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Zou D, Chang J, Lu S, Xu J, Hu P, Zhang K, Sun X, Guo W, Li Y, Liu Z, Ren H. Analysis of virulence proteins in pathogenic Acinetobacter baumannii to provide early warning of zoonotic risk. Microbiol Res 2023; 266:127222. [DOI: 10.1016/j.micres.2022.127222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 09/18/2022] [Accepted: 10/03/2022] [Indexed: 11/05/2022]
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Chowdhury AR, Mukherjee D, Singh AK, Chakravortty D. Loss of outer membrane protein A (OmpA) impairs the survival of Salmonella Typhimurium by inducing membrane damage in the presence of ceftazidime and meropenem. J Antimicrob Chemother 2022; 77:3376-3389. [PMID: 36177811 DOI: 10.1093/jac/dkac327] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 09/05/2022] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVES Salmonella enterica serovar Typhimurium is one of the significant non-typhoidal Salmonella serovars that causes gastroenteritis. The rapid development of antimicrobial resistance necessitates studying new antimicrobials and their therapeutic targets in this pathogen. Our study aimed to investigate the role of four prominent outer membrane porins of S. Typhimurium, namely OmpA, OmpC, OmpD and OmpF, in developing resistance against ceftazidime and meropenem. METHODS The antibiotic-mediated inhibition of bacterial growth was determined by measuring the absorbance and the resazurin assay. DiBAC4 (Bis-(1,3-Dibutylbarbituric Acid)Trimethine Oxonol), 2,7-dichlorodihydrofluoroscein diacetate (DCFDA) and propidium iodide were used to determine the outer membrane depolarization, reactive oxygen species (ROS) generation and subsequent killing of Salmonella. The expression of oxidative stress-response and efflux pump genes was quantified by quantitative RT-qPCR. HPLC was done to determine the amount of antibiotics that entered the bacteria. The damage to the bacterial outer membrane was studied by confocal and atomic force microscopy. The in vivo efficacy of ceftazidime and meropenem were tested in the C57BL/6 mouse model. RESULTS Deleting ompA reduced the survival of Salmonella in the presence of ceftazidime and meropenem. Massive outer membrane depolarization and reduced expression of oxidative stress-response genes in S. Typhimurium ΔompA hampered its growth in the presence of antibiotics. The enhanced uptake of antibiotics and decreased expression of efflux pump genes in S. Typhimurium ΔompA resulted in damage to the bacterial outer membrane. The clearance of the S. Typhimurium ΔompA from C57BL/6 mice with ceftazidime treatment proved the role of OmpA in rendering protection against β-lactam antibiotics. CONCLUSIONS OmpA protects S. Typhimurium from two broad-spectrum β-lactam antibiotics, ceftazidime and meropenem, by maintaining the stability of the outer membrane.
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Affiliation(s)
- Atish Roy Chowdhury
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka 560012, India.,Division of Biological Sciences, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Debapriya Mukherjee
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka 560012, India.,Division of Biological Sciences, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Ashish Kumar Singh
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka 560012, India.,Division of Biological Sciences, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka 560012, India.,Division of Biological Sciences, Indian Institute of Science, Bangalore, Karnataka 560012, India.,School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
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Sariyer E. The role of Acinetobacter baumannii CarO outer membrane protein in carbapenems influx. Res Microbiol 2022; 173:103966. [DOI: 10.1016/j.resmic.2022.103966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 04/27/2022] [Accepted: 05/18/2022] [Indexed: 10/18/2022]
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4
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Zhu T, Lei Z, Qu S, Zhao F, Yan L, Chen M, Zhou XW, Di Q, Zhao Y. Comparison of the outer membrane proteomes between clinical carbapenem-resistant and susceptible Acinetobacter baumannii. Lett Appl Microbiol 2022; 74:873-882. [PMID: 35138649 DOI: 10.1111/lam.13672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 02/03/2022] [Accepted: 02/06/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND AIM Carbapenem resistance has become a major obstacle in combating Acinetobacter baumannii infections. Although enzymatic degradation by β-lactamases is the pivotal mechanism of carbapenem resistance, porin deficiency has also been implicated in the mechanism. In this study, outer membrane proteins (OMPs) pattern of a clinical multidrug-resistant A. baumannii isolate were analyzed in order to attain a deeper understanding of carbapenem resistance strategies. METHODS OMPs extracts respectively separated from carbapenem-resistant and -susceptible clinical A. baumannii isolates were compared using two-dimensional polyacrylamide gel electrophoresis. Differentially expressed proteins were identified by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF). RESULTS Twenty-three differently expressed proteins were identified between the resistant and susceptible isolates. Among them, six were annotated convincingly as OMPs in UniProt database. CarO was found absent from the resistant isolate and the expression levels of Omp33-36 and Omp25 were significantly lower than that in the susceptible counterpart. Strikingly, a LysM domain/BON superfamily protein, which has been linked to carbapenem resistance in Klebsiella pneumoniae, was found underexpressed by 10-fold in the resistant isolate. CONCLUSION Our study verified some porins which have been proven to play an important role in bacterial resistance against carbapenems. Underexpression of the LysM domain/BON superfamily protein may indicate its possible engagement in bacterial drug resistance, but its actual role requires more investigation.
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Affiliation(s)
- Tao Zhu
- Department of Medical Microbiology and Immunology, Wannan Medical College, Wuhu, 241002, PR China
| | - Zhongying Lei
- Department of Laboratory Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, PR China
| | - Su Qu
- Shanghai Vitalgen BioPharma Co, Ltd, Shanghai, 201108, PR China
| | - Fuju Zhao
- Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, PR China
| | - Liang Yan
- Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, PR China
| | - Mingliang Chen
- Department of Microbiology, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, 200336, PR China
| | - Xin Wen Zhou
- Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, PR China
| | - Qu Di
- Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, PR China
| | - Yanfeng Zhao
- Department of Laboratory Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, PR China
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McMillan HM, Kuehn MJ. The extracellular vesicle generation paradox: a bacterial point of view. EMBO J 2021; 40:e108174. [PMID: 34636061 PMCID: PMC8561641 DOI: 10.15252/embj.2021108174] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 06/29/2021] [Accepted: 07/28/2021] [Indexed: 12/23/2022] Open
Abstract
All bacteria produce secreted vesicles that carry out a variety of important biological functions. These extracellular vesicles can improve adaptation and survival by relieving bacterial stress and eliminating toxic compounds, as well as by facilitating membrane remodeling and ameliorating inhospitable environments. However, vesicle production comes with a price. It is energetically costly and, in the case of colonizing pathogens, it elicits host immune responses, which reduce bacterial viability. This raises an interesting paradox regarding why bacteria produce vesicles and begs the question as to whether the benefits of producing vesicles outweigh their costs. In this review, we discuss the various advantages and disadvantages associated with Gram-negative and Gram-positive bacterial vesicle production and offer perspective on the ultimate score. We also highlight questions needed to advance the field in determining the role for vesicles in bacterial survival, interkingdom communication, and virulence.
