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Kavanaugh LG, Dey D, Shafer WM, Conn GL. Structural and functional diversity of Resistance-Nodulation-Division (RND) efflux pump transporters with implications for antimicrobial resistance. Microbiol Mol Biol Rev 2024; 88:e0008923. [PMID: 39235227 PMCID: PMC11426026 DOI: 10.1128/mmbr.00089-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2024] Open
Abstract
SUMMARYThe discovery of bacterial efflux pumps significantly advanced our understanding of how bacteria can resist cytotoxic compounds that they encounter. Within the structurally and functionally distinct families of efflux pumps, those of the Resistance-Nodulation-Division (RND) superfamily are noteworthy for their ability to reduce the intracellular concentration of structurally diverse antimicrobials. RND systems are possessed by many Gram-negative bacteria, including those causing serious human disease, and frequently contribute to resistance to multiple antibiotics. Herein, we review the current literature on the structure-function relationships of representative transporter proteins of tripartite RND efflux pumps of clinically important pathogens. We emphasize their contribution to bacterial resistance to clinically used antibiotics, host defense antimicrobials and other biocides, as well as highlighting structural similarities and differences among efflux transporters that help bacteria survive in the face of antimicrobials. Furthermore, we discuss technical advances that have facilitated and advanced efflux pump research and suggest future areas of investigation that will advance antimicrobial development efforts.
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Affiliation(s)
- Logan G Kavanaugh
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
- Graduate Program in Microbiology and Molecular Genetics, Emory University, Atlanta, Georgia, USA
| | - Debayan Dey
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | - William M Shafer
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA
- Laboratories of Microbial Pathogenesis, VA Medical Research Service, Veterans Affairs Medical Center, Decatur, Georgia, USA
- Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Graeme L Conn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
- Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia, USA
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2
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Klenotic PA, Yu EW. Structural analysis of resistance-nodulation cell division transporters. Microbiol Mol Biol Rev 2024; 88:e0019823. [PMID: 38551344 PMCID: PMC11332337 DOI: 10.1128/mmbr.00198-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2024] Open
Abstract
SUMMARYInfectious bacteria have both intrinsic and acquired mechanisms to combat harmful biocides that enter the cell. Through adaptive pressures, many of these pathogens have become resistant to many, if not all, of the current antibiotics used today to treat these often deadly infections. One prominent mechanism is the upregulation of efflux systems, especially the resistance-nodulation-cell division class of exporters. These tripartite systems consist of an inner membrane transporter coupled with a periplasmic adaptor protein and an outer membrane channel to efficiently transport a diverse array of substrates from inside the cell to the extracellular space. Detailed mechanistic insight into how these inner membrane transporters recognize and shuttle their substrates can ultimately inform both new antibiotic and efflux pump inhibitor design. This review examines the structural basis of substrate recognition of these pumps and the molecular mechanisms underlying multidrug extrusion, which in turn mediate antimicrobial resistance in bacterial pathogens.
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Affiliation(s)
- Philip A. Klenotic
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Edward W. Yu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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3
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Al-Fadhli AH, Jamal WY. Recent advances in gene-editing approaches for tackling antibiotic resistance threats: a review. Front Cell Infect Microbiol 2024; 14:1410115. [PMID: 38994001 PMCID: PMC11238145 DOI: 10.3389/fcimb.2024.1410115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Accepted: 06/11/2024] [Indexed: 07/13/2024] Open
Abstract
Antibiotic resistance, a known global health challenge, involves the flow of bacteria and their genes among animals, humans, and their surrounding environment. It occurs when bacteria evolve and become less responsive to the drugs designated to kill them, making infections harder to treat. Despite several obstacles preventing the spread of genes and bacteria, pathogens regularly acquire novel resistance factors from other species, which reduces their ability to prevent and treat such bacterial infections. This issue requires coordinated efforts in healthcare, research, and public awareness to address its impact on human health worldwide. This review outlines how recent advances in gene editing technology, especially CRISPR/Cas9, unveil a breakthrough in combating antibiotic resistance. Our focus will remain on the relationship between CRISPR/cas9 and its impact on antibiotic resistance and its related infections. Moreover, the prospects of this new advanced research and the challenges of adopting these technologies against infections will be outlined by exploring its different derivatives and discussing their advantages and limitations over others, thereby providing a corresponding reference for the control and prevention of the spread of antibiotic resistance.
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Affiliation(s)
- Amani H Al-Fadhli
- Laboratory Sciences, Department of Medical, Faculty of Allied Health Sciences, Health Sciences Center (HSC), Kuwait University, Jabriya, Kuwait
| | - Wafaa Yousef Jamal
- Department of Microbiology, College of Medicine, Kuwait University, Jabriya, Kuwait
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Tambat R, Kinthada RK, Saral Sariyer A, Leus IV, Sariyer E, D'Cunha N, Zhou H, Leask M, Walker JK, Zgurskaya HI. AdeIJK Pump-Specific Inhibitors Effective against Multidrug Resistant Acinetobacter baumannii. ACS Infect Dis 2024; 10:2239-2249. [PMID: 38787939 DOI: 10.1021/acsinfecdis.4c00190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
Multidrug-resistant Acinetobacter baumannii is a serious threat pathogen rapidly spreading in clinics and causing a range of complicated human infections. The major contributor to A. baumannii antibiotic resistance is the overproduction of AdeIJK and AdeABC multidrug efflux pumps of the resistance-nodulation-division (RND) superfamily of proteins. The dominant role of efflux in antibiotic resistance and the relatively high permeability of the A. baumannii outer membrane to amphiphilic compounds make this pathogen a promising target for the discovery of clinically relevant efflux pump inhibitors. In this study, we identified 4,6-diaminoquoniline analogs with inhibitory activities against A. baumannii AdeIJK efflux pump and followed up on these compounds with a focused synthetic program to improve the target specificity and to reduce cytotoxicity. We identified several candidates that potentiate antibacterial activities of antibiotics erythromycin, tetracycline, and novobiocin not only in the laboratory antibiotic susceptible strain A. baumannii ATCC17978 but also in multidrug-resistant clinical isolates AB5075 and AYE. The best analogs potentiated the activities of antibiotics in low micromolar concentrations, did not have antibacterial activities on their own, inhibited AdeIJK-mediated efflux of its fluorescent substrate ethidium ion, and had low cytotoxicity in A549 human lung epithelial cells.
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Affiliation(s)
- Rushikesh Tambat
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Rama Kumar Kinthada
- School of Medicine, Saint Louis University, St. Louis, Missouri 63110, United States
| | - Aysegul Saral Sariyer
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Artvin Coruh University, 08000 Artvin, Turkey
| | - Inga V Leus
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Emrah Sariyer
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Artvin Coruh University, 08000 Artvin, Turkey
- Vocational School of Health Services, Medical Laboratory Techniques, Artvin Coruh University, 08000 Artvin, Turkey
| | - Napoleon D'Cunha
- School of Medicine, Saint Louis University, St. Louis, Missouri 63110, United States
| | - Hinman Zhou
- School of Medicine, Saint Louis University, St. Louis, Missouri 63110, United States
| | - Makaila Leask
- School of Medicine, Saint Louis University, St. Louis, Missouri 63110, United States
| | - John K Walker
- School of Medicine, Saint Louis University, St. Louis, Missouri 63110, United States
- Department of Chemistry, Saint Louis University, St. Louis, Missouri 63110, United States
| | - Helen I Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States
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5
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Manrique PD, Leus IV, López CA, Mehla J, Malloci G, Gervasoni S, Vargiu AV, Kinthada RK, Herndon L, Hengartner NW, Walker JK, Rybenkov VV, Ruggerone P, Zgurskaya HI, Gnanakaran S. Predicting permeation of compounds across the outer membrane of P. aeruginosa using molecular descriptors. Commun Chem 2024; 7:84. [PMID: 38609430 PMCID: PMC11015012 DOI: 10.1038/s42004-024-01161-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
The ability Gram-negative pathogens have at adapting and protecting themselves against antibiotics has increasingly become a public health threat. Data-driven models identifying molecular properties that correlate with outer membrane (OM) permeation and growth inhibition while avoiding efflux could guide the discovery of novel classes of antibiotics. Here we evaluate 174 molecular descriptors in 1260 antimicrobial compounds and study their correlations with antibacterial activity in Gram-negative Pseudomonas aeruginosa. The descriptors are derived from traditional approaches quantifying the compounds' intrinsic physicochemical properties, together with, bacterium-specific from ensemble docking of compounds targeting specific MexB binding pockets, and all-atom molecular dynamics simulations in different subregions of the OM model. Using these descriptors and the measured inhibitory concentrations, we design a statistical protocol to identify predictors of OM permeation/inhibition. We find consistent rules across most of our data highlighting the role of the interaction between the compounds and the OM. An implementation of the rules uncovered in our study is shown, and it demonstrates the accuracy of our approach in a set of previously unseen compounds. Our analysis sheds new light on the key properties drug candidates need to effectively permeate/inhibit P. aeruginosa, and opens the gate to similar data-driven studies in other Gram-negative pathogens.
