ as a cofactor. Mn 2+ , but not other divalent cations, could substitute for Mg 2+ . Under these conditions, the enzyme exhibited typical Michaelis-Menten kinetics with respect to NBD-C6-ceramide (K m,app =19.2 ± 5.5 μM; V max,app =2586.29 ± 231.99 pmol/min/mg enzyme) and ATP (K m,app =0.29 ± 0.07 mM; V max,app =10067.57 ± 996.85 pmol/min/mg enzyme). Phylogenetic analysis of CpgB revealed that CpgB belongs to a new class of ceramide kinases which is distinct from its eukaryotic counterpart; furthermore, the pharmacological inhibitor of human ceramide kinase (NVP-231) had no effect on CpgB. The characterization of a new bacterial ceramide kinase opens avenues for understanding the structure and function of the various microbial phosphorylated sphingolipids.
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10
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Quan H, Gong X, Chen Q, Zheng F, Yu Y, Liu D, Wang W, Chu Y. Functional Characterization of a Novel SMR-Type Efflux Pump RanQ, Mediating Quaternary Ammonium Compound Resistance in Riemerella anatipestifer. Microorganisms 2023; 11:microorganisms11040907. [PMID: 37110330 PMCID: PMC10142375 DOI: 10.3390/microorganisms11040907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/28/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023] Open
Abstract
Riemerella anatipestifer (R. anatipestifer) is a multidrug-resistant bacterium and an important pathogen responsible for major economic losses in the duck industry. Our previous study revealed that the efflux pump is an important resistance mechanism of R. anatipestifer. Bioinformatics analysis indicated that the GE296_RS02355 gene (denoted here as RanQ), a putative small multidrug resistance (SMR)-type efflux pump, is highly conserved in R. anatipestifer strains and important for the multidrug resistance. In the present study, we characterized the GE296_RS02355 gene in R. anatipestifer strain LZ-01. First, the deletion strain RA-LZ01ΔGE296_RS02355 and complemented strain RA-LZ01cΔGE296_RS02355 were constructed. When compared with that of the wild-type (WT) strain RA-LZ01, the mutant strain ΔRanQ showed no significant influence on bacterial growth, virulence, invasion and adhesion, morphology biofilm formation ability, and glucose metabolism. In addition, the ΔRanQ mutant strain did not alter the drug resistance phenotype of the WT strain RA-LZ01 and displayed enhanced sensitivity toward structurally related quaternary ammonium compounds, such as benzalkonium chloride and methyl viologen, which show high efflux specificity and selectivity. This study may help elucidate the unprecedented biological functions of the SMR-type efflux pump in R. anatipestifer. Thus, if this determinant is horizontally transferred, it could cause the spread of quaternary ammonium compound resistance among bacterial species.
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Affiliation(s)
- Heng Quan
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
- State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
| | - Xiaowei Gong
- State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
| | - Qiwei Chen
- State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Correspondence: (Q.C.); (W.W.)
| | - Fuying Zheng
- State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
| | - Yongfeng Yu
- State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
| | - Donghui Liu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
- State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
| | - Wenhui Wang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
- Correspondence: (Q.C.); (W.W.)
| | - Yuefeng Chu
- State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
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11
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Enosi Tuipulotu D, Feng S, Pandey A, Zhao A, Ngo C, Mathur A, Lee J, Shen C, Fox D, Xue Y, Kay C, Kirkby M, Lo Pilato J, Kaakoush NO, Webb D, Rug M, Robertson AAB, Tessema MB, Pang S, Degrandi D, Pfeffer K, Augustyniak D, Blumenthal A, Miosge LA, Brüstle A, Yamamoto M, Reading PC, Burgio G, Man SM. Immunity against Moraxella catarrhalis requires guanylate-binding proteins and caspase-11-NLRP3 inflammasomes. EMBO J 2023; 42:e112558. [PMID: 36762431 PMCID: PMC10015372 DOI: 10.15252/embj.2022112558] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 01/17/2023] [Accepted: 01/19/2023] [Indexed: 02/11/2023] Open
Abstract
Moraxella catarrhalis is an important human respiratory pathogen and a major causative agent of otitis media and chronic obstructive pulmonary disease. Toll-like receptors contribute to, but cannot fully account for, the complexity of the immune response seen in M. catarrhalis infection. Using primary mouse bone marrow-derived macrophages to examine the host response to M. catarrhalis infection, our global transcriptomic and targeted cytokine analyses revealed activation of immune signalling pathways by both membrane-bound and cytosolic pattern-recognition receptors. We show that M. catarrhalis and its outer membrane vesicles or lipooligosaccharide (LOS) can activate the cytosolic innate immune sensor caspase-4/11, gasdermin-D-dependent pyroptosis, and the NLRP3 inflammasome in human and mouse macrophages. This pathway is initiated by type I interferon signalling and guanylate-binding proteins (GBPs). We also show that inflammasomes and GBPs, particularly GBP2, are required for the host defence against M. catarrhalis in mice. Overall, our results reveal an essential role for the interferon-inflammasome axis in cytosolic recognition and immunity against M. catarrhalis, providing new molecular targets that may be used to mitigate pathological inflammation triggered by this pathogen.
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Affiliation(s)
- Daniel Enosi Tuipulotu
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Shouya Feng
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Abhimanu Pandey
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Anyang Zhao
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Chinh Ngo
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Anukriti Mathur
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Jiwon Lee
- Centre for Advanced MicroscopyThe Australian National UniversityCanberraACTAustralia
| | - Cheng Shen
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Daniel Fox
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Yansong Xue
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Callum Kay
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Max Kirkby
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Jordan Lo Pilato
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | | | - Daryl Webb
- Centre for Advanced MicroscopyThe Australian National UniversityCanberraACTAustralia
| | - Melanie Rug
- Centre for Advanced MicroscopyThe Australian National UniversityCanberraACTAustralia
| | - Avril AB Robertson
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQLDAustralia
| | - Melkamu B Tessema
- Department of Microbiology and ImmunologyThe University of Melbourne, The Peter Doherty Institute for Infection and ImmunityMelbourneVICAustralia
| | - Stanley Pang
- Antimicrobial Resistance and Infectious Diseases (AMRID) Research LaboratoryMurdoch UniversityMurdochWAAustralia
- Department of Microbiology, PathWest Laboratory Medicine‐WAFiona Stanley HospitalMurdochWAAustralia
| | - Daniel Degrandi
- Institute of Medical Microbiology and Hospital HygieneHeinrich‐Heine‐University DüsseldorfDüsseldorfGermany
| | - Klaus Pfeffer
- Institute of Medical Microbiology and Hospital HygieneHeinrich‐Heine‐University DüsseldorfDüsseldorfGermany
| | - Daria Augustyniak
- Department of Pathogen Biology and Immunology, Faculty of Biological SciencesUniversity of WroclawWroclawPoland
| | - Antje Blumenthal
- Frazer InstituteThe University of QueenslandQLDBrisbaneAustralia
| | - Lisa A Miosge
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Anne Brüstle
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Masahiro Yamamoto
- Department of Immunoparasitology, Research Institute for Microbial DiseasesOsaka UniversityOsakaJapan
- Laboratory of Immunoparasitology, WPI Immunology Frontier Research CenterOsaka UniversityOsakaJapan
| | - Patrick C Reading
- Department of Microbiology and ImmunologyThe University of Melbourne, The Peter Doherty Institute for Infection and ImmunityMelbourneVICAustralia
- WHO Collaborating Centre for Reference and Research on InfluenzaVictorian Infectious Diseases Reference Laboratory, The Peter Doherty Institute for Infection and ImmunityMelbourneVICAustralia
| | - Gaetan Burgio
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Si Ming Man
- Division of Immunology and Infectious Disease, The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
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12
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Colistin Resistance in Acinetobacter baumannii: Molecular Mechanisms and Epidemiology. Antibiotics (Basel) 2023; 12:antibiotics12030516. [PMID: 36978383 PMCID: PMC10044110 DOI: 10.3390/antibiotics12030516] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/17/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Acinetobacter baumannii is recognized as a clinically significant pathogen causing a wide spectrum of nosocomial infections. Colistin was considered a last-resort antibiotic for the treatment of infections caused by multidrug-resistant A. baumannii. Since the reintroduction of colistin, a number of mechanisms of colistin resistance in A. baumannii have been reported, including complete loss of LPS by inactivation of the biosynthetic pathway, modifications of target LPS driven by the addition of phosphoethanolamine (PEtN) moieties to lipid A mediated by the chromosomal pmrCAB operon and eptA gene-encoded enzymes or plasmid-encoded mcr genes and efflux of colistin from the cell. In addition to resistance to colistin, widespread heteroresistance is another feature of A. baumannii that leads to colistin treatment failure. This review aims to present a critical assessment of relevant published (>50 experimental papers) up-to-date knowledge on the molecular mechanisms of colistin resistance in A. baumannii with a detailed review of implicated mutations and the global distribution of colistin-resistant strains.
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13
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Romano K, Hung D. Targeting LPS biosynthesis and transport in gram-negative bacteria in the era of multi-drug resistance. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119407. [PMID: 36543281 PMCID: PMC9922520 DOI: 10.1016/j.bbamcr.2022.119407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 11/09/2022] [Accepted: 11/18/2022] [Indexed: 12/23/2022]
Abstract
Gram-negative bacteria pose a major threat to human health in an era fraught with multi-drug resistant bacterial infections. Despite extensive drug discovery campaigns over the past decades, no new antibiotic target class effective against gram-negative bacteria has become available to patients since the advent of the carbapenems in 1985. Antibiotic discovery efforts against gram-negative bacteria have been hampered by limited intracellular accumulation of xenobiotics, in large part due to the impermeable cell envelope comprising lipopolysaccharide (LPS) in the outer leaflet of the outer membrane, as well as a panoply of efflux pumps. The biosynthesis and transport of LPS are essential to the viability and virulence of most gram-negative bacteria. Thus, both LPS biosynthesis and transport are attractive pathways to target therapeutically. In this review, we summarize the LPS biosynthesis and transport pathways and discuss efforts to find small molecule inhibitors against targets within these pathways.