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Affiliation(s)
- Hannah M McMillan
- Department of Molecular Genetics and MicrobiologyDuke UniversityDurhamNCUSA
| | - Meta J Kuehn
- Department of BiochemistryDuke UniversityDurhamNCUSA
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The Functional Significance of Hydrophobic Residue Distribution in Bacterial Beta-Barrel Transmembrane Proteins. MEMBRANES 2021; 11:membranes11080580. [PMID: 34436343 PMCID: PMC8399255 DOI: 10.3390/membranes11080580] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/25/2021] [Accepted: 07/27/2021] [Indexed: 12/13/2022]
Abstract
β-barrel membrane proteins have several important biological functions, including transporting water and solutes across the membrane. They are active in the highly hydrophobic environment of the lipid membrane, as opposed to soluble proteins, which function in a more polar, aqueous environment. Globular soluble proteins typically have a hydrophobic core and a polar surface that interacts favorably with water. In the fuzzy oil drop (FOD) model, this distribution is represented by the 3D Gauss function (3DG). In contrast, membrane proteins expose hydrophobic residues on the surface, and, in the case of ion channels, the polar residues face inwards towards a central pore. The distribution of hydrophobic residues in membrane proteins can be characterized by means of 1–3DG, a complementary 3D Gauss function. Such an analysis was carried out on the transmembrane proteins of bacteria, which, despite the considerable similarities of their super-secondary structure (β-barrel), have highly differentiated properties in terms of stabilization based on hydrophobic interactions. The biological activity and substrate specificity of these proteins are determined by the distribution of the polar and nonpolar amino acids. The present analysis allowed us to compare the ways in which the different proteins interact with antibiotics and helped us understand their relative importance in the development of the resistance mechanism. We showed that beta barrel membrane proteins with a hydrophobic core interact less strongly with the molecules they transport.
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Hawley KL, Montezuma-Rusca JM, Delgado KN, Singh N, Uversky VN, Caimano MJ, Radolf JD, Luthra A. Structural Modeling of the Treponema pallidum Outer Membrane Protein Repertoire: a Road Map for Deconvolution of Syphilis Pathogenesis and Development of a Syphilis Vaccine. J Bacteriol 2021; 203:e0008221. [PMID: 33972353 PMCID: PMC8407342 DOI: 10.1128/jb.00082-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/27/2021] [Indexed: 01/11/2023] Open
Abstract
Treponema pallidum, an obligate human pathogen, has an outer membrane (OM) whose physical properties, ultrastructure, and composition differ markedly from those of phylogenetically distant Gram-negative bacteria. We developed structural models for the outer membrane protein (OMP) repertoire (OMPeome) of T. pallidum Nichols using solved Gram-negative structures, computational tools, and small-angle X-ray scattering (SAXS) of selected recombinant periplasmic domains. The T. pallidum "OMPeome" harbors two "stand-alone" proteins (BamA and LptD) involved in OM biogenesis and four paralogous families involved in the influx/efflux of small molecules: 8-stranded β-barrels, long-chain-fatty-acid transporters (FadLs), OM factors (OMFs) for efflux pumps, and T. pallidum repeat proteins (Tprs). BamA (TP0326), the central component of a β-barrel assembly machine (BAM)/translocation and assembly module (TAM) hybrid, possesses a highly flexible polypeptide-transport-associated (POTRA) 1-5 arm predicted to interact with TamB (TP0325). TP0515, an LptD ortholog, contains a novel, unstructured C-terminal domain that models inside the β-barrel. T. pallidum has four 8-stranded β-barrels, each containing positively charged extracellular loops that could contribute to pathogenesis. Three of five FadL-like orthologs have a novel α-helical, presumptively periplasmic C-terminal extension. SAXS and structural modeling further supported the bipartite membrane topology and tridomain architecture of full-length members of the Tpr family. T. pallidum's two efflux pumps presumably extrude noxious small molecules via four coexpressed OMFs with variably charged tunnels. For BamA, LptD, and OMFs, we modeled the molecular machines that deliver their substrates into the OM or external milieu. The spirochete's extended families of OM transporters collectively confer a broad capacity for nutrient uptake. The models also furnish a structural road map for vaccine development. IMPORTANCE The unusual outer membrane (OM) of T. pallidum, the syphilis spirochete, is the ultrastructural basis for its well-recognized capacity for invasiveness, immune evasion, and persistence. In recent years, we have made considerable progress in identifying T. pallidum's repertoire of OMPs. Here, we developed three-dimensional (3D) models for the T. pallidum Nichols OMPeome using structural modeling, bioinformatics, and solution scattering. The OM contains three families of OMP transporters, an OMP family involved in the extrusion of noxious molecules, and two "stand-alone" proteins involved in OM biogenesis. This work represents a major advance toward elucidating host-pathogen interactions during syphilis; understanding how T. pallidum, an extreme auxotroph, obtains a wide array of biomolecules from its obligate human host; and developing a vaccine with global efficacy.
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Affiliation(s)
- Kelly L. Hawley
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Division of Infectious Diseases and Immunology, Connecticut Children’s, Hartford, Connecticut, USA
| | - Jairo M. Montezuma-Rusca
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Division of Infectious Diseases, UConn Health, Farmington, Connecticut, USA
| | | | - Navreeta Singh
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
| | - Vladimir N. Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Melissa J. Caimano
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Justin D. Radolf
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
- Department of Genetics and Genome Sciences, UConn Health, Farmington, Connecticut, USA
- Department of Immunology, UConn Health, Farmington, Connecticut, USA
| | - Amit Luthra
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
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Acinetobacter baumannii Antibiotic Resistance Mechanisms. Pathogens 2021; 10:pathogens10030373. [PMID: 33808905 PMCID: PMC8003822 DOI: 10.3390/pathogens10030373] [Citation(s) in RCA: 184] [Impact Index Per Article: 61.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 03/16/2021] [Accepted: 03/18/2021] [Indexed: 12/11/2022] Open
Abstract
Acinetobacter baumannii is a Gram-negative ESKAPE microorganism that poses a threat to public health by causing severe and invasive (mostly nosocomial) infections linked with high mortality rates. During the last years, this pathogen displayed multidrug resistance (MDR), mainly due to extensive antibiotic abuse and poor stewardship. MDR isolates are associated with medical history of long hospitalization stays, presence of catheters, and mechanical ventilation, while immunocompromised and severely ill hosts predispose to invasive infections. Next-generation sequencing techniques have revolutionized diagnosis of severe A. baumannii infections, contributing to timely diagnosis and personalized therapeutic regimens according to the identification of the respective resistance genes. The aim of this review is to describe in detail all current knowledge on the genetic background of A. baumannii resistance mechanisms in humans as regards beta-lactams (penicillins, cephalosporins, carbapenems, monobactams, and beta-lactamase inhibitors), aminoglycosides, tetracyclines, fluoroquinolones, macrolides, lincosamides, streptogramin antibiotics, polymyxins, and others (amphenicols, oxazolidinones, rifamycins, fosfomycin, diaminopyrimidines, sulfonamides, glycopeptide, and lipopeptide antibiotics). Mechanisms of antimicrobial resistance refer mainly to regulation of antibiotic transportation through bacterial membranes, alteration of the antibiotic target site, and enzymatic modifications resulting in antibiotic neutralization. Virulence factors that may affect antibiotic susceptibility profiles and confer drug resistance are also being discussed. Reports from cases of A. baumannii coinfection with SARS-CoV-2 during the COVID-19 pandemic in terms of resistance profiles and MDR genes have been investigated.