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Affiliation(s)
- Pedro D Manrique
- Physics Department, George Washington University, Washington, 20052, DC, USA.
| | - Inga V Leus
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, 73019, OK, USA
| | - César A López
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, 87545, NM, USA
| | - Jitender Mehla
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, 73019, OK, USA
| | - Giuliano Malloci
- Department of Physics, University of Cagliari, Monserrato, 20052, CA, Italy
| | - Silvia Gervasoni
- Department of Physics, University of Cagliari, Monserrato, 20052, CA, Italy
| | - Attilio V Vargiu
- Department of Physics, University of Cagliari, Monserrato, 20052, CA, Italy
| | - Rama K Kinthada
- Department of Pharmacology and Physiology, Saint Louis University, St. Louis, 63103, MO, USA
| | - Liam Herndon
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, 87545, NM, USA
| | - Nicolas W Hengartner
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, 87545, NM, USA
| | - John K Walker
- Department of Pharmacology and Physiology, Saint Louis University, St. Louis, 63103, MO, USA
| | - Valentin V Rybenkov
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, 73019, OK, USA
| | - Paolo Ruggerone
- Department of Physics, University of Cagliari, Monserrato, 20052, CA, Italy
| | - Helen I Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, 73019, OK, USA
| | - S Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, 87545, NM, USA.
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Shang Y, Zhang Y, Wang R, Peng Y, Ding B, Liu Y, Li C, Feng L, Liu H, Yang C, Tang Y. Deciphering the molecular and functional basis of TMexCD1: the plasmid-encoded efflux pump of resistance-nodulation-division superfamily. Antimicrob Agents Chemother 2024; 68:e0167823. [PMID: 38477539 PMCID: PMC10989000 DOI: 10.1128/aac.01678-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 02/15/2024] [Indexed: 03/14/2024] Open
Abstract
Horizontal gene transfer has been demonstrated to be an important driver for the emergency of multidrug-resistant pathogens. Recently, a transferable gene cluster tmexCD1-toprJ1 of the resistance-nodulation-division (RND) superfamily was identified in the plasmids of animal-derived Klebsiella pneumoniae strains, with a higher efflux capacity for various drugs than the Escherichia coli AcrAB-TolC homolog system. In this study, we focused on the differences in the inner membrane pump of these two systems and identified some key residues that contribute to the robust efflux activity of the TMexCD1 system. With the aid of homologous modeling and molecular docking, eight residues from the proximal binding pocket (PBP) and nine from the distal binding pocket (DBP) were selected and subjected to site-directed mutagenesis. Several of them, such as S134, I139, D181, and A290, were shown to be important for substrate binding in the DBP region, and all residues in PBP and DBP showed certain substrate preferences. Apart from the conservative switch loop (L613-623TMexD1) previously identified in the E. coli AcrB (EcAcrB), a relatively unconservative loop (L665-675TMexD1) at the bottom of PBP was proposed as a critical element for the robust activity of TMexD1, due to variations at sites E669, G670, N673, and S674 compared to EcAcrAB, and the significantly altered efflux activity due to their mutations. The conservation and flexibility of these key factors can contribute to the evolution of the RND efflux pumps and thus serve as potential targets for developing inhibitors to block the widespread of the TMexCD1 system.
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Affiliation(s)
- Yan Shang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
- Poultry Institute, Shandong Academy of Agricultural Sciences, Jinan, China
| | - Ye Zhang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Ruimin Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Yishu Peng
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Bo Ding
- Shandong Institute for Food and Drug Control, Jinan, China
- School of Pharmaceutical Sciences, Shandong University, Jinan, China
| | - Yuanxiang Liu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Chongzhou Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Luhua Feng
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Honglei Liu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Chunyu Yang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Yajie Tang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, China
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7
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Allemailem KS. Recent Advances in Understanding the Molecular Mechanisms of Multidrug Resistance and Novel Approaches of CRISPR/Cas9-Based Genome-Editing to Combat This Health Emergency. Int J Nanomedicine 2024; 19:1125-1143. [PMID: 38344439 PMCID: PMC10859101 DOI: 10.2147/ijn.s453566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 01/26/2024] [Indexed: 02/15/2024] Open
Abstract
The rapid spread of multidrug resistance (MDR), due to abusive use of antibiotics has led to global health emergency, causing substantial morbidity and mortality. Bacteria attain MDR by different means such as antibiotic modification/degradation, target protection/modification/bypass, and enhanced efflux mechanisms. The classical approaches of counteracting MDR bacteria are expensive and time-consuming, thus, it is highly significant to understand the molecular mechanisms of this resistance to curb the problem from core level. The revolutionary approach of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated sequence 9 (CRISPR/Cas9), considered as a next-generation genome-editing tool presents an innovative opportunity to precisely target and edit bacterial genome to alter their MDR strategy. Different bacteria possessing antibiotic resistance genes such as mecA, ermB, ramR, tetA, mqrB and blaKPC that have been targeted by CRISPR/Cas9 to re-sensitize these pathogens against antibiotics, such as methicillin, erythromycin, tigecycline, colistin and carbapenem, respectively. The CRISPR/Cas9 from S. pyogenes is the most widely studied genome-editing tool, consisting of a Cas9 DNA endonuclease associated with tracrRNA and crRNA, which can be systematically coupled as sgRNA. The targeting strategies of CRISPR/Cas9 to bacterial cells is mediated through phage, plasmids, vesicles and nanoparticles. However, the targeting approaches of this genome-editing tool to specific bacteria is a challenging task and still remains at a very preliminary stage due to numerous obstacles awaiting to be solved. This review elaborates some recent updates about the molecular mechanisms of antibiotic resistance and the innovative role of CRISPR/Cas9 system in modulating these resistance mechanisms. Furthermore, the delivery approaches of this genome-editing system in bacterial cells are discussed. In addition, some challenges and future prospects are also described.
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Affiliation(s)
- Khaled S Allemailem
- Department of Medical Laboratories, College of Applied Medical Sciences, Qassim University, Buraydah51452, Saudi Arabia
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8
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Wilhelm J, Pos KM. Molecular insights into the determinants of substrate specificity and efflux inhibition of the RND efflux pumps AcrB and AdeB. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001438. [PMID: 38358391 PMCID: PMC10924465 DOI: 10.1099/mic.0.001438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/30/2024] [Indexed: 02/16/2024]
Abstract
Gram-negative bacterial members of the Resistance Nodulation and cell Division (RND) superfamily form tripartite efflux pump systems that span the cell envelope. One of the intriguing features of the multiple drug efflux members of this superfamily is their ability to recognize different classes of antibiotics, dyes, solvents, bile salts, and detergents. This review provides an overview of the molecular mechanisms of multiple drug efflux catalysed by the tripartite RND efflux system AcrAB-TolC from Eschericha coli. The determinants for sequential or simultaneous multiple substrate binding and efflux pump inhibitor binding are discussed. A comparison is made with the determinants for substrate binding of AdeB from Acinetobacter baumannii, which acts within the AdeABC multidrug efflux system. There is an apparent general similarity between the structures of AcrB and AdeB and their substrate specificity. However, the presence of distinct conformational states and different drug efflux capacities as revealed by single-particle cryo-EM and mutational analysis suggest that the drug binding and transport features exhibited by AcrB may not be directly extrapolated to the homolog AdeB efflux pump.
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Affiliation(s)
- Julia Wilhelm
- Institute of Biochemistry, Goethe-University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt am Main, Germany
| | - Klaas Martinus Pos
- Institute of Biochemistry, Goethe-University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt am Main, Germany
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Abstract
In a recent study by Inga V. Leus, Sean R. Roberts, Anhthu Trinh, Edward W. Yu, and Helen I. Zgurskaya (J Bacteriol, 2023, https://doi.org/10.1128/jb.00217-23), it was found that the clinically relevant resistance-nodulation-cell division (RND)-type AdeABC antibiotic efflux pump from Acinetobacter baumannii exhibits close communication between its antibiotic binding sites. Alterations in one of them can have far-reaching impacts on the drug translocation pathway. These insights could reshape our understanding of RND-type efflux pump mechanisms.
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Affiliation(s)
- Klaas Martinus Pos
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
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10
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Leus IV, Roberts SR, Trinh A, W. Yu E, Zgurskaya HI. Nonadditive functional interactions between ligand-binding sites of the multidrug efflux pump AdeB from Acinetobacter baumannii. J Bacteriol 2024; 206:e0021723. [PMID: 37850798 PMCID: PMC10809976 DOI: 10.1128/jb.00217-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 09/12/2023] [Indexed: 10/19/2023] Open
Abstract
Multidrug efflux is one of the major mechanisms of antibiotic resistance identified in clinical isolates of the human pathogen Acinetobacter baumannii. The multiple antibiotic resistance in this species is often enabled by the overproduction of the tripartite efflux pump AdeABC. In this pump, AdeB is the inner membrane transporter from the resistance-nodulation-division (RND) superfamily of proteins, which is responsible for the recognition and efflux of multiple structurally unrelated compounds. Like other RND transporters, AdeB is a trimeric protein with ligand-binding sites located in the large periplasmic domains. Previous structural studies, however, highlighted the uniqueness of AdeB interactions with ligands. Up to three ligand molecules were bound to one protomer of AdeB, mapping its substrate translocation path. In this study, we introduced single and double substitutions in the identified ligand-binding sites of AdeB. Our results show that the mechanism of substrate translocation by AdeB is different from that of other characterized RND transporters and that the functional interactions between the sites are nonadditive. We identified AdeB mutants with both the loss and the gain of antibiotic susceptibility phenotypes, as well as AdeB mutations making A. baumannii cells overproducing such pump variants even more susceptible to multiple antibiotics than efflux-deficient cells. IMPORTANCE Multidrug efflux pumps of the resistance-nodulation-division superfamily of proteins are important contributors to various aspects of bacterial physiology and antibiotic resistance. Studies of the best-characterized model transporter AcrB from Escherichia coli suggested that these transporters operate by a functional rotation mechanism in which various substrates bind to at least two different binding sites. This study suggests that the mechanism of AdeB is distinct and that the binding sites in this transporter are functionally linked.
