1
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Loperena-Barber M, Elizalde-Bielsa A, Salvador-Bescós M, Ruiz-Rodríguez P, Pellegrini JM, Renau-Mínguez C, Lancaster R, Zúñiga-Ripa A, Iriarte M, Bengoechea JA, Coscollá M, Gorvel JP, Moriyón I, Conde-Álvarez R. "Phylogenomic insights into brucellaceae: The Pseudochrobactrum algeriensis case". INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2024; 123:105625. [PMID: 38906517 DOI: 10.1016/j.meegid.2024.105625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 06/17/2024] [Accepted: 06/17/2024] [Indexed: 06/23/2024]
Abstract
The genus Pseudochrobactrum encompasses free-living bacteria phylogenetically close to Ochrobactrum opportunistic pathogens and to Brucella, facultative intracellular parasites causing brucellosis, a worldwide-extended and grave zoonosis. Recently, Pseudochrobactrum strains were isolated from Brucella natural hosts on Brucella selective media, potentially causing diagnostic confusions. Strikingly, P. algeriensis was isolated from cattle lymph nodes, organs that are inimical to bacteria. Here, we analyse P. algeriensis potential virulence factors in comparison with Ochrobactrum and Brucella. Consistent with genomic analyses, Western-Blot analyses confirmed that P. algeriensis lacks the ability to synthesize the N-formylperosamine O-polysaccharide characteristic of the lipopolysaccharide (LPS) of smooth Brucella core species. However, unlike other Pseudochrobactrum but similar to some early diverging brucellae, P. algeriensis carries genes potentially synthetizing a rhamnose-based O-polysaccharide LPS. Lipid A analysis by MALDI-TOF demonstrated that P. algeriensis LPS bears a lipid A with a reduced pathogen-associated molecular pattern, a trait shared with Ochrobactrum and Brucella that is essential to generate a highly stable outer membrane and to delay immune activation. Also, although not able to multiply intracellularly in macrophages, the analysis of P. algeriensis cell lipid envelope revealed the presence of large amounts of cationic aminolipids, which may account for the extremely high resistance of P. algeriensis to bactericidal peptides and could favor colonization of mucosae and transient survival in Brucella hosts. However, two traits critical in Brucella pathogenicity are either significantly different (T4SS [VirB]) or absent (erythritol catabolic pathway) in P. algeriensis. This work shows that, while diverging in other characteristics, lipidic envelope features relevant in Brucella pathogenicity are conserved in Brucellaceae. The constant presence of these features strongly suggests that reinforcement of the envelope integrity as an adaptive advantage in soil was maintained in Brucella because of the similarity of some environmental challenges, such as the action of cationic peptide antibiotics and host defense peptides. This information adds knowledge about the evolution of Brucellaceae, and also underlines the taxonomical differences of the three genera compared.
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Affiliation(s)
- Maite Loperena-Barber
- Instituto de Investigación Sanitaria de Navarra (IdISNA) and Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Aitor Elizalde-Bielsa
- Instituto de Investigación Sanitaria de Navarra (IdISNA) and Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Miriam Salvador-Bescós
- Instituto de Investigación Sanitaria de Navarra (IdISNA) and Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Paula Ruiz-Rodríguez
- Institute for Integrative Systems Biology, Universidad de Valencia-CSIC, Valencia, Spain
| | | | - Chantal Renau-Mínguez
- Institute for Integrative Systems Biology, Universidad de Valencia-CSIC, Valencia, Spain
| | - Rebecca Lancaster
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Amaia Zúñiga-Ripa
- Instituto de Investigación Sanitaria de Navarra (IdISNA) and Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Maite Iriarte
- Instituto de Investigación Sanitaria de Navarra (IdISNA) and Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Jose A Bengoechea
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Mireia Coscollá
- Institute for Integrative Systems Biology, Universidad de Valencia-CSIC, Valencia, Spain
| | - Jean-Pierre Gorvel
- Centre d'Immunologie de Marseille-Luminy, CNRS, INSERM, Aix-Marseille University, Marseille, France
| | - Ignacio Moriyón
- Instituto de Investigación Sanitaria de Navarra (IdISNA) and Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Raquel Conde-Álvarez
- Instituto de Investigación Sanitaria de Navarra (IdISNA) and Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain.
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2
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Kyselová L, Řezanka T. Stereochemistry of aminoacylated cardiolipins and phosphatidylglycerols from bacteria. Electrophoresis 2024; 45:980-988. [PMID: 37860988 DOI: 10.1002/elps.202300165] [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: 07/26/2023] [Revised: 09/26/2023] [Accepted: 10/08/2023] [Indexed: 10/21/2023]
Abstract
Hydrophilic interaction liquid chromatography (HILIC) connected with electrospray high-resolution tandem mass spectrometry (MS) was used for the analysis of unusual amino acid (AA) substituted phosphatidylglycerols (PG) and cardiolipins (CL) in mesophilic and thermophilic bacteria. Individual peaks from the lipid class separation by HILIC were isolated and hydrolyzed to determine the absolute configuration of the aminoacyl side chain. The configuration of the aminoacyl side chain was assigned by indirect liquid chromatography (LC) enantiomer separation after the hydrolysis of the aminoacylated (aminoacyl) lipids using N-(4-nitrophenoxycarbonyl)-l-phenylalanine 2-methoxyethyl ester as chiral derivatizing agent and reversed phase LC-MS for analysis. When two chromatographic methods were combined, less common AAs, such as d-allo-Ile and d-allo-Thr, were identified. The taxonomic classification of bacteria showed that bacteria of the family Bacillaceae (Bacillus and Geobacillus) produce branched-chain AAs, that is, d-allo-Ile, d-Ile, and d-Leu. These AAs were present only in the genera Bacillus and Geobacillus and not in Alicyclobacillus acidoterrestris (family Alicyclobacillaceae). On the contrary, hydroxy AAs, that is, l- and d-Thr, and l- and d-allo-Thr, were identified as aminoacyl-PG and aminoacyl-CL in A. acidoterrestris and were not present in the genera Bacillus and Geobacillus. Therefore, the complete analysis made it possible to identify the stereochemistry of AAs in aminoacyl PGs and CLs and use this fact for chemotaxonomy.
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Affiliation(s)
- Lucie Kyselová
- Research Institute of Brewing and Malting, Prague, Czech Republic
| | - Tomáš Řezanka
- Institute of Microbiology, Czech Academy of Sciences, Prague, Czech Republic
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3
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Christensen PM, Martin J, Uppuluri A, Joyce LR, Wei Y, Guan Z, Morcos F, Palmer KL. Lipid discovery enabled by sequence statistics and machine learning. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.12.562061. [PMID: 37873101 PMCID: PMC10592805 DOI: 10.1101/2023.10.12.562061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Bacterial membranes are complex and dynamic, arising from an array of evolutionary pressures. One enzyme that alters membrane compositions through covalent lipid modification is MprF. We recently identified that Streptococcus agalactiae MprF synthesizes lysyl-phosphatidylglycerol (Lys-PG) from anionic PG, and a novel cationic lipid, lysyl-glucosyl-diacylglycerol (Lys-Glc-DAG), from neutral glycolipid Glc-DAG. This unexpected result prompted us to investigate whether Lys-Glc-DAG occurs in other MprF-containing bacteria, and whether other novel MprF products exist. Here, we studied protein sequence features determining MprF substrate specificity. First, pairwise analyses identified several streptococcal MprFs synthesizing Lys-Glc-DAG. Second, a restricted Boltzmann machine-guided approach led us to discover an entirely new substrate for MprF in Enterococcus , diglucosyl-diacylglycerol (Glc2-DAG), and an expanded set of organisms that modify glycolipid substrates using MprF. Overall, we combined the wealth of available sequence data with machine learning to model evolutionary constraints on MprF sequences across the bacterial domain, thereby identifying a novel cationic lipid.
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4
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Gill CP, Phan C, Platt V, Worrell D, Andl T, Roy H. The MprF homolog LysX synthesizes lysyl-diacylglycerol contributing to antibiotic resistance and virulence. Microbiol Spectr 2023; 11:e0142923. [PMID: 37768052 PMCID: PMC10580965 DOI: 10.1128/spectrum.01429-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 07/10/2023] [Indexed: 09/29/2023] Open
Abstract
Lysyl-diacylglycerol (Lys-DAG) was identified three decades ago in Mycobacterium phlei, but the biosynthetic pathway and function of this aminoacylated lipid have since remained uncharacterized. Combining genetic methods, mass spectrometry, and biochemical approaches, we show that the multiple peptide resistance factor (MprF) homolog LysX from Corynebacterium pseudotuberculosis and two mycobacterial species is responsible for Lys-DAG synthesis. LysX is conserved in most Actinobacteria and was previously implicated in the synthesis of another modified lipid, lysyl-phosphatidylglycerol (Lys-PG), in Mycobacterium tuberculosis. Although we detected low levels of Lys-PG in the membrane of C. pseudotuberculosis, our data suggest that Lys-PG is not directly synthesized by LysX and may require an additional downstream pathway, which is as yet undefined. Our results show that LysX in C. pseudotuberculosis is a major factor of resistance against a variety of positively charged antibacterial agents, including cationic antimicrobial peptides (e.g., human peptide LL-37 and polymyxin B) and aminoglycosides (e.g., gentamycin and apramycin). Deletion of lysX caused an increase in cellular membrane permeability without dissipation of the membrane potential, suggesting that loss of the protein does not result in mechanical damage to the cell membrane. Furthermore, lysX-deficient cells exhibited an attenuated virulence phenotype in a Galleria mellonella infection model, supporting a role for LysX during infection. Altogether, Lys-DAG represents a novel molecular determinant for antimicrobial resistance and virulence that may be widespread in Actinobacteria and points to a richer landscape than previously realized of lipid components contributing to overall membrane physiology in this important bacterial phylum. IMPORTANCE In the past two decades, tRNA-dependent modification of membrane phosphatidylglycerol has been implicated in altering the biochemical properties of the cell surface, thereby enhancing the antimicrobial resistance and virulence of various bacterial pathogens. Here, we show that in several Actinobacteria, the multifunctional protein LysX attaches lysine to diacylglycerol instead of phosphatidylglycerol. We found that lysyl-diacylglycerol (Lys-DAG) confers high levels of resistance against various cationic antimicrobial peptides and aminoglycosides and also enhances virulence. Our data show that Lys-DAG is a lipid commonly found in important actinobacterial pathogens, including Mycobacterium and Corynebacterium species.