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Prajapati JD, Kleinekathöfer U, Winterhalter M. How to Enter a Bacterium: Bacterial Porins and the Permeation of Antibiotics. Chem Rev 2021; 121:5158-5192. [PMID: 33724823 DOI: 10.1021/acs.chemrev.0c01213] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Despite tremendous successes in the field of antibiotic discovery seen in the previous century, infectious diseases have remained a leading cause of death. More specifically, pathogenic Gram-negative bacteria have become a global threat due to their extraordinary ability to acquire resistance against any clinically available antibiotic, thus urging for the discovery of novel antibacterial agents. One major challenge is to design new antibiotics molecules able to rapidly penetrate Gram-negative bacteria in order to achieve a lethal intracellular drug accumulation. Protein channels in the outer membrane are known to form an entry route for many antibiotics into bacterial cells. Up until today, there has been a lack of simple experimental techniques to measure the antibiotic uptake and the local concentration in subcellular compartments. Hence, rules for translocation directly into the various Gram-negative bacteria via the outer membrane or via channels have remained elusive, hindering the design of new or the improvement of existing antibiotics. In this review, we will discuss the recent progress, both experimentally as well as computationally, in understanding the structure-function relationship of outer-membrane channels of Gram-negative pathogens, mainly focusing on the transport of antibiotics.
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Affiliation(s)
| | | | - Mathias Winterhalter
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen 28759, Germany
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Touhidinia M, Sefid F, Bidakhavidi M. Design of a Multi-epitope Vaccine Against Acinetobacter baumannii Using Immunoinformatics Approach. Int J Pept Res Ther 2021; 27:2417-2437. [PMID: 34483787 PMCID: PMC8397861 DOI: 10.1007/s10989-021-10262-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2021] [Indexed: 02/07/2023]
Abstract
Acinetobacter baumannii is one of the most successful pathogens causing nosocomial infections and has significantly multidrug-resistant. So far, there are no certain treatments to protect against infection with A. baumannii, therefore an effective A. baumannii vaccine needed. The purpose of this study was to predict antigenic epitopes of CarO protein for designing the A. baumannii vaccine using immunoinformatics analysis. CarO protein is one of the most important factors in the resistance against the antibiotic Carbapenem. In this study, T and B-cell epitopes of CarO protein were predicted and screened based on the antigenicity, toxicity, allergenicity features. The epitopes were linked by suitable linkers. Four different adjuvants were attached to the vaccine constructs which among them, vaccine construct 3 was chosen to predict the secondary and the 3D structure of the vaccine. The refinement process was performed to improve the quality of the 3D model structure; the validation process is performed using the Ramachandran plot and ProSA z-score. The designed vaccine's binding affinity to six various HLA molecules and TLR 2 and TLR4 were evaluated by molecular docking. Finally, in silico gene cloning was performed in the pET28a (+) vector. The findings suggest that the vaccine may be a promising vaccine to prevent A. baumannii infection.
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Affiliation(s)
- Maryam Touhidinia
- Department of Biology, Faculty of Science, Yazd University, Yazd, Iran
| | - Fatemeh Sefid
- Department of Medical Genetics, Shahid Sadoughi University of Medical Science, Yazd, Iran
- Department of Biology, Science and Art University, Yazd, Iran
| | - Mozhgan Bidakhavidi
- Department of Biology, Faculty of Science, Yazd University, Yazd, Iran
- Department of Nursing, Nursing and Midwifery Research, Shahid Sadoughi University of Medical Sciences and Health Services, Yazd, Iran
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11
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Labrador-Herrera G, Pérez-Pulido AJ, Álvarez-Marín R, Casimiro-Soriguer CS, Cebrero-Cangueiro T, Morán-Barrio J, Pachón J, Viale AM, Pachón-Ibáñez ME. Virulence role of the outer membrane protein CarO in carbapenem-resistant Acinetobacter baumannii. Virulence 2020; 11:1727-1737. [PMID: 33300460 PMCID: PMC7733888 DOI: 10.1080/21505594.2020.1855912] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Novel approaches to treat carbapenem-resistant Acinetobacter baumannii (CRAB) infections are urgently needed and anti-virulence drugs represent promising alternatives, but our knowledge on potential targets is scarce. We searched for potential A. baumannii virulence factors by whole-genome sequencing-based comparisons of CRAB clinical isolates causing bloodstream infections secondary to ventilator-associated pneumonia from demographics and clinically homogeneous patients, who received optimal treatment but with different clinical outcomes. Thus, the carO gene was interrupted in CRAB isolates from surviving patients, while it was intact in isolates from non-surviving patients, and proteomic/immunoblot techniques corroborated it. When the virulence role of A. baumannii CarO was analyzed in model systems, isogenic ΔcarO mutants and a CRAB clinical isolate with truncated CarO, showed lower ability to adhere and invade A549 cells and in vivo virulence. This unnoticed virulence role for CarO postulate this A. baumannii outer membrane protein as a potential target for new therapies against CRAB infections.
