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Burkholderia cenocepacia Lipopolysaccharide Modification and Flagellin Glycosylation Affect Virulence but Not Innate Immune Recognition in Plants. mBio 2015; 6:e00679. [PMID: 26045541 PMCID: PMC4462625 DOI: 10.1128/mbio.00679-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
UNLABELLED Burkholderia cenocepacia causes opportunistic infections in plants, insects, animals, and humans, suggesting that "virulence" depends on the host and its innate susceptibility to infection. We hypothesized that modifications in key bacterial molecules recognized by the innate immune system modulate host responses to B. cenocepacia. Indeed, modification of lipopolysaccharide (LPS) with 4-amino-4-deoxy-L-arabinose and flagellin glycosylation attenuates B. cenocepacia infection in Arabidopsis thaliana and Galleria mellonella insect larvae. However, B. cenocepacia LPS and flagellin triggered rapid bursts of nitric oxide and reactive oxygen species in A. thaliana leading to activation of the PR-1 defense gene. These responses were drastically reduced in plants with fls2 (flagellin FLS2 host receptor kinase), Atnoa1 (nitric oxide-associated protein 1), and dnd1-1 (reduced production of nitric oxide) null mutations. Together, our results indicate that LPS modification and flagellin glycosylation do not affect recognition by plant receptors but are required for bacteria to establish overt infection. IMPORTANCE Virulence and pathogenicity are properties ascribed to microbes, which actually require careful consideration of the host. Using the term "pathogen" to define a microbe without considering its host has recently been debated, since the microbe's capacity to establish a niche in a given host is a critical feature associated with infection. Opportunistic bacteria are a perfect example of microbes whose ability to cause disease is intimately related to the host's ability to recognize and respond to the infection. Here, we use the opportunistic bacterium Burkholderia cenocepacia and the host plant Arabidopsis thaliana to investigate the role of bacterial surface molecules, namely, lipopolysaccharide and flagellin, in contributing to infection and also in eliciting a host response. We reveal that both molecules can be modified by glycosylation, and although the modifications are critical for the bacteria to establish an infection, they do not impact the host's ability to recognize the pathogen.
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Podnecky NL, Rhodes KA, Schweizer HP. Efflux pump-mediated drug resistance in Burkholderia. Front Microbiol 2015; 6:305. [PMID: 25926825 PMCID: PMC4396416 DOI: 10.3389/fmicb.2015.00305] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 03/27/2015] [Indexed: 12/17/2022] Open
Abstract
Several members of the genus Burkholderia are prominent pathogens. Infections caused by these bacteria are difficult to treat because of significant antibiotic resistance. Virtually all Burkholderia species are also resistant to polymyxin, prohibiting use of drugs like colistin that are available for treatment of infections caused by most other drug resistant Gram-negative bacteria. Despite clinical significance and antibiotic resistance of Burkholderia species, characterization of efflux pumps lags behind other non-enteric Gram-negative pathogens such as Acinetobacter baumannii and Pseudomonas aeruginosa. Although efflux pumps have been described in several Burkholderia species, they have been best studied in Burkholderia cenocepacia and B. pseudomallei. As in other non-enteric Gram-negatives, efflux pumps of the resistance nodulation cell division (RND) family are the clinically most significant efflux systems in these two species. Several efflux pumps were described in B. cenocepacia, which when expressed confer resistance to clinically significant antibiotics, including aminoglycosides, chloramphenicol, fluoroquinolones, and tetracyclines. Three RND pumps have been characterized in B. pseudomallei, two of which confer either intrinsic or acquired resistance to aminoglycosides, macrolides, chloramphenicol, fluoroquinolones, tetracyclines, trimethoprim, and in some instances trimethoprim+sulfamethoxazole. Several strains of the host-adapted B. mallei, a clone of B. pseudomallei, lack AmrAB-OprA, and are therefore aminoglycoside and macrolide susceptible. B. thailandensis is closely related to B. pseudomallei, but non-pathogenic to humans. Its pump repertoire and ensuing drug resistance profile parallels that of B. pseudomallei. An efflux pump in B. vietnamiensis plays a significant role in acquired aminoglycoside resistance. Summarily, efflux pumps are significant players in Burkholderia drug resistance.