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Affiliation(s)
- K.P. Romano
- Division of Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital, Boston, MA, USA,The Broad Institute of MIT and Harvard, Cambridge, MA, USA,Department of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, MA, USA
| | - D.T. Hung
- The Broad Institute of MIT and Harvard, Cambridge, MA, USA,Department of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, MA, USA,Department of Genetics, Harvard Medical School, Boston, MA, USA,Corresponding author at: The Broad Institute of MIT and Harvard, Cambridge, MA, USA. (D.T. Hung)
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14
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Sperandeo P, Martorana AM, Zaccaria M, Polissi A. Targeting the LPS export pathway for the development of novel therapeutics. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119406. [PMID: 36473551 DOI: 10.1016/j.bbamcr.2022.119406] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 10/14/2022] [Accepted: 11/01/2022] [Indexed: 12/12/2022]
Abstract
The rapid rise of multi-resistant bacteria is a global health threat. This is especially serious for Gram-negative bacteria in which the impermeable outer membrane (OM) acts as a shield against antibiotics. The development of new drugs with novel modes of actions to combat multi-drug resistant pathogens requires the selection of suitable processes to be targeted. The LPS export pathway is an excellent under exploited target for drug development. Indeed, LPS is the major determinant of the OM permeability barrier, and its biogenetic pathway is conserved in most Gram-negatives. Here we describe efforts to identify inhibitors of the multiprotein Lpt system that transports LPS to the cell surface. Despite none of these molecules has been approved for clinical use, they may represent valuable compounds for optimization. Finally, the recent discovery of a link between inhibition of LPS biogenesis and changes in peptidoglycan structure uncovers additional targets to develop novel therapeutic strategies.
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Affiliation(s)
- Paola Sperandeo
- Department of Pharmacological and Biomolecular Sciences, Via Balzaretti 9, 20133 Milano, Italy
| | - Alessandra M Martorana
- Department of Pharmacological and Biomolecular Sciences, Via Balzaretti 9, 20133 Milano, Italy
| | - Marta Zaccaria
- Department of Pharmacological and Biomolecular Sciences, Via Balzaretti 9, 20133 Milano, Italy
| | - Alessandra Polissi
- Department of Pharmacological and Biomolecular Sciences, Via Balzaretti 9, 20133 Milano, Italy.
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15
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Bjanes E, Zhou J, Qayum T, Krishnan N, Zurich RH, Menon ND, Hoffman A, Fang RH, Zhang L, Nizet V. Outer Membrane Vesicle-Coated Nanoparticle Vaccine Protects Against Acinetobacter baumannii Pneumonia and Sepsis. ADVANCED NANOBIOMED RESEARCH 2023; 3:2200130. [PMID: 37151210 PMCID: PMC10156090 DOI: 10.1002/anbr.202200130] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The highly multidrug-resistant (MDR) Gram-negative bacterial pathogen Acinetobacter baumannii is a top global health priority where an effective vaccine could protect susceptible populations and limit resistance acquisition. Outer membrane vesicles (OMVs) shed from Gram-negative bacteria are enriched with virulence factors and membrane lipids but heterogeneous in size and cargo. We report a vaccine platform combining precise and replicable nanoparticle technology with immunogenic A. baumannii OMVs (Ab-OMVs). Gold nanoparticle cores coated with Ab-OMVs (Ab-NPs) induced robust IgG titers in rabbits that enhanced human neutrophil opsonophagocytic killing and passively protected against lethal A. baumannii sepsis in mice. Active Ab-NP immunization in mice protected against sepsis and pneumonia, accompanied by B cell recruitment to draining lymph nodes, activation of dendritic cell markers, improved splenic neutrophil responses, and mitigation of proinflammatory cytokine storm. Nanoparticles are an efficient and efficacious platform for OMV vaccine delivery against A. baumannii and perhaps other high-priority MDR pathogens.
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Affiliation(s)
- Elisabet Bjanes
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California San Diego, La Jolla, California 92093, USA
| | - Jiarong Zhou
- Department of Nanoengineering, University of California San Diego, La Jolla, California 92093, USA
| | - Tariq Qayum
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California San Diego, La Jolla, California 92093, USA
| | - Nishta Krishnan
- Department of Nanoengineering, University of California San Diego, La Jolla, California 92093, USA
| | - Raymond H. Zurich
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California San Diego, La Jolla, California 92093, USA
| | - Nitasha D. Menon
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California San Diego, La Jolla, California 92093, USA
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kerala, India
| | - Alexandria Hoffman
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California San Diego, La Jolla, California 92093, USA
| | - Ronnie H. Fang
- Department of Nanoengineering, University of California San Diego, La Jolla, California 92093, USA
| | - Liangfang Zhang
- Department of Nanoengineering, University of California San Diego, La Jolla, California 92093, USA
| | - Victor Nizet
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California San Diego, La Jolla, California 92093, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093, USA
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16
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Ye C, Guo X, Wu J, Wang M, Ding H, Ren X. CCL20/CCR6 Mediated Macrophage Activation and Polarization Can Promote Adenoid Epithelial Inflammation in Adenoid Hypertrophy. J Inflamm Res 2022; 15:6843-6855. [PMID: 36583131 PMCID: PMC9793726 DOI: 10.2147/jir.s390210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
Background Adenoid hypertrophy (AH) is a chronic or acute obstruction-related ailment of the upper respiratory tract that arises as an inflammatory response to exposure of bacteria, viruses or allergies. Activation and polarization of macrophages are key processes in inflammation-related disorders like AH and CCL20/CCR6 axis is a critical therapeutic target. Purpose To determine that CCL20/CCR6 mediated macrophage activation and polarization can promote adenoid epithelial inflammation in AH. Methods To support this claim, CCL20 and CCR6 expressions were studied in clinical AH samples. In addition, the expressions of cytokines such as TNF-α, IL-1β, IL-6, IL-17, IL-10 and TGF-β were analysed. In vitro, human adenoid epithelial cells were co-cultured with polarized THP-1 and T lymphocyte H9 cells to study the expressions of several inflammatory markers. Results The expressions of M1 macrophage markers CD86 and IL-17 were significantly increased, whereas the expressions of M2 macrophage markers CD206 and FOXP3 were significantly decreased. The THP-1 cells were successfully polarized to M0, M1 and M2 macrophages. The survival of macrophages improved after 24 hr of induction and enhanced TGF-β expression was observed. The expressions of the inflammatory cytokines IL-6, TNF-α, IL-1β and CCL20 increased significantly. Conclusion Collectively, these results suggest that the CCL20/CCR6 mediated macrophage activation and polarization into M1-type macrophages can promote adenoid epithelial inflammation in AH. Further studies are warranted to determine the roles of inflammatory markers in the pathophysiology of AH and identifying potential targets.
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Affiliation(s)
- Chenchen Ye
- The First Clinical College, Nanjing University of Chinese Medicine, Nanjing, 210046, People’s Republic of China,Department of Pediatrics, Yixing Hospital of Traditional Chinese Medicine, Yixing, 214200, People’s Republic of China
| | - Xinxue Guo
- Department of Pediatrics, Yixing Hospital of Traditional Chinese Medicine, Yixing, 214200, People’s Republic of China
| | - Jiani Wu
- Department of Pediatrics, Yixing Hospital of Traditional Chinese Medicine, Yixing, 214200, People’s Republic of China
| | - Minhua Wang
- Department of Pediatrics, Yixing Hospital of Traditional Chinese Medicine, Yixing, 214200, People’s Republic of China
| | - Haiyan Ding
- Department of Pediatrics, Yixing Hospital of Traditional Chinese Medicine, Yixing, 214200, People’s Republic of China
| | - Xianzhi Ren
- The First Clinical College, Nanjing University of Chinese Medicine, Nanjing, 210046, People’s Republic of China,Department of Pediatrics, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, 210046, People’s Republic of China,Department of Pediatrics, Jiangsu Provincial Hospital of Traditional Chinese Medicine, Nanjing, 210046, People’s Republic of China,Correspondence: Xianzhi Ren, Department of Pediatrics, Jiangsu Provincial Hospital of Traditional Chinese Medicine, Nanjing, 210046, People’s Republic of China, Email
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17
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Kamoshida G, Yamada N, Nakamura T, Yamaguchi D, Kai D, Yamashita M, Hayashi C, Kanda N, Sakaguchi M, Morimoto H, Sawada T, Okada T, Kaya Y, Takemoto N, Yahiro K. Preferential Selection of Low-Frequency, Lipopolysaccharide-Modified, Colistin-Resistant Mutants with a Combination of Antimicrobials in Acinetobacter baumannii. Microbiol Spectr 2022; 10:e0192822. [PMID: 36173297 PMCID: PMC9602988 DOI: 10.1128/spectrum.01928-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 09/13/2022] [Indexed: 12/31/2022] Open
Abstract
Colistin, which targets lipopolysaccharide (LPS), is used as a last-resort drug against severe infections caused by drug-resistant Acinetobacter baumannii. However, A. baumannii possesses two colistin-resistance mechanisms. LPS modification caused by mutations in pmrAB genes is often observed in clinical isolates of multidrug-resistant Gram-negative pathogens. In addition to LPS modification, A. baumannii has a unique colistin resistance mechanism, a complete loss of LPS due to mutations in the lpxACD genes, which are involved in LPS biosynthesis. This study aimed to elucidate the detailed mechanism of the emergence of colistin-resistant A. baumannii using strains with the same genetic background. Various colistin-resistant strains were generated experimentally using colistin alone and in combination with other antimicrobials, such as meropenem and ciprofloxacin, and the mutation spectrum was analyzed. In vitro selection of A. baumannii in the presence of colistin led to the emergence of strains harboring mutations in lpxACD genes, resulting in LPS-deficient colistin-resistant strains. However, combination of colistin with other antimicrobials led to the selection of pmrAB mutant strains, resulting in strains with modified LPS (LPS-modified strains). Further, the LPS-deficient strains showed decreased fitness and increased susceptibility to many antibiotics and disinfectants. As LPS-deficient strains have a higher biological cost than LPS-modified strains, our findings suggested that pmrAB mutants are more likely to be isolated in clinical settings. We provide novel insights into the mechanisms of resistance to colistin and provide substantial solutions along with precautions for facilitating current research and treatment of colistin-resistant A. baumannii infections. IMPORTANCE Acinetobacter baumannii has developed resistance to various antimicrobial drugs, and its drug-resistant strains cause nosocomial infections. Controlling these infections has become a global clinical challenge. Carbapenem antibiotics are the frontline treatment drugs for infectious diseases caused by A. baumannii. For patients with infections caused by carbapenem-resistant A. baumannii, colistin-based therapy is often the only treatment option. However, A. baumannii readily acquires resistance to colistin. Many patients infected with colistin-resistant A. baumannii undergo colistin treatment before isolation of the colistin-resistant strain, and it is hypothesized that colistin resistance predominantly emerges under selective pressure during colistin therapy. Although the concomitant use of colistin and carbapenems has been reported to have a synergistic effect in vitro against carbapenem-resistant A. baumannii strains, our observations strongly suggest the need for attention to the emergence of strains with a modified lipopolysaccharide during treatment.