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Affiliation(s)
- Gema Labrador-Herrera
- Clinical Unit of Infectious Diseases, Microbiology, and Preventive Medicine, University Hospital Virgen del Rocío , Seville, Spain.,Institute of Biomedicine of Seville (IBiS), University of Seville/CSIC/University Hospital Virgen del Rocío , Seville, Spain
| | - Antonio J Pérez-Pulido
- Andalusian Centre for Developmental Biology (CABD, UPO-CSIC-JA), Faculty of Experimental Sciences (Genetics Area), Pablo de Olavide University , Seville, Spain
| | - Rocío Álvarez-Marín
- Clinical Unit of Infectious Diseases, Microbiology, and Preventive Medicine, University Hospital Virgen del Rocío , Seville, Spain.,Institute of Biomedicine of Seville (IBiS), University of Seville/CSIC/University Hospital Virgen del Rocío , Seville, Spain
| | - Carlos S Casimiro-Soriguer
- Andalusian Centre for Developmental Biology (CABD, UPO-CSIC-JA), Faculty of Experimental Sciences (Genetics Area), Pablo de Olavide University , Seville, Spain
| | - Tania Cebrero-Cangueiro
- Clinical Unit of Infectious Diseases, Microbiology, and Preventive Medicine, University Hospital Virgen del Rocío , Seville, Spain.,Institute of Biomedicine of Seville (IBiS), University of Seville/CSIC/University Hospital Virgen del Rocío , Seville, Spain.,Department of Medicine, University of Seville , Seville, Spain
| | - Jorgelina Morán-Barrio
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR) , Rosario, Argentina
| | - Jerónimo Pachón
- Institute of Biomedicine of Seville (IBiS), University of Seville/CSIC/University Hospital Virgen del Rocío , Seville, Spain.,Department of Medicine, University of Seville , Seville, Spain
| | - Alejandro M Viale
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, Universidad Nacional de Rosario (UNR) , Rosario, Argentina
| | - María Eugenia Pachón-Ibáñez
- Clinical Unit of Infectious Diseases, Microbiology, and Preventive Medicine, University Hospital Virgen del Rocío , Seville, Spain.,Institute of Biomedicine of Seville (IBiS), University of Seville/CSIC/University Hospital Virgen del Rocío , Seville, Spain
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12
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Veith PD, Gorasia DG, Reynolds EC. Towards defining the outer membrane proteome of Porphyromonas gingivalis. Mol Oral Microbiol 2020; 36:25-36. [PMID: 33124778 DOI: 10.1111/omi.12320] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 01/18/2023]
Abstract
Porphyromonas gingivalis is a Gram-negative anaerobic pathogen found in subgingival plaque associated with progressive periodontitis. Proteins associated with the outer membrane (OM) of Gram-negative pathogens are particularly important for understanding virulence and for developing vaccines. The aim of this study was to establish a reliable list of outer membrane associated proteins (Omps) for this organism. Starting with a list of 99 experimentally determined Omps, several bioinformatics tools were used to predict a further 52 proteins, leading to a predicted OM proteome of 151 proteins. The tools used included databases of protein families, prediction of OM β-barrels and structural homology. The list includes 33 T9SS cargo proteins, 43 lipoproteins and 66 OM β-barrel proteins with some overlap between categories. The proteins are discussed both in these structural categories as well as their various functions in OM biogenesis, nutrient acquisition, protein secretion, adhesion and efflux. Proteins that were previously shown to be part of large complexes are highlighted and cross reference is provided to a previous major study of protein localization in P. gingivalis. Finally, proteins were also scored according to their level of conservation within the Bacteroidales taxon. Low scores were shown to correlate with virulence factors and may be predictive of novel virulence factors.
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Affiliation(s)
- Paul D Veith
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Dhana G Gorasia
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Eric C Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
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13
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Uppalapati SR, Sett A, Pathania R. The Outer Membrane Proteins OmpA, CarO, and OprD of Acinetobacter baumannii Confer a Two-Pronged Defense in Facilitating Its Success as a Potent Human Pathogen. Front Microbiol 2020; 11:589234. [PMID: 33123117 PMCID: PMC7573547 DOI: 10.3389/fmicb.2020.589234] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/11/2020] [Indexed: 12/12/2022] Open
Abstract
Of all the ESKAPE pathogens, carbapenem-resistant and multidrug-resistant Acinetobacter baumannii is the leading cause of hospital-acquired and ventilator-associated pneumonia. A. baumannii infections are notoriously hard to eradicate due to its propensity to rapidly acquire multitude of resistance determinants and the virulence factor cornucopia elucidated by the bacterium that help it fend off a wide range of adverse conditions imposed upon by host and environment. One such weapon in the arsenal of A. baumannii is the outer membrane protein (OMP) compendium. OMPs in A. baumannii play distinctive roles in facilitating the bacterial acclimatization to antibiotic- and host-induced stresses, albeit following entirely different mechanisms. OMPs are major immunogenic proteins in bacteria conferring bacteria host-fitness advantages including immune evasion, stress tolerance, and resistance to antibiotics and antibacterials. In this review, we summarize the current knowledge of major A. baumannii OMPs and discuss their versatile role in antibiotic resistance and virulence. Specifically, we explore how OmpA, CarO, and OprD-like porins mediate antibiotic and amino acid shuttle and host virulence.
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Affiliation(s)
- Siva R Uppalapati
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, India
| | - Abhiroop Sett
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, India
| | - Ranjana Pathania
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, India
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14
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Roe C, Williamson CHD, Vazquez AJ, Kyger K, Valentine M, Bowers JR, Phillips PD, Harrison V, Driebe E, Engelthaler DM, Sahl JW. Bacterial Genome Wide Association Studies (bGWAS) and Transcriptomics Identifies Cryptic Antimicrobial Resistance Mechanisms in Acinetobacter baumannii. Front Public Health 2020; 8:451. [PMID: 33014966 PMCID: PMC7493718 DOI: 10.3389/fpubh.2020.00451] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 07/21/2020] [Indexed: 12/14/2022] Open
Abstract
Antimicrobial resistance (AMR) in the nosocomial pathogen, Acinetobacter baumannii, is becoming a serious public health threat. While some mechanisms of AMR have been reported, understanding novel mechanisms of resistance is critical for identifying emerging resistance. One of the first steps in identifying novel AMR mechanisms is performing genotype/phenotype association studies; however, performing these studies is complicated by the plastic nature of the A. baumannii pan-genome. In this study, we compared the antibiograms of 12 antimicrobials associated with multiple drug families for 84 A. baumannii isolates, many isolated in Arizona, USA. in silico screening of these genomes for known AMR mechanisms failed to identify clear correlations for most drugs. We then performed a bacterial genome wide association study (bGWAS) looking for associations between all possible 21-mers; this approach generally failed to identify mechanisms that explained the resistance phenotype. In order to decrease the genomic noise associated with population stratification, we compared four phylogenetically-related pairs of isolates with differing susceptibility profiles. RNA-Sequencing (RNA-Seq) was performed on paired isolates and differentially-expressed genes were identified. In these isolate pairs, five different potential mechanisms were identified, highlighting the difficulty of broad AMR surveillance in this species. To verify and validate differential expression, amplicon sequencing was performed. These results suggest that a diagnostic platform based on gene expression rather than genomics alone may be beneficial in certain surveillance efforts. The implementation of such advanced diagnostics coupled with increased AMR surveillance will potentially improve A. baumannii infection treatment and patient outcomes.