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Affiliation(s)
- Nicole L Podnecky
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biological Sciences, Colorado State University Fort Collins, CO, USA
| | - Katherine A Rhodes
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biological Sciences, Colorado State University Fort Collins, CO, USA ; Department of Molecular Genetics and Microbiology, College of Medicine, Emerging Pathogens Institute, Institute for Therapeutic Innovation, University of Florida Gainesville, FL, USA
| | - Herbert P Schweizer
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biological Sciences, Colorado State University Fort Collins, CO, USA ; Department of Molecular Genetics and Microbiology, College of Medicine, Emerging Pathogens Institute, Institute for Therapeutic Innovation, University of Florida Gainesville, FL, USA
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Mansour SC, de la Fuente-Núñez C, Hancock REW. Peptide IDR-1018: modulating the immune system and targeting bacterial biofilms to treat antibiotic-resistant bacterial infections. J Pept Sci 2014; 21:323-9. [PMID: 25358509 DOI: 10.1002/psc.2708] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 09/22/2014] [Accepted: 09/22/2014] [Indexed: 12/29/2022]
Abstract
Host defense (antimicrobial) peptides, produced by all complex organisms, typically contain an abundance of positively charged and hydrophobic amino acid residues. A small synthetic peptide termed innate defense regulator (IDR-)1018 was derived by substantial modification of the bovine neutrophil host defense peptide bactenecin. Here, we review its intriguing properties that include anti-infective, anti-inflammatory, wound healing, and anti-biofilm activities. It was initially developed as an immune modulator with an ability to selectively enhance chemokine production and polarize cellular differentiation while suppressing/balancing the pro-inflammatory response. In this regard, it has demonstrated in vivo activity in murine models including enhancement of wound healing and an ability to protect against Staphylococcus aureus, multidrug resistant Mycobacterium tuberculosis, herpes virus, and inflammatory disorders, including cerebral malaria and neuronal damage in a pre-term birth model. More recently, IDR-1018 was shown, in a broad-spectrum fashion, to selectively target bacterial biofilms, which are adaptively resistant to many antibiotics and represent the most common growth state of bacteria in human infections. Furthermore, IDR-1018 demonstrated synergy with conventional antibiotics to both prevent biofilm formation and treat pre-existing biofilms. These data are consistent with a strong potential as an adjunctive therapy against antibiotic-resistant infections.
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Affiliation(s)
- Sarah C Mansour
- Department of Microbiology and Immunology, University of British Columbia, 232-2259 Lower Mall Research Station, Vancouver, BC, V6T 1Z4, Canada
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Olaitan AO, Diene SM, Gupta SK, Adler A, Assous MV, Rolain JM. Genome analysis of NDM-1 producing Morganella morganii clinical isolate. Expert Rev Anti Infect Ther 2014; 12:1297-305. [PMID: 25081858 DOI: 10.1586/14787210.2014.944504] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVE To analyze the resistome and virulence genes of Morganella morganii F675, a multidrug-resistant clinical isolate using whole genome sequencing (WGS). METHODS M. morganii F675 was isolated from a patient from Jerusalem, Israel. WGS was performed using both 454 and SOLiD sequencing technologies. Analyses of the bacterial resistome and other virulence genes were performed in addition to comparison with other available M. morganii genomes. RESULTS The assembled sequence had a genome size of 4,127,528 bp with G+C content of 51%. The resistome consisted of 13 antibiotic resistance genes including blaNDM-1 located in a plasmid likely acquired from Acinetobacter spp. Moreover, we characterized for the first time the whole lipid A biosynthesis pathway in this species along with the O-antigen gene cluster, the urease gene cluster and several other virulence genes. CONCLUSION The WGS analysis of this pathogen further provides insight into its pathogenicity and resistance to antibiotics.