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Affiliation(s)
- Inga V. Leus
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Sean R. Roberts
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Anhthu Trinh
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Edward W. Yu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
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11
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Zhang Z, Tringides ML, Morgan CE, Miyagi M, Mears JA, Hoppel CL, Yu EW. High-Resolution Structural Proteomics of Mitochondria Using the 'Build and Retrieve' Methodology. Mol Cell Proteomics 2023; 22:100666. [PMID: 37839702 PMCID: PMC10709515 DOI: 10.1016/j.mcpro.2023.100666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 10/06/2023] [Accepted: 10/11/2023] [Indexed: 10/17/2023] Open
Abstract
The application of integrated systems biology to the field of structural biology is a promising new direction, although it is still in the infant stages of development. Here we report the use of single particle cryo-EM to identify multiple proteins from three enriched heterogeneous fractions prepared from human liver mitochondrial lysate. We simultaneously identify and solve high-resolution structures of nine essential mitochondrial enzymes with key metabolic functions, including fatty acid catabolism, reactive oxidative species clearance, and amino acid metabolism. Our methodology also identified multiple distinct members of the acyl-CoA dehydrogenase family. This work highlights the potential of cryo-EM to explore tissue proteomics at the atomic level.
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Affiliation(s)
- Zhemin Zhang
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Marios L Tringides
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Christopher E Morgan
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Masaru Miyagi
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Jason A Mears
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Charles L Hoppel
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Edward W Yu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.
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12
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Jiménez-Castellanos JC, Pradel E, Compagne N, Vieira Da Cruz A, Flipo M, Hartkoorn RC. Characterization of pyridylpiperazine-based efflux pump inhibitors for Acinetobacter baumannii. JAC Antimicrob Resist 2023; 5:dlad112. [PMID: 37881353 PMCID: PMC10594211 DOI: 10.1093/jacamr/dlad112] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 09/23/2023] [Indexed: 10/27/2023] Open
Abstract
Objectives In Acinetobacter baumannii, multidrug efflux pumps belonging to the resistance-nodulation-division (RND) superfamily result in decreased antibiotic susceptibility. Improving the activity of current antibiotics via efflux pump inhibitors (EPIs) represents an attractive alternative approach to control this bacterium. Pyridylpiperazines (PyrPips) are a new class of EPIs that can effectively inhibit the Escherichia coli RND efflux pump AcrAB-TolC and boost the activity of several antibiotics. Here we have evaluated and characterized whether the PyrPip chemical family is also able to boost antibiotic activity through inhibition of the RND efflux pumps in A. baumannii. Methods Comparative structural modelling and docking, structure-activity relationship studies alongside molecular genetic approaches were deployed to improve, characterize and validate PyrPips' target. Results We showed that two enhanced PyrPip EPIs are capable of rescuing the activity of different classes of antibiotics in A. baumannii. By expressing A. baumannii main efflux pumps (AdeB, AdeG and AdeJ) individually in E. coli recombinant strains, we could gain further insights about the EPIs' capacity to act upon each pump. Finally, we showed that PyrPip EPIs are mostly acting through AdeJ inhibition via interactions with two key charged residues, namely E959 and E963. Conclusions Our work demonstrates that PyrPip EPIs are capable of inhibiting RND efflux pumps of A. baumannii, and thus may present a promising chemical scaffold for further development.
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Affiliation(s)
- Juan-Carlos Jiménez-Castellanos
- Université de Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019, UMR 9017, CIIL, Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Elizabeth Pradel
- Université de Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019, UMR 9017, CIIL, Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Nina Compagne
- Université de Lille, INSERM, Institut Pasteur de Lille, U1177, Drugs and Molecules for Living Systems, F-59000 Lille, France
| | - Anais Vieira Da Cruz
- Université de Lille, INSERM, Institut Pasteur de Lille, U1177, Drugs and Molecules for Living Systems, F-59000 Lille, France
| | - Marion Flipo
- Université de Lille, INSERM, Institut Pasteur de Lille, U1177, Drugs and Molecules for Living Systems, F-59000 Lille, France
| | - Ruben C Hartkoorn
- Université de Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019, UMR 9017, CIIL, Center for Infection and Immunity of Lille, F-59000 Lille, France
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13
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Tuo Y, Tang Y, Yang R, Zhao X, Luo M, Zhou X, Wang Y. Virtual screening and biological activity evaluation of novel efflux pump inhibitors targeting AdeB. Int J Biol Macromol 2023; 250:126109. [PMID: 37544561 DOI: 10.1016/j.ijbiomac.2023.126109] [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: 05/15/2023] [Revised: 07/16/2023] [Accepted: 07/31/2023] [Indexed: 08/08/2023]
Abstract
The AdeABC efflux pump is an important mechanism causing multidrug resistance in Acinetobacter baumannii, and its main component AdeB can recognize carbapenems, aminoglycosides, and other multi-class antibiotics and efflux them intracellularly, which is an ideal target for the development of anti-multidrug resistant bacteria drugs. Here, we combined multiple computer-aided drug design methods to target AdeB to identify promising novel structural inhibitors. Virtual screening was performed by molecular docking and molecular dynamics simulation (MD) and 12 potential compounds were identified from the databases. Meanwhile, their biological activities were validated by in vitro activity assays, and ChemDiv L676-2179 (γ-IFN), ChemDiv L676-1461, and Chembridge 53717615 were confirmed to suppress efflux effects and restore antibiotic susceptibility of resistant bacteria, which are expected to be developed as adjuvant drugs for the treatment of multi-drug resistant Acinetobacter baumannii clinical infections.
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Affiliation(s)
- Yan Tuo
- School of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China; Chongqing University Cancer Hospital, Chongqing 400030, China
| | - Yuelu Tang
- School of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China; Chongqing University Cancer Hospital, Chongqing 400030, China
| | - Ran Yang
- School of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China
| | - XueMin Zhao
- School of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China
| | - Minghe Luo
- School of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China
| | - Xing Zhou
- School of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China
| | - Yuanqiang Wang
- School of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China; Chongqing Key Laboratory of Medicinal Chemistry & Molecular Pharmacology, Chongqing University of Technology, Chongqing 400054, China; Chongqing Key Laboratory of Target Based Drug Screening and Activity Evaluation, Chongqing University of Technology, Chongqing 400054, China.
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14
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Shakibaie MR, Modaresi F, Azizi O, Tadjrobehkar O, Ghaemi MM. Amphiphilic peptide Mastoparan-B induces conformational changes within the AdeB efflux pump, down-regulates adeB gene expression, and restores antibiotic susceptibility in an MDR strain of Acinetobacter baumannii. Proteins 2023; 91:1205-1221. [PMID: 37455426 DOI: 10.1002/prot.26539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 05/11/2023] [Accepted: 05/30/2023] [Indexed: 07/18/2023]
Abstract
Mastoparan B (MP-B) is an amphiphilic peptide with a potent antimicrobial activity against most Gram-negative bacteria. However, there is little information available on the inhibition of the Acinetobacter baumannii resistance-nodulation-cell-division (RND) efflux pump using this antimicrobial peptide. Here, we carried out a series of in-silico experiments to find the mechanisms underlying the anti-efflux activity of MP-B using a multi-drug resistant (MDR) strain of A. baumannii (AB). According to our findings, MP-B demonstrated a potent antibacterial activity against an MDR-AB (minimum inhibitory concentration [MIC] = 1 μg/mL) followed by a 20-fold reduction in the adeB gene expression in the presence of sub-MIC of this peptide. Using Groningen Machine for Chemicals Simulation (GROMACS) via PyMOL Graphical User Interface (GUI), (we observed that, the AdeB transporter had conserved helix-turn-helix regions and a tight pore rich in Phe and Ala residues. To understand how inhibition of the AdeB is achieved, we generated 20 apo-MP-B poses using the InterPep and SiteMap tools. The high-quality model was created by homology modeling and used for docking via AutoDock/Vina to identify the MP-B binding sites. We established that the most apo-MP-B formed H-bonds to the backbone of five amino acids in the Helix-5. As a result, the dihedral angles of the involved amino acids shift by 9.0-9.6 Ǻ, causing a change in the conformation of the AdeB protein. This led to helix conformation stereoisomerization and block the AdeB activity. MP-B presumably has dual mechanisms. (1) It blocks the AdeB transporter by changing its conformation. (2) MP-B influences the adeB gene expression by binding to G-protein which laterally controls efflux regulators like MarA, RamA, SoxS, and Rob proteins.