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Affiliation(s)
- Cameron P. Gill
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Christopher Phan
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Vivien Platt
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Danielle Worrell
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Thomas Andl
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Hervé Roy
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
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5
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Kitoun C, Saidjalolov S, Bouquet D, Djago F, Remaury QB, Sargueil B, Poinot P, Etheve-Quelquejeu M, Iannazzo L. Traceless Staudinger Ligation to Access Stable Aminoacyl- or Peptidyl-Dinucleotide. ACS OMEGA 2023; 8:3850-3860. [PMID: 36743074 PMCID: PMC9893454 DOI: 10.1021/acsomega.2c06135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 10/26/2022] [Indexed: 06/18/2023]
Abstract
Aminoacyl- and peptidyl-tRNA are specific biomolecules involved in many biological processes, from ribosomal protein synthesis to the synthesis of peptidoglycan precursors. Here, we report a post-synthetic approach based on traceless Staudinger ligation for the synthesis of a stable amide bond to access aminoacyl- or peptidyl-di-nucleotide. A series of amino-acid and peptide ester phenyl phosphines were synthetized, and their reactivity was studied on a 2'-N3 di-nucleotide. The corresponding 2'-amide di-nucleotides were obtained and characterized by LC-HRMS, and mechanistic interpretations of the influence of the amino acid phenyl ester phosphine were proposed. We also demonstrated that enzymatic 5'-OH phosphorylation is compatible with the acylated di-nucleotide, allowing the possibility to access stable aminoacylated-tRNA.
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Affiliation(s)
- Camélia Kitoun
- Université
Paris Cité, CNRS, Laboratoire de Chimie et Biochimie Pharmacologiques
et Toxicologiques, Paris F-75006, France
| | - Saidbakhrom Saidjalolov
- Université
Paris Cité, CNRS, Laboratoire de Chimie et Biochimie Pharmacologiques
et Toxicologiques, Paris F-75006, France
| | - Delphine Bouquet
- Université
Paris Cité, CNRS, Laboratoire de Chimie et Biochimie Pharmacologiques
et Toxicologiques, Paris F-75006, France
| | - Fabiola Djago
- Institut
de Chimie des Milieux et Matériaux de Poitiers IC2MP, Université
de Poitiers, UMR 7285, Poitiers 86073, France
| | - Quentin Blancart Remaury
- Institut
de Chimie des Milieux et Matériaux de Poitiers IC2MP, Université
de Poitiers, UMR 7285, Poitiers 86073, France
| | - Bruno Sargueil
- Université
Paris Cité, CNRS, UMR 8038/CiTCoM, Paris F-75006, France
| | - Pauline Poinot
- Institut
de Chimie des Milieux et Matériaux de Poitiers IC2MP, Université
de Poitiers, UMR 7285, Poitiers 86073, France
| | - Mélanie Etheve-Quelquejeu
- Université
Paris Cité, CNRS, Laboratoire de Chimie et Biochimie Pharmacologiques
et Toxicologiques, Paris F-75006, France
| | - Laura Iannazzo
- Université
Paris Cité, CNRS, Laboratoire de Chimie et Biochimie Pharmacologiques
et Toxicologiques, Paris F-75006, France
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6
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Joyce LR, Doran KS. Gram-positive bacterial membrane lipids at the host-pathogen interface. PLoS Pathog 2023; 19:e1011026. [PMID: 36602959 DOI: 10.1371/journal.ppat.1011026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Luke R Joyce
- University of Colorado Anschutz Medical Campus, Department of Immunology and Microbiology, Aurora, Colorado, United States of America
| | - Kelly S Doran
- University of Colorado Anschutz Medical Campus, Department of Immunology and Microbiology, Aurora, Colorado, United States of America
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7
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Grob G, Hemmerle M, Yakobov N, Mahmoudi N, Fischer F, Senger B, Becker HD. tRNA-dependent addition of amino acids to cell wall and membrane components. Biochimie 2022; 203:93-105. [DOI: 10.1016/j.biochi.2022.09.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 09/23/2022] [Accepted: 09/26/2022] [Indexed: 11/16/2022]
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8
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Boldrin F, Cioetto Mazzabò L, Lanéelle MA, Rindi L, Segafreddo G, Lemassu A, Etienne G, Conflitti M, Daffé M, Garzino Demo A, Manganelli R, Marrakchi H, Provvedi R. LysX2 is a Mycobacterium tuberculosis membrane protein with an extracytoplasmic MprF-like domain. BMC Microbiol 2022; 22:85. [PMID: 35365094 PMCID: PMC8974105 DOI: 10.1186/s12866-022-02493-2] [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: 09/29/2021] [Accepted: 03/11/2022] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Aminoacyl-phosphatidylglycerol (aaPG) synthases are bacterial enzymes that usually catalyze transfer of aminoacyl residues to the plasma membrane phospholipid phosphatidylglycerol (PG). The result is introduction of positive charges onto the cytoplasmic membrane, yielding reduced affinity towards cationic antimicrobial peptides, and increased resistance to acidic environments. Therefore, these enzymes represent an important defense mechanism for many pathogens, including Staphylococcus aureus and Mycobacterium tuberculosis (Mtb), which are known to encode for lysyl-(Lys)-PG synthase MprF and LysX, respectively. Here, we used a combination of bioinformatic, genetic and bacteriological methods to characterize a protein encoded by the Mtb genome, Rv1619, carrying a domain with high similarity to MprF-like domains, suggesting that this protein could be a new aaPG synthase family member. However, unlike homologous domains of MprF and LysX that are positioned in the cytoplasm, we predicted that the MprF-like domain in LysX2 is in the extracytoplasmic region. RESULTS Using genetic fusions to the Escherichia coli proteins PhoA and LacZ of LysX2, we confirmed this unique membrane topology, as well as LysX and MprF as benchmarks. Expression of lysX2 in Mycobacterium smegmatis increased cell resistance to human β-defensin 2 and sodium nitrite, enhanced cell viability and delayed biofilm formation in acidic pH environment. Remarkably, MtLysX2 significantly reduced the negative charge on the bacterial surface upon exposure to an acidic environment. Additionally, we found LysX2 orthologues in major human pathogens and in rapid-growing mycobacteria frequently associated with human infections, but not in environmental and non-pathogenic mycobacteria. CONCLUSIONS Overall, our data suggest that LysX2 is a prototype of a new class within the MprF-like protein family that likely enhances survival of the pathogenic species through its catalytic domain which is exposed to the extracytoplasmic side of the cell membrane and is required to decrease the negative charge on the bacterial surface through a yet uncharacterized mechanism.
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Affiliation(s)
| | | | - Marie-Antoinette Lanéelle
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Laura Rindi
- Department of Translational Research, University of Pisa, Pisa, Italy
| | - Greta Segafreddo
- Department of Molecular Medicine, University of Padua, Padua, Italy
| | - Anne Lemassu
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Gilles Etienne
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Marta Conflitti
- Department of Molecular Medicine, University of Padua, Padua, Italy
| | - Mamadou Daffé
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Alfredo Garzino Demo
- Department of Molecular Medicine, University of Padua, Padua, Italy
- Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland, USA
| | | | - Hedia Marrakchi
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
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9
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MacDermott-Opeskin HI, Gupta V, O’Mara ML. Lipid-mediated antimicrobial resistance: a phantom menace or a new hope? Biophys Rev 2022; 14:145-162. [PMID: 35251360 PMCID: PMC8880301 DOI: 10.1007/s12551-021-00912-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/14/2021] [Indexed: 02/06/2023] Open
Abstract
Abstract The proposition of a post-antimicrobial era is all the more realistic with the continued rise of antimicrobial resistance. The development of new antimicrobials is failing to counter the ever-increasing rates of bacterial antimicrobial resistance. This necessitates novel antimicrobials and drug targets. The bacterial cell membrane is an essential and highly conserved cellular component in bacteria and acts as the primary barrier for entry of antimicrobials into the cell. Although previously under-exploited as an antimicrobial target, the bacterial cell membrane is attractive for the development of novel antimicrobials due to its importance in pathogen viability. Bacterial cell membranes are diverse assemblies of macromolecules built around a central lipid bilayer core. This lipid bilayer governs the overall membrane biophysical properties and function of its membrane-embedded proteins. This mini-review will outline the mechanisms by which the bacterial membrane causes and controls resistance, with a focus on alterations in the membrane lipid composition, chemical modification of constituent lipids, and the efflux of antimicrobials by membrane-embedded efflux systems. Thorough insight into the interplay between membrane-active antimicrobials and lipid-mediated resistance is needed to enable the rational development of new antimicrobials. In particular, the union of computational approaches and experimental techniques for the development of innovative and efficacious membrane-active antimicrobials is explored.
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Affiliation(s)
- Hugo I. MacDermott-Opeskin
- Research School of Chemistry, College of Science, The Australian National University, Canberra, ACT 2601 Australia
| | - Vrinda Gupta
- Research School of Chemistry, College of Science, The Australian National University, Canberra, ACT 2601 Australia
| | - Megan L. O’Mara
- Research School of Chemistry, College of Science, The Australian National University, Canberra, ACT 2601 Australia
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10
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Joyce LR, Manzer HS, da C. Mendonça J, Villarreal R, Nagao PE, Doran KS, Palmer KL, Guan Z. Identification of a novel cationic glycolipid in Streptococcus agalactiae that contributes to brain entry and meningitis. PLoS Biol 2022; 20:e3001555. [PMID: 35180210 PMCID: PMC8893666 DOI: 10.1371/journal.pbio.3001555] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 03/03/2022] [Accepted: 01/26/2022] [Indexed: 12/17/2022] Open
Abstract
Bacterial membrane lipids are critical for membrane bilayer formation, cell division, protein localization, stress responses, and pathogenesis. Despite their critical roles, membrane lipids have not been fully elucidated for many pathogens. Here, we report the discovery of a novel cationic glycolipid, lysyl-glucosyl-diacylglycerol (Lys-Glc-DAG), which is synthesized in high abundance by the bacterium Streptococcus agalactiae (Group B Streptococcus, GBS). To our knowledge, Lys-Glc-DAG is more positively charged than any other known lipids. Lys-Glc-DAG carries 2 positive net charges per molecule, distinct from the widely described lysylated phospholipid lysyl-phosphatidylglycerol (Lys-PG) that carries one positive net charge due to the presence of a negatively charged phosphate moiety. We use normal phase liquid chromatography (NPLC) coupled with electrospray ionization (ESI) high-resolution tandem mass spectrometry (HRMS/MS) and genetic approaches to determine that Lys-Glc-DAG is synthesized by the enzyme MprF in GBS, which covalently modifies the neutral glycolipid Glc-DAG with the cationic amino acid lysine. GBS is a leading cause of neonatal meningitis, which requires traversal of the endothelial blood–brain barrier (BBB). We demonstrate that GBS strains lacking mprF exhibit a significant decrease in the ability to invade BBB endothelial cells. Further, mice challenged with a GBSΔmprF mutant developed bacteremia comparably to wild-type (WT) infected mice yet had less recovered bacteria from brain tissue and a lower incidence of meningitis. Thus, our data suggest that Lys-Glc-DAG may contribute to bacterial uptake into host cells and disease progression. Importantly, our discovery provides a platform for further study of cationic lipids at the host–pathogen interface. Bacterial membrane lipids are critical for membrane bilayer formation, cell division, protein localization, stress responses, and pathogenesis. This study shows that the enzyme MprF in Streptococcus agalactiae synthesizes a novel cationic lipid, Lysyl-Glucosyl-Diacylglycerol, which aids meningitis progression in vivo.