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Affiliation(s)
- Go Kamoshida
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Noriteru Yamada
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Tomoka Nakamura
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Daiki Yamaguchi
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Daichi Kai
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Maho Yamashita
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Chiaki Hayashi
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Nana Kanda
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Moe Sakaguchi
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Hitoshi Morimoto
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Teppei Sawada
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Tomoko Okada
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Yuki Kaya
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Norihiko Takemoto
- Pathogenic Microbe Laboratory, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Kinnosuke Yahiro
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
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18
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Gauthier AE, Rotjan RD, Kagan JC. Lipopolysaccharide detection by the innate immune system may be an uncommon defence strategy used in nature. Open Biol 2022; 12:220146. [PMID: 36196535 PMCID: PMC9533005 DOI: 10.1098/rsob.220146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 09/09/2022] [Indexed: 11/12/2022] Open
Abstract
Since the publication of the Janeway's Pattern Recognition hypothesis in 1989, study of pathogen-associated molecular patterns (PAMPs) and their immuno-stimulatory activities has accelerated. Most studies in this area have been conducted in model organisms, which leaves many open questions about the universality of PAMP biology across living systems. Mammals have evolved multiple proteins that operate as receptors for the PAMP lipopolysaccharide (LPS) from Gram-negative bacteria, but LPS is not immuno-stimulatory in all eukaryotes. In this review, we examine the history of LPS as a PAMP in mammals, recent data on LPS structure and its ability to activate mammalian innate immune receptors, and how these activities compare across commonly studied eukaryotes. We discuss why LPS may have evolved to be immuno-stimulatory in some eukaryotes but not others and propose two hypotheses about the evolution of PAMP structure based on the ecology and environmental context of the organism in question. Understanding PAMP structures and stimulatory mechanisms across multi-cellular life will provide insights into the evolutionary origins of innate immunity and may lead to the discovery of new PAMP variations of scientific and therapeutic interest.
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Affiliation(s)
- Anna E. Gauthier
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
- Program in Virology, Harvard Medical School, Boston, MA, USA
| | - Randi D. Rotjan
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Jonathan C. Kagan
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
- Harvard Medical School, and Boston Children's Hospital, Division of Immunology, Division of Gastroenterology, USA
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19
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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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20
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Zik JJ, Yoon SH, Guan Z, Stankeviciute Skidmore G, Gudoor RR, Davies KM, Deutschbauer AM, Goodlett DR, Klein EA, Ryan KR. Caulobacter lipid A is conditionally dispensable in the absence of fur and in the presence of anionic sphingolipids. Cell Rep 2022; 39:110888. [PMID: 35649364 PMCID: PMC9393093 DOI: 10.1016/j.celrep.2022.110888] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/29/2022] [Accepted: 05/06/2022] [Indexed: 01/12/2023] Open
Abstract
Lipid A, the membrane-anchored portion of lipopolysaccharide (LPS), is an essential component of the outer membrane (OM) of nearly all Gram-negative bacteria. Here we identify regulatory and structural factors that together render lipid A nonessential in Caulobacter crescentus. Mutations in the ferric uptake regulator fur allow Caulobacter to survive in the absence of either LpxC, which catalyzes an early step of lipid A synthesis, or CtpA, a tyrosine phosphatase homolog we find is needed for wild-type lipid A structure and abundance. Alterations in Fur-regulated processes, rather than iron status per se, underlie the ability to survive when lipid A synthesis is blocked. Fitness of lipid A-deficient Caulobacter requires an anionic sphingolipid, ceramide phosphoglycerate (CPG), which also mediates sensitivity to the antibiotic colistin. Our results demonstrate that, in an altered regulatory landscape, anionic sphingolipids can support the integrity of a lipid A-deficient OM. Lipid A, the membrane-anchoring segment of lipopolysaccharide, is generally considered to be an essential component of the Gram-negative bacterial outer membrane. Zik et al. show that deletion of the transcriptional regulator fur and synthesis of the anionic sphingolipid ceramide phosphoglycerate enable Caulobacter crescentus to survive without lipid A.
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Affiliation(s)
- Justin J Zik
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Sung Hwan Yoon
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Gabriele Stankeviciute Skidmore
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ 08102, USA; Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
| | - Ridhi R Gudoor
- Molecular Biosciences and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Karen M Davies
- Molecular Biosciences and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Adam M Deutschbauer
- Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - David R Goodlett
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA; Department of Biochemistry & Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada; University of Victoria-Genome BC Proteomics Centre, Victoria, BC V8Z 7X8, Canada
| | - Eric A Klein
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ 08102, USA; Biology Department, Rutgers University-Camden, Camden, NJ 08102, USA; Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
| | - Kathleen R Ryan
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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21
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Potential cannabidiol (CBD) repurposing as antibacterial and promising therapy of CBD plus polymyxin B (PB) against PB-resistant gram-negative bacilli. Sci Rep 2022; 12:6454. [PMID: 35440801 PMCID: PMC9018834 DOI: 10.1038/s41598-022-10393-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 03/04/2022] [Indexed: 01/24/2023] Open
Abstract
This study aimed to assess the ultrapure cannabidiol (CBD) antibacterial activity and to investigate the antibacterial activity of the combination CBD + polymyxin B (PB) against Gram-negative (GN) bacteria, including PB-resistant Gram-negative bacilli (GNB). We used the standard broth microdilution method, checkerboard assay, and time-kill assay. CBD exhibited antibacterial activity against Gram-positive bacteria, lipooligosaccharide (LOS)-expressing GN diplococcus (GND) (Neisseria gonorrhoeae, Neisseria meningitidis, Moraxella catarrhalis), and Mycobacterium tuberculosis, but not against GNB. For most of the GNB studied, our results showed that low concentrations of PB (≤ 2 µg/mL) allow CBD (≤ 4 µg/mL) to exert antibacterial activity against GNB (e.g., Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii), including PB-resistant GNB. CBD + PB also showed additive and/or synergistic effect against LOS-expressing GND. Time-kill assays results showed that the combination CBD + PB leads to a greater reduction in the number of colony forming units per milliliter compared to CBD and PB alone, at the same concentration used in combination, and the combination CBD + PB was synergistic for all four PB-resistant K. pneumoniae isolates evaluated. Our results show that CBD has translational potential and should be further explored as a repurposed antibacterial agent in clinical trials. The antibacterial efficacy of the combination CBD + PB against multidrug-resistant and extensively drug-resistant GNB, especially PB-resistant K. pneumoniae, is particularly promising.
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22
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Di Lorenzo F, Duda KA, Lanzetta R, Silipo A, De Castro C, Molinaro A. A Journey from Structure to Function of Bacterial Lipopolysaccharides. Chem Rev 2021; 122:15767-15821. [PMID: 34286971 DOI: 10.1021/acs.chemrev.0c01321] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Lipopolysaccharide (LPS) is a crucial constituent of the outer membrane of most Gram-negative bacteria, playing a fundamental role in the protection of bacteria from environmental stress factors, in drug resistance, in pathogenesis, and in symbiosis. During the last decades, LPS has been thoroughly dissected, and massive information on this fascinating biomolecule is now available. In this Review, we will give the reader a third millennium update of the current knowledge of LPS with key information on the inherent peculiar carbohydrate chemistry due to often puzzling sugar residues that are uniquely found on it. Then, we will drive the reader through the complex and multifarious immunological outcomes that any given LPS can raise, which is strictly dependent on its chemical structure. Further, we will argue about issues that still remain unresolved and that would represent the immediate future of LPS research. It is critical to address these points to complete our notions on LPS chemistry, functions, and roles, in turn leading to innovative ways to manipulate the processes involving such a still controversial and intriguing biomolecule.
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Affiliation(s)
- Flaviana Di Lorenzo
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy
| | - Katarzyna A Duda
- Research Center Borstel Leibniz Lung Center, Parkallee 4a, 23845 Borstel, Germany
| | - Rosa Lanzetta
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy
| | - Alba Silipo
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy
| | - Cristina De Castro
- Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Department of Agricultural Sciences, University of Naples Federico II, Via Università 96, 80055 Portici, Naples, Italy
| | - Antonio Molinaro
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Department of Chemistry, School of Science, Osaka University, 1-1 Osaka University Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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23
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Guest RL, Rutherford ST, Silhavy TJ. Border Control: Regulating LPS Biogenesis. Trends Microbiol 2021; 29:334-345. [PMID: 33036869 PMCID: PMC7969359 DOI: 10.1016/j.tim.2020.09.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/11/2020] [Accepted: 09/14/2020] [Indexed: 12/20/2022]
Abstract
The outer membrane (OM) is a defining feature of Gram-negative bacteria that serves as a permeability barrier and provides rigidity to the cell. Critical to OM function is establishing and maintaining an asymmetrical bilayer structure with phospholipids in the inner leaflet and the complex glycolipid lipopolysaccharide (LPS) in the outer leaflet. Cells ensure this asymmetry by regulating the biogenesis of lipid A, the conserved and essential anchor of LPS. Here we review the consequences of disrupting the regulatory components that control lipid A biogenesis, focusing on the rate-limiting step performed by LpxC. Dissection of these processes provides critical insights into bacterial physiology and potential new targets for antibiotics able to overcome rapidly spreading resistance mechanisms.