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Affiliation(s)
- Mohammad Reza Shakibaie
- Department of Microbiology and Virology, Kerman University of Medical Sciences, Kerman, Iran
- Gastroenterology Hepatology Research Center, Institute of Basic and Clinical Physiology, Kerman University of Medical Sciences, Kerman, Iran
| | - Farzan Modaresi
- Department of Microbiology, School of Medicine, Jahrom University of Medical Sciences, Jahrom, Iran
| | - Omid Azizi
- Department of Laboratory Sciences, and Health Sciences Research center, Torbat Heydariyeh University of Medical Sciences, Torbate Heydarieh, Iran
| | - Omid Tadjrobehkar
- Department of Microbiology and Virology, Kerman University of Medical Sciences, Kerman, Iran
| | - Mohammad Mehdi Ghaemi
- Medical Informatics Research Center, Institute for Futures Studies in Health, Kerman University of Medical Sciences, Kerman, Iran
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15
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Zhang Z, Lizer N, Wu Z, Morgan CE, Yan Y, Zhang Q, Yu EW. Cryo-Electron Microscopy Structures of a Campylobacter Multidrug Efflux Pump Reveal a Novel Mechanism of Drug Recognition and Resistance. Microbiol Spectr 2023; 11:e0119723. [PMID: 37289051 PMCID: PMC10434076 DOI: 10.1128/spectrum.01197-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 05/18/2023] [Indexed: 06/09/2023] Open
Abstract
Campylobacter jejuni is a bacterium that is commonly present in the intestinal tracts of animals. It is also a major foodborne pathogen that causes gastroenteritis in humans. The most predominant and clinically important multidrug efflux system in C. jejuni is the CmeABC (Campylobacter multidrug efflux) pump, a tripartite system that includes an inner membrane transporter (CmeB), a periplasmic fusion protein (CmeA), and an outer membrane channel protein (CmeC). This efflux protein machinery mediates resistance to a number of structurally diverse antimicrobial agents. A recently identified CmeB variant, termed resistance enhancing CmeB (RE-CmeB), can increase its multidrug efflux pump activity, likely by influencing antimicrobial recognition and extrusion. Here, we report structures of RE-CmeB in its apo form as well as in the presence of four different drugs by using single-particle cryo-electron microscopy (cryo-EM). Coupled with mutagenesis and functional studies, this structural information allows us to identify critical amino acids that are important for drug resistance. We also report that RE-CmeB utilizes a somewhat unique subset of residues to bind different drugs, thereby optimizing its ability to accommodate different compounds with distinct scaffolds. These findings provide insights into the structure-function relationship of this newly emerged antibiotic efflux transporter variant in Campylobacter. IMPORTANCE Campylobacter jejuni has emerged as one of the most problematic and highly antibiotic-resistant pathogens, worldwide. The Centers for Disease Control and Prevention have designated antibiotic-resistant C. jejuni as a serious antibiotic resistance threat in the United States. We recently identified a C. jejuni resistance enhancing CmeB (RE-CmeB) variant that can increase its multidrug efflux pump activity and confers an exceedingly high-level of resistance to fluoroquinolones. Here, we report the cryo-EM structures of this prevalent and clinically important C. jejuni RE-CmeB multidrug efflux pump in both the absence and presence of four antibiotics. These structures allow us to understand the action mechanism for multidrug recognition in this pump. Our studies will ultimately inform an era in structure-guided drug design to combat multidrug resistance in these Gram-negative pathogens.
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Affiliation(s)
- Zhemin Zhang
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Nicholas Lizer
- Department of Veterinary Microbiology, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Zuowei Wu
- Department of Veterinary Microbiology, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Christopher E. Morgan
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Yuqi Yan
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Qijing Zhang
- Department of Veterinary Microbiology, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Edward W. Yu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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16
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Kato T, Okada U, Hung LW, Yamashita E, Kim HB, Kim CY, Terwilliger TC, Schweizer HP, Murakami S. Crystal structures of multidrug efflux transporters from Burkholderia pseudomallei suggest details of transport mechanism. Proc Natl Acad Sci U S A 2023; 120:e2215072120. [PMID: 37428905 PMCID: PMC10629574 DOI: 10.1073/pnas.2215072120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 05/24/2023] [Indexed: 07/12/2023] Open
Abstract
BpeB and BpeF are multidrug efflux transporters from Burkholderia pseudomallei that enable multidrug resistance. Here, we report the crystal structures of BpeB and BpeF at 2.94 Å and 3.0 Å resolution, respectively. BpeB was found as an asymmetric trimer, consistent with the widely-accepted functional rotation mechanism for this type of transporter. One of the monomers has a distinct structure that we interpret as an intermediate along this functional cycle. Additionally, a detergent molecule bound in a previously undescribed binding site provides insights into substrate translocation through the pathway. BpeF shares structural similarities with the crystal structure of OqxB from Klebsiella pneumoniae, where both are symmetric trimers composed of three "binding"-state monomers. The structures of BpeB and BpeF further our understanding of the functional mechanisms of transporters belonging to the HAE1-RND superfamily.
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Affiliation(s)
- Takaaki Kato
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama226-8501, Japan
| | - Ui Okada
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama226-8501, Japan
| | - Li-Wei Hung
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM87545
| | - Eiki Yamashita
- Institute for Protein Research, Osaka University, Osaka565-0871, Japan
| | - Heung-Bok Kim
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM87545
| | - Chang-Yub Kim
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM87545
| | - Thomas C. Terwilliger
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM87545
- New Mexico Consortium, Los Alamos, NM87544
| | - Herbert P. Schweizer
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, AZ86011
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ86011
| | - Satoshi Murakami
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama226-8501, Japan
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17
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Darby EM, Trampari E, Siasat P, Gaya MS, Alav I, Webber MA, Blair JMA. Molecular mechanisms of antibiotic resistance revisited. Nat Rev Microbiol 2023; 21:280-295. [PMID: 36411397 DOI: 10.1038/s41579-022-00820-y] [Citation(s) in RCA: 263] [Impact Index Per Article: 263.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2022] [Indexed: 11/22/2022]
Abstract
Antibiotic resistance is a global health emergency, with resistance detected to all antibiotics currently in clinical use and only a few novel drugs in the pipeline. Understanding the molecular mechanisms that bacteria use to resist the action of antimicrobials is critical to recognize global patterns of resistance and to improve the use of current drugs, as well as for the design of new drugs less susceptible to resistance development and novel strategies to combat resistance. In this Review, we explore recent advances in understanding how resistance genes contribute to the biology of the host, new structural details of relevant molecular events underpinning resistance, the identification of new resistance gene families and the interactions between different resistance mechanisms. Finally, we discuss how we can use this information to develop the next generation of antimicrobial therapies.
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Affiliation(s)
- Elizabeth M Darby
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | | | - Pauline Siasat
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | | | - Ilyas Alav
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Mark A Webber
- Quadram Institute Bioscience, Norwich Research Park, Norwich, UK.
- Medical School, University of East Anglia, Norwich Research Park, Norwich, UK.
| | - Jessica M A Blair
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK.
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18
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Athar M, Gervasoni S, Catte A, Basciu A, Malloci G, Ruggerone P, Vargiu AV. Tripartite efflux pumps of the RND superfamily: what did we learn from computational studies? MICROBIOLOGY (READING, ENGLAND) 2023; 169. [PMID: 36972322 DOI: 10.1099/mic.0.001307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
Bacterial resistance to antibiotics has been long recognized as a priority to address for human health. Among all micro-organisms, the so-called multi-drug resistant (MDR) bacteria, which are resistant to most, if not all drugs in our current arsenal, are particularly worrisome. The World Health Organization has prioritized the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter species) pathogens, which include four Gram-negative bacterial species. In these bacteria, active extrusion of antimicrobial compounds out of the cell by means of 'molecular guns' known as efflux pumps is a main determinant of MDR phenotypes. The resistance-nodulation-cell division (RND) superfamily of efflux pumps connecting the inner and outer membrane in Gram-negative bacteria is crucial to the onset of MDR and virulence, as well as biofilm formation. Thus, understanding the molecular basis of the interaction of antibiotics and inhibitors with these pumps is key to the design of more effective therapeutics. With the aim to contribute to this challenge, and complement and inspire experimental research, in silico studies on RND efflux pumps have flourished in recent decades. Here, we review a selection of such investigations addressing the main determinants behind the polyspecificity of these pumps, the mechanisms of substrate recognition, transport and inhibition, as well as the relevance of their assembly for proper functioning, and the role of protein-lipid interactions. The journey will end with a perspective on the role of computer simulations in addressing the challenges posed by these beautifully complex machineries and in supporting the fight against the spread of MDR bacteria.