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Affiliation(s)
- Chandler Roe
- Northern Arizona University, Flagstaff, AZ, United States
| | | | | | - Kristen Kyger
- Northern Arizona University, Flagstaff, AZ, United States
| | - Michael Valentine
- Translational Genomics Research Institute, Flagstaff, AZ, United States
| | - Jolene R. Bowers
- Translational Genomics Research Institute, Flagstaff, AZ, United States
| | | | - Veronica Harrison
- Translational Genomics Research Institute, Flagstaff, AZ, United States
| | - Elizabeth Driebe
- Translational Genomics Research Institute, Flagstaff, AZ, United States
| | | | - Jason W. Sahl
- Northern Arizona University, Flagstaff, AZ, United States
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15
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Putative β-Barrel Outer Membrane Proteins of the Bovine Digital Dermatitis-Associated Treponemes: Identification, Functional Characterization, and Immunogenicity. Infect Immun 2020; 88:IAI.00050-20. [PMID: 32122940 PMCID: PMC7171239 DOI: 10.1128/iai.00050-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 02/20/2020] [Indexed: 12/25/2022] Open
Abstract
Bovine digital dermatitis (BDD), an infectious disease of the bovine foot with a predominant treponemal etiology, is a leading cause of lameness in dairy and beef herds worldwide. BDD is poorly responsive to antimicrobial therapy and exhibits a relapsing clinical course; an effective vaccine is therefore urgently sought. Using a reverse vaccinology approach, the present study surveyed the genomes of the three BDD-associated Treponema phylogroups for putative β-barrel outer membrane proteins and considered their potential as vaccine candidates. Selection criteria included the presence of a signal peptidase I cleavage site, a predicted β-barrel fold, and cross-phylogroup homology. Four candidate genes were overexpressed in Escherichia coli BL21(DE3), refolded, and purified. Consistent with their classification as β-barrel OMPs, circular-dichroism spectroscopy revealed the adoption of a predominantly β-sheet secondary structure. These recombinant proteins, when screened for their ability to adhere to immobilized extracellular matrix (ECM) components, exhibited a diverse range of ligand specificities. All four proteins specifically and dose dependently adhered to bovine fibrinogen. One recombinant protein was identified as a candidate diagnostic antigen (disease specificity, 75%). Finally, when adjuvanted with aluminum hydroxide and administered to BDD-naive calves using a prime-boost vaccination protocol, these proteins were immunogenic, eliciting specific IgG antibodies. In summary, we present the description of four putative treponemal β-barrel OMPs that exhibit the characteristics of multispecific adhesins. The observed interactions with fibrinogen may be critical to host colonization and it is hypothesized that vaccination-induced antibody blockade of these interactions will impede treponemal virulence and thus be of therapeutic value.
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16
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Zgurskaya HI, Rybenkov VV. Permeability barriers of Gram-negative pathogens. Ann N Y Acad Sci 2020; 1459:5-18. [PMID: 31165502 PMCID: PMC6940542 DOI: 10.1111/nyas.14134] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/06/2019] [Accepted: 05/13/2019] [Indexed: 12/13/2022]
Abstract
Most clinical antibiotics do not have efficacy against Gram-negative pathogens, mainly because these cells are protected by the permeability barrier comprising the two membranes with active efflux. The emergence of multidrug-resistant Gram-negative strains threatens the utility even of last resort therapeutic treatments. Significant efforts at different levels of resolution are currently focused on finding a solution to this nonpermeation problem and developing new approaches to the optimization of drug activities against multidrug-resistant pathogens. The exceptional efficiency of the Gram-negative permeability barrier is the result of a complex interplay between the two opposing fluxes of drugs across the two membranes. In this review, we describe the current state of understanding of the problem and the recent advances in theoretical and empirical approaches to characterization of drug permeation and active efflux in Gram-negative bacteria.
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Affiliation(s)
- Helen I Zgurskaya
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma
| | - Valentin V Rybenkov
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma
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17
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Tohidinia M, Moshtaghioun SM, Sefid F, Falahati A. Functional Exposed Amino Acids of CarO Analysis as a Potential Vaccine Candidate in Acinetobacter Baumannii. Int J Pept Res Ther 2019. [DOI: 10.1007/s10989-019-09923-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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18
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Zhu LJ, Chen XY, Hou PF. Mutation of CarO participates in drug resistance in imipenem-resistant Acinetobacter baumannii. J Clin Lab Anal 2019; 33:e22976. [PMID: 31318107 PMCID: PMC6805298 DOI: 10.1002/jcla.22976] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 06/03/2019] [Accepted: 06/21/2019] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVE Acinetobacter baumannii has become an important problem because of the high drug resistance rate. The aim of this study was to assess the antimicrobial resistance profile and explore the role of membrane porin in imipenem resistance of A baumannii. METHODS A total of 63 isolates of imipenem-resistant A baumannii (IRAB) and 21 of imipenem-sensitive A baumannii (ISAB) were collected. Susceptibility testing to 16 kinds of antimicrobial agents was conducted by K-B method. PCR technique was used to detect carO and oprD genes, and sequencing was performed to compare the sequence between IRAB and ISAB. Three-dimensional structure model of CarO protein was established. RESULTS While ISAB isolates presented sensitive to most classes of antibiotics, isolates of IRAB displayed much higher resistance rate except tigecycline (3.2%), cefoperazone/sulbactam (28.6%), and minocycline (30.2%). All 84 isolates were observed carrying both carO and oprD genes. Further sequencing revealed important mutations of carO gene existed in IRAB in comparison with ISAB. Meanwhile, significant differences in three-dimensional structure of carO protein molecule were also found between IRAB and ISAB. CONCLUSIONS The drug resistance profile of IRAB is increasingly severe in clinical settings. Mutation of CarO was identified as one of the molecular mechanisms involved in imipenem resistance in A baumannii.