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Affiliation(s)
- Randi L Guest
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Steven T Rutherford
- Department of Infectious Diseases, Genentech Inc., South San Francisco, CA, USA
| | - Thomas J Silhavy
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
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24
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Tzani-Tzanopoulou P, Skliros D, Megremis S, Xepapadaki P, Andreakos E, Chanishvili N, Flemetakis E, Kaltsas G, Taka S, Lebessi E, Doudoulakakis A, Papadopoulos NG. Interactions of Bacteriophages and Bacteria at the Airway Mucosa: New Insights Into the Pathophysiology of Asthma. FRONTIERS IN ALLERGY 2021; 1:617240. [PMID: 35386933 PMCID: PMC8974763 DOI: 10.3389/falgy.2020.617240] [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: 10/14/2020] [Accepted: 12/29/2020] [Indexed: 12/16/2022] Open
Abstract
The airway epithelium is the primary site where inhaled and resident microbiota interacts between themselves and the host, potentially playing an important role on allergic asthma development and pathophysiology. With the advent of culture independent molecular techniques and high throughput technologies, the complex composition and diversity of bacterial communities of the airways has been well-documented and the notion of the lungs' sterility definitively rejected. Recent studies indicate that the microbial composition of the asthmatic airways across the spectrum of disease severity, differ significantly compared with healthy individuals. In parallel, a growing body of evidence suggests that bacterial viruses (bacteriophages or simply phages), regulating bacterial populations, are present in almost every niche of the human body and can also interact directly with the eukaryotic cells. The triptych of airway epithelial cells, bacterial symbionts and resident phages should be considered as a functional and interdependent unit with direct implications on the respiratory and overall homeostasis. While the role of epithelial cells in asthma pathophysiology is well-established, the tripartite interactions between epithelial cells, bacteria and phages should be scrutinized, both to better understand asthma as a system disorder and to explore potential interventions.
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Affiliation(s)
- Panagiota Tzani-Tzanopoulou
- Allergy and Clinical Immunology Unit, 2nd Pediatric Clinic, National and Kapodistrian University of Athens, Athens, Greece
| | - Dimitrios Skliros
- Laboratory of Molecular Biology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, Athens, Greece
| | - Spyridon Megremis
- Division of Evolution and Genomic Sciences, University of Manchester, Manchester, United Kingdom
| | - Paraskevi Xepapadaki
- Allergy and Clinical Immunology Unit, 2nd Pediatric Clinic, National and Kapodistrian University of Athens, Athens, Greece
| | - Evangelos Andreakos
- Center for Clinical, Experimental Surgery and Translational Research of the Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Nina Chanishvili
- Laboratory for Genetics of Microorganisms and Bacteriophages, Eliava Institute of Bacteriophage, Microbiology & Virology, Tbilisi, GA, United States
| | - Emmanouil Flemetakis
- Laboratory of Molecular Biology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, Athens, Greece
| | - Grigoris Kaltsas
- Department of Electrical and Electronic Engineering, University of West Attica, Athens, Greece
| | - Styliani Taka
- Allergy and Clinical Immunology Unit, 2nd Pediatric Clinic, National and Kapodistrian University of Athens, Athens, Greece
| | - Evangelia Lebessi
- Department of Microbiology, P. & A. Kyriakou Children's Hospital, Athens, Greece
| | | | - Nikolaos G Papadopoulos
- Allergy and Clinical Immunology Unit, 2nd Pediatric Clinic, National and Kapodistrian University of Athens, Athens, Greece.,Division of Evolution and Genomic Sciences, University of Manchester, Manchester, United Kingdom
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25
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Simpson BW, Trent MS. Pushing the envelope: LPS modifications and their consequences. Nat Rev Microbiol 2020; 17:403-416. [PMID: 31142822 DOI: 10.1038/s41579-019-0201-x] [Citation(s) in RCA: 236] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The defining feature of the Gram-negative cell envelope is the presence of two cellular membranes, with the specialized glycolipid lipopolysaccharide (LPS) exclusively found on the surface of the outer membrane. The surface layer of LPS contributes to the stringent permeability properties of the outer membrane, which is particularly resistant to permeation of many toxic compounds, including antibiotics. As a common surface antigen, LPS is recognized by host immune cells, which mount defences to clear pathogenic bacteria. To alter properties of the outer membrane or evade the host immune response, Gram-negative bacteria chemically modify LPS in a wide variety of ways. Here, we review key features and physiological consequences of LPS biogenesis and modifications.
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Affiliation(s)
- Brent W Simpson
- Department of Infectious Diseases, University of Georgia, Athens, GA, USA
| | - M Stephen Trent
- Department of Infectious Diseases, University of Georgia, Athens, GA, USA. .,Center for Vaccines and Immunology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA. .,Department of Microbiology, Franklin College of Arts and Sciences, University of Georgia, Athens, GA, USA.
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26
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Yan H, Ma D, Yang S, Ni Z, Fang W. Effluent lipopolysaccharide is a prompt marker of peritoneal dialysis-related gram-negative peritonitis. Perit Dial Int 2020; 40:455-461. [PMID: 32063187 DOI: 10.1177/0896860819896134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND To investigate the value of effluent lipopolysaccharide (LPS) for early detection of gram-negative peritonitis (GNP) in peritoneal dialysis (PD) patients. METHODS PD-related peritonitis episodes occurring between January 2016 and December 2018 were included in the study. Effluent LPS and the other infectious parameters were measured at peritonitis presentation, and peritonitis was categorized as GNP, non-GNP, and culture-negative peritonitis. Receiver operating characteristic (ROC) analysis was employed to evaluate the efficacy of effluent LPS to distinguish GNP. RESULTS A total of 161 peritonitis episodes were analyzed, including 49 GNP episodes and 82 non-GNP episodes. In contrast with non-GNP, GNP presented with higher effluent leukocyte count (3236 (1497-6144) vs. 1904 (679-4071) cell mm-3, p = 0.008), increased effluent LPS (1.552 (0.502-2.500) vs. 0.016 (0.010-0.030) EU mL-1, p < 0.001), lower blood leukocyte count (9.95 ± 3.18 vs. 11.56 ± 4.37 × 109 L-1, p = 0.017), greater neutrophil predominance (87.1 ± 4.6% vs. 83.4 ± 7.7%, p = 0.001), and greater "procalcitonin" (PCT, 4.90 (2.20-12.60) vs. 1.00 (0.51-4.07) µg L-1, p < 0.001). It took 5.2 ± 3.1 h to report the results of effluent LPS. Effluent LPS cutoff value of >0.035 EU mL-1 showed an area under the ROC curve of 0.972 (95% CI 0.951-0.994, p < 0.001) in differentiating GNP from non-GNP with a sensitivity of 100% and a specificity of 80.5%, and its joint utilization with PCT further increased the specificity (91.4%) to discriminate GNP. CONCLUSIONS PD effluent LPS could be an applicable early marker of gram-negative organism-related peritonitis in PD patients.
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Affiliation(s)
- Hao Yan
- Department of Nephrology, Renji Hospital, School of Medicine, 71140Shanghai Jiaotong University, People's Republic of China.,Shanghai Center for Peritoneal Dialysis Research, People's Republic of China
| | - Dahua Ma
- Department of Nephrology, Renji Hospital, School of Medicine, 71140Shanghai Jiaotong University, People's Republic of China.,Shanghai Center for Peritoneal Dialysis Research, People's Republic of China
| | - Shuang Yang
- Department of Clinical Laboratory, Renji Hospital, School of Medicine, 71140Shanghai Jiaotong University, People's Republic of China
| | - Zhaohui Ni
- Department of Nephrology, Renji Hospital, School of Medicine, 71140Shanghai Jiaotong University, People's Republic of China.,Shanghai Center for Peritoneal Dialysis Research, People's Republic of China
| | - Wei Fang
- Department of Nephrology, Renji Hospital, School of Medicine, 71140Shanghai Jiaotong University, People's Republic of China.,Shanghai Center for Peritoneal Dialysis Research, People's Republic of China
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27
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MacNair CR, Tsai CN, Brown ED. Creative targeting of the Gram-negative outer membrane in antibiotic discovery. Ann N Y Acad Sci 2019; 1459:69-85. [PMID: 31762048 DOI: 10.1111/nyas.14280] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/30/2019] [Accepted: 10/31/2019] [Indexed: 12/13/2022]
Abstract
The rising threat of multidrug-resistant Gram-negative bacteria is exacerbated by the scarcity of new antibiotics in the development pipeline. Permeability through the outer membrane remains one of the leading hurdles in discovery efforts. However, the essentiality of a robust outer membrane makes itself an intriguing antimicrobial target. Herein, we review drug discovery efforts targeting the outer membrane and the prospective antimicrobial leads identified.
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Affiliation(s)
- Craig R MacNair
- Michael G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Caressa N Tsai
- Michael G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Eric D Brown
- Michael G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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28
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John CM, Feng D, Jarvis GA. Treatment of human challenge and MDR strains of Neisseria gonorrhoeae with LpxC inhibitors. J Antimicrob Chemother 2019; 73:2064-2071. [PMID: 29726994 DOI: 10.1093/jac/dky151] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 03/29/2018] [Indexed: 11/15/2022] Open
Abstract
Objectives Inhibitors of UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC), which catalyses the second step in the biosynthesis of lipid A, have been developed as potential antibiotics for Gram-negative infections. Our objectives were to determine the effect of LpxC inhibition on the in vitro survival and inflammatory potential of Neisseria gonorrhoeae. Methods Survival of four human challenge strains was determined after treatment with two LpxC inhibitors for 2 and 4 h. To confirm results from treatment and assess their anti-inflammatory effect, the expression of TNF-α by human THP-1 monocytic cells infected with bacteria in the presence of the LpxC inhibitors was quantified. Cytotoxicity of inhibitors for THP-1 cells was evaluated by release of lactate dehydrogenase. Survival of five MDR strains was determined after 2 h of treatment with an LpxC inhibitor and the effect of co-treatment on MICs of ceftriaxone and azithromycin was examined. Results The inhibitors had bactericidal activity against the four human challenge and five MDR strains with one compound exhibiting complete killing at ≥5 mg/L after either 2 or 4 h of treatment. Treatment of gonococci infecting THP-1 monocytic cells reduced the levels of TNF-α probably owing to reduced numbers of bacteria and a lower level of expression of lipooligosaccharide. Neither inhibitor exhibited cytotoxicity for THP-1 cells. The MIC of azithromycin was slightly lowered by sublethal treatment of two MDR strains with an LpxC inhibitor. Conclusions Our in vitro results demonstrated promising efficacy of LpxC inhibition of N. gonorrhoeae that warrants further investigation particularly owing to the rise in MDR gonorrhoea.