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Affiliation(s)
- Mohd Athar
- Physics Department, University of Cagliari, Cittadella Universitaria, SP 8 km 0.700, 09042, Monserrato (CA), Italy
| | - Silvia Gervasoni
- Physics Department, University of Cagliari, Cittadella Universitaria, SP 8 km 0.700, 09042, Monserrato (CA), Italy
| | - Andrea Catte
- Physics Department, University of Cagliari, Cittadella Universitaria, SP 8 km 0.700, 09042, Monserrato (CA), Italy
| | - Andrea Basciu
- Physics Department, University of Cagliari, Cittadella Universitaria, SP 8 km 0.700, 09042, Monserrato (CA), Italy
| | - Giuliano Malloci
- Physics Department, University of Cagliari, Cittadella Universitaria, SP 8 km 0.700, 09042, Monserrato (CA), Italy
| | - Paolo Ruggerone
- Physics Department, University of Cagliari, Cittadella Universitaria, SP 8 km 0.700, 09042, Monserrato (CA), Italy
| | - Attilio Vittorio Vargiu
- Physics Department, University of Cagliari, Cittadella Universitaria, SP 8 km 0.700, 09042, Monserrato (CA), Italy
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19
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Cryo-EM Structures of AcrD Illuminate a Mechanism for Capturing Aminoglycosides from Its Central Cavity. mBio 2023; 14:e0338322. [PMID: 36625574 PMCID: PMC9973356 DOI: 10.1128/mbio.03383-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The Escherichia coli acriflavine resistance protein D (AcrD) is an efflux pump that belongs to the resistance-nodulation-cell division (RND) superfamily. Its primary function is to provide resistance to aminoglycoside-based drugs by actively extruding these noxious compounds out of E. coli cells. AcrD can also mediate resistance to a limited range of other amphiphilic agents, including bile acids, novobiocin, and fusidic acids. As there is no structural information available for any aminoglycoside-specific RND pump, here we describe cryo-electron microscopy (cryo-EM) structures of AcrD in the absence and presence of bound gentamicin. These structures provide new information about the RND superfamily of efflux pumps, specifically, that three negatively charged residues central to the aminoglycoside-binding site are located within the ceiling of the central cavity of the AcrD trimer. Thus, it is likely that AcrD is capable of picking up aminoglycosides via this central cavity. Through the combination of cryo-EM structural determination, mutagenesis analysis, and molecular simulation, we show that charged residues are critically important for this pump to shuttle drugs directly from the central cavity to the funnel of the AcrD trimer for extrusion. IMPORTANCE Here, we report cryo-EM structures of the AcrD aminoglycoside efflux pump in the absence and presence of bound gentamicin, posing the possibility that this pump is capable of capturing aminoglycosides from the central cavity of the AcrD trimer. The results indicate that AcrD utilizes charged residues to bind and export drugs, mediating resistance to these antibiotics.
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20
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RND Pump-Mediated Efflux of Amotosalen, a Compound Used in Pathogen Inactivation Technology to Enhance Safety of Blood Transfusion Products, May Compromise Its Gram-Negative Anti-Bacterial Activity. mSphere 2023; 8:e0067322. [PMID: 36853056 PMCID: PMC10117049 DOI: 10.1128/msphere.00673-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023] Open
Abstract
Pathogen inactivation is a strategy to improve the safety of transfusion products. The only pathogen reduction technology for blood products currently approved in the US utilizes a psoralen compound, called amotosalen, in combination with UVA light to inactivate bacteria, viruses, and protozoa. Psoralens have structural similarity to bacterial multidrug efflux pump substrates. As these efflux pumps are often overexpressed in multidrug-resistant pathogens, we tested whether contemporary drug-resistant pathogens might show resistance to amotosalen and other psoralens based on multidrug efflux mechanisms through genetic, biophysical, and molecular modeling analysis. The main efflux systems in Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa are tripartite resistance-nodulation-cell division (RND) systems, which span the inner and outer membranes of Gram-negative pathogens, and expel antibiotics from the bacterial cytoplasm into the extracellular space. We provide evidence that amotosalen is an efflux substrate for the E. coli AcrAB, Acinetobacter baumannii AdeABC, and P. aeruginosa MexXY RND efflux pumps. Furthermore, we show that the MICs for contemporary Gram-negative bacterial isolates for these species and others in vitro approached and exceeded the concentration of amotosalen used in the approved platelet and plasma inactivation procedures. These findings suggest that otherwise safe and effective inactivation methods should be further studied to identify possible gaps in their ability to inactivate contemporary, multidrug-resistant bacterial pathogens. IMPORTANCE Pathogen inactivation is a strategy to enhance the safety of transfused blood products. We identify the compound, amotosalen, widely used for pathogen inactivation, as a bacterial multidrug efflux substrate. Specifically, experiments suggest that amotosalen is pumped out of bacteria by major efflux pumps in E. coli, Acinetobacter baumannii, and Pseudomonas aeruginosa. Such efflux pumps are often overexpressed in multidrug-resistant pathogens. Importantly, the MICs for contemporary multidrug-resistant Enterobacterales, Acinetobacter baumannii, Pseudomonas aeruginosa, Burkholderia spp., and Stenotrophomonas maltophilia isolates approached or exceeded the amotosalen concentration used in approved platelet and plasma inactivation procedures, potentially as a result of efflux pump activity. Although there are important differences in methodology between our experiments and blood product pathogen inactivation, these findings suggest that otherwise safe and effective inactivation methods should be further studied to identify possible gaps in their ability to inactivate contemporary, multidrug-resistant bacterial pathogens.
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21
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Morgan CE, Zhang Z, Miyagi M, Golczak M, Yu EW. Toward structural-omics of the bovine retinal pigment epithelium. Cell Rep 2022; 41:111876. [PMID: 36577381 PMCID: PMC9875382 DOI: 10.1016/j.celrep.2022.111876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 10/12/2022] [Accepted: 12/02/2022] [Indexed: 12/28/2022] Open
Abstract
The use of an integrated systems biology approach to investigate tissues and organs has been thought to be impracticable in the field of structural biology, where the techniques mainly focus on determining the structure of a particular biomacromolecule of interest. Here, we report the use of cryoelectron microscopy (cryo-EM) to define the composition of a raw bovine retinal pigment epithelium (RPE) lysate. From this sample, we simultaneously identify and solve cryo-EM structures of seven different RPE enzymes whose functions affect neurotransmitter recycling, iron metabolism, gluconeogenesis, glycolysis, axonal development, and energy homeostasis. Interestingly, dysfunction of these important proteins has been directly linked to several neurodegenerative disorders, including Huntington's disease, amyotrophic lateral sclerosis (ALS), Parkinson's disease, Alzheimer's disease, and schizophrenia. Our work underscores the importance of cryo-EM in facilitating tissue and organ proteomics at the atomic level.
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Affiliation(s)
- Christopher E. Morgan
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA,Department of Chemistry, Thiel College, Greenville, PA 16125, USA,These authors contributed equally
| | - Zhemin Zhang
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA,These authors contributed equally
| | - Masaru Miyagi
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Marcin Golczak
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA,Cleveland Center for Membrane and Structural Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Edward W. Yu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA,Cleveland Center for Membrane and Structural Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA,Lead contact,Correspondence:
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22
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Michaud ME, Allen RA, Morrison-Lewis KR, Sanchez CA, Minbiole KPC, Post SJ, Wuest WM. Quaternary Phosphonium Compound Unveiled as a Potent Disinfectant against Highly Resistant Acinetobacter baumannii Clinical Isolates. ACS Infect Dis 2022; 8:2307-2314. [PMID: 36301313 DOI: 10.1021/acsinfecdis.2c00382] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Acinetobacter baumannii is classified as a highest threat pathogen, urgently necessitating novel antimicrobials that evade resistance to combat its spread. Quaternary ammonium compounds (QACs) have afforded a valuable first line of defense against antimicrobial resistant pathogens as broad-spectrum amphiphilic disinfectant molecules. However, a paucity of innovation in this space has driven the emergence of QAC resistance. Through this work, we sought to identify next-generation disinfectant molecules with efficacy against highly resistant A. baumannii clinical isolates. We selected 12 best-in-class molecules from our previous investigations of quaternary ammonium and quaternary phosphonium compounds (QPCs) to test against a panel of 35 resistant A. baumannii clinical isolates. The results highlighted the efficacy of our next-generation compounds over leading commercial QACs, with our best-in-class QAC (2Pyr-11,11) and QPC (P6P-10,10) displaying improved activities with a few exceptions. Furthermore, we elucidated a correlation between colistin resistance and QAC resistance, wherein the only pan-resistant isolate of the panel, also harboring colistin resistance, exhibited resistance to all tested QACs. Notably, P6P-10,10 maintained efficacy against this strain with an IC90 of 3 μM. In addition, P6P-10,10 displayed minimum biofilm eradication concentrations as low as 32 μM against extensively drug resistant clinical isolates. Lastly, examining the development of disinfectant resistance and cross-resistance, we generated QAC-resistant A. baumannii mutants and observed the development of QAC cross-resistance. In contrast, neither disinfectant resistance nor cross-resistance was observed in A. baumannii under P6P-10,10 treatment. Taken together, the results of this work illustrate the need for novel disinfectant compounds to treat resistant pathogens, such as A. baumannii, and underscore the promise of QPCs, such as P6P-10,10, as viable next-generation disinfectant molecules.