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Affiliation(s)
- Li-Jing Zhu
- Department of Clinical Laboratory, Lianshui County People's Hospital, Lianshui, China
| | - Xiao-Ying Chen
- Department of Clinical Laboratory, School of Medicine, RenJi Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Pan-Fei Hou
- Department of Clinical Laboratory, Lianshui County People's Hospital, Lianshui, China
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19
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Bhamidimarri SP, Zahn M, Prajapati JD, Schleberger C, Söderholm S, Hoover J, West J, Kleinekathöfer U, Bumann D, Winterhalter M, van den Berg B. A Multidisciplinary Approach toward Identification of Antibiotic Scaffolds for Acinetobacter baumannii. Structure 2019; 27:268-280.e6. [DOI: 10.1016/j.str.2018.10.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 08/19/2018] [Accepted: 10/23/2018] [Indexed: 11/16/2022]
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20
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Abellón-Ruiz J, Zahn M, Baslé A, van den Berg B. Crystal structure of theAcinetobacter baumanniiouter membrane protein Omp33. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2018; 74:852-860. [DOI: 10.1107/s205979831800904x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 06/20/2018] [Indexed: 12/31/2022]
Abstract
Acinetobacter baumanniiis becoming a major threat to human health due to its multidrug resistance. This is owing in a large part to the low permeability of its outer membrane (OM), which prevents high internal antibiotic concentrations and makes antibiotic-resistance mechanisms more effective. To exploit OM channels as potential delivery vehicles for future antibiotics, structural information is required. One abundant OM protein inA. baumanniiis Omp33. This protein has been reported to be important for thein vivofitness and virulence ofA. baumannii, but its structure is not known. Here, the X-ray crystal structure of Omp33 is reported at a resolution of 2.1 Å. Omp33 has a 14-β-stranded barrel without stable extracellular loop constrictions. Instead, an extended and unusual periplasmic turn connecting β-strands 2 and 3 is present, which folds into the pore lumen and completely blocks the aqueous channel. The Omp33 structure helps in understanding howA. baumanniiOM proteins contribute to the low permeability of the cell envelope of this bacterium and suggests that Omp33 might function as a gated channel.
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21
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Khorsi K, Messai Y, Ammari H, Hamidi M, Bakour R. ISAba36 inserted into the outer membrane protein gene carO and associated with the carbapenemase gene bla OXA-24-like in Acinetobacter baumannii. J Glob Antimicrob Resist 2018; 15:107-108. [PMID: 30172044 DOI: 10.1016/j.jgar.2018.08.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 08/05/2018] [Accepted: 08/20/2018] [Indexed: 10/28/2022] Open
Affiliation(s)
- Khadidja Khorsi
- Laboratory of Cellular and Molecular Biology, Faculty of Biological Sciences, University of Sciences and Technology Houari Boumediene, P.B. 32 El-Alia, Bab Ezzouar 16111, Algiers, Algeria
| | - Yamina Messai
- Laboratory of Cellular and Molecular Biology, Faculty of Biological Sciences, University of Sciences and Technology Houari Boumediene, P.B. 32 El-Alia, Bab Ezzouar 16111, Algiers, Algeria
| | - Houria Ammari
- University Hospital Isaad Hassani, Rue Ibrahim Hadjeras, Beni Messous 16206, Algiers, Algeria
| | - Moufida Hamidi
- Hospital Salim Zemirli, Route de Baraki, BP N°71, El Harrach 16000, Algiers, Algeria
| | - Rabah Bakour
- Laboratory of Cellular and Molecular Biology, Faculty of Biological Sciences, University of Sciences and Technology Houari Boumediene, P.B. 32 El-Alia, Bab Ezzouar 16111, Algiers, Algeria.
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22
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Abstract
Collective antibiotic drug resistance is a global threat, especially with respect to Gram-negative bacteria. The low permeability of the bacterial outer cell wall has been identified as a challenging barrier that prevents a sufficient antibiotic effect to be attained at low doses of the antibiotic. The Gram-negative bacterial cell envelope comprises an outer membrane that delimits the periplasm from the exterior milieu. The crucial mechanisms of antibiotic entry via outer membrane includes general diffusion porins (Omps) responsible for hydrophilic antibiotics and lipid-mediated pathway for hydrophobic antibiotics. The protein and lipid arrangements of the outer membrane have had a strong impact on the understanding of bacteria and their resistance to many types of antibiotics. Thus, one of the current challenges is effective interpretation at the molecular basis of the outer membrane permeability. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in solute influx. Moreover, it aims toward further understanding and exploration of prospects to improve our knowledge of physicochemical limitations that direct the translocation of antibiotics via bacterial outer membrane.
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Affiliation(s)
- Ishan Ghai
- School of Engineering and Life Sciences, Jacobs University, Bremen, Germany.,Consultation Division, RSGBIOGEN, New Delhi, India
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23
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Iyer R, Moussa SH, Durand-Réville TF, Tommasi R, Miller A. Acinetobacter baumannii OmpA Is a Selective Antibiotic Permeant Porin. ACS Infect Dis 2018; 4:373-381. [PMID: 29260856 DOI: 10.1021/acsinfecdis.7b00168] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OmpAAb is a conserved, abundantly expressed outer membrane porin in Acinetobacter baumannii whose presumed role in antibiotic permeation has not been clearly demonstrated. In this report, we use a titratable heterologous expression system to express OmpAAb in isolation and demonstrate selective passage of small molecule antibiotics through OmpAAb. ETX2514, a recently discovered broad-spectrum β-lactamase inhibitor, in combination with sulbactam, is currently in clinical testing for the treatment of drug-resistant A. baumannii infections. We demonstrate that ETX2514 permeates OmpAAb and potentiates the activity of sulbactam in an OmpAAb-dependent manner. In addition, we show that small modifications in the structure of ETX2514 differentially affect its passage through OmpAAb, revealing unique structure-porin-permeation relationships. Finally, we confirm the contribution of OmpAAb to bacterial fitness using a murine thigh model of A. baumannii infection. These results, combined with the high sequence homology of OmpA across Acinetobacter spp., suggest that optimization of antibiotic entry through OmpAAb may prove to be a feasible medicinal chemistry design strategy for future antibacterial discovery efforts.
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Affiliation(s)
- Ramkumar Iyer
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Samir H. Moussa
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | | | - Ruben Tommasi
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Alita Miller
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
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24
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Benkerrou D, Ceccarelli M. Free energy calculations and molecular properties of substrate translocation through OccAB porins. Phys Chem Chem Phys 2018. [DOI: 10.1039/c7cp08299a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We investigated with molecular modeling the translocation of simple substrates through four similar specific bacterial porins from the Acinetobacter baumannii pathogen providing structure–function analysis at the molecular level.