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Affiliation(s)
- Abiola Olumuyiwa Olaitan
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE) CNRS-IRD UMR 6236, Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université, Marseille, France
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Fosmidomycin decreases membrane hopanoids and potentiates the effects of colistin on Burkholderia multivorans clinical isolates. Antimicrob Agents Chemother 2014; 58:5211-9. [PMID: 24957830 DOI: 10.1128/aac.02705-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Burkholderia cepacia complex (Bcc) pulmonary infections in people living with cystic fibrosis (CF) are difficult to treat because of the extreme intrinsic resistance of most isolates to a broad range of antimicrobials. Fosmidomycin is an antibacterial and antiparasitic agent that disrupts the isoprenoid biosynthesis pathway, a precursor to hopanoid biosynthesis. Hopanoids are involved in membrane stability and contribute to polymyxin resistance in Bcc bacteria. Checkerboard MIC assays determined that although isolates of the Bcc species B. multivorans were highly resistant to treatment with fosmidomycin or colistin (polymyxin E), antimicrobial synergy was observed in certain isolates when the antimicrobials were used in combination. Treatment with fosmidomycin decreased the MIC of colistin for isolates as much as 64-fold to as low as 8 μg/ml, a concentration achievable with colistin inhalation therapy. A liquid chromatography-tandem mass spectrometry technique was developed for the accurate quantitative determination of underivatized hopanoids in total lipid extracts, and bacteriohopanetetrol cyclitol ether (BHT-CE) was found to be the dominant hopanoid made by B. multivorans. The amount of BHT-CE made was significantly reduced upon fosmidomycin treatment of the bacteria. Uptake assays with 1-N-phenylnaphthylamine were used to determine that dual treatment with fosmidomycin and colistin increases membrane permeability, while binding assays with boron-dipyrromethene-conjugated polymyxin B illustrated that the addition of fosmidomycin had no impact on polymyxin binding. This work indicates that pharmacological suppression of membrane hopanoids with fosmidomycin treatment can increase the susceptibility of certain clinical B. multivorans isolates to colistin, an agent currently in use to treat pulmonary infections in CF patients.
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Garcia JR, Laughton AM, Malik Z, Parker BJ, Trincot C, S L Chiang S, Chung E, Gerardo NM. Partner associations across sympatric broad-headed bug species and their environmentally acquired bacterial symbionts. Mol Ecol 2014; 23:1333-1347. [PMID: 24384031 DOI: 10.1111/mec.12655] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 12/12/2013] [Accepted: 12/13/2013] [Indexed: 12/01/2022]
Abstract
Many organisms have intimate associations with beneficial microbes acquired from the environment. These host-symbiont associations can be specific and stable, but they are prone to lower partner specificity and more partner-switching than vertically transmitted mutualisms. To investigate partner specificity in an environmentally acquired insect symbiosis, we used 16S rRNA gene and multilocus sequencing to survey the bacterial population in the bacteria-harbouring organ (crypts) of 49 individuals across four sympatric broad-headed bug species (Alydus calcaratus, A. conspersus, A. tomentosus and Megalotomus quinquespinosus). Similar to other insect-bacteria associations, Burkholderia spp. were the most common residents of the crypts in all four insect species (77.2% of recovered sequences). Burkholderia presence was associated with prolonged survival to adulthood in A. tomentosus, suggesting a beneficial role of these specialized associations. Burkholderia were also found in environmental reservoirs in the insects' habitat, which may facilitate acquisition by insects by increasing Burkholderia-insect encounters. Symbiont establishment could also be facilitated by resistance to insect defences; zone of inhibition assays demonstrated that Burkholderia and other bacteria isolated from crypts are resistant to insect defences that limit growth of Escherichia coli. Alternatively, the insects' defences may not efficiently kill a broad range of bacteria. Although the symbiosis is targeted to Burkholderia, the insects' crypts housed other bacteria, including non-Burkholderiaceae species. There is no significant effect of host insect species on Burkholderia distribution, suggesting a lack of strong partner specificity at finer scales. The presence of frequent partner-switching between sympatric insects and their symbionts likely prevents tight co-evolutionary dynamics.