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Affiliation(s)
- Marina E Michaud
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Ryan A Allen
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | | | - Christian A Sanchez
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Kevin P C Minbiole
- Department of Chemistry, Villanova University, Villanova, Pennsylvania 19085, United States
| | - Savannah J Post
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - William M Wuest
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia 30322, United States
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23
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Catte A, K. Ramaswamy V, Vargiu AV, Malloci G, Bosin A, Ruggerone P. Common recognition topology of mex transporters of Pseudomonas aeruginosa revealed by molecular modelling. Front Pharmacol 2022; 13:1021916. [PMID: 36438787 PMCID: PMC9691783 DOI: 10.3389/fphar.2022.1021916] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 10/24/2022] [Indexed: 11/13/2022] Open
Abstract
The secondary transporters of the resistance-nodulation-cell division (RND) superfamily mediate multidrug resistance in Gram-negative bacteria like Pseudomonas aeruginosa. Among these RND transporters, MexB, MexF, and MexY, with partly overlapping specificities, have been implicated in pathogenicity. Only the structure of the former has been resolved experimentally, which together with the lack of data about the functional dynamics of the full set of transporters, limited a systematic investigation of the molecular determinants defining their peculiar and shared features. In a previous work (Ramaswamy et al., Front. Microbiol., 2018, 9, 1144), we compared at an atomistic level the two main putative recognition sites (named access and deep binding pockets) of MexB and MexY. In this work, we expand the comparison by performing extended molecular dynamics (MD) simulations of these transporters and the pathologically relevant transporter MexF. We employed a more realistic model of the inner phospholipid membrane of P. aeruginosa and more accurate force-fields. To elucidate structure/dynamics-activity relationships we performed physico-chemical analyses and mapped the binding propensities of several organic probes on all transporters. Our data revealed the presence, also in MexF, of a few multifunctional sites at locations equivalent to the access and deep binding pockets detected in MexB. Furthermore, we report for the first time about the multidrug binding abilities of two out of five gates of the channels deputed to peripheral (early) recognition of substrates. Overall, our findings help to define a common “recognition topology” characterizing Mex transporters, which can be exploited to optimize transport and inhibition propensities of antimicrobial compounds.
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24
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Moseng MA, Su CC, Rios K, Cui M, Lyu M, Glaza P, Klenotic PA, Delpire E, Yu EW. Inhibition mechanism of NKCC1 involves the carboxyl terminus and long-range conformational coupling. SCIENCE ADVANCES 2022; 8:eabq0952. [PMID: 36306358 PMCID: PMC9616490 DOI: 10.1126/sciadv.abq0952] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
The Na-K-2Cl cotransporter-1 (NKCC1) is an electroneutral Na+-dependent transporter responsible for simultaneously translocating Na+, K+, and Cl- ions into cells. In human tissue, NKCC1 plays a critical role in regulating cytoplasmic volume, fluid intake, chloride homeostasis, and cell polarity. Here, we report four structures of human NKCC1 (hNKCC1), both in the absence and presence of loop diuretic (bumetanide or furosemide), using single-particle cryo-electron microscopy. These structures allow us to directly observe various novel conformations of the hNKCC1 dimer. They also reveal two drug-binding sites located at the transmembrane and cytosolic carboxyl-terminal domains, respectively. Together, our findings enable us to delineate an inhibition mechanism that involves a coupled movement between the cytosolic and transmembrane domains of hNKCC1.
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Affiliation(s)
- Mitchell A. Moseng
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Chih-Chia Su
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Kerri Rios
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Boston, MA 02115, USA
| | - Meinan Lyu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Przemyslaw Glaza
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Philip A. Klenotic
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Edward W. Yu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Structural Basis of Peptide-Based Antimicrobial Inhibition of a Resistance-Nodulation-Cell Division Multidrug Efflux Pump. Microbiol Spectr 2022; 10:e0299022. [PMID: 36121287 PMCID: PMC9603588 DOI: 10.1128/spectrum.02990-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Bacterial efflux pumps in the resistance-nodulation-cell division (RND) family of Gram-negative bacteria contribute significantly to the development of antimicrobial resistance by many pathogens. In this study, we selected the MtrD transporter protein of Neisseria gonorrhoeae as it is the sole RND pump possessed by this strictly human pathogen and can export multiple antimicrobials, including antibiotics, bile salts, detergents, dyes, and antimicrobial peptides. Using knowledge from our previously published structures of MtrD in the presence or absence of bound antibiotics as a model and the known ability of MtrCDE to export cationic antimicrobial peptides, we hypothesized that cationic peptides could be accommodated within MtrD binding sites. Furthermore, we thought that MtrD-bound peptides lacking antibacterial action could sensitize bacteria to an antibiotic normally exported by the MtrCDE efflux pump or other similar RND-type pumps possessed by different Gram-negative bacteria. We now report the identification of a novel nonantimicrobial cyclic cationic antimicrobial peptide, which we termed CASP (cationic antibiotic-sensitizing peptide). By single-particle cryo-electron microscopy, we found that CASP binds within the periplasmic cleft region of MtrD using overlapping and distinct amino acid contact sites that interact with another cyclic peptide (colistin) or a linear human cationic antimicrobial peptide derived from human LL-37. While CASP could not sensitize Neisseria gonorrhoeae to an antibiotic (novobiocin) that is a substrate for RND pumps, it could do so against multiple Gram-negative, rod-shaped bacteria. We propose that CASP (or future derivatives) could serve as an adjuvant for the antibiotic treatment of certain Gram-negative infections previously thwarted by RND transporters. IMPORTANCE RND efflux pumps can export numerous antimicrobials that enter Gram-negative bacteria, and their action can reduce the efficacy of antibiotics and provide decreased susceptibility to various host antimicrobials. Here, we identified a cationic antibiotic-sensitizing peptide (CASP) that binds within the periplasmic cleft of an RND transporter protein (MtrD) produced by Neisseria gonorrhoeae. Surprisingly, CASP was able to render rod-shaped Gram-negative bacteria, but not gonococci, susceptible to an antibiotic that is a substrate for the gonococcal MtrCDE efflux pump. CASP (or its future derivatives) could be used as an adjuvant to treat infections for which RND efflux contributes to multidrug resistance.
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Photocatalytic Bacterial Inactivation of Acinetobacter baumannli on Cu/TiO2/Diatomite. Catalysts 2022. [DOI: 10.3390/catal12101217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cu4Ti2O/TiO2/diatomite with double interface Cu4Ti2O/TiO2 and rutile/anatase heterojunction were fabricated, which demonstrated good antibacterial activity (100%) against Acinetobacter baumannii. Cu/TiO2/diatomite prepared under optimum preparation conditions (added diatomite, 0.005 g; Cu, 0.005 g; reaction temperature, 180 °C; reaction time, 8 h) exhibited high antibacterial activity (100%) against A. baumannii. For the Cu/TiO2/diatomite powders, their structural, compositional, optical and morphological traits were characterized by XRD, SEM, TEM, XPS, BET, FTIR, Mapping, and DRS. It was shown that Cu/TiO2/diatomite under optimum conditions consisted of the double interface Cu4Ti2O/TiO2 and rutile/anatase heterojunction with the narrowest band gap and largest BET surface area, pore size, and pore volume. Then, it could exhibit the best photocatalytic activity.
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Potentiate the activity of current antibiotics by naringin dihydrochalcone targeting the AdeABC efflux pump of multidrug-resistant Acinetobacter baumannii. Int J Biol Macromol 2022; 217:592-605. [PMID: 35841965 DOI: 10.1016/j.ijbiomac.2022.07.065] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/07/2022] [Accepted: 07/08/2022] [Indexed: 11/23/2022]
Abstract
Acinetobacter baumannii is an ESKAPE pathogen responsible for severe nosocomial infections. Among all the mechanisms contributing to multidrug resistance, efflux pumps have gained significant attention due to their widespread distribution among bacterial species and broad substrate specificity. This study has investigated the diverse roles of efflux pumps present in carbapenem-resistant A. baumannii (CRAB) and screen an efflux pump inhibitor. The result showed the presence of AdeABC, AdeFGH, AdeIJK, and AbeM efflux pumps in CRAB, and experimental studies using gene mutants demonstrated the significant role of AdeABC in carbapenem resistance, biofilm formation, surface motility, pathogenesis, bacterial adherence, and invasion to the host cells. The structure-based ligand screening, molecular mechanics, molecular dynamics simulation, and experimental validation using efflux pump mutants and antibiotic accumulation assay identified naringin dihydrochalcone (NDC) as the lead against AdeB. This lead was selected as a capping agent for silver nanoparticles. The NDC-capped silver nanoparticles (NDC-AgNPs) were characterized by UV-spectroscopy, Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and scanning electron microscopy (SEM). The investigated molecular mechanism showed that the NDC-AgNPs possessed multiple mechanisms of action. In addition to efflux inhibitory activity, it also generates reactive oxygen and nitrogen species as well as causes change in the electrochemical gradient in CRAB. The proton gradient is important for the function of AdeABC; hence altering the electrochemical gradient also disrupts its efflux activity. Moreover, A. baumannii did not develop any resistance against NDC-AgNPs till several generations which were investigated. The NDC-AgNPs were also found to be effective against carbapenem-resistant clinical isolates of A. baumannii. Therefore, the present study provided an insight into the efflux pump mediated carbapenem resistance and possible inhibitor NDC-AgNPs to combat AdeABC efflux pump mediated resistance.