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Affiliation(s)
- Constance M John
- Center for Immunochemistry, Veterans Affairs Medical Center, 4150 Clement Street, San Francisco, CA, USA.,Department of Laboratory Medicine, University of California, San Francisco, CA, USA
| | - Dongxiao Feng
- Center for Immunochemistry, Veterans Affairs Medical Center, 4150 Clement Street, San Francisco, CA, USA
| | - Gary A Jarvis
- Center for Immunochemistry, Veterans Affairs Medical Center, 4150 Clement Street, San Francisco, CA, USA.,Department of Laboratory Medicine, University of California, San Francisco, CA, USA
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29
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Robust Suppression of Lipopolysaccharide Deficiency in Acinetobacter baumannii by Growth in Minimal Medium. J Bacteriol 2019; 201:JB.00420-19. [PMID: 31451545 DOI: 10.1128/jb.00420-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 08/19/2019] [Indexed: 12/12/2022] Open
Abstract
Lipopolysaccharide (LPS) is normally considered to be essential for viability in Gram-negative bacteria but can be removed in Acinetobacter baumannii Mutant cells lacking this component of the outer membrane show growth and morphological defects. Here, we report that growth rates equivalent to the wild type can be achieved simply by propagation in minimal medium. The loss of LPS requires that cells rely on phospholipids for both leaflets of the outer membrane. We show that growth rate in the absence of LPS is not limited by nutrient availability but by the rate of outer membrane biogenesis. We hypothesize that because cells grow more slowly, outer membrane synthesis ceases to be rate limiting in minimal medium.IMPORTANCE Gram-negative bacteria are defined by their asymmetric outer membrane that consists of phospholipids on the inner leaflet and lipopolysaccharide (LPS) in the outer leaflet. LPS is essential in all but a few Gram-negative species; the reason for this differential essentiality is not well understood. One species that can survive without LPS, Acinetobacter baumannii, shows characteristic growth and morphology phenotypes. We show that these phenotypes can be suppressed under conditions of slow growth and describe how LPS loss is connected to the growth defects. In addition to better defining the challenges A. baumannii cells face in the absence of LPS, we provide a new hypothesis that may explain the species-dependent conditional essentiality.
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30
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Sperandeo P, Polissi A, De Fabiani E. Fat Matters for Bugs: How Lipids and Lipid Modifications Make the Difference in Bacterial Life. EUR J LIPID SCI TECH 2019. [DOI: 10.1002/ejlt.201900204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Paola Sperandeo
- Dipartimento di Scienze Farmacologiche e BiomolecolariUniversità degli Studi di MilanoVia Balzaretti 920133MilanoItaly
| | - Alessandra Polissi
- Dipartimento di Scienze Farmacologiche e BiomolecolariUniversità degli Studi di MilanoVia Balzaretti 920133MilanoItaly
| | - Emma De Fabiani
- Dipartimento di Scienze Farmacologiche e BiomolecolariUniversità degli Studi di MilanoVia Balzaretti 920133MilanoItaly
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31
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Powers MJ, Herrera CM, Tucker AT, Davies BW, Trent MS. Isolation of Lipid Cell Envelope Components from Acinetobacter baumannii. Methods Mol Biol 2019; 1946:233-252. [PMID: 30798560 DOI: 10.1007/978-1-4939-9118-1_22] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
With the increasing occurrence of antibiotic resistance among Acinetobacter sp., the race is on for researchers to not only isolate resistant isolates but also utilize basic and applied microbiological techniques to study mechanisms of resistance. For many antibiotics, the limit of efficacy against Gram-negative bacteria is dependent on its ability to permeate the outer membrane and access its target. As such, it is critical that researchers be able to isolate and analyze the lipid components of the cell envelope from any number of Acinetobacter sp. that are either resistant or sensitive to antibiotics of interest. The following chapter provides in-depth protocols to confirm the presence or absence of lipooligosaccharide (LOS) in Acinetobacter sp., isolate lipid A, and glycerophospholipids and analyze them using qualitative (mass spectrometry) and semiquantitative (thin-layer chromatography) methods.
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Affiliation(s)
- Matthew J Powers
- Department of Microbiology, University of Georgia, Athens, GA, USA.,Department of Infectious Diseases, University of Georgia, Athens, GA, USA
| | - Carmen M Herrera
- Department of Infectious Diseases, University of Georgia, Athens, GA, USA
| | - Ashley T Tucker
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Bryan W Davies
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA.,Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA.,Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX, USA.,John Ring LaMontagne Center for Infectious Diseases, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA
| | - M Stephen Trent
- Department of Microbiology, University of Georgia, Athens, GA, USA. .,Department of Infectious Diseases, University of Georgia, Athens, GA, USA.
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32
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Dubourg G, Edouard S, Raoult D. Relationship between nasopharyngeal microbiota and patient's susceptibility to viral infection. Expert Rev Anti Infect Ther 2019; 17:437-447. [PMID: 31106653 DOI: 10.1080/14787210.2019.1621168] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Introduction: The burden of respiratory viral infections is a global public health concern with significant mortality, morbidity, and economic impact. While Koch's postulate led to considering only the etiological agent, numerous works have demonstrated that commensal microbes could contribute to both the susceptibility and the severity of these infections, in particular those of the nasopharynx. Areas covered: Herein, we first propose to briefly recall the historical background that led to considering microbes inhabiting the nasopharyngeal microbiota as a potential contributor to human viral infections. We describe the evolution of the normal nasopharyngeal microbiota composition over time, especially during the first year of life. We aimed to resume the changes of the nasopharyngeal microbiota during viral respiratory infections. We also develop how nasopharyngeal microbiota could contribute to the acquisition of respiratory viral infections. We finally provide the potential therapeutic perspectives deriving from these findings. Expert opinion: Prospective studies focusing on children have identified that nasopharyngeal microbiota composition is associated with predisposition to acute respiratory illness and bronchiolitis, while data are scarce regarding adults. For the latter, further works are needed, in particular as a part of the multi-OMICS approach that should probably be performed in conjunction with gut microbiota studies.
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Affiliation(s)
- Grégory Dubourg
- a IRD, Assistance Publique Hôpitaux de Marseille (APHM), Microbes, Evolution, Phylogeny and Infection (MEPHI) , Aix Marseille University , Marseille , France.,b IHU-Méditerranée Infection , Marseille , France
| | - Sophie Edouard
- a IRD, Assistance Publique Hôpitaux de Marseille (APHM), Microbes, Evolution, Phylogeny and Infection (MEPHI) , Aix Marseille University , Marseille , France.,b IHU-Méditerranée Infection , Marseille , France
| | - Didier Raoult
- a IRD, Assistance Publique Hôpitaux de Marseille (APHM), Microbes, Evolution, Phylogeny and Infection (MEPHI) , Aix Marseille University , Marseille , France.,b IHU-Méditerranée Infection , Marseille , France
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33
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Abstract
The cell envelope is the first line of defense between a bacterium and the world-at-large. Often, the initial steps that determine the outcome of chemical warfare, bacteriophage infections, and battles with other bacteria or the immune system greatly depend on the structure and composition of the bacterial cell surface. One of the most studied bacterial surface molecules is the glycolipid known as lipopolysaccharide (LPS), which is produced by most Gram-negative bacteria. Much of the initial attention LPS received in the early 1900s was owed to its ability to stimulate the immune system, for which the glycolipid was commonly known as endotoxin. It was later discovered that LPS also creates a permeability barrier at the cell surface and is a main contributor to the innate resistance that Gram-negative bacteria display against many antimicrobials. Not surprisingly, these important properties of LPS have driven a vast and still prolific body of literature for more than a hundred years. LPS research has also led to pioneering studies in bacterial envelope biogenesis and physiology, mostly using Escherichia coli and Salmonella as model systems. In this review, we will focus on the fundamental knowledge we have gained from studies of the complex structure of the LPS molecule and the biochemical pathways for its synthesis, as well as the transport of LPS across the bacterial envelope and its assembly at the cell surface.
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34
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Abstract
In Gram-negative bacteria, the outer membrane protects the cell against many toxic molecules, and the peptidoglycan layer provides protection against osmotic challenges, allowing bacterial cells to survive in changing environments. Maintaining cell envelope integrity is therefore a question of life or death for a bacterial cell. Here we show that Escherichia coli cells activate the LD-transpeptidase LdtD to introduce 3-3 cross-links in the peptidoglycan layer when the integrity of the outer membrane is compromised, and this response is required to avoid cell lysis. This peptidoglycan remodeling program is a strategy to increase the overall robustness of the bacterial cell envelope in response to defects in the outer membrane. Gram-negative bacteria have a tripartite cell envelope with the cytoplasmic membrane (CM), a stress-bearing peptidoglycan (PG) layer, and the asymmetric outer membrane (OM) containing lipopolysaccharide (LPS) in the outer leaflet. Cells must tightly coordinate the growth of their complex envelope to maintain cellular integrity and OM permeability barrier function. The biogenesis of PG and LPS relies on specialized macromolecular complexes that span the entire envelope. In this work, we show that Escherichia coli cells are capable of avoiding lysis when the transport of LPS to the OM is compromised, by utilizing LD-transpeptidases (LDTs) to generate 3-3 cross-links in the PG. This PG remodeling program relies mainly on the activities of the stress response LDT, LdtD, together with the major PG synthase PBP1B, its cognate activator LpoB, and the carboxypeptidase PBP6a. Our data support a model according to which these proteins cooperate to strengthen the PG in response to defective OM synthesis.