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Affiliation(s)
- J R Garcia
- Biology Department, Emory University, O. Wayne Rollins Research Center, 1510 Clifton Rd, Atlanta, GA, 30322, USA
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Guilhelmelli F, Vilela N, Albuquerque P, Derengowski LDS, Silva-Pereira I, Kyaw CM. Antibiotic development challenges: the various mechanisms of action of antimicrobial peptides and of bacterial resistance. Front Microbiol 2013; 4:353. [PMID: 24367355 PMCID: PMC3856679 DOI: 10.3389/fmicb.2013.00353] [Citation(s) in RCA: 334] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 11/06/2013] [Indexed: 12/15/2022] Open
Abstract
Antimicrobial peptides (AMPs) are natural antibiotics produced by various organisms such as mammals, arthropods, plants, and bacteria. In addition to antimicrobial activity, AMPs can induce chemokine production, accelerate angiogenesis, and wound healing and modulate apoptosis in multicellular organisms. Originally, their antimicrobial mechanism of action was thought to consist solely of an increase in pathogen cell membrane permeability, but it has already been shown that several AMPs do not modulate membrane permeability in the minimal lethal concentration. Instead, they exert their effects by inhibiting processes such as protein and cell wall synthesis, as well as enzyme activity, among others. Although resistance to these molecules is uncommon several pathogens developed different strategies to overcome AMPs killing such as surface modification, expression of efflux pumps, and secretion of proteases among others. This review describes the various mechanisms of action of AMPs and how pathogens evolve resistance to them.
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Affiliation(s)
- Fernanda Guilhelmelli
- Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
| | - Nathália Vilela
- Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
| | - Patrícia Albuquerque
- Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
| | - Lorena da S Derengowski
- Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
| | - Ildinete Silva-Pereira
- Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
| | - Cynthia M Kyaw
- Laboratório de Microbiologia, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
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Baugh L, Gallagher LA, Patrapuvich R, Clifton MC, Gardberg AS, Edwards TE, Armour B, Begley DW, Dieterich SH, Dranow DM, Abendroth J, Fairman JW, Fox D, Staker BL, Phan I, Gillespie A, Choi R, Nakazawa-Hewitt S, Nguyen MT, Napuli A, Barrett L, Buchko GW, Stacy R, Myler PJ, Stewart LJ, Manoil C, Van Voorhis WC. Combining functional and structural genomics to sample the essential Burkholderia structome. PLoS One 2013; 8:e53851. [PMID: 23382856 PMCID: PMC3561365 DOI: 10.1371/journal.pone.0053851] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 12/05/2012] [Indexed: 11/19/2022] Open
Abstract
Background The genus Burkholderia includes pathogenic gram-negative bacteria that cause melioidosis, glanders, and pulmonary infections of patients with cancer and cystic fibrosis. Drug resistance has made development of new antimicrobials critical. Many approaches to discovering new antimicrobials, such as structure-based drug design and whole cell phenotypic screens followed by lead refinement, require high-resolution structures of proteins essential to the parasite. Methodology/Principal Findings We experimentally identified 406 putative essential genes in B. thailandensis, a low-virulence species phylogenetically similar to B. pseudomallei, the causative agent of melioidosis, using saturation-level transposon mutagenesis and next-generation sequencing (Tn-seq). We selected 315 protein products of these genes based on structure-determination criteria, such as excluding very large and/or integral membrane proteins, and entered them into the Seattle Structural Genomics Center for Infection Disease (SSGCID) structure determination pipeline. To maximize structural coverage of these targets, we applied an “ortholog rescue” strategy for those producing insoluble or difficult to crystallize proteins, resulting in the addition of 387 orthologs (or paralogs) from seven other Burkholderia species into the SSGCID pipeline. This structural genomics approach yielded structures from 31 putative essential targets from B. thailandensis, and 25 orthologs from other Burkholderia species, yielding an overall structural coverage for 49 of the 406 essential gene families, with a total of 88 depositions into the Protein Data Bank. Of these, 25 proteins have properties of a potential antimicrobial drug target i.e., no close human homolog, part of an essential metabolic pathway, and a deep binding pocket. We describe the structures of several potential drug targets in detail. Conclusions/Significance This collection of structures, solubility and experimental essentiality data provides a resource for development of drugs against infections and diseases caused by Burkholderia. All expression clones and proteins created in this study are freely available by request.