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25
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Synergy between Active Efflux and Outer Membrane Diffusion Defines Rules of Antibiotic Permeation into Gram-Negative Bacteria. mBio 2017; 8:mBio.01172-17. [PMID: 29089426 PMCID: PMC5666154 DOI: 10.1128/mbio.01172-17] [Citation(s) in RCA: 136] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Gram-negative bacteria are notoriously resistant to antibiotics, but the extent of the resistance varies broadly between species. We report that in significant human pathogens Acinetobacter baumannii, Pseudomonas aeruginosa, and Burkholderia spp., the differences in antibiotic resistance are largely defined by their penetration into the cell. For all tested antibiotics, the intracellular penetration was determined by a synergistic relationship between active efflux and the permeability barrier. We found that the outer membrane (OM) and efflux pumps select compounds on the basis of distinct properties and together universally protect bacteria from structurally diverse antibiotics. On the basis of their interactions with the permeability barriers, antibiotics can be divided into four clusters that occupy defined physicochemical spaces. Our results suggest that rules of intracellular penetration are intrinsic to these clusters. The identified specificities in the permeability barriers should help in the designing of successful therapeutic strategies against antibiotic-resistant pathogens.IMPORTANCE Multidrug-resistant strains of Gram-negative pathogens rapidly spread in clinics. Significant efforts worldwide are currently directed to finding the rules of permeation of antibiotics across two membrane envelopes of these bacteria. This study created the tools for analysis of and identified the major differences in antibacterial activities that distinguish the permeability barriers of P. aeruginosa, A. baumannii, Burkholderia thailandensis, and B. cepacia We conclude that synergy between active efflux and the outer membrane barrier universally protects Gram-negative bacteria from antibiotics. We also found that the diversity of antibiotics affected by active efflux and outer membrane barriers is broader than previously thought and that antibiotics cluster according to specific biological determinants such as the requirement of specific porins in the OM, targeting of the OM, or specific recognition by efflux pumps. No universal rules of antibiotic permeation into Gram-negative bacteria apparently exist. Our results suggest that antibiotic clusters are defined by specific rules of permeation and that further studies could lead to their discovery.
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26
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Abstract
One of the main fundamental mechanisms of antibiotic resistance in Gram-negative bacteria comprises an effective change in the membrane permeability to antibiotics. The Gram-negative bacterial complex cell envelope comprises an outer membrane that delimits the periplasm from the exterior environment. The outer membrane contains numerous protein channels, termed as porins or nanopores, which are mainly involved in the influx of hydrophilic compounds, including antibiotics. Bacterial adaptation to reduce influx through these outer membrane proteins (Omps) is one of the crucial mechanisms behind antibiotic resistance. Thus to interpret the molecular basis of the outer membrane permeability is the current challenge. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in antibiotic influx. Further, it aims to study the bacterial response to antibiotic membrane permeability and hopefully provoke a discussion toward understanding and further exploration of prospects to improve our knowledge on physicochemical parameters that direct the translocation of antibiotics through the bacterial membrane protein channels.
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Affiliation(s)
- Ishan Ghai
- School of Engineering and Life Sciences, Jacobs University, Bremen
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27
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Scorciapino MA, Acosta-Gutierrez S, Benkerrou D, D'Agostino T, Malloci G, Samanta S, Bodrenko I, Ceccarelli M. Rationalizing the permeation of polar antibiotics into Gram-negative bacteria. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:113001. [PMID: 28155846 DOI: 10.1088/1361-648x/aa543b] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The increasing level of antibiotic resistance in Gram-negative bacteria, together with the lack of new potential drug scaffolds in the pipeline, make the problem of infectious diseases a global challenge for modern medicine. The main reason that Gram-negative bacteria are particularly challenging is the presence of an outer cell-protecting membrane, which is not present in Gram-positive species. Such an asymmetric bilayer is a highly effective barrier for polar molecules. Several protein systems are expressed in the outer membrane to control the internal concentration of both nutrients and noxious species, in particular: (i) water-filled channels that modulate the permeation of polar molecules and ions according to concentration gradients, and (ii) efflux pumps to actively expel toxic compounds. Thus, besides expressing specific enzymes for drugs degradation, Gram-negative bacteria can also resist by modulating the influx and efflux of antibiotics, keeping the internal concentration low. However, there are no direct and robust experimental methods capable of measuring the permeability of small molecules, thus severely limiting our knowledge of the molecular mechanisms that ultimately control the permeation of antibiotics through the outer membrane. This is the innovation gap to be filled for Gram-negative bacteria. This review is focused on the permeation of small molecules through porins, considered the main path for the entry of polar antibiotics into Gram-negative bacteria. A fundamental understanding of how these proteins are able to filter small molecules is a prerequisite to design/optimize antibacterials with improved permeation. The level of sophistication of modern molecular modeling algorithms and the advances in new computer hardware has made the simulation of such complex processes possible at the molecular level. In this work we aim to share our experience and perspectives in the context of a multidisciplinary extended collaboration within the IMI-Translocation consortium. The synergistic combination of structural data, in vitro assays and computer simulations has proven to give new insights towards the identification and description of physico-chemical properties modulating permeation. Once similar general rules are identified, we believe that the use of virtual screening techniques will be very helpful in searching for new molecular scaffolds with enhanced permeation, and that molecular modeling will be of fundamental assistance to the optimization stage.
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Affiliation(s)
- Mariano Andrea Scorciapino
- Department of Biomedical Sciences, Biochemistry Unit, University of Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700-09042 Monserrato (CA), Italy
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28
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The Acinetobacter Outer Membrane Contains Multiple Specific Channels for Carbapenem β-Lactams as Revealed by Kinetic Characterization Analyses of Imipenem Permeation into Acinetobacter baylyi Cells. Antimicrob Agents Chemother 2017; 61:AAC.01737-16. [PMID: 28069648 DOI: 10.1128/aac.01737-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/28/2016] [Indexed: 12/31/2022] Open
Abstract
The number and type of outer membrane (OM) channels responsible for carbapenem uptake in Acinetobacter are still not well defined. Here, we addressed these questions by using Acinetobacter baylyi as a model species and a combination of methodologies aimed to characterize OM channels in their original membrane environment. Kinetic and competition analyses of imipenem (IPM) uptake by A. baylyi whole cells allowed us to identify different carbapenem-specific OM uptake sites. Comparative analyses of IPM uptake by A. baylyi wild-type (WT) cells and ΔcarO mutants lacking CarO indicated that this OM protein provided a carbapenem uptake site displaying saturable kinetics and common binding sites for basic amino acids compatible with a specific channel. The kinetic analysis uncovered another carbapenem-specific channel displaying a somewhat lower affinity for IPM than that of CarO and, in addition, common binding sites for basic amino acids as determined by competition studies. The use of A. baylyi gene deletion mutants lacking OM proteins proposed to function in carbapenem uptake in Acinetobacter baumannii indicated that CarO and OprD/OccAB1 mutants displayed low but consistent reductions in susceptibility to different carbapenems, including IPM, meropenem, and ertapenem. These two mutants also showed impaired growth on l-Arg but not on other carbon sources, further supporting a role of CarO and OprD/OccAB1 in basic amino acid and carbapenem uptake. A multiple-carbapenem-channel scenario may provide clues to our understanding of the contribution of OM channel loss or mutation to the carbapenem-resistant phenotype evolved by pathogenic members of the Acinetobacter genus.