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Differential Binding of Carbapenems with the AdeABC Efflux Pump and Modulation of the Expression of AdeB Linked to Novel Mutations within Two-Component System AdeRS in Carbapenem-Resistant Acinetobacter baumannii. mSystems 2022; 7:e0021722. [PMID: 35735748 PMCID: PMC9426577 DOI: 10.1128/msystems.00217-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Resistance-nodulation-division-type efflux system AdeABC plays an important role in carbapenem resistance among Acinetobacter baumannii. However, a knowledge gap is observed regarding the role of its regulator AdeRS in carbapenem-resistant A. baumannii (CRAB). This study effectively combines microbiological analysis with an in-silico structural approach to understand the contribution of AdeRS among CRAB (n = 38). Additionally, molecular docking was performed for the first time to study the interaction of FDA-approved carbapenems and pump inhibitor PAβN with the open and closed structure of AdeB at the three binding sites (periplasmic, proximal, distal). It was observed that open conformation of AdeB facilitates the binding of carbapenems and PAβN at entrance and proximal sites compared to the closed conformation. PAβN was found to block carbapenem interacting residues in AdeB, establishing its role as a competitive inhibitor of AdeB substrates. Overexpression of AdeABC was detected by q-RT-PCR among 29% of CRABs, and several mutations within AdeS (GLY186VAL, SER188PHE, GLU121LYS, VAL255ILE) and AdeR (VAL120ILE, ALA136VAL) were detected by sequencing. The sequence and structure-based study of AdeRS was performed to analyze the probable effect of these mutations on regulation of the two-component system (TCS), especially, utilizing its three-dimensional structure. AdeS mutations inhibited the transfer of a phosphate group to AdeR, preventing the binding of AdeR to the intercistronic region, leading to overexpression of AdeABC. The elucidation of the role of mutations in AdeRS improves our understanding of TCS-based regulation. Identification of the key residues of AdeB interacting with carbapenems and PAβN may help in future designing of novel inhibitors. IMPORTANCE AdeABC is an important efflux pump in A. baumannii that plays a role in resistance toward different antibiotics including the “last resort” antibiotic, carbapenem. This pump is regulated by a two-component system, AdeRS. To understand the binding of carbapenems with AdeABC and pump inhibition by PAβN, we analyzed for the first time the possible atomic level interactions of carbapenems and PAβN with AdeB. In the current study, AdeRS-associated novel mutations in clinical A. baumannii are reported for the first time, and a sequence-structure based in-silico approach was used to interpret their role in AdeABC overexpression, leading to carbapenem resistance. None of the previous studies had undertaken both these aspects simultaneously. This study analyzes the open and closed conformation of AdeB, their binding with carbapenems, and key residues involved in it. This helps in visualizing the plausible atomic level causes of pump inhibition driving the discovery of novel inhibitors.
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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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Proximal Binding Pocket Arg717 Substitutions in Escherichia coli AcrB Cause Clinically Relevant Divergencies in Resistance Profiles. Antimicrob Agents Chemother 2022; 66:e0239221. [PMID: 35311521 PMCID: PMC9017336 DOI: 10.1128/aac.02392-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Recent mutations in RND efflux pumps in clinical strains have further increased multidrug resistance. We show that R717L and R717Q substitutions (found in azithromycin-resistant Salmonella enterica spp.) in the Escherichia coli efflux pump AcrB dramatically increase macrolide, as well as fluoroquinolone, resistance. On the other hand, cells became more susceptible to novobiocin and β-lactam cloxacillin. We urge the control of, and adjustments to, treatments with antibiotics and the need for novel antibiotics and efflux pump inhibitors.
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Migliaccio A, Esposito EP, Bagattini M, Berisio R, Triassi M, De Gregorio E, Zarrilli R. Inhibition of AdeB, AceI, and AmvA Efflux Pumps Restores Chlorhexidine and Benzalkonium Susceptibility in Acinetobacter baumannii ATCC 19606. Front Microbiol 2022; 12:790263. [PMID: 35197939 PMCID: PMC8859242 DOI: 10.3389/fmicb.2021.790263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/23/2021] [Indexed: 01/17/2023] Open
Abstract
The management of infections caused by Acinetobacter baumannii is hindered by its intrinsic tolerance to a wide variety of biocides. The aim of the study was to analyze the role of different A. baumannii efflux pumps (EPs) in tolerance to chlorhexidine (CHX) and benzalkonium (BZK) and identify non-toxic compounds, which can restore susceptibility to CHX and BZK in A. baumannii. A. baumannii ATCC 19606 strain was tolerant to both CHX and BZK with MIC and MBC value of 32 mg/L. CHX subMIC concentrations increased the expression of adeB and adeJ (RND superfamily), aceI (PACE family) and amvA (MFS superfamily) EP genes. The values of CHX MIC and MBC decreased by eightfold in ΔadeB and twofold in ΔamvA or ΔaceI mutants, respectively, while not affected in ΔadeJ mutant; EPs double and triple deletion mutants showed an additive effect on CHX MIC. CHX susceptibility was restored in double and triple deletion mutants with inactivation of adeB gene. BZK MIC was decreased by fourfold in ΔadeB mutant, and twofold in ΔamvA and ΔaceI mutants, respectively; EPs double and triple deletion mutants showed an additive effect on BZK MIC. BZK susceptibility was recovered in ΔadeB ΔaceI ΔadeJ and ΔamvA ΔadeB ΔadeJ triple mutants. The structural comparison of AdeB and AdeJ protomers showed a more negatively charged entrance binding site and F-loop in AdeB, which may favor the transport of CHX. The carbonyl cyanide m-chlorophenylhydrazine protonophore (CCCP) EP inhibitor reduced dose-dependently CHX MIC in A. baumannii ATCC 19606 and in ΔadeJ, ΔaceI, or ΔamvA mutants, but not in ΔadeB mutant. Either piperine (PIP) or resveratrol (RV) at non-toxic concentrations inhibited CHX MIC in A. baumannii ATCC 19606 parental strain and EPs gene deletion mutants, and CHX-induced EP gene expression. Also, RV inhibited BZK MIC and EP genes expression in A. baumannii ATCC 19606 parental strain and EPs mutants. These results demonstrate that tolerance to CHX and BZK in A. baumannii is mediated by the activation of AdeB, AceI and AmvA EPs, AdeB playing a major role. Importantly, inhibition of EP genes expression by RV restores CHX and BZK susceptibility in A. baumannii.
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Affiliation(s)
| | - Eliana Pia Esposito
- Department of Public Health, University of Naples Federico II, Naples, Italy
| | - Maria Bagattini
- Department of Public Health, University of Naples Federico II, Naples, Italy
| | - Rita Berisio
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy
| | - Maria Triassi
- Department of Public Health, University of Naples Federico II, Naples, Italy
| | - Eliana De Gregorio
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy
- *Correspondence: Eliana De Gregorio,
| | - Raffaele Zarrilli
- Department of Public Health, University of Naples Federico II, Naples, Italy
- Raffaele Zarrilli,
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Gan WK, Liew HS, Pua LJW, Ng XY, Fong KW, Cheong SL, Liew YK, Low ML. Novel Cu(II) Schiff Base Complex Combination with Polymyxin B/Phenylalanine-Arginine β-Naphthylamide Against Various Bacterial Strains. Int J Pept Res Ther 2022. [DOI: 10.1007/s10989-021-10358-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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33
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Webber A, Ratnaweera M, Harris A, Luisi BF, Ntsogo Enguéné VY. A Model for Allosteric Communication in Drug Transport by the AcrAB-TolC Tripartite Efflux Pump. Antibiotics (Basel) 2022; 11:52. [PMID: 35052929 PMCID: PMC8773123 DOI: 10.3390/antibiotics11010052] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/22/2021] [Accepted: 12/28/2021] [Indexed: 01/30/2023] Open
Abstract
RND family efflux pumps are complex macromolecular machines involved in multidrug resistance by extruding antibiotics from the cell. While structural studies and molecular dynamics simulations have provided insights into the architecture and conformational states of the pumps, the path followed by conformational changes from the inner membrane protein (IMP) to the periplasmic membrane fusion protein (MFP) and to the outer membrane protein (OMP) in tripartite efflux assemblies is not fully understood. Here, we investigated AcrAB-TolC efflux pump's allostery by comparing resting and transport states using difference distance matrices supplemented with evolutionary couplings data and buried surface area measurements. Our analysis indicated that substrate binding by the IMP triggers quaternary level conformational changes in the MFP, which induce OMP to switch from the closed state to the open state, accompanied by a considerable increase in the interface area between the MFP subunits and between the OMPs and MFPs. This suggests that the pump's transport-ready state is at a more favourable energy level than the resting state, but raises the puzzle of how the pump does not become stably trapped in a transport-intermediate state. We propose a model for pump allostery that includes a downhill energetic transition process from a proposed 'activated' transport state back to the resting pump.