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Affiliation(s)
- Luke R. Joyce
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, United States of America
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Haider S. Manzer
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Jéssica da C. Mendonça
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- Rio de Janeiro State University, Roberto Alcântara Gomes Biology Institute, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ricardo Villarreal
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Prescilla E. Nagao
- Rio de Janeiro State University, Roberto Alcântara Gomes Biology Institute, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Kelly S. Doran
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- * E-mail: (KSD); (KLP); (ZG)
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, United States of America
- * E-mail: (KSD); (KLP); (ZG)
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail: (KSD); (KLP); (ZG)
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11
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Yakobov N, Mahmoudi N, Grob G, Yokokawa D, Saga Y, Kushiro T, Worrell D, Roy H, Schaller H, Senger B, Huck L, Riera Gascon G, Becker HD, Fischer F. RNA-dependent synthesis of ergosteryl-3β-O-glycine in Ascomycota expands the diversity of steryl-amino acids. J Biol Chem 2022; 298:101657. [PMID: 35131263 PMCID: PMC8913301 DOI: 10.1016/j.jbc.2022.101657] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 01/13/2022] [Accepted: 01/16/2022] [Indexed: 12/11/2022] Open
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12
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Slavetinsky CJ, Hauser JN, Gekeler C, Slavetinsky J, Geyer A, Kraus A, Heilingbrunner D, Wagner S, Tesar M, Krismer B, Kuhn S, Ernst CM, Peschel A. Sensitizing Staphylococcus aureus to antibacterial agents by decoding and blocking the lipid flippase MprF. eLife 2022; 11:66376. [PMID: 35044295 PMCID: PMC8806190 DOI: 10.7554/elife.66376] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 01/18/2022] [Indexed: 11/13/2022] Open
Abstract
The pandemic of antibiotic resistance represents a major human health threat demanding new antimicrobial strategies. MprF is the synthase and flippase of the phospholipid lysyl-phosphatidylglycerol that increases virulence and resistance of methicillin-resistant Staphylococcus aureus (MRSA) and other pathogens to cationic host defense peptides and antibiotics. With the aim to design MprF inhibitors that could sensitize MRSA to antimicrobial agents and support the clearance of staphylococcal infections with minimal selection pressure, we developed MprF-targeting monoclonal antibodies, which bound and blocked the MprF flippase subunit. Antibody M-C7.1 targeted a specific loop in the flippase domain that proved to be exposed at both sides of the bacterial membrane, thereby enhancing the mechanistic understanding of bacterial lipid translocation. M-C7.1 rendered MRSA susceptible to host antimicrobial peptides and antibiotics such as daptomycin, and it impaired MRSA survival in human phagocytes. Thus, MprF inhibitors are recommended for new anti-virulence approaches against MRSA and other bacterial pathogens.
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Affiliation(s)
| | | | - Cordula Gekeler
- Department of Infection Biology, Eberhard Karls University Tübingen
| | | | - André Geyer
- Department of Infection Biology, Eberhard Karls University Tübingen
| | | | | | - Samuel Wagner
- Cluster of Excellence 'Controlling Microbes to Fight Infections', University of Tübingen
| | | | - Bernhard Krismer
- Department of Infection Biology, Eberhard Karls University Tübingen
| | - Sebastian Kuhn
- Department of Infection Biology, Eberhard Karls University Tübingen
| | - Christoph M Ernst
- Department of Molecular Biology and Center for Computational and Integrative Biology, Broad Institute
| | - Andreas Peschel
- Department of Infection Biology, Eberhard Karls University Tübingen
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13
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Jeong H, Kim J. Unique anticodon loop conformation with the flipped-out wobble nucleotide in the crystal structure of unbound tRNA Val. RNA (NEW YORK, N.Y.) 2021; 27:1330-1338. [PMID: 34315814 PMCID: PMC8522699 DOI: 10.1261/rna.078863.121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/24/2021] [Indexed: 06/13/2023]
Abstract
During protein synthesis on ribosome, tRNA recognizes its cognate codon of mRNA through base-pairing with the anticodon. The 5'-end nucleotide of the anticodon is capable of wobble base-pairing, offering a molecular basis for codon degeneracy. The wobble nucleotide is often targeted for post-transcriptional modification, which affects the specificity and fidelity of the decoding process. Flipping-out of a wobble nucleotide in the anticodon loop has been proposed to be necessary for modifying enzymes to access the target nucleotide, which has been captured in selective structures of protein-bound complexes. Meanwhile, all other structures of free or ribosome-bound tRNA display anticodon bases arranged in stacked conformation. We report the X-ray crystal structure of unbound tRNAVal1 to a 2.04 Å resolution showing two different conformational states of wobble uridine in the anticodon loop, one stacked on the neighboring base and the other swiveled out toward solvent. In addition, the structure reveals a rare magnesium ion coordination to the nitrogen atom of a nucleobase, which has been sampled very rarely among known structures of nucleic acids.
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MESH Headings
- Anticodon/chemistry
- Anticodon/genetics
- Anticodon/metabolism
- Base Pairing
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Metals/metabolism
- Models, Molecular
- Nucleic Acid Conformation
- Protein Biosynthesis
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Transfer, Val/chemistry
- RNA, Transfer, Val/genetics
- RNA, Transfer, Val/metabolism
- Ribosomes/genetics
- Ribosomes/metabolism
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Affiliation(s)
- Hyeonju Jeong
- Department of Chemistry, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - Jungwook Kim
- Department of Chemistry, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
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14
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Phospholipid translocation captured in a bifunctional membrane protein MprF. Nat Commun 2021; 12:2927. [PMID: 34006869 PMCID: PMC8131360 DOI: 10.1038/s41467-021-23248-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 04/16/2021] [Indexed: 01/07/2023] Open
Abstract
As a large family of membrane proteins crucial for bacterial physiology and virulence, the Multiple Peptide Resistance Factors (MprFs) utilize two separate domains to synthesize and translocate aminoacyl phospholipids to the outer leaflets of bacterial membranes. The function of MprFs enables Staphylococcus aureus and other pathogenic bacteria to acquire resistance to daptomycin and cationic antimicrobial peptides. Here we present cryo-electron microscopy structures of MprF homodimer from Rhizobium tropici (RtMprF) at two different states in complex with lysyl-phosphatidylglycerol (LysPG). RtMprF contains a membrane-embedded lipid-flippase domain with two deep cavities opening toward the inner and outer leaflets of the membrane respectively. Intriguingly, a hook-shaped LysPG molecule is trapped inside the inner cavity with its head group bent toward the outer cavity which hosts a second phospholipid-binding site. Moreover, RtMprF exhibits multiple conformational states with the synthase domain adopting distinct positions relative to the flippase domain. Our results provide a detailed framework for understanding the mechanisms of MprF-mediated modification and translocation of phospholipids.
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15
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Abstract
The aminoacylation reaction is one of most extensively studied cellular processes. The so-called "canonical" reaction is carried out by direct charging of an amino acid (aa) onto its corresponding transfer RNA (tRNA) by the cognate aminoacyl-tRNA synthetase (aaRS), and the canonical usage of the aminoacylated tRNA (aa-tRNA) is to translate a messenger RNA codon in a translating ribosome. However, four out of the 22 genetically-encoded aa are made "noncanonically" through a two-step or indirect route that usually compensate for a missing aaRS. Additionally, from the 22 proteinogenic aa, 13 are noncanonically used, by serving as substrates for the tRNA- or aa-tRNA-dependent synthesis of other cellular components. These nontranslational processes range from lipid aminoacylation, and heme, aa, antibiotic and peptidoglycan synthesis to protein degradation. This chapter focuses on these noncanonical usages of aa-tRNAs and the ways of generating them, and also highlights the strategies that cells have evolved to balance the use of aa-tRNAs between protein synthesis and synthesis of other cellular components.
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16
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Mechanisms of bactericidal action and resistance of polymyxins for Gram-positive bacteria. Appl Microbiol Biotechnol 2020; 104:3771-3780. [PMID: 32157424 DOI: 10.1007/s00253-020-10525-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/25/2020] [Accepted: 03/03/2020] [Indexed: 10/24/2022]
Abstract
Polymyxins are cationic antimicrobial peptides used as the last-line therapy to treat multidrug-resistant Gram-negative bacterial infections. The bactericidal activity of polymyxins against Gram-negative bacteria relies on the electrostatic interaction between the positively charged polymyxins and the negatively charged lipid A of lipopolysaccharide (LPS). Given that Gram-positive bacteria lack an LPS-containing outer membrane, it is generally acknowledged that polymyxins are less active against Gram-positive bacteria. However, Gram-positive bacteria produce negatively charged teichoic acids, which may act as the target of polymyxins. More and more studies suggest that polymyxins have potential as a treatment for Gram-positive bacterial infection. This mini-review discusses recent advances in the mechanism of the antibacterial activity and resistance of polymyxins in Gram-positive bacteria.Key Points• Teichoic acids play a key role in the action of polymyxins on Gram-positive bacteria.• Polymyxin kills Gram-positive bacteria by disrupting cell surface and oxidative damage.• Modification of teichoic acids and phospholipids contributes to polymyxin resistance in Gram-positive bacteria.• Polymyxins have potential as a treatment for Gram-positive bacterial infection.
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17
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Baindara P, Ghosh AK, Mandal SM. Coevolution of Resistance Against Antimicrobial Peptides. Microb Drug Resist 2020; 26:880-899. [PMID: 32119634 DOI: 10.1089/mdr.2019.0291] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Antimicrobial peptides (AMPs) are produced by all forms of life, ranging from eukaryotes to prokaryotes, and they are a crucial component of innate immunity, involved in clearing infection by inhibiting pathogen colonization. In the recent past, AMPs received high attention due to the increase of extensive antibiotic resistance by these pathogens. AMPs exhibit a diverse spectrum of activity against bacteria, fungi, parasites, and various types of cancer. AMPs are active against various bacterial pathogens that cause disease in animals and plants. However, because of the coevolution of host and pathogen interaction, bacteria have developed the mechanisms to sense and exhibit an adaptive response against AMPs. These resistance mechanisms are playing an important role in bacterial virulence within the host. Here, we have discussed the different resistance mechanisms used by gram-positive and gram-negative bacteria to sense and combat AMP actions. Understanding the mechanism of AMP resistance may provide directions toward the development of novel therapeutic strategies to control multidrug-resistant pathogens.