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35
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Abstract
Gram-negative bacteria have an outer membrane that is positioned at the frontline of the cell's interaction with the environment and that serves as a barrier against noxious molecules including many antibiotics. This protective function mainly relies on lipopolysaccharide, a complex glycolipid located in the outer leaflet of the outer membrane. In this chapter we will first summarize lipopolysaccharide structure, functions and biosynthetic pathway and then we will discuss how it is transported and assembled to the cell surface. This is a remarkably complex process, as amphipathic lipopolysaccharide molecules must traverse three different cellular compartments to reach their final destination.
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36
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Carretero-Ledesma M, García-Quintanilla M, Martín-Peña R, Pulido MR, Pachón J, McConnell MJ. Phenotypic changes associated with Colistin resistance due to Lipopolysaccharide loss in Acinetobacter baumannii. Virulence 2018; 9:930-942. [PMID: 29638177 PMCID: PMC5955468 DOI: 10.1080/21505594.2018.1460187] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Acinetobacter baumannii can acquire resistance to colistin via complete loss of lipopolysaccharide (LPS) biosynthesis due to mutations in the lpxA, lpxC and lpxD genes. However, although colistin is increasingly being used for the treatment of multidrug resistant infections, very few A. baumannii clinical isolates develop colistin resistance through loss of LPS biosynthesis. This may suggest that LPS loss affects virulence traits that play a role in the transmission and pathogenesis of A. baumannii. In this study we characterize multiple virulence phenotypes of colistin resistant, LPS-deficient derivatives of the ATCC 19606 strain and five multidrug resistant clinical isolates and their colistin resistant, LPS-deficient derivatives. Our results indicate that LPS loss results in growth defects compared to the parental strain in vitro both in laboratory media and human serum (competition indices of 0.58 and 7.0 × 10−7, respectively) and reduced ability to grow and disseminate in vivo (competition index 6.7 × 10−8). Infection with the LPS-deficient strain resulted in lower serum levels of pro-inflammatory cytokines TNF-α and IL-6 compared to the parent strain, and was less virulent in a mouse model of disseminated sepsis. LPS loss also significantly affected biofilm production, surface motility, growth under iron limitation and susceptibility to multiple disinfectants used in the clinical setting. These results demonstrate that LPS loss has a significant effect on multiple virulence traits, and may provide insight into the low incidence of colistin resistant strains lacking LPS that have been reported in the clinical setting.
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Affiliation(s)
- Marta Carretero-Ledesma
- a Clinical Unit of Infectious Diseases, Clinical Microbiology and Preventive Medicine; Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío/CSIC /University of Seville , Seville , Spain
| | - Meritxell García-Quintanilla
- a Clinical Unit of Infectious Diseases, Clinical Microbiology and Preventive Medicine; Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío/CSIC /University of Seville , Seville , Spain
| | - Reyes Martín-Peña
- a Clinical Unit of Infectious Diseases, Clinical Microbiology and Preventive Medicine; Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío/CSIC /University of Seville , Seville , Spain
| | - Marina R Pulido
- a Clinical Unit of Infectious Diseases, Clinical Microbiology and Preventive Medicine; Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío/CSIC /University of Seville , Seville , Spain
| | - Jerónimo Pachón
- a Clinical Unit of Infectious Diseases, Clinical Microbiology and Preventive Medicine; Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío/CSIC /University of Seville , Seville , Spain.,b Department of Medicine , University of Seville , Seville , Spain
| | - Michael J McConnell
- a Clinical Unit of Infectious Diseases, Clinical Microbiology and Preventive Medicine; Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío/CSIC /University of Seville , Seville , Spain
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37
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Phospholipid retention in the absence of asymmetry strengthens the outer membrane permeability barrier to last-resort antibiotics. Proc Natl Acad Sci U S A 2018; 115:E8518-E8527. [PMID: 30087182 DOI: 10.1073/pnas.1806714115] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The outer membrane of Gram-negative bacteria is a critical barrier that prevents entry of noxious compounds. Integral to this functionality is the presence of lipopolysaccharide (LPS) or lipooligosaccharide (LOS), a molecule that is located exclusively in the outer leaflet of the outer membrane. Its lipid anchor, lipid A, is a glycolipid whose hydrophobicity and net negative charge are primarily responsible for the robustness of the membrane. Because of this, lipid A is a hallmark of Gram-negative physiology and is generally essential for survival. Rare exceptions have been described, including Acinetobacter baumannii, which can survive in the absence of lipid A, albeit with significant growth and membrane permeability defects. Here, we show by an evolution experiment that LOS-deficient A. baumannii can rapidly improve fitness over the course of only 120 generations. We identified two factors which negatively contribute to fitness in the absence of LOS, Mla and PldA. These proteins are involved in glycerophospholipid transport (Mla) and lipid degradation (PldA); both are active only on mislocalized, surface-exposed glycerophospholipids. Elimination of these two mechanisms was sufficient to cause a drastic fitness improvement in LOS-deficient A. baumannii The LOS-deficient double mutant grows as robustly as LOS-positive wild-type bacteria while remaining resistant to the last-resort polymyxin antibiotics. These data provide strong biological evidence for the directionality of Mla-mediated glycerophospholipid transport in Gram-negative bacteria and furthers our knowledge of asymmetry-maintenance mechanisms in the context of the outer membrane barrier.
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38
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Wang T, Yu Y, Liang X, Luo S, He Z, Sun Z, Jiang Y, Omsland A, Zhou P, Song L. Lipid A Has Significance for Optimal Growth of Coxiella burnetii in Macrophage-Like THP-1 Cells and to a Lesser Extent in Axenic Media and Non-phagocytic Cells. Front Cell Infect Microbiol 2018; 8:192. [PMID: 29938202 PMCID: PMC6002510 DOI: 10.3389/fcimb.2018.00192] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 05/22/2018] [Indexed: 02/02/2023] Open
Abstract
Lipid A is an essential basal component of lipopolysaccharide of most Gram-negative bacteria. Inhibitors targeting LpxC, a conserved enzyme in lipid A biosynthesis, are antibiotic candidates against Gram-negative pathogens. Here we report the characterization of the role of lipid A in Coxiella burnetii growth in axenic media, monkey kidney cells (BGMK and Vero), and macrophage-like THP-1 cells by using a potent LpxC inhibitor -LPC-011. We first determined the susceptibility of C. burnetii LpxC to LPC-011 in a surrogate E. coli model. In E. coli, the minimum inhibitory concentration (MIC) of LPC-011 against C. burnetii LpxC is < 0.05 μg/mL, a value lower than the inhibitor's MIC against E. coli LpxC. Considering the inhibitor's problematic pharmacokinetic properties in vivo and Coxiella's culturing time up to 7 days, the stability of LPC-011 in cell cultures was assessed. We found that regularly changing inhibitor-containing media was required for sustained inhibition of C. burnetii LpxC in cells. Under inhibitor treatment, Coxiella has reduced growth yields in axenic media and during replication in non-phagocytic cells, and has a reduced number of productive vacuoles in such cells. Inhibiting lipid A biosynthesis in C. burnetii by the inhibitor was shown in a phase II strain transformed with chlamydial kdtA. This exogenous KdtA enzyme modifies Coxiella lipid A with an α-Kdo-(2 → 8)-α-Kdo epitope that can be detected by anti-chlamydia genus antibodies. In inhibitor-treated THP-1 cells, Coxiella shows severe growth defects characterized by poor vacuole formation and low growth yields. Coxiella progenies prepared from inhibitor-treated cells retain the capability of normally infecting all tested cells in the absence of the inhibitor, which suggests a dispensable role of lipid A for infection and early vacuole development. In conclusion, our data suggest that lipid A has significance for optimal development of Coxiella-containing vacuoles, and for robust multiplication of C. burnetii in macrophage-like THP-1 cells. Unlike many bacteria, C. burnetii replication in axenic media and non-phagocytic cells was less dependent on normal lipid A biosynthesis.
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Affiliation(s)
- Tao Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yonghui Yu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiaofei Liang
- Department of Chemistry, Duke University, Durham, NC, United States
| | - Shengdong Luo
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zemin He
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zhihui Sun
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yongqiang Jiang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Anders Omsland
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| | - Pei Zhou
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Lihua Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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39
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Cell-based screen for discovering lipopolysaccharide biogenesis inhibitors. Proc Natl Acad Sci U S A 2018; 115:6834-6839. [PMID: 29735709 DOI: 10.1073/pnas.1804670115] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
New drugs are needed to treat gram-negative bacterial infections. These bacteria are protected by an outer membrane which prevents many antibiotics from reaching their cellular targets. The outer leaflet of the outer membrane contains LPS, which is responsible for creating this permeability barrier. Interfering with LPS biogenesis affects bacterial viability. We developed a cell-based screen that identifies inhibitors of LPS biosynthesis and transport by exploiting the nonessentiality of this pathway in Acinetobacter We used this screen to find an inhibitor of MsbA, an ATP-dependent flippase that translocates LPS across the inner membrane. Treatment with the inhibitor caused mislocalization of LPS to the cell interior. The discovery of an MsbA inhibitor, which is universally conserved in all gram-negative bacteria, validates MsbA as an antibacterial target. Because our cell-based screen reports on the function of the entire LPS biogenesis pathway, it could be used to identify compounds that inhibit other targets in the pathway, which can provide insights into vulnerabilities of the gram-negative cell envelope.