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Affiliation(s)
- Loren Baugh
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Larry A. Gallagher
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Rapatbhorn Patrapuvich
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Matthew C. Clifton
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | - Anna S. Gardberg
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | - Thomas E. Edwards
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | - Brianna Armour
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | - Darren W. Begley
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | | | - David M. Dranow
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | - Jan Abendroth
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | - James W. Fairman
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | - David Fox
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | - Bart L. Staker
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | - Isabelle Phan
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Angela Gillespie
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Disease, University of Washington, Seattle, Washington, United States of America
| | - Ryan Choi
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Disease, University of Washington, Seattle, Washington, United States of America
| | - Steve Nakazawa-Hewitt
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Disease, University of Washington, Seattle, Washington, United States of America
| | - Mary Trang Nguyen
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Disease, University of Washington, Seattle, Washington, United States of America
| | - Alberto Napuli
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Disease, University of Washington, Seattle, Washington, United States of America
| | - Lynn Barrett
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Disease, University of Washington, Seattle, Washington, United States of America
| | - Garry W. Buchko
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Robin Stacy
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Peter J. Myler
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- Department of Medical Education and Biomedical Informatics, University of Washington, Seattle, Washington
| | - Lance J. Stewart
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Emerald BioStructures, Bainbridge Island, Washington, United States of America
| | - Colin Manoil
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Wesley C. Van Voorhis
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Disease, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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Lima TB, Pinto MFS, Ribeiro SM, de Lima LA, Viana JC, Gomes Júnior N, Cândido EDS, Dias SC, Franco OL. Bacterial resistance mechanism: what proteomics can elucidate. FASEB J 2013; 27:1291-303. [PMID: 23349550 DOI: 10.1096/fj.12-221127] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Antibiotics are important therapeutic agents commonly used for the control of bacterial infectious diseases; however, resistance to antibiotics has become a global public health problem. Therefore, effective therapy in the treatment of resistant bacteria is necessary and, to achieve this, a detailed understanding of mechanisms that underlie drug resistance must be sought. To fill the multiple gaps that remain in understanding bacterial resistance, proteomic tools have been used to study bacterial physiology in response to antibiotic stress. In general, the global analysis of changes in the protein composition of bacterial cells in response to treatment with antibiotic agents has made it possible to construct a database of proteins involved in the process of resistance to drugs with similar mechanisms of action. In the past few years, progress in using proteomic tools has provided the most realistic picture of the infective process, since these tools detect the end products of gene biosynthetic pathways, which may eventually determine a biological phenotype. In most bacterial species, alterations occur in energy and nitrogen metabolism regulation; glucan biosynthesis is up-regulated; amino acid, protein, and nucleotide synthesis is affected; and various proteins show a stress response after exposing these microorganisms to antibiotics. These issues have been useful in identifying targets for the development of novel antibiotics and also in understanding, at the molecular level, how bacteria resist antibiotics.