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Affiliation(s)
- Piyush Baindara
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Ananta K Ghosh
- Department of Biotechnology, Central Research Facility, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Santi M Mandal
- Department of Biotechnology, Central Research Facility, Indian Institute of Technology Kharagpur, Kharagpur, India
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18
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Groenewold MK, Hebecker S, Fritz C, Czolkoss S, Wiesselmann M, Heinz DW, Jahn D, Narberhaus F, Aktas M, Moser J. Virulence of Agrobacterium tumefaciens requires lipid homeostasis mediated by the lysyl-phosphatidylglycerol hydrolase AcvB. Mol Microbiol 2018; 111:269-286. [PMID: 30353924 DOI: 10.1111/mmi.14154] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2018] [Indexed: 12/24/2022]
Abstract
Agrobacterium tumefaciens transfers oncogenic T-DNA via the type IV secretion system (T4SS) into plants causing tumor formation. The acvB gene encodes a virulence factor of unknown function required for plant transformation. Here we specify AcvB as a periplasmic lysyl-phosphatidylglycerol (L-PG) hydrolase, which modulates L-PG homeostasis. Through functional characterization of recombinant AcvB variants, we showed that the C-terminal domain of AcvB (residues 232-456) is sufficient for full enzymatic activity and defined key residues for catalysis. Absence of the hydrolase resulted in ~10-fold increase in L-PG in Agrobacterium membranes and abolished T-DNA transfer and tumor formation. Overproduction of the L-PG synthase gene (lpiA) in wild-type A. tumefaciens resulted in a similar increase in the L-PG content (~7-fold) and a virulence defect even in the presence of intact AcvB. These results suggest that elevated L-PG amounts (either by overproduction of the synthase or absence of the hydrolase) are responsible for the virulence phenotype. Gradually increasing the L-PG content by complementation with different acvB variants revealed that cellular L-PG levels above 3% of total phospholipids interfere with T-DNA transfer. Cumulatively, this study identified AcvB as a novel virulence factor required for membrane lipid homeostasis and T-DNA transfer.
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Affiliation(s)
- Maike K Groenewold
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Stefanie Hebecker
- Institute for Microbiology, Technische Universität Braunschweig, 38106, Braunschweig, Germany
| | - Christiane Fritz
- Lehrstuhl für Biologie der Mikroorganismen, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Simon Czolkoss
- Lehrstuhl für Biologie der Mikroorganismen, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Milan Wiesselmann
- Institute for Microbiology, Technische Universität Braunschweig, 38106, Braunschweig, Germany
| | - Dirk W Heinz
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Dieter Jahn
- Institute for Microbiology, Technische Universität Braunschweig, 38106, Braunschweig, Germany
| | - Franz Narberhaus
- Lehrstuhl für Biologie der Mikroorganismen, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Meriyem Aktas
- Lehrstuhl für Biologie der Mikroorganismen, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Jürgen Moser
- Institute for Microbiology, Technische Universität Braunschweig, 38106, Braunschweig, Germany
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19
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Luo Y, Javed MA, Deneer H. Comparative study on nutrient depletion-induced lipidome adaptations in Staphylococcus haemolyticus and Staphylococcus epidermidis. Sci Rep 2018; 8:2356. [PMID: 29402937 PMCID: PMC5799182 DOI: 10.1038/s41598-018-20801-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 01/24/2018] [Indexed: 11/09/2022] Open
Abstract
Staphylococcus species are emerging opportunistic pathogens that cause outbreaks of hospital and community-acquired infections. Some of these bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) are difficult to treat due to their resistance to multiple antibiotics. We carried out a comparative study on the lipidome adaptations in response to starvation in the two most common coagulase-negative Staphylococcus species: a S. epidermidis strain sensitive to ampicillin and erythromycin and a S. haemolyticus strain resistant to both. The predominant fatty acid composition in glycerolipids was (17:0-15:0) in both bacteria. During the exponential phase, the two bacterial lipidomes were similar. Both were dominated by diacylglycerol (DAG), phosphatidylglycerol (PG), lysyl-phosphatidylglycerol (Lysyl-PG) and Diglucosyl-diacylglycerol (DGDG). Alanyl-PG was detected in small amounts in both bacterial lipids. N-succinyl-lysyl-PG was detected only in S. haemolyticus, while lysyl-DAG only in S. epidermidis. As the two bacteria entered stationary phase, both lipidomes became essentially nitrogen-free. Both bacteria accumulated large amounts of free fatty acids. Strikingly, the lipidome of S. epidermidis became dominated by cardiolipin (CL), while that of S. haemolyticus was simplified to DGDG and PG. The S. epidermidis strain also produced acyl-phosphatidylglycerol (APG) in the stationary phase.
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Affiliation(s)
- Yu Luo
- Department of Biochemistry, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
| | - Muhammad Afzal Javed
- Department of Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Harry Deneer
- Department of Pathology and Laboratory Medicine, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Molecular Microbiology Laboratory, Division of Clinical Microbiology, Saskatoon Health Region, Saskatoon, Saskatchewan, Canada
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20
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Fields RN, Roy H. Deciphering the tRNA-dependent lipid aminoacylation systems in bacteria: Novel components and structural advances. RNA Biol 2017; 15:480-491. [PMID: 28816600 PMCID: PMC6103681 DOI: 10.1080/15476286.2017.1356980] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
tRNA-dependent addition of amino acids to lipids on the outer surface of the bacterial membrane results in decreased effectiveness of antimicrobials such as cationic antimicrobial peptides (CAMPs) that target the membrane, and increased virulence of several pathogenic species. After a brief introduction to CAMPs and the various bacterial resistance mechanisms used to counteract these compounds, this review focuses on recent advances in tRNA-dependent pathways for lipid modification in bacteria. Phenotypes associated with amino acid lipid modifications and regulation of their expression will also be discussed.
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Affiliation(s)
- Rachel N Fields
- a Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida , Orlando , Florida , United States of America
| | - Hervé Roy
- a Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida , Orlando , Florida , United States of America
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21
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López-Lara IM, Geiger O. Bacterial lipid diversity. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1287-1299. [DOI: 10.1016/j.bbalip.2016.10.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 10/10/2016] [Accepted: 10/11/2016] [Indexed: 11/25/2022]
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22
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Rashid R, Cazenave-Gassiot A, Gao IH, Nair ZJ, Kumar JK, Gao L, Kline KA, Wenk MR. Comprehensive analysis of phospholipids and glycolipids in the opportunistic pathogen Enterococcus faecalis. PLoS One 2017; 12:e0175886. [PMID: 28423018 PMCID: PMC5397010 DOI: 10.1371/journal.pone.0175886] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Accepted: 04/02/2017] [Indexed: 02/07/2023] Open
Abstract
Enterococcus faecalis is a Gram-positive, opportunistic, pathogenic bacterium that causes a significant number of antibiotic-resistant infections in hospitalized patients. The development of antibiotic resistance in hospital-associated pathogens is a formidable public health threat. In E. faecalis and other Gram-positive pathogens, correlations exist between lipid composition and antibiotic resistance. Resistance to the last-resort antibiotic daptomycin is accompanied by a decrease in phosphatidylglycerol (PG) levels, whereas multiple peptide resistance factor (MprF) converts anionic PG into cationic lysyl-PG via a trans-esterification reaction, providing resistance to cationic antimicrobial peptides. Unlike previous studies that relied on thin layer chromatography and spectrophotometry, we have performed liquid chromatography-tandem mass spectrometry (LC-MS/MS) directly on lipids extracted from E. faecalis, and quantified the phospholipids through multiple reaction monitoring (MRM). In the daptomycin-sensitive E. faecalis strain OG1RF, we have identified 17 PGs, 8 lysyl-PGs (LPGs), 23 cardiolipins (CL), 3 glycerophospho-diglucosyl-diacylglycerols (GPDGDAG), 5 diglucosyl-diacylglycerols (DGDAG), 3 diacylglycerols (DAGs), and 4 triacylglycerols (TAGs). We have quantified PG and shown that PG levels vary during growth of E. faecalis in vitro. We also show that two daptomycin-resistant (DapR) strains of E. faecalis have substantially lower levels of PG and LPG levels. Since LPG levels in these strains are lower, daptomycin resistance is likely due to the reduction in PG. This lipidome map is the first comprehensive analysis of membrane phospholipids and glycolipids in the important human pathogen E. faecalis, for which antimicrobial resistance and altered lipid homeostasis have been intimately linked.
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Affiliation(s)
- Rafi Rashid
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Amaury Cazenave-Gassiot
- Singapore Lipidomics Incubator, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Iris H. Gao
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Zeus J. Nair
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Jaspal K. Kumar
- Singapore Lipidomics Incubator, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Liang Gao
- Singapore Lipidomics Incubator, National University of Singapore, Singapore, Singapore
- Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Kimberly A. Kline
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- * E-mail: (KAK); (MRW)
| | - Markus R. Wenk
- Singapore Lipidomics Incubator, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Singapore
- * E-mail: (KAK); (MRW)
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23
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Slavetinsky C, Kuhn S, Peschel A. Bacterial aminoacyl phospholipids - Biosynthesis and role in basic cellular processes and pathogenicity. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:1310-1318. [PMID: 27940309 DOI: 10.1016/j.bbalip.2016.11.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Revised: 11/28/2016] [Accepted: 11/30/2016] [Indexed: 10/20/2022]
Abstract
The bacterial cell membrane accomplishes the controlled exchange of molecules with the extracellular space and mediates specific interactions with the environment. However, the cytoplasmic membrane also includes vulnerable targets for antimicrobial agents. A common feature of cationic antimicrobial peptides (CAMPs) produced by other bacteria or by the host immune system is to utilize the negative charge of bacterial phospholipids such as phosphatidylglycerol (PG) or cardiolipin (CL) for initial adherence and subsequent penetration into the membrane bilayer. To resist cationic antimicrobials many bacteria integrate positive charges into the membrane surface. This is accomplished by aminoacylation of negatively charged (PG) or (CL) with alanine, arginine, or lysine residues. The Multiple Peptide Resistance Factor (MprF) of Staphylococcus aureus is the prototype of a highly conserved protein family of aminoacyl phosphatidylglycerol synthases (aaPGSs) which modify PG or CL with amino acids. MprF is an oligomerizing membrane protein responsible for both, synthesis of lysyl phosphatidylglycerol (LysPG) in the inner leaflet of the cytoplasmic membrane and translocation of LysPG to the outer leaflet. This review focuses on occurrence, synthesis and function of bacterial aminoacyl phospholipids (aaPLs) and on the role of such lipids in basic cellular processes and pathogenicity. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.
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Affiliation(s)
- Christoph Slavetinsky
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology, University of Tübingen, 72076 Tübingen, Germany; German Centre for Infection Research (DZIF), Partner Site Tübingen, 72076 Tübingen, Germany
| | - Sebastian Kuhn
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology, University of Tübingen, 72076 Tübingen, Germany; German Centre for Infection Research (DZIF), Partner Site Tübingen, 72076 Tübingen, Germany
| | - Andreas Peschel
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology, University of Tübingen, 72076 Tübingen, Germany; German Centre for Infection Research (DZIF), Partner Site Tübingen, 72076 Tübingen, Germany.