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40
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Richie DL, Wang L, Chan H, De Pascale G, Six DA, Wei JR, Dean CR. A pathway-directed positive growth restoration assay to facilitate the discovery of lipid A and fatty acid biosynthesis inhibitors in Acinetobacter baumannii. PLoS One 2018; 13:e0193851. [PMID: 29505586 PMCID: PMC5837183 DOI: 10.1371/journal.pone.0193851] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Accepted: 02/19/2018] [Indexed: 11/19/2022] Open
Abstract
Acinetobacter baumannii ATCC 19606 can grow without lipooligosaccharide (LOS). Lack of LOS can result from disruption of the early lipid A biosynthetic pathway genes lpxA, lpxC or lpxD. Although LOS itself is not essential for growth of A. baumannii ATCC 19606, it was previously shown that depletion of the lipid A biosynthetic enzyme LpxK in cells inhibited growth due to the toxic accumulation of lipid A pathway intermediates. Growth of LpxK-depleted cells was restored by chemical inhibition of LOS biosynthesis using CHIR-090 (LpxC) and fatty acid biosynthesis using cerulenin (FabB/F) and pyridopyrimidine (acetyl-CoA-carboxylase). Here, we expand on this by showing that inhibition of enoyl-acyl carrier protein reductase (FabI), responsible for converting trans-2-enoyl-ACP into acyl-ACP during the fatty acid elongation cycle also restored growth during LpxK depletion. Inhibition of fatty acid biosynthesis during LpxK depletion rescued growth at 37°C, but not at 30°C, whereas rescue by LpxC inhibition was temperature independent. We exploited these observations to demonstrate proof of concept for a targeted medium-throughput growth restoration screening assay to identify small molecule inhibitors of LOS and fatty acid biosynthesis. The differential temperature dependence of fatty acid and LpxC inhibition provides a simple means by which to separate growth stimulating compounds by pathway. Targeted cell-based screening platforms such as this are important for faster identification of compounds inhibiting pathways of interest in antibacterial discovery for clinically relevant Gram-negative pathogens.
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Affiliation(s)
- Daryl L. Richie
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Lisha Wang
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Helen Chan
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Gianfranco De Pascale
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - David A. Six
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Jun-Rong Wei
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Charles R. Dean
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
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41
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Powers MJ, Trent MS. Expanding the paradigm for the outer membrane: Acinetobacter baumannii in the absence of endotoxin. Mol Microbiol 2017; 107:47-56. [PMID: 29114953 DOI: 10.1111/mmi.13872] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2017] [Indexed: 12/30/2022]
Abstract
Asymmetry in the outer membrane has long defined the cell envelope of Gram-negative bacteria. This asymmetry, with lipopolysaccharide (LPS) or lipooligosaccharide (LOS) exclusively in the outer leaflet of the membrane, establishes an impermeable barrier that protects the cell from a number of stressors in the environment. Work done over the past 5 years has shown that Acinetobacter baumannii has the remarkable capability to survive with inactivated production of lipid A biosynthesis and the absence of LOS in its outer membrane. The implications of LOS-deficient A. baumannii are far-reaching - from impacts on cell envelope biogenesis and maintenance, bacterial physiology, antibiotic resistance and virulence. This review examines recent work that has contributed to our understanding of LOS-deficiency and compares it to studies done on Neisseria meningitidis and Moraxella catarrhalis; the two other organisms with this capability.
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Affiliation(s)
- Matthew Joseph Powers
- Department of Infectious Diseases, University of Georgia, 510 DW Brooks Drive, Athens, GA 30602, USA.,Department of Microbiology, University of Georgia, Athens, GA, USA
| | - M Stephen Trent
- Department of Infectious Diseases, University of Georgia, 510 DW Brooks Drive, Athens, GA 30602, USA
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42
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Blakeway LV, Tan A, Peak IRA, Seib KL. Virulence determinants of Moraxella catarrhalis: distribution and considerations for vaccine development. MICROBIOLOGY-SGM 2017; 163:1371-1384. [PMID: 28893369 DOI: 10.1099/mic.0.000523] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Moraxella catarrhalis is a human-restricted opportunistic bacterial pathogen of the respiratory mucosa. It frequently colonizes the nasopharynx asymptomatically, but is also an important causative agent of otitis media (OM) in children, and plays a significant role in acute exacerbations of chronic obstructive pulmonary disease (COPD) in adults. As the current treatment options for M. catarrhalis infection in OM and exacerbations of COPD are often ineffective, the development of an efficacious vaccine is warranted. However, no vaccine candidates for M. catarrhalis have progressed to clinical trials, and information regarding the distribution of M. catarrhalis virulence factors and vaccine candidates is inconsistent in the literature. It is largely unknown if virulence is associated with particular strains or subpopulations of M. catarrhalis, or if differences in clinical manifestation can be attributed to the heterogeneous expression of specific M. catarrhalis virulence factors in the circulating population. Further investigation of the distribution of M. catarrhalis virulence factors in the context of carriage and disease is required so that vaccine development may be targeted at relevant antigens that are conserved among disease-causing strains. The challenge of determining which of the proposed M. catarrhalis virulence factors are relevant to human disease is amplified by the lack of a standardized M. catarrhalis typing system to facilitate direct comparisons of worldwide isolates. Here we summarize and evaluate proposed relationships between M. catarrhalis subpopulations and specific virulence factors in the context of colonization and disease, as well as the current methods used to infer these associations.
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Affiliation(s)
- Luke V Blakeway
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Aimee Tan
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Ian R A Peak
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia.,School of Medical Science, Griffith University, Gold Coast, Queensland, Australia
| | - Kate L Seib
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
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43
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Sperandeo P, Martorana AM, Polissi A. The lipopolysaccharide transport (Lpt) machinery: A nonconventional transporter for lipopolysaccharide assembly at the outer membrane of Gram-negative bacteria. J Biol Chem 2017; 292:17981-17990. [PMID: 28878019 DOI: 10.1074/jbc.r117.802512] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The outer membrane (OM) of Gram-negative is a unique lipid bilayer containing LPS in its outer leaflet. Because of the presence of amphipathic LPS molecules, the OM behaves as an effective permeability barrier that makes Gram-negative bacteria inherently resistant to many antibiotics. This review focuses on LPS biogenesis and discusses recent advances that have contributed to our understanding of how this complex molecule is transported across the cellular envelope and is assembled at the OM outer leaflet. Clearly, this knowledge represents an important platform for the development of novel therapeutic options to manage Gram-negative infections.
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Affiliation(s)
- Paola Sperandeo
- From the Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan and
| | - Alessandra M Martorana
- the Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milan, Italy
| | - Alessandra Polissi
- From the Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan and
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44
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El Hag M, Feng Z, Su Y, Wang X, Yassin A, Chen S, Peng D, Liu X. Contribution of the csgA and bcsA genes to Salmonella enterica serovar Pullorum biofilm formation and virulence. Avian Pathol 2017; 46:541-547. [PMID: 28470089 DOI: 10.1080/03079457.2017.1324198] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Salmonella biofilm formation is important to environmental stress resistance and virulence. However, the roles of the csgA and bcsA genes, which affect curli protein and cellulose production, respectively, in Salmonella enterica serovar Pullorum, are unknown. Here we constructed deletions in the csgA and bcsA genes in S. enterica serovar Pullorum strain S6702 and evaluated several aspects of biofilm formation and virulence. ΔcsgA showed decreased production of curli fimbriae, while ΔbcsA had reduced cellulose production. Both mutants had a reduced ability to form biofilms. ΔcsgA was reduced in adhesion and invasion to HeLa cells and exhibited decreased intracellular proliferation in HD11 macrophages. ΔbcsA exhibited increased proliferation in HD11 cells and replicated better in chicken spleens, as compared to the wild-type strain. ΔcsgA virulence was attenuated in assays involving oral challenge of one-day-old chickens.
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Affiliation(s)
- Muhanad El Hag
- a College of Veterinary Medicine , Yangzhou University , Yangzhou , People's Republic of China.,b Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses , Yangzhou , People' Republic of China.,c Jiangsu Research Centre of Engineering and Technology for Prevention and Control of Poultry Disease , Yangzhou , People' Republic of China.,d Faculty of Public and Environmental Health , University of Khartoum , Khartoum , Sudan
| | - Zheng Feng
- a College of Veterinary Medicine , Yangzhou University , Yangzhou , People's Republic of China.,b Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses , Yangzhou , People' Republic of China.,c Jiangsu Research Centre of Engineering and Technology for Prevention and Control of Poultry Disease , Yangzhou , People' Republic of China
| | - Yangyang Su
- a College of Veterinary Medicine , Yangzhou University , Yangzhou , People's Republic of China.,b Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses , Yangzhou , People' Republic of China.,c Jiangsu Research Centre of Engineering and Technology for Prevention and Control of Poultry Disease , Yangzhou , People' Republic of China
| | - Xiao Wang
- a College of Veterinary Medicine , Yangzhou University , Yangzhou , People's Republic of China.,b Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses , Yangzhou , People' Republic of China.,c Jiangsu Research Centre of Engineering and Technology for Prevention and Control of Poultry Disease , Yangzhou , People' Republic of China
| | - Afrah Yassin
- b Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses , Yangzhou , People' Republic of China.,d Faculty of Public and Environmental Health , University of Khartoum , Khartoum , Sudan
| | - Sujuan Chen
- a College of Veterinary Medicine , Yangzhou University , Yangzhou , People's Republic of China.,b Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses , Yangzhou , People' Republic of China.,c Jiangsu Research Centre of Engineering and Technology for Prevention and Control of Poultry Disease , Yangzhou , People' Republic of China
| | - Daxin Peng
- a College of Veterinary Medicine , Yangzhou University , Yangzhou , People's Republic of China.,b Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses , Yangzhou , People' Republic of China.,c Jiangsu Research Centre of Engineering and Technology for Prevention and Control of Poultry Disease , Yangzhou , People' Republic of China
| | - Xiufan Liu
- a College of Veterinary Medicine , Yangzhou University , Yangzhou , People's Republic of China.,b Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses , Yangzhou , People' Republic of China.,c Jiangsu Research Centre of Engineering and Technology for Prevention and Control of Poultry Disease , Yangzhou , People' Republic of China
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45
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Zhou P, Zhao J. Structure, inhibition, and regulation of essential lipid A enzymes. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:1424-1438. [PMID: 27940308 DOI: 10.1016/j.bbalip.2016.11.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/28/2016] [Accepted: 11/30/2016] [Indexed: 10/20/2022]
Abstract
The Raetz pathway of lipid A biosynthesis plays a vital role in the survival and fitness of Gram-negative bacteria. Research efforts in the past three decades have identified individual enzymes of the pathway and have provided a mechanistic understanding of the action and regulation of these enzymes at the molecular level. This article reviews the discovery, biochemical and structural characterization, and regulation of the essential lipid A enzymes, as well as continued efforts to develop novel antibiotics against Gram-negative pathogens by targeting lipid A biosynthesis. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.