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Affiliation(s)
- Anya Webber
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK; (A.W.); (A.H.)
| | - Malitha Ratnaweera
- Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK;
| | - Andrzej Harris
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK; (A.W.); (A.H.)
| | - Ben F. Luisi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK; (A.W.); (A.H.)
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Structural and functional analysis of the promiscuous AcrB and AdeB efflux pumps suggests different drug binding mechanisms. Nat Commun 2021; 12:6919. [PMID: 34824229 PMCID: PMC8617272 DOI: 10.1038/s41467-021-27146-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 10/26/2021] [Indexed: 11/08/2022] Open
Abstract
Upon antibiotic stress Gram-negative pathogens deploy resistance-nodulation-cell division-type tripartite efflux pumps. These include a H+/drug antiporter module that recognizes structurally diverse substances, including antibiotics. Here, we show the 3.5 Å structure of subunit AdeB from the Acinetobacter baumannii AdeABC efflux pump solved by single-particle cryo-electron microscopy. The AdeB trimer adopts mainly a resting state with all protomers in a conformation devoid of transport channels or antibiotic binding sites. However, 10% of the protomers adopt a state where three transport channels lead to the closed substrate (deep) binding pocket. A comparison between drug binding of AdeB and Escherichia coli AcrB is made via activity analysis of 20 AdeB variants, selected on basis of side chain interactions with antibiotics observed in the AcrB periplasmic domain X-ray co-structures with fusidic acid (2.3 Å), doxycycline (2.1 Å) and levofloxacin (2.7 Å). AdeABC, compared to AcrAB-TolC, confers higher resistance to E. coli towards polyaromatic compounds and lower resistance towards antibiotic compounds.
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35
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Su CC, Klenotic PA, Cui M, Lyu M, Morgan CE, Yu EW. Structures of the mycobacterial membrane protein MmpL3 reveal its mechanism of lipid transport. PLoS Biol 2021; 19:e3001370. [PMID: 34383749 PMCID: PMC8384468 DOI: 10.1371/journal.pbio.3001370] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 08/24/2021] [Accepted: 07/21/2021] [Indexed: 01/09/2023] Open
Abstract
The mycobacterial membrane protein large 3 (MmpL3) transporter is essential and required for shuttling the lipid trehalose monomycolate (TMM), a precursor of mycolic acid (MA)-containing trehalose dimycolate (TDM) and mycolyl arabinogalactan peptidoglycan (mAGP), in Mycobacterium species, including Mycobacterium tuberculosis and Mycobacterium smegmatis. However, the mechanism that MmpL3 uses to facilitate the transport of fatty acids and lipidic elements to the mycobacterial cell wall remains elusive. Here, we report 7 structures of the M. smegmatis MmpL3 transporter in its unbound state and in complex with trehalose 6-decanoate (T6D) or TMM using single-particle cryo-electron microscopy (cryo-EM) and X-ray crystallography. Combined with calculated results from molecular dynamics (MD) and target MD simulations, we reveal a lipid transport mechanism that involves a coupled movement of the periplasmic domain and transmembrane helices of the MmpL3 transporter that facilitates the shuttling of lipids to the mycobacterial cell wall.
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Affiliation(s)
- Chih-Chia Su
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Philip A. Klenotic
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Boston, Massachusetts, United States of America
| | - Meinan Lyu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Christopher E. Morgan
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Edward W. Yu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
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Zwama M, Nishino K. Ever-Adapting RND Efflux Pumps in Gram-Negative Multidrug-Resistant Pathogens: A Race against Time. Antibiotics (Basel) 2021; 10:774. [PMID: 34201908 PMCID: PMC8300642 DOI: 10.3390/antibiotics10070774] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/11/2021] [Accepted: 06/14/2021] [Indexed: 01/13/2023] Open
Abstract
The rise in multidrug resistance (MDR) is one of the greatest threats to human health worldwide. MDR in bacterial pathogens is a major challenge in healthcare, as bacterial infections are becoming untreatable by commercially available antibiotics. One of the main causes of MDR is the over-expression of intrinsic and acquired multidrug efflux pumps, belonging to the resistance-nodulation-division (RND) superfamily, which can efflux a wide range of structurally different antibiotics. Besides over-expression, however, recent amino acid substitutions within the pumps themselves-causing an increased drug efflux efficiency-are causing additional worry. In this review, we take a closer look at clinically, environmentally and laboratory-evolved Gram-negative bacterial strains and their decreased drug sensitivity as a result of mutations directly in the RND-type pumps themselves (from Escherichia coli, Salmonella enterica, Neisseria gonorrhoeae, Pseudomonas aeruginosa, Acinetobacter baumannii and Legionella pneumophila). We also focus on the evolution of the efflux pumps by comparing hundreds of efflux pumps to determine where conservation is concentrated and where differences in amino acids can shed light on the broad and even broadening drug recognition. Knowledge of conservation, as well as of novel gain-of-function efflux pump mutations, is essential for the development of novel antibiotics and efflux pump inhibitors.
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Affiliation(s)
- Martijn Zwama
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Kunihiko Nishino
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Ibaraki, Osaka 567-0047, Japan
- Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565-0871, Japan
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Cryo-EM Determination of Eravacycline-Bound Structures of the Ribosome and the Multidrug Efflux Pump AdeJ of Acinetobacter baumannii. mBio 2021; 12:e0103121. [PMID: 34044590 PMCID: PMC8263017 DOI: 10.1128/mbio.01031-21] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antibiotic-resistant strains of the Gram-negative pathogen Acinetobacter baumannii have emerged as a significant global health threat. One successful therapeutic option to treat bacterial infections has been to target the bacterial ribosome. However, in many cases, multidrug efflux pumps within the bacterium recognize and extrude these clinically important antibiotics designed to inhibit the protein synthesis function of the bacterial ribosome. Thus, multidrug efflux within A. baumannii and other highly drug-resistant strains is a major cause of failure of drug-based treatments of infectious diseases. We here report the first structures of the Acinetobacterdrug efflux (Ade)J pump in the presence of the antibiotic eravacycline, using single-particle cryo-electron microscopy (cryo-EM). We also describe cryo-EM structures of the eravacycline-bound forms of the A. baumannii ribosome, including the 70S, 50S, and 30S forms. Our data indicate that the AdeJ pump primarily uses hydrophobic interactions to bind eravacycline, while the 70S ribosome utilizes electrostatic interactions to bind this drug. Our work here highlights how an antibiotic can bind multiple bacterial targets through different mechanisms and potentially enables drug optimization by taking advantage of these different modes of ligand binding.
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An Analysis of the Novel Fluorocycline TP-6076 Bound to Both the Ribosome and Multidrug Efflux Pump AdeJ from Acinetobacter baumannii. mBio 2021; 13:e0373221. [PMID: 35100868 PMCID: PMC8805024 DOI: 10.1128/mbio.03732-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Antibiotic resistance among bacterial pathogens continues to pose a serious global health threat. Multidrug-resistant (MDR) strains of the Gram-negative organism Acinetobacter baumannii utilize a number of resistance determinants to evade current antibiotics. One of the major resistance mechanisms employed by these pathogens is the use of multidrug efflux pumps. These pumps extrude xenobiotics directly out of bacterial cells, resulting in treatment failures when common antibiotics are administered. Here, the structure of the novel tetracycline antibiotic TP-6076, bound to both the Acinetobacter drug efflux pump AdeJ and the ribosome from Acinetobacter baumannii, using single-particle cryo-electron microscopy (cryo-EM), is elucidated. In this work, the structure of the AdeJ-TP-6076 complex is solved, and we show that AdeJ utilizes a network of hydrophobic interactions to recognize this fluorocycline. Concomitant with this, we elucidate three structures of TP-6076 bound to the A. baumannii ribosome and determine that its binding is stabilized largely by electrostatic interactions. We then compare the differences in binding modes between TP-6076 and the related tetracycline antibiotic eravacycline in both targets. These differences suggest that modifications to the tetracycline core may be able to alter AdeJ binding while maintaining interactions with the ribosome. Together, this work highlights how different mechanisms are used to stabilize the binding of tetracycline-based compounds to unique bacterial targets and provides guidance for the future clinical development of tetracycline antibiotics. IMPORTANCE Treatment of antibiotic-resistant organisms such as A. baumannii represents an ongoing issue for modern medicine. The multidrug efflux pump AdeJ serves as a major resistance determinant in A. baumannii through its action of extruding antibiotics from the cell. In this work, we use cryo-EM to show how AdeJ recognizes the experimental tetracycline antibiotic TP-6076 and prevents this drug from interacting with the A. baumannii ribosome. Since AdeJ and the ribosome use different binding modes to stabilize interactions with TP-6076, exploiting these differences may guide future drug development for combating antibiotic-resistant A. baumannii and potentially other strains of MDR bacteria.
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