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24
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Atila M, Katselis G, Chumala P, Luo Y. Characterization of N-Succinylation of L-Lysylphosphatidylglycerol in Bacillus subtilis Using Tandem Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1606-1613. [PMID: 27506207 DOI: 10.1007/s13361-016-1455-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/11/2016] [Accepted: 07/13/2016] [Indexed: 06/06/2023]
Abstract
Phospholipids generally dominate in bacterial lipids. The negatively charged nature of phospholipids renders bacteria susceptible to cationic antibiotic peptides. In comparison with Gram-negative bacteria, Gram-positive bacteria in general have much less zwitterionic phosphatidylethanolamine. However, they are known for producing aminoacylated phosphatidylglycerol (PG), especially positively charged L-lysyl-PG, which is catalyzed by lysyl-PG synthase MprF, which appears to have a broad range of specificity for L-aminoacyl transfer RNAs. In addition, many Gram-positive bacteria also have a dlt-gene-coded D-alanylation pathway for lipoteichoic acids and wall teichoic acids covalently attached to a glycolipid or peptidoglycan. D-Alanylation also masks the dominant negative charge of the phosphate-rich polymers of teichoic acids. Using mass spectrometry, we have recently observed that precursor scans in negative mode for deprotonated amino acid fragments were most sensitive for ester-linked amino acids. Such a scan for precursors generating an m/z 145 lysyl anion revealed lysyl-PG as well as an additional species 100 m/z units greater than lysyl-PG. This unexpected species corresponded precisely to the expected mass of N-succinylated lysyl-PG. Tandem mass spectrometry revealed a precise match to the fragmentation pattern of this putative new species. PG, lysyl-PG, and N-succinyl-lysyl-PG may form a complete loop of charge reversal from -1 to +1 and then back to -1. Analogous charge reversal by N-succinylation of lysine residues in the bacterial as well as eukaryotic proteomes has been recently discovered as a major posttranslational modification. Such modification in bacterial lipids is possibly catalyzed by an enzyme homologous to the enzymes that modify lysine residues in proteins. Graphical Abstract ᅟ.
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Affiliation(s)
- Metin Atila
- Department of Biochemistry, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - George Katselis
- Canadian Centre for Health and Safety in Agriculture/Department of Medicine, Core Mass Spectrometry Facility, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Paulos Chumala
- Canadian Centre for Health and Safety in Agriculture/Department of Medicine, Core Mass Spectrometry Facility, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Yu Luo
- Department of Biochemistry, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
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25
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Fozo EM, Rucks EA. The Making and Taking of Lipids: The Role of Bacterial Lipid Synthesis and the Harnessing of Host Lipids in Bacterial Pathogenesis. Adv Microb Physiol 2016; 69:51-155. [PMID: 27720012 DOI: 10.1016/bs.ampbs.2016.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In order to survive environmental stressors, including those induced by growth in the human host, bacterial pathogens will adjust their membrane physiology accordingly. These physiological changes also include the use of host-derived lipids to alter their own membranes and feed central metabolic pathways. Within the host, the pathogen is exposed to many stressful stimuli. A resulting adaptation is for pathogens to scavenge the host environment for readily available lipid sources. The pathogen takes advantage of these host-derived lipids to increase or decrease the rigidity of their own membranes, to provide themselves with valuable precursors to feed central metabolic pathways, or to impact host signalling and processes. Within, we review the diverse mechanisms that both extracellular and intracellular pathogens employ to alter their own membranes as well as their use of host-derived lipids in membrane synthesis and modification, in order to increase survival and perpetuate disease within the human host. Furthermore, we discuss how pathogen employed mechanistic utilization of host-derived lipids allows for their persistence, survival and potentiation of disease. A more thorough understanding of all of these mechanisms will have direct consequences for the development of new therapeutics, and specifically, therapeutics that target pathogens, while preserving normal flora.
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Affiliation(s)
- E M Fozo
- University of Tennessee, Knoxville, TN, United States.
| | - E A Rucks
- Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States.
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26
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Grube CD, Roy H. A Quantitative Spectrophotometric Assay to Monitor the tRNA-Dependent Pathway for Lipid Aminoacylation In Vitro. ACTA ACUST UNITED AC 2016; 21:722-8. [PMID: 27073192 DOI: 10.1177/1087057116642987] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 03/14/2016] [Indexed: 11/15/2022]
Abstract
The transfer RNA (tRNA)-dependent pathway for lipid aminoacylation is a two-step pathway composed of (1) a tRNA aminoacylation step catalyzed by an aminoacyl-tRNA synthetase, forming a specific aa-tRNA, and (2) a tRNA-dependent transfer step in which the amino acid acylating the tRNA is transferred to an acceptor lipid. The latter step is catalyzed by a transferase located within the cytoplasmic membrane of certain bacteria. Lipid aminoacylation modifies the biochemical properties of the membrane and enhances resistance of some pathogens to various classes of antimicrobial agents and components of the innate immune response. Lipid aminoacylation has also been linked to increased virulence of various pathogenic bacteria. Inhibition of this mechanism would render pathogens more susceptible to existing drugs or to natural defenses of a host organism. Because lipid aminoacylation is widespread in many bacterial genera and absent from eukaryotes, and because the tRNA aminoacylation step of this pathway is also used in protein biosynthesis (a process essential for bacterial life), this pathway represents an attractive target for drug design. We have reconstituted the lipid aminoacylation pathway in vitro and optimized it for high-throughput screening of libraries of compounds to simultaneously identify inhibitors targeting each step of the pathway in a single assay.
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Affiliation(s)
- Christopher D Grube
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Hervé Roy
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
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Atila M, Luo Y. Profiling and tandem mass spectrometry analysis of aminoacylated phospholipids in Bacillus subtilis . F1000Res 2016; 5:121. [PMID: 26998233 PMCID: PMC4792211 DOI: 10.12688/f1000research.7842.2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/29/2016] [Indexed: 01/13/2023] Open
Abstract
Cationic modulation of the dominantly negative electrostatic structure of phospholipids plays an important role in bacterial response to changes in the environment. In addition to zwitterionic phosphatidylethanolamine, Gram-positive bacteria are also abundant in positively charged lysyl-phosphatidylglycerol. Increased amounts of both types of lipids render Gram-positive bacterial cells more resistant to cationic antibiotic peptides such as defensins. Lysyl and alanyl-phosphatidylglycerol as well as alanyl-cardiolipin have also been studied by mass spectroscopy. Phospholipids modified by other amino acids have been discovered by chemical analysis of the lipid lysate but have yet to be studied by mass spectroscopy. We exploited the high sensitivity of modern mass spectroscopy in searching for substructures in complex mixtures to establish a sensitive and thorough screen for aminoacylated phospholipids. The search for deprotonated aminoacyl anions in lipid extracted from
Bacillus subtilis strain 168 yielded strong evidence as well as relative abundance of aminoacyl-phosphatidylglycerols, which serves as a crude measure of the specificity of aminoacyl-phosphatidylglycerol synthase MprF. No aminoacyl-cardiolipin was found. More importantly, the second most abundant species in this category is D-alanyl-phosphatidylglycerol, suggesting a possible role in the D-alanylation pathway of wall- and lipo-teichoic acids.
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Affiliation(s)
- Metin Atila
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Canada
| | - Yu Luo
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Canada
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Steinbuch KB, Fridman M. Mechanisms of resistance to membrane-disrupting antibiotics in Gram-positive and Gram-negative bacteria. MEDCHEMCOMM 2016. [DOI: 10.1039/c5md00389j] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A diverse repertoire of mechanisms has evolved to confer resistance to bacterial membrane disrupting antimicrobial cationic amphiphiles.
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Affiliation(s)
- Kfir B. Steinbuch
- School of Chemistry
- Beverly Raymond Sackler Faculty of Exact Sciences
- Tel Aviv University
- Tel Aviv
- Israel
| | - Micha Fridman
- School of Chemistry
- Beverly Raymond Sackler Faculty of Exact Sciences
- Tel Aviv University
- Tel Aviv
- Israel
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29
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Smith AM, Harrison JS, Grube CD, Sheppe AEF, Sahara N, Ishii R, Nureki O, Roy H. tRNA-dependent alanylation of diacylglycerol and phosphatidylglycerol in Corynebacterium glutamicum. Mol Microbiol 2015; 98:681-93. [PMID: 26235234 DOI: 10.1111/mmi.13150] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2015] [Indexed: 12/12/2022]
Abstract
Aminoacyl-phosphatidylglycerol synthases (aaPGSs) are membrane proteins that utilize aminoacylated tRNAs to modify membrane lipids with amino acids. Aminoacylation of membrane lipids alters the biochemical properties of the cytoplasmic membrane and enables bacteria to adapt to changes in environmental conditions. aaPGSs utilize alanine, lysine and arginine as modifying amino acids, and the primary lipid recipients have heretofore been defined as phosphatidylglycerol (PG) and cardiolipin. Here we identify a new pathway for lipid aminoacylation, conserved in many Actinobacteria, which results in formation of Ala-PG and a novel alanylated lipid, Alanyl-diacylglycerol (Ala-DAG). Ala-DAG formation in Corynebacterium glutamicum is dependent on the activity of an aaPGS homolog, whereas formation of Ala-PG requires the same enzyme acting in concert with a putative esterase encoded upstream. The presence of alanylated lipids is sufficient to enhance the bacterial fitness of C. glutamicum cultured in the presence of certain antimicrobial agents, and elucidation of this system expands the known repertoire of membrane lipids acting as substrates for amino acid modification in bacterial cells.