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Affiliation(s)
- Thais Bergamin Lima
- Centro de Análises Proteômicas e Bioquímicas, Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasilia, Brazil
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Fritsche S, Knappe D, Berthold N, von Buttlar H, Hoffmann R, Alber G. Absence ofin vitroinnate immunomodulation by insect-derived short proline-rich antimicrobial peptides points to direct antibacterial actionin vivo. J Pept Sci 2012; 18:599-608. [DOI: 10.1002/psc.2440] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 07/09/2012] [Accepted: 07/09/2012] [Indexed: 12/25/2022]
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Hamad MA, Di Lorenzo F, Molinaro A, Valvano MA. Aminoarabinose is essential for lipopolysaccharide export and intrinsic antimicrobial peptide resistance inBurkholderia cenocepacia†. Mol Microbiol 2012; 85:962-74. [DOI: 10.1111/j.1365-2958.2012.08154.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Juhas M, Stark M, von Mering C, Lumjiaktase P, Crook DW, Valvano MA, Eberl L. High confidence prediction of essential genes in Burkholderia cenocepacia. PLoS One 2012; 7:e40064. [PMID: 22768221 PMCID: PMC3386938 DOI: 10.1371/journal.pone.0040064] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 05/31/2012] [Indexed: 01/01/2023] Open
Abstract
Background Essential genes are absolutely required for the survival of an organism. The identification of essential genes, besides being one of the most fundamental questions in biology, is also of interest for the emerging science of synthetic biology and for the development of novel antimicrobials. New antimicrobial therapies are desperately needed to treat multidrug-resistant pathogens, such as members of the Burkholderia cepacia complex. Methodology/Principal Findings We hypothesize that essential genes may be highly conserved within a group of evolutionary closely related organisms. Using a bioinformatics approach we determined that the core genome of the order Burkholderiales consists of 649 genes. All but two of these identified genes were located on chromosome 1 of Burkholderia cenocepacia. Although many of the 649 core genes of Burkholderiales have been shown to be essential in other bacteria, we were also able to identify a number of novel essential genes present mainly, or exclusively, within this order. The essentiality of some of the core genes, including the known essential genes infB, gyrB, ubiB, and valS, as well as the so far uncharacterized genes BCAL1882, BCAL2769, BCAL3142 and BCAL3369 has been confirmed experimentally in B. cenocepacia. Conclusions/Significance We report on the identification of essential genes using a novel bioinformatics strategy and provide bioinformatics and experimental evidence that the large majority of the identified genes are indeed essential. The essential genes identified here may represent valuable targets for the development of novel antimicrobials and their detailed study may shed new light on the functions required to support life.
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Affiliation(s)
- Mario Juhas
- Department of Microbiology, Institute of Plant Biology, University of Zurich, Zurich, Switzerland
- * E-mail: (MJ); (LE)
| | - Manuel Stark
- Institute of Molecular Life Sciences and Swiss Institute of Bioinformatics, University of Zurich, Zurich, Switzerland
| | - Christian von Mering
- Institute of Molecular Life Sciences and Swiss Institute of Bioinformatics, University of Zurich, Zurich, Switzerland
| | | | - Derrick W. Crook
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Miguel A. Valvano
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - Leo Eberl
- Department of Microbiology, Institute of Plant Biology, University of Zurich, Zurich, Switzerland
- * E-mail: (MJ); (LE)
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Gruenheid S, Le Moual H. Resistance to antimicrobial peptides in Gram-negative bacteria. FEMS Microbiol Lett 2012; 330:81-9. [PMID: 22339775 DOI: 10.1111/j.1574-6968.2012.02528.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 01/30/2012] [Accepted: 02/11/2012] [Indexed: 01/06/2023] Open
Abstract
Antimicrobial peptides (AMPs) are present in virtually all organisms and are an ancient and critical component of innate immunity. In mammals, AMPs are present in phagocytic cells, on body surfaces such as skin and mucosa, and in secretions and body fluids such as sweat, saliva, urine, and breast milk, consistent with their role as part of the first line of defense against a wide range of pathogenic microorganisms including bacteria, viruses, and fungi. AMPs are microbicidal and have also been shown to act as immunomodulators with chemoattractant and signaling activities. During the co-evolution of hosts and bacterial pathogens, bacteria have developed the ability to sense and initiate an adaptive response to AMPs to resist their bactericidal activity. Here, we review the various mechanisms used by Gram-negative bacteria to sense and resist AMP-mediated killing. These mechanisms play an important role in bacterial resistance to host-derived AMPs that are encountered during the course of infection. Bacterial resistance to AMPs should also be taken into consideration in the development and use of AMPs as anti-infective agents, for which there is currently a great deal of academic and commercial interest.