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29
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Wu X, Chavez JD, Schweppe DK, Zheng C, Weisbrod CR, Eng JK, Murali A, Lee SA, Ramage E, Gallagher LA, Kulasekara HD, Edrozo ME, Kamischke CN, Brittnacher MJ, Miller SI, Singh PK, Manoil C, Bruce JE. In vivo protein interaction network analysis reveals porin-localized antibiotic inactivation in Acinetobacter baumannii strain AB5075. Nat Commun 2016; 7:13414. [PMID: 27834373 PMCID: PMC5114622 DOI: 10.1038/ncomms13414] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 09/30/2016] [Indexed: 12/13/2022] Open
Abstract
The nosocomial pathogen Acinetobacter baumannii is a frequent cause of hospital-acquired infections worldwide and is a challenge for treatment due to its evolved resistance to antibiotics, including carbapenems. Here, to gain insight on A. baumannii antibiotic resistance mechanisms, we analyse the protein interaction network of a multidrug-resistant A. baumannii clinical strain (AB5075). Using in vivo chemical cross-linking and mass spectrometry, we identify 2,068 non-redundant cross-linked peptide pairs containing 245 intra- and 398 inter-molecular interactions. Outer membrane proteins OmpA and YiaD, and carbapenemase Oxa-23 are hubs of the identified interaction network. Eighteen novel interactors of Oxa-23 are identified. Interactions of Oxa-23 with outer membrane porins OmpA and CarO are verified with co-immunoprecipitation analysis. Furthermore, transposon mutagenesis of oxa-23 or interactors of Oxa-23 demonstrates changes in meropenem or imipenem sensitivity in strain AB5075. These results provide a view of porin-localized antibiotic inactivation and increase understanding of bacterial antibiotic resistance mechanisms.
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Affiliation(s)
- Xia Wu
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
| | - Juan D. Chavez
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
| | - Devin K. Schweppe
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
| | - Chunxiang Zheng
- Department of Chemistry, University of Washington, Seattle, Washington 98109, USA
| | - Chad R. Weisbrod
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
| | - Jimmy K. Eng
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
| | - Ananya Murali
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
| | - Samuel A. Lee
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
| | - Elizabeth Ramage
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
| | - Larry A. Gallagher
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
| | | | - Mauna E. Edrozo
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA
| | | | | | - Samuel I. Miller
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA
- Department of Medicine, University of Washington, Seattle, Washington 98195, USA
| | - Pradeep K. Singh
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA
- Department of Medicine, University of Washington, Seattle, Washington 98195, USA
| | - Colin Manoil
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
| | - James E. Bruce
- Department of Genome Sciences, University of Washington, 850 Republican Street, Brotman Building Room 154, Seattle, Washington 98109, USA
- Department of Chemistry, University of Washington, Seattle, Washington 98109, USA
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30
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Zahn M, Bhamidimarri SP, Baslé A, Winterhalter M, van den Berg B. Structural Insights into Outer Membrane Permeability of Acinetobacter baumannii. Structure 2016; 24:221-31. [PMID: 26805524 DOI: 10.1016/j.str.2015.12.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 12/16/2015] [Accepted: 12/16/2015] [Indexed: 12/26/2022]
Abstract
Bacterial resistance against antibiotics is an increasing global health problem. In Gram-negative bacteria the low permeability of the outer membrane (OM) is a major factor contributing to resistance, making it important to understand channel-mediated small-molecule passage of the OM. Acinetobacter baumannii has five Occ (OM carboxylate channel) proteins, which collectively are of major importance for the entry of small molecules. To improve our understanding of the OM permeability of A. baumannii, we present here the X-ray crystal structures of four Occ proteins, renamed OccAB1 to OccAB4. In addition we have carried out a biochemical and biophysical characterization using electrophysiology and liposome swelling experiments, providing information on substrate specificities. We identify OccAB1 as having the largest pore of the Occ proteins with corresponding high rates of small-molecule uptake, and we suggest that the future design of efficient antibiotics should focus on scaffolds that can permeate efficiently through the OccAB1 channel.
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Affiliation(s)
- Michael Zahn
- Institute for Cellular and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | | | - Arnaud Baslé
- Institute for Cellular and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Mathias Winterhalter
- School of Engineering and Science, Jacobs University Bremen, 28759 Bremen, Germany
| | - Bert van den Berg
- Institute for Cellular and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
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31
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Pothula KR, Solano CJF, Kleinekathöfer U. Simulations of outer membrane channels and their permeability. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:1760-71. [PMID: 26721326 DOI: 10.1016/j.bbamem.2015.12.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 12/15/2015] [Accepted: 12/17/2015] [Indexed: 12/25/2022]
Abstract
Channels in the outer membrane of Gram-negative bacteria provide essential pathways for the controlled and unidirectional transport of ions, nutrients and metabolites into the cell. At the same time the outer membrane serves as a physical barrier for the penetration of noxious substances such as antibiotics into the bacteria. Most antibiotics have to pass through these membrane channels to either reach cytoplasmic bound targets or to further cross the hydrophobic inner membrane. Considering the pharmaceutical significance of antibiotics, understanding the functional role and mechanism of these channels is of fundamental importance in developing strategies to design new drugs with enhanced permeation abilities. Due to the biological complexity of membrane channels and experimental limitations, computer simulations have proven to be a powerful tool to investigate the structure, dynamics and interactions of membrane channels. Considerable progress has been made in computer simulations of membrane channels during the last decade. The goal of this review is to provide an overview of the computational techniques and their roles in modeling the transport across outer membrane channels. A special emphasis is put on all-atom molecular dynamics simulations employed to better understand the transport of molecules. Moreover, recent molecular simulations of ion, substrate and antibiotics translocation through membrane pores are briefly summarized. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov.
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Affiliation(s)
- Karunakar R Pothula
- Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Carlos J F Solano
- Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Ulrich Kleinekathöfer
- Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
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32
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Zgurskaya HI, López CA, Gnanakaran S. Permeability Barrier of Gram-Negative Cell Envelopes and Approaches To Bypass It. ACS Infect Dis 2015; 1:512-522. [PMID: 26925460 DOI: 10.1021/acsinfecdis.5b00097] [Citation(s) in RCA: 369] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Gram-negative bacteria are intrinsically resistant to many antibiotics. Species that have acquired multidrug resistance and cause infections that are effectively untreatable present a serious threat to public health. The problem is broadly recognized and tackled at both the fundamental and applied levels. This paper summarizes current advances in understanding the molecular bases of the low permeability barrier of Gram-negative pathogens, which is the major obstacle in discovery and development of antibiotics effective against such pathogens. Gaps in knowledge and specific strategies to break this barrier and to achieve potent activities against difficult Gram-negative bacteria are also discussed.
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Affiliation(s)
- Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Cesar A. López
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - S. Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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