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Affiliation(s)
- Angela M Smith
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32826, USA
| | - Jesse S Harrison
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32826, USA
| | - Christopher D Grube
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32826, USA
| | - Austin E F Sheppe
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32826, USA
| | - Nahoko Sahara
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, 113-0033, Tokyo, Japan.,RIKEN Advanced Science Institute, Wako-shi, 351-0198, Saitama, Japan
| | - Ryohei Ishii
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, 113-0033, Tokyo, Japan.,RIKEN Advanced Science Institute, Wako-shi, 351-0198, Saitama, Japan
| | - Osamu Nureki
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, 113-0033, Tokyo, Japan.,RIKEN Advanced Science Institute, Wako-shi, 351-0198, Saitama, Japan
| | - Hervé Roy
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32826, USA
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Structures of two bacterial resistance factors mediating tRNA-dependent aminoacylation of phosphatidylglycerol with lysine or alanine. Proc Natl Acad Sci U S A 2015; 112:10691-6. [PMID: 26261323 DOI: 10.1073/pnas.1511167112] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cytoplasmic membrane is probably the most important physical barrier between microbes and the surrounding habitat. Aminoacylation of the polar head group of the phospholipid phosphatidylglycerol (PG) catalyzed by Ala-tRNA(Ala)-dependent alanyl-phosphatidylglycerol synthase (A-PGS) or by Lys-tRNA(Lys)-dependent lysyl-phosphatidylglycerol synthase (L-PGS) enables bacteria to cope with cationic peptides that are harmful to the integrity of the cell membrane. Accordingly, these synthases also have been designated as multiple peptide resistance factors (MprF). They consist of a separable C-terminal catalytic domain and an N-terminal transmembrane flippase domain. Here we present the X-ray crystallographic structure of the catalytic domain of A-PGS from the opportunistic human pathogen Pseudomonas aeruginosa. In parallel, the structure of the related lysyl-phosphatidylglycerol-specific L-PGS domain from Bacillus licheniformis in complex with the substrate analog L-lysine amide is presented. Both proteins reveal a continuous tunnel that allows the hydrophobic lipid substrate PG and the polar aminoacyl-tRNA substrate to access the catalytic site from opposite directions. Substrate recognition of A-PGS versus L-PGS was investigated using misacylated tRNA variants. The structural work presented here in combination with biochemical experiments using artificial tRNA or artificial lipid substrates reveals the tRNA acceptor stem, the aminoacyl moiety, and the polar head group of PG as the main determinants for substrate recognition. A mutagenesis approach yielded the complementary amino acid determinants of tRNA interaction. These results have broad implications for the design of L-PGS and A-PGS inhibitors that could render microbial pathogens more susceptible to antimicrobial compounds.
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31
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Abstract
The dramatic rise in the incidence of antibiotic resistance demands that new therapeutic options will have to be developed. One potentially interesting class of antimicrobials are the modified bacteriocins termed lantibiotics, which are bacterially produced, posttranslationally modified, lanthionine/methyllanthionine-containing peptides. It is interesting that low levels of resistance have been reported for lantibiotics compared with commercial antibiotics. Given that there are very few examples of naturally occurring lantibiotic resistance, attempts have been made to deliberately induce resistance phenotypes in order to investigate this phenomenon. Mechanisms that hinder the action of lantibiotics are often innate systems that react to the presence of any cationic peptides/proteins or ones which result from cell well damage, rather than being lantibiotic specific. Such resistance mechanisms often arise due to altered gene regulation following detection of antimicrobials/cell wall damage by sensory proteins at the membrane. This facilitates alterations to the cell wall or changes in the composition of the membrane. Other general forms of resistance include the formation of spores or biofilms, which are a common mechanistic response to many classes of antimicrobials. In rare cases, bacteria have been shown to possess specific antilantibiotic mechanisms. These are often species specific and include the nisin lytic protein nisinase and the phenomenon of immune mimicry.
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Affiliation(s)
- Lorraine A Draper
- School of Microbiology, University College Cork, Cork, Ireland Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
| | - Paul D Cotter
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland
| | - Colin Hill
- School of Microbiology, University College Cork, Cork, Ireland Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
| | - R Paul Ross
- School of Microbiology, University College Cork, Cork, Ireland Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
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Mutations associated with reduced surotomycin susceptibility in Clostridium difficile and Enterococcus species. Antimicrob Agents Chemother 2015; 59:4139-47. [PMID: 25941217 DOI: 10.1128/aac.00526-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 04/24/2015] [Indexed: 12/12/2022] Open
Abstract
Clostridium difficile infection (CDI) is an urgent public health concern causing considerable clinical and economic burdens. CDI can be treated with antibiotics, but recurrence of the disease following successful treatment of the initial episode often occurs. Surotomycin is a rapidly bactericidal cyclic lipopeptide antibiotic that is in clinical trials for CDI treatment and that has demonstrated superiority over vancomycin in preventing CDI relapse. Surotomycin is a structural analogue of the membrane-active antibiotic daptomycin. Previously, we utilized in vitro serial passage experiments to derive C. difficile strains with reduced surotomycin susceptibilities. The parent strains used included ATCC 700057 and clinical isolates from the restriction endonuclease analysis (REA) groups BI and K. Serial passage experiments were also performed with vancomycin-resistant and vancomycin-susceptible Enterococcus faecium and Enterococcus faecalis. The goal of this study is to identify mutations associated with reduced surotomycin susceptibility in C. difficile and enterococci. Illumina sequence data generated for the parent strains and serial passage isolates were compared. We identified nonsynonymous mutations in genes coding for cardiolipin synthase in C. difficile ATCC 700057, enoyl-(acyl carrier protein) reductase II (FabK) and cell division protein FtsH2 in C. difficile REA type BI, and a PadR family transcriptional regulator in C. difficile REA type K. Among the 4 enterococcal strain pairs, 20 mutations were identified, and those mutations overlap those associated with daptomycin resistance. These data give insight into the mechanism of action of surotomycin against C. difficile, possible mechanisms for resistance emergence during clinical use, and the potential impacts of surotomycin therapy on intestinal enterococci.
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Sohlenkamp C, Geiger O. Bacterial membrane lipids: diversity in structures and pathways. FEMS Microbiol Rev 2015; 40:133-59. [DOI: 10.1093/femsre/fuv008] [Citation(s) in RCA: 571] [Impact Index Per Article: 63.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/05/2015] [Indexed: 12/22/2022] Open
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The lipid-modifying multiple peptide resistance factor is an oligomer consisting of distinct interacting synthase and flippase subunits. mBio 2015; 6:mBio.02340-14. [PMID: 25626904 PMCID: PMC4324311 DOI: 10.1128/mbio.02340-14] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
UNLABELLED Phospholipids are synthesized at the inner leaflet of the bacterial cytoplasmic membrane but have to be translocated to the outer leaflet to maintain membrane lipid bilayer composition and structure. Even though phospholipid flippases have been proposed to exist in bacteria, only one such protein, MprF, has been described. MprF is a large integral membrane protein found in several prokaryotic phyla, whose C terminus modifies phosphatidylglycerol (PG), the most common bacterial phospholipid, with lysine or alanine to modulate the membrane surface charge and, as a consequence, confer resistance to cationic antimicrobial agents such as daptomycin. In addition, MprF is a flippase for the resulting lipids, Lys-PG or Ala-PG. Here we demonstrate that the flippase activity resides in the N-terminal 6 to 8 transmembrane segments of the Staphylococcus aureus MprF and that several conserved, charged amino acids and a proline residue are crucial for flippase function. MprF protects S. aureus against the membrane-active antibiotic daptomycin only when both domains are present, but the two parts do not need to be covalently linked and can function in trans. The Lys-PG synthase and flippase domains were each found to homo-oligomerize and also to interact with each other, which illustrates how the two functional domains may act together. Moreover, full-length MprF proteins formed oligomers, indicating that MprF functions as a dimer or larger oligomer. Together our data reveal how bacterial phospholipid flippases may function in the context of lipid biosynthetic processes. IMPORTANCE Bacterial cytoplasmic membranes are crucial for maintaining and protecting cellular integrity. For instance, they have to cope with membrane-damaging agents such as cationic antimicrobial peptides (CAMPs) produced by competing bacteria (bacteriocins), secreted by eukaryotic host cells (defensins), or used as antimicrobial therapy (daptomycin). The MprF protein is found in many Gram-positive, Gram-negative, and even archaeal commensals or pathogens and confers resistance to CAMPs by modifying anionic phospholipids with amino acids, thereby compromising the membrane interaction of CAMPs. Here we describe how MprF does not only modify phospholipids but uses an additional, distinct domain for translocating the resulting lysinylated phospholipids to the outer leaflet of the membrane. We reveal critical details for the structure and function of MprF, the first dedicated prokaryotic phospholipid flippase, which may pave the way for targeting MprF with new antimicrobials that would not kill bacteria but sensitize them to antibiotics and innate host defense molecules.
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Ronneau S, Moussa S, Barbier T, Conde-Álvarez R, Zuniga-Ripa A, Moriyon I, Letesson JJ. Brucella, nitrogen and virulence. Crit Rev Microbiol 2014; 42:507-25. [PMID: 25471320 DOI: 10.3109/1040841x.2014.962480] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The brucellae are α-Proteobacteria causing brucellosis, an important zoonosis. Although multiplying in endoplasmic reticulum-derived vacuoles, they cause no cell death, suggesting subtle but efficient use of host resources. Brucellae are amino-acid prototrophs able to grow with ammonium or use glutamate as the sole carbon-nitrogen source in vitro. They contain more than twice amino acid/peptide/polyamine uptake genes than the amino-acid auxotroph Legionella pneumophila, which multiplies in a similar vacuole, suggesting a different nutritional strategy. During these two last decades, many mutants of key actors in nitrogen metabolism (transporters, enzymes, regulators, etc.) have been described to be essential for full virulence of brucellae. Here, we review the genomic and experimental data on Brucella nitrogen metabolism and its connection with virulence. An analysis of various aspects of this metabolism (transport, assimilation, biosynthesis, catabolism, respiration and regulation) has highlighted differences and similarities in nitrogen metabolism with other α-Proteobacteria. Together, these data suggest that, during their intracellular life cycle, the brucellae use various nitrogen sources for biosynthesis, catabolism and respiration following a strategy that requires prototrophy and a tight regulation of nitrogen use.
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Affiliation(s)
| | - Simon Moussa
- a UNamur, URBM 61 rue de Bruxelles , Namur , Belgium and
| | | | - Raquel Conde-Álvarez
- b Departamento de Microbiología , Edificio de Investigación, Universidad de Navarra , Pamplona , Spain
| | - Amaia Zuniga-Ripa
- b Departamento de Microbiología , Edificio de Investigación, Universidad de Navarra , Pamplona , Spain
| | - Ignacio Moriyon
- b Departamento de Microbiología , Edificio de Investigación, Universidad de Navarra , Pamplona , Spain
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Nawrocki KL, Crispell EK, McBride SM. Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria. Antibiotics (Basel) 2014; 3:461-92. [PMID: 25419466 PMCID: PMC4239024 DOI: 10.3390/antibiotics3040461] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 09/25/2014] [Accepted: 09/28/2014] [Indexed: 01/09/2023] Open
Abstract
Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis.
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Affiliation(s)
- Kathryn L Nawrocki
- Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Rd, Atlanta, GA 30322, USA; (K.L.N.); (E.K.C.)
| | - Emily K Crispell
- Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Rd, Atlanta, GA 30322, USA; (K.L.N.); (E.K.C.)
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Rd, Atlanta, GA 30322, USA; (K.L.N.); (E.K.C.)