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Affiliation(s)
- Samantha Gruenheid
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
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Inhibition of bacterial biofilm formation and swarming motility by a small synthetic cationic peptide. Antimicrob Agents Chemother 2012; 56:2696-704. [PMID: 22354291 DOI: 10.1128/aac.00064-12] [Citation(s) in RCA: 318] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Biofilms cause up to 80% of infections and are difficult to treat due to their substantial multidrug resistance compared to their planktonic counterparts. Based on the observation that human peptide LL-37 is able to block biofilm formation at concentrations below its MIC, we screened for small peptides with antibiofilm activity and identified novel synthetic cationic peptide 1037 of only 9 amino acids in length. Peptide 1037 had very weak antimicrobial activity, but at 1/30th the MIC the peptide was able to effectively prevent biofilm formation (>50% reduction in cell biomass) by the Gram-negative pathogens Pseudomonas aeruginosa and Burkholderia cenocepacia and Gram-positive Listeria monocytogenes. Using a flow cell system and a widefield fluorescence microscope, 1037 was shown to significantly reduce biofilm formation and lead to cell death in biofilms. Microarray and follow-up studies showed that, in P. aeruginosa, 1037 directly inhibited biofilms by reducing swimming and swarming motilities, stimulating twitching motility, and suppressing the expression of a variety of genes involved in biofilm formation (e.g., PA2204). Comparison of microarray data from cells treated with peptides LL-37 and 1037 enabled the identification of 11 common P. aeruginosa genes that have a role in biofilm formation and are proposed to represent functional targets of these peptides. Peptide 1037 shows promise as a potential therapeutic agent against chronic, recurrent biofilm infections caused by a variety of bacteria.
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Fjell CD, Hiss JA, Hancock REW, Schneider G. Designing antimicrobial peptides: form follows function. Nat Rev Drug Discov 2011; 11:37-51. [PMID: 22173434 DOI: 10.1038/nrd3591] [Citation(s) in RCA: 1350] [Impact Index Per Article: 103.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Multidrug-resistant bacteria are a severe threat to public health. Conventional antibiotics are becoming increasingly ineffective as a result of resistance, and it is imperative to find new antibacterial strategies. Natural antimicrobials, known as host defence peptides or antimicrobial peptides, defend host organisms against microbes but most have modest direct antibiotic activity. Enhanced variants have been developed using straightforward design and optimization strategies and are being tested clinically. Here, we describe advanced computer-assisted design strategies that address the difficult problem of relating primary sequence to peptide structure, and are delivering more potent, cost-effective, broad-spectrum peptides as potential next-generation antibiotics.
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Affiliation(s)
- Christopher D Fjell
- Centre for Microbial Diseases and Immunity Research, University of British Columbia, 2259 Lower Mall, Vancouver, British Columbia V6T 1Z4, Canada
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Identification of hopanoid biosynthesis genes involved in polymyxin resistance in Burkholderia multivorans. Antimicrob Agents Chemother 2011; 56:464-71. [PMID: 22006009 DOI: 10.1128/aac.00602-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A major challenge to clinical therapy of Burkholderia cepacia complex (Bcc) pulmonary infections is their innate resistance to a broad range of antimicrobials, including polycationic agents such as aminoglycosides, polymyxins, and cationic peptides. To identify genetic loci associated with this phenotype, a transposon mutant library was constructed in B. multivorans ATCC 17616 and screened for increased susceptibility to polymyxin B. Compared to the parent strain, mutant 26D7 exhibited 8- and 16-fold increases in susceptibility to polymyxin B and colistin, respectively. Genetic analysis of mutant 26D7 indicated that the transposon inserted into open reading frame (ORF) Bmul_2133, part of a putative hopanoid biosynthesis gene cluster. A strain with a mutation in another ORF in this cluster, Bmul_2134, was constructed and named RMI19. Mutant RMI19 also had increased polymyxin susceptibility. Hopanoids are analogues of eukaryotic sterols involved in membrane stability and barrier function. Strains with mutations in Bmul_2133 and Bmul_2134 showed increased permeability to 1-N-phenylnaphthylamine in the presence of increasing concentrations of polymyxin, suggesting that the putative hopanoid biosynthesis genes are involved in stabilizing outer membrane permeability, contributing to polymyxin resistance. Results from a dansyl-polymyxin binding assay demonstrated that polymyxin B does not bind well to the parent or mutant strains, suggesting that Bmul_2133 and Bmul_2134 contribute to polymyxin B resistance by a mechanism that is independent of lipopolysaccharide (LPS) binding. Through this work, we propose a role for hopanoid biosynthesis as part of the multiple antimicrobial resistance phenotype in Bcc bacteria.
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