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Affiliation(s)
- Pei Zhou
- Department of Biochemistry, Duke University Medical Center, Research Drive, DUMC 3711, Durham, NC 27710, USA.
| | - Jinshi Zhao
- Department of Biochemistry, Duke University Medical Center, Research Drive, DUMC 3711, Durham, NC 27710, USA
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46
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Employing Escherichia coli-derived outer membrane vesicles as an antigen delivery platform elicits protective immunity against Acinetobacter baumannii infection. Sci Rep 2016; 6:37242. [PMID: 27849050 PMCID: PMC5110958 DOI: 10.1038/srep37242] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 10/27/2016] [Indexed: 01/11/2023] Open
Abstract
Outer membrane vesicles (OMVs) have proven to be highly immunogenic and induced an immune response against bacterial infection in human clinics and animal models. We sought to investigate whether engineered OMVs can be a feasible antigen-delivery platform for efficiently inducing specific antibody responses. In this study, Omp22 (an outer membrane protein of A. baumannii) was displayed on E. coli DH5α-derived OMVs (Omp22-OMVs) using recombinant gene technology. The morphological features of Omp22-OMVs were similar to those of wild-type OMVs (wtOMVs). Immunization with Omp22-OMVs induced high titers of Omp22-specific antibodies. In a murine sepsis model, Omp22-OMV immunization significantly protected mice from lethal challenge with a clinically isolated A. baumannii strain, which was evidenced by the increased survival rate of the mice, the reduced bacterial burdens in the lung, spleen, liver, kidney, and blood, and the suppressed serum levels of inflammatory cytokines. In vitro opsonophagocytosis assays showed that antiserum collected from Omp22-OMV-immunized mice had bactericidal activity against clinical isolates, which was partly specific antibody-dependent. These results strongly indicated that engineered OMVs could display a whole heterologous protein (~22 kDa) on the surface and effectively induce specific antibody responses, and thus OMVs have the potential to be a feasible vaccine platform.
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47
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Zhou Y, Zhou J, Wang D, Gao Q, Mu X, Gao S, Liu X. Evaluation of ompA and pgtE genes in determining pathogenicity in Salmonella enterica serovar Enteritidis. Vet J 2016; 218:19-26. [PMID: 27938704 DOI: 10.1016/j.tvjl.2016.10.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 10/27/2016] [Accepted: 10/29/2016] [Indexed: 02/02/2023]
Abstract
Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) is a major causative agent of gastroenteritis in humans. This important food-borne pathogen also colonises the intestinal tracts of poultry and can spread systemically, especially in chickens. To identify the S. Enteritidis virulence genes involved in infection and colonisation of chickens, chromosomal deletion mutants of the ompA and pgtE genes, which encode essential components of omptins, were constructed. There were no significant differences between the wild-type and ompA and pgtE mutants in a series of in vitro assays, including an intracellular survival assay, survival in specific-pathogen-free (SPF) chicken serum, and in vitro competition assays. In contrast, in vivo competition assays revealed that ompA and pgtE mutants underwent attenuated growth in liver, cardiac blood, spleen, lung, and kidney compared to a wild-type strain (CVCC3378). When tested in SPF chickens, ompA or pgtE gene inactivation substantially reduced organ colonisation and delayed systemic infection compared with the wild-type strain. Colonisation was restored in S. Enteritidis mutants by reintroduction of the whole ompA or pgtE gene with the native promoters. The results of this study demonstrate that ompA and pgtE play an important role in the pathogenesis of S. Enteritidis and its ability to infect chickens.
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Affiliation(s)
- Y Zhou
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - J Zhou
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - D Wang
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Q Gao
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - X Mu
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - S Gao
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China.
| | - X Liu
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
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Sperandeo P, Martorana AM, Polissi A. Lipopolysaccharide biogenesis and transport at the outer membrane of Gram-negative bacteria. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:1451-1460. [PMID: 27760389 DOI: 10.1016/j.bbalip.2016.10.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/11/2016] [Accepted: 10/13/2016] [Indexed: 01/10/2023]
Abstract
The outer membrane (OM) of Gram-negative bacteria is an asymmetric lipid bilayer containing a unique glycolipid, lipopolysaccharide (LPS) in its outer leaflet. LPS molecules confer to the OM peculiar permeability barrier properties enabling Gram-negative bacteria to exclude many toxic compounds, including clinically useful antibiotics, and to survive harsh environments. Transport of LPS poses several problems to the cells due to the amphipatic nature of this molecule. In this review we summarize the current knowledge on the LPS transport machinery, discuss the challenges associated with this process and present the solutions that bacterial cells have evolved to address the problem of LPS transport and assembly at the cell surface. Finally, we discuss how knowledge on LPS biogenesis can be translated for the development of novel antimicrobial therapies. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.
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Affiliation(s)
- Paola Sperandeo
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy.
| | - Alessandra M Martorana
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Alessandra Polissi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy.
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A penicillin-binding protein inhibits selection of colistin-resistant, lipooligosaccharide-deficient Acinetobacter baumannii. Proc Natl Acad Sci U S A 2016; 113:E6228-E6237. [PMID: 27681618 DOI: 10.1073/pnas.1611594113] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Gram-negative bacterial outer membrane fortifies the cell against environmental toxins including antibiotics. Unique glycolipids called lipopolysaccharide/lipooligosaccharide (LPS/LOS) are enriched in the cell-surface monolayer of the outer membrane and promote antimicrobial resistance. Colistin, which targets the lipid A domain of LPS/LOS to lyse the cell, is the last-line treatment for multidrug-resistant Gram-negative infections. Lipid A is essential for the survival of most Gram-negative bacteria, but colistin-resistant Acinetobacter baumannii lacking lipid A were isolated after colistin exposure. Previously, strain ATCC 19606 was the only A. baumannii strain demonstrated to subsist without lipid A. Here, we show that other A. baumannii strains can also survive without lipid A, but some cannot, affording a unique model to study endotoxin essentiality. We assessed the capacity of 15 clinical A. baumannii isolates including 9 recent clinical isolates to develop colistin resistance through inactivation of the lipid A biosynthetic pathway, the products of which assemble the LOS precursor. Our investigation determined that expression of the well-conserved penicillin-binding protein (PBP) 1A, prevented LOS-deficient colony isolation. The glycosyltransferase activity of PBP1A, which aids in the polymerization of the peptidoglycan cell wall, was lethal to LOS-deficient A. baumannii Global transcriptomic analysis of a PBP1A-deficient mutant and four LOS-deficient A. baumannii strains showed a concomitant increase in transcription of lipoproteins and their transporters. Examination of the LOS-deficient A. baumannii cell surface demonstrated that specific lipoproteins were overexpressed and decorated the cell surface, potentially compensating for LOS removal. This work expands our knowledge of lipid A essentiality and elucidates a drug resistance mechanism.
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Richie DL, Takeoka KT, Bojkovic J, Metzger LE, Rath CM, Sawyer WS, Wei JR, Dean CR. Toxic Accumulation of LPS Pathway Intermediates Underlies the Requirement of LpxH for Growth of Acinetobacter baumannii ATCC 19606. PLoS One 2016; 11:e0160918. [PMID: 27526195 PMCID: PMC4985137 DOI: 10.1371/journal.pone.0160918] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 07/27/2016] [Indexed: 12/05/2022] Open
Abstract
The lipid A moiety of lipopolysaccharide (LPS) is the main constituent of the outer leaflet of the Gram-negative bacterial outer membrane (OM) and is essential in many Gram-negative pathogens. An exception is Acinetobacter baumannii ATCC 19606, where mutants lacking enzymes occurring early in lipid A biosynthesis (LpxA, LpxC or LpxD), and correspondingly lacking LPS, can grow. In contrast, we show here that LpxH, an enzyme that occurs downstream of LpxD in the lipid A biosynthetic pathway, is essential for growth in this strain. Multiple attempts to disrupt lpxH on the genome were unsuccessful, and when LpxH expression was controlled by an isopropyl β-d-1-thiogalactopyranoside (IPTG) inducible promoter, cell growth under typical laboratory conditions required IPTG induction. Mass spectrometry analysis of cells shifted from LpxH-induced to uninduced (and whose growth was correspondingly slowing as LpxH was depleted) showed a large cellular accumulation of UDP-2,3-diacyl-GlcN (substrate of LpxH), a C14:0(3-OH) acyl variant of the LpxD substrate (UDP-3-O-[(R)-3-OH-C14]-GlcN), and disaccharide 1-monophosphate (DSMP). Furthermore, the viable cell counts of the LpxH depleted cultures dropped modestly, and electron microscopy revealed clear defects at the cell (inner) membrane, suggesting lipid A intermediate accumulation was toxic. Consistent with this, blocking the synthesis of these intermediates by inhibition of the upstream LpxC enzyme using CHIR-090 abrogated the requirement for IPTG induction of LpxH. Taken together, these data indicate that LpxH is essential for growth in A. baumannii ATCC19606, because, unlike earlier pathway steps like LpxA or LpxC, blockage of LpxH causes accumulation of detergent-like pathway intermediates that prevents cell growth.
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Affiliation(s)
- Daryl L. Richie
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Kenneth T. Takeoka
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Jade Bojkovic
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Louis E. Metzger
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Christopher M. Rath
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - William S. Sawyer
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Jun-Rong Wei
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
| | - Charles R. Dean
- Novartis Institutes for BioMedical Research, Emeryville, CA, United States of America
- * E-mail:
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