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A genetic screen in Myxococcus xanthus identifies mutants that uncouple outer membrane exchange from a downstream cellular response. J Bacteriol 2014; 196:4324-32. [PMID: 25266387 DOI: 10.1128/jb.02217-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Upon physical contact with sibling cells, myxobacteria transiently fuse their outer membranes (OMs) and exchange OM proteins and lipids. From previous work, TraA and TraB were identified to be essential factors for OM exchange (OME) in donor and recipient cells. To define the genetic complexity of OME, we carried out a comprehensive forward genetic screen. The screen was based on the observation that Myxococcus xanthus nonmotile cells, by a Tra-dependent mechanism, block swarm expansion of motile cells when mixed. Thus, mutants defective in OME or a downstream responsive pathway were readily identified as escape flares from mixed inocula seeded on agar. This screen was surprisingly powerful, as we found >50 mutants defective in OME. Importantly, all of the mutations mapped to the traAB operon, suggesting that there may be few, if any, proteins besides TraA and TraB directly required for OME. We also found a second and phenotypically different class of mutants that exhibited wild-type OME but were defective in a responsive pathway. This pathway is postulated to control inner membrane homeostasis by covalently attaching amino acids to phospholipids. The identified proteins are homologous to the Staphylococcus aureus MprF protein, which is involved in membrane adaptation and antibiotic resistance. Interestingly, we also found that a small number of nonmotile cells were sufficient to block the swarming behavior of a large gliding-proficient population. This result suggests that an OME-derived signal could be amplified from a few nonmotile producers to act on many responder cells.
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38
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Giessen TW, Marahiel MA. The tRNA-dependent biosynthesis of modified cyclic dipeptides. Int J Mol Sci 2014; 15:14610-31. [PMID: 25196600 PMCID: PMC4159871 DOI: 10.3390/ijms150814610] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 08/01/2014] [Accepted: 08/18/2014] [Indexed: 01/28/2023] Open
Abstract
In recent years it has become apparent that aminoacyl-tRNAs are not only crucial components involved in protein biosynthesis, but are also used as substrates and amino acid donors in a variety of other important cellular processes, ranging from bacterial cell wall biosynthesis and lipid modification to protein turnover and secondary metabolite assembly. In this review, we focus on tRNA-dependent biosynthetic pathways that generate modified cyclic dipeptides (CDPs). The essential peptide bond-forming catalysts responsible for the initial generation of a CDP-scaffold are referred to as cyclodipeptide synthases (CDPSs) and use loaded tRNAs as their substrates. After initially discussing the phylogenetic distribution and organization of CDPS gene clusters, we will focus on structural and catalytic properties of CDPSs before turning to two recently characterized CDPS-dependent pathways that assemble modified CDPs. Finally, possible applications of CDPSs in the rational design of structural diversity using combinatorial biosynthesis will be discussed before concluding with a short outlook.
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Affiliation(s)
- Tobias W Giessen
- Department of Chemistry/Biochemistry and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, Hans-Meerwein-Strasse-4, 35032 Marburg, Germany.
| | - Mohamed A Marahiel
- Department of Chemistry/Biochemistry and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, Hans-Meerwein-Strasse-4, 35032 Marburg, Germany.
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Abstract
Transfer RNAs (tRNA) are best known for their role as adaptors during translation of the genetic code. Beyond their canonical role during protein biosynthesis, tRNAs also perform additional functions in both prokaryotes and eukaryotes for example in regulating gene expression. Aminoacylated tRNAs have also been implicated as substrates for non-ribosomal peptide bond formation, post-translational protein labeling, modification of phospholipids in the cell membrane, and antibiotic biosyntheses. Most recently tRNA fragments, or tRFs, have also been recognized to play regulatory roles. Here, we examine in more detail some of the new functions emerging for tRNA in a variety of cellular processes outside of protein synthesis.
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Affiliation(s)
- Medha Raina
- Department of Microbiology, The Ohio State Biochemistry Program, The Ohio State University Columbus, OH, USA ; Center for RNA Biology, The Ohio State University Columbus, OH, USA
| | - Michael Ibba
- Department of Microbiology, The Ohio State Biochemistry Program, The Ohio State University Columbus, OH, USA ; Center for RNA Biology, The Ohio State University Columbus, OH, USA
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40
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Custer JE, Goddard BD, Matter SF, Kaneshiro ES. The relative proportions of different lipid classes and their fatty acid compositions change with culture age in the cariogenic dental pathogen Streptococcus mutans UA159. Lipids 2014; 49:543-54. [PMID: 24748493 DOI: 10.1007/s11745-014-3904-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/28/2014] [Indexed: 11/27/2022]
Abstract
The oral cariogenic bacterial pathogen Streptococcus mutans strain UA159 has become an important research organism strain since its genome was sequenced. However, there is a paucity of information on its lipidome using direct analytical biochemical approaches. We here report on comprehensive analyses of the major lipid classes and their fatty acids in cells grown in batch standing cultures. Using 2-D high-performance thin-layer chromatography lipid class composition changes were detected with culture age. More lipid components were detected in the stationary-phase compared to log-phase cells. The major lipids identified included 1,3-bis(sn-3'-phosphatidyl)-sn-glycerol (phosphatidylglycerol), 1,3-diphosphatidylglycerol (cardiolipin), aminoacyl-phosphatidylglycerol, monoglucosyldiacylglycerol, diglucosyldiacylglycerol, diglucosylmonoacylglycerol and, glycerophosphoryldiglucosyldiacylglycerol. Culture age also affected the fatty acid composition of the total polar lipid fraction. Thus, the major lipid classes detected in log-phase and stationary-phase cells were isolated and their fatty acids were analyzed by gas-liquid chromatography to determine the basis for the fatty acid compositional changes in the total polar lipid fraction. The analyses showed that the relative proportions of these acids changed with culture age within individual lipid classes. Hence fatty acid changes in the total polar lipid fraction reflected changes in both lipid class composition and fatty acid compositions within individual lipid classes.
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Affiliation(s)
- Jenny E Custer
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, 45221-0006, USA
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41
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Goldfine H. Charge counter charge: bacterial response to antimicrobial cationic peptides and more. Virulence 2014; 5:451-3. [PMID: 24705072 PMCID: PMC4063804 DOI: 10.4161/viru.28662] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- Howard Goldfine
- Department of Microbiology; Perelman School of Medicine; University of Pennsylvania; Philadelphia, PA USA
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42
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Dare K, Shepherd J, Roy H, Seveau S, Ibba M. LysPGS formation in Listeria monocytogenes has broad roles in maintaining membrane integrity beyond antimicrobial peptide resistance. Virulence 2014; 5:534-46. [PMID: 24603093 DOI: 10.4161/viru.28359] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Listeria monocytogenes is an intracellular, foodborne gastrointestinal pathogen that is primarily responsible for causing listeriosis or food poisoning in otherwise healthy individuals. Infections that arise during pregnancy or within immune compromised individuals are much more serious resulting in the risk of fetal termination or fetal fatality postpartum in the former and septicemia or meningitis with a 20% fatality rate in the latter. While the roles of internalin proteins and listeriolysin-O in the infection process are well characterized, the specific roles of lysine-modified phospholipids in the membrane of L. monocytogenes are not. Investigation into the lipid bilayer composition of L. monocytogenes indicated that the overall proportions of lipids, including lysylcardiolipin and lysylphosphatidylglycerol (LysPG), vary with growth temperature and growth phase. In addition, we demonstrate that LysPG formation is essential for L. monocytogenes survival in the presence of increased osmolytic stress but has no effect on bacterial adherence, invasion or survival in the presence of physiologically relevant concentrations of human neutrophil peptide (HNP-1). In the absence of LysPG synthesis, L. monocytogenes unexpectedly retained flagellum-mediated motility at 37 °C. Taken together, these findings show that LysPG formation in L. monocytogenes has broader functions in virulence and survival beyond its known role in the modification of membrane potential previously observed in other bacteria.
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Affiliation(s)
- Kiley Dare
- Department of Microbiology; The Ohio State University; Columbus, OH USA
| | - Jennifer Shepherd
- Department of Microbiology; The Ohio State University; Columbus, OH USA
| | - Hervé Roy
- Department of Microbiology; The Ohio State University; Columbus, OH USA
| | - Stephanie Seveau
- Department of Microbiology; The Ohio State University; Columbus, OH USA
| | - Michael Ibba
- Department of Microbiology; The Ohio State University; Columbus, OH USA; Ohio State Biochemistry Program; Center for RNA Biology; The Ohio State University; Columbus, OH USA
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43
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Focal targeting by human β-defensin 2 disrupts localized virulence factor assembly sites in Enterococcus faecalis. Proc Natl Acad Sci U S A 2013; 110:20230-5. [PMID: 24191013 DOI: 10.1073/pnas.1319066110] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Virulence factor secretion and assembly occurs at spatially restricted foci in some Gram-positive bacteria. Given the essentiality of the general secretion pathway in bacteria and the contribution of virulence factors to disease progression, the foci that coordinate these processes are attractive antimicrobial targets. In this study, we show in Enterococcus faecalis that SecA and Sortase A, required for the attachment of virulence factors to the cell wall, localize to discrete domains near the septum or nascent septal site as the bacteria proceed through the cell cycle. We also demonstrate that cationic human β-defensins interact with E. faecalis at discrete septal foci, and this exposure disrupts sites of localized secretion and sorting. Modification of anionic lipids by multiple peptide resistance factor, a protein that confers antimicrobial peptide resistance by electrostatic repulsion, renders E. faecalis more resistant to killing by defensins and less susceptible to focal targeting by the cationic antimicrobial peptides. These data suggest a paradigm in which focal targeting by antimicrobial peptides is linked to their killing efficiency and to disruption of virulence factor assembly.
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Shepherd J, Ibba M. Direction of aminoacylated transfer RNAs into antibiotic synthesis and peptidoglycan-mediated antibiotic resistance. FEBS Lett 2013; 587:2895-904. [PMID: 23907010 DOI: 10.1016/j.febslet.2013.07.036] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 07/17/2013] [Indexed: 12/30/2022]
Abstract
Prokaryotic aminoacylated-transfer RNAs often need to be efficiently segregated between translation and other cellular biosynthetic pathways. Many clinically relevant bacteria, including Streptococcus pneumoniae, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa direct some aminoacylated-tRNA species into peptidoglycan biosynthesis and/or membrane phospholipid modification. Subsequent indirect peptidoglycan cross-linkage or change in membrane permeability is often a prerequisite for high-level antibiotic resistance. In Streptomycetes, aminoacylated-tRNA species are used for antibiotic synthesis as well as antibiotic resistance. The direction of coding aminoacylated-tRNA molecules away from translation and into antibiotic resistance and synthesis pathways are discussed in this review.
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Affiliation(s)
- Jennifer Shepherd
- Department of Microbiology and Center for RNA Biology, Ohio State University, Columbus, OH 43210-1292, USA
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Parsons JB, Rock CO. Bacterial lipids: metabolism and membrane homeostasis. Prog Lipid Res 2013; 52:249-76. [PMID: 23500459 PMCID: PMC3665635 DOI: 10.1016/j.plipres.2013.02.002] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 02/27/2013] [Accepted: 02/28/2013] [Indexed: 11/29/2022]
Abstract
Membrane lipid homeostasis is a vital facet of bacterial cell physiology. For decades, research in bacterial lipid synthesis was largely confined to the Escherichia coli model system. This basic research provided a blueprint for the biochemistry of lipid metabolism that has largely defined the individual steps in bacterial fatty acid and phospholipids synthesis. The advent of genomic sequencing has revealed a surprising amount of diversity in the genes, enzymes and genetic organization of the components responsible for bacterial lipid synthesis. Although the chemical steps in fatty acid synthesis are largely conserved in bacteria, there are surprising differences in the structure and cofactor requirements for the enzymes that perform these reactions in Gram-positive and Gram-negative bacteria. This review summarizes how the explosion of new information on the diversity of biochemical and genetic regulatory mechanisms has impacted our understanding of bacterial lipid homeostasis. The potential and problems of developing therapeutics that block pathogen phospholipid synthesis are explored and evaluated. The study of bacterial lipid metabolism continues to be a rich source for new biochemistry that underlies the variety and adaptability of bacterial life styles.
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Affiliation(s)
- Joshua B Parsons
- Department of Infectious Diseases, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
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Smith AM, Harrison JS, Sprague KM, Roy H. A conserved hydrolase responsible for the cleavage of aminoacylphosphatidylglycerol in the membrane of Enterococcus faecium. J Biol Chem 2013; 288:22768-76. [PMID: 23793054 DOI: 10.1074/jbc.m113.484402] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aminoacylphosphatidylglycerol synthases (aaPGSs) are enzymes that transfer amino acids from aminoacyl-tRNAs (aa-tRNAs) to phosphatidylglycerol (PG) to form aa-PG in the cytoplasmic membrane of bacteria. aa-PGs provide bacteria with resistance to a range of antimicrobial compounds and stress conditions. Enterococcus faecium encodes a triple-specific aaPGS (RakPGS) that utilizes arginine, alanine, and lysine as substrates. Here we identify a novel hydrolase (AhyD), encoded immediately adjacent to rakPGS in E. faecium, which is responsible for the hydrolysis of aa-PG. The genetic synteny of aaPGS and ahyD is conserved in >60 different bacterial species. Deletion of ahyD in E. faecium resulted in increased formation of Ala-PG and Lys-PG and increased sensitivity to bacitracin. Our results suggest that AhyD and RakPGS act together to maintain optimal levels of aa-PG in the bacterial membrane to confer resistance to certain antimicrobial compounds and stress conditions.
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Affiliation(s)
- Angela M Smith
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32826, USA
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47
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Arendt W, Groenewold MK, Hebecker S, Dickschat JS, Moser J. Identification and characterization of a periplasmic aminoacyl-phosphatidylglycerol hydrolase responsible for Pseudomonas aeruginosa lipid homeostasis. J Biol Chem 2013; 288:24717-30. [PMID: 23792962 DOI: 10.1074/jbc.m113.482935] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Specific aminoacylation of the phospholipid phosphatidylglycerol (PG) with alanine (or with lysine) was shown to render various organisms less susceptible to antimicrobial agents and environmental stresses. In this study, we make use of the opportunistic pathogen Pseudomonas aeruginosa to decode ORF PA0919-dependent lipid homeostasis. Analysis of the polar lipid content of the deletion mutant ΔPA0919 indicated significantly enlarged levels of alanyl-PG. The resulting phenotype manifested an increased susceptibility to several antimicrobial compounds when compared with the wild type. A pH-dependent PA0919 promoter located within the upstream gene PA0920 was identified. Localization experiments demonstrated that the PA0919 protein is anchored to the periplasmic surface of the inner bacterial membrane. The recombinant overproduction of wild type and several site-directed mutant proteins in the periplasm of Escherichia coli facilitated a detailed in vitro analysis of the enzymatic PA0919 function. A series of artificial substrates (p-nitrophenyl esters of various amino acids/aliphatic acids) indicated enzymatic hydrolysis of the alanine, glycine, or lysine moiety of the respective ester substrates. Our final in vitro activity assay in the presence of radioactively labeled alanyl-PG then revealed hydrolysis of the aminoacyl linkage, resulting in the formation of alanine and PG. Consequently, PA0919 was termed alanyl-PG hydrolase. The elucidated enzymatic activity implies a new regulatory circuit for the appropriate tuning of cellular alanyl-PG concentrations.
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Affiliation(s)
- Wiebke Arendt
- Institute for Microbiology, Technische Universität Braunschweig, 38106 Braunschweig, Germany
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48
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Rogers TE, Ataide SF, Dare K, Katz A, Seveau S, Roy H, Ibba M. A pseudo-tRNA modulates antibiotic resistance in Bacillus cereus. PLoS One 2012; 7:e41248. [PMID: 22815980 PMCID: PMC3399842 DOI: 10.1371/journal.pone.0041248] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/19/2012] [Indexed: 01/18/2023] Open
Abstract
Bacterial genomic islands are often flanked by tRNA genes, which act as sites for the integration of foreign DNA into the host chromosome. For example, Bacillus cereus ATCC14579 contains a pathogenicity island flanked by a predicted pseudo-tRNA, tRNAOther, which does not function in translation. Deletion of tRNAOther led to significant changes in cell wall morphology and antibiotic resistance and was accompanied by changes in the expression of numerous genes involved in oxidative stress responses, several of which contain significant complementarities to sequences surrounding tRNAOther. This suggested that tRNAOther might be expressed as part of a larger RNA, and RACE analysis subsequently confirmed the existence of several RNA species that significantly extend both the 3′ and 5′-ends of tRNAOther. tRNAOther expression levels were found to be responsive to changes in extracellular iron concentration, consistent with the presence of three putative ferric uptake regulator (Fur) binding sites in the 5′ leader region of one of these larger RNAs. Taken together with previous data, this study now suggests that tRNAOther may function by providing a tRNA-like structural element within a larger regulatory RNA. These findings illustrate that while integration of genomic islands often leaves tRNA genes intact and functional, in other instances inactivation may generate tRNA-like elements that are then recruited to other functions in the cell.
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Affiliation(s)
- Theresa E. Rogers
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
| | - Sandro F. Ataide
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
| | - Kiley Dare
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
| | - Assaf Katz
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
| | - Stephanie Seveau
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
| | - Hervé Roy
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, United States of America
| | - Michael Ibba
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
- Ohio State Biochemistry Program, Ohio State University, Columbus, Ohio, United States of America
- Center for RNA Biology, Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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Bao Y, Sakinc T, Laverde D, Wobser D, Benachour A, Theilacker C, Hartke A, Huebner J. Role of mprF1 and mprF2 in the pathogenicity of Enterococcus faecalis. PLoS One 2012; 7:e38458. [PMID: 22723861 PMCID: PMC3377626 DOI: 10.1371/journal.pone.0038458] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 05/05/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Enterococcus faecalis is one of the leading causes of nosocomial infections. Due to its innate and acquired resistance to most antibiotics, identification of new targets for antimicrobial treatment of E. faecalis is a high priority. The multiple peptide resistance factor MprF, which was first described in Staphylococcus aureus, modifies phosphatidylglycerol with lysin and reduces the negative charge of the membrane, thus increasing resistance to cationic antimicrobial peptides. We studied the effect of mprF in E. faecalis regarding influence on bacterial physiology and virulence. RESULTS Two putative mprF paralogs (mprF1 and mprF2) were identified in E. faecalis by BLAST search using the well-described S. aureus gene as a lead. Two deletion mutants in E. faecalis 12030 were created by homologous recombination. Analysis of both mutants by thin-layer chromatography showed that inactivation of mprF2 abolishes the synthesis of three distinct amino-phosphatidylglycerols (PGs). In contrast, deletion of mprF1 did not interfere with the biosynthesis of amino-PG. Inactivation of mprF2 increased susceptibility against several antimicrobial peptides and resulted in a 42% increased biofilm formation compared to wild-type mprF. However, resistance to opsonic killing was increased in the mutant, while virulence in a mouse bacteremia model was unchanged. CONCLUSION Our data suggest that only mprF2 is involved in the aminoacylation of PG in enterococci, and is probably responsible for synthesis of Lys-PG, Ala-PG, and Arg-PG, while mprF1 does not seem to have a role in aminoacylation. As in other Gram-positive pathogens, aminoacylation through MprF2 increases resistance against cationic antimicrobial peptides. Unlike mprF found in other bacteria, mprF2 does not seem to be a major virulence factor in enterococci.
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Affiliation(s)
- Yinyin Bao
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
- EA4655 U2RM Stress/Virulence, Université de Caen Basse-Normandie, Caen, France
| | - Tuerkan Sakinc
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Diana Laverde
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Dominique Wobser
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Abdellah Benachour
- EA4655 U2RM Stress/Virulence, Université de Caen Basse-Normandie, Caen, France
| | - Christian Theilacker
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Axel Hartke
- EA4655 U2RM Stress/Virulence, Université de Caen Basse-Normandie, Caen, France
| | - Johannes Huebner
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
- * E-mail:
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50
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Alanyl-phosphatidylglycerol and lysyl-phosphatidylglycerol are translocated by the same MprF flippases and have similar capacities to protect against the antibiotic daptomycin in Staphylococcus aureus. Antimicrob Agents Chemother 2012; 56:3492-7. [PMID: 22491694 DOI: 10.1128/aac.00370-12] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lysinylation of negatively charged phosphatidylglycerol by MprF proteins reduces the affinity of cationic antimicrobial peptides (CAMPs) for bacterial cytoplasmic membranes and reduces the susceptibility of several Gram-positive bacterial pathogens to CAMPs. MprF of Staphylococcus aureus encompasses a lysyl-phosphatidylglycerol (Lys-PG) synthase and a Lys-PG flippase domain. In contrast, Clostridium perfringens encodes two MprF homologs which specifically synthesize alanyl-phosphatidylglycerol (Ala-PG) or Lys-PG, while only the Lys-PG synthase is fused to a putative flippase domain. It remains unknown whether cationic Lys-PG and zwitterionic Ala-PG differ in their capacities to be translocated by MprF flippases and if both can reduce CAMP susceptibility in Gram-positive bacteria. By expressing the MprF proteins of C. perfringens in an S. aureus mprF deletion mutant, we found that both lipids can be efficiently produced in S. aureus. Simultaneous expression of the Lys-PG and Ala-PG synthases led to the production of both lipids and slightly increased the overall amounts of aminoacyl phospholipids. Ala-PG production by the corresponding C. perfringens enzyme did not affect susceptibility to CAMPs such as nisin and gallidermin or to the CAMP-like antibiotic daptomycin. However, coexpression of the Ala-PG synthase with flippase domains of Lys-PG synthesizing MprF proteins led to a wild-type level of daptomycin susceptibility, indicating that Ala-PG can also protect bacterial membranes against daptomycin and suggesting that Lys-PG flippases can also translocate the related lipid Ala-PG. Thus, bacterial aminoacyl phospholipid flippases exhibit more relaxed substrate specificity and Ala-PG and Lys-PG are more similar in their capacities to modulate membrane functions than anticipated.
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