1
|
Wall BJ, Sharma KK, O’Brien EA, Donovan A, VanVeller B. General Installation of (4 H)-Imidazolone cis-Amide Bioisosteres Along the Peptide Backbone. J Am Chem Soc 2024; 146:11648-11656. [PMID: 38629317 PMCID: PMC11062833 DOI: 10.1021/jacs.3c13825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Imidazolones represent an important class of heterocycles present in a wide range of pharmaceuticals, metabolites, and bioactive natural products and serve as the active chromophore in green fluorescent protein. Recently, imidazolones have received attention for their ability to act as a nonaromatic amide bond bioisotere which improves pharmacological properties. Herein, we present a tandem amidine installation and cyclization with an adjacent ester to yield (4H)-imidazolone products. Using amino acid building blocks, we can access the first examples of α-chiral imidazolones that have been previously inaccessible. Additionally, our method is amenable to on-resin installation which can be seamlessly integrated into existing solid-phase peptide synthesis protocols. Finally, we show that peptide imidazolones are potent cis-amide bond surrogates that preorganize linear peptides for head-to-tail macrocyclization. This work represents the first general approach to the backbone and side-chain insertion of imidazolone bioisosteres at various positions in linear and cyclic peptides.
Collapse
Affiliation(s)
- Brendan J. Wall
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
| | | | | | - Aaron Donovan
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
| | - Brett VanVeller
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
| |
Collapse
|
2
|
Cain BN, Hergenrother PJ. Using permeation guidelines to design new antibiotics-A PASsagE into Pseudomonas aeruginosa. Clin Transl Med 2024; 14:e1600. [PMID: 38426413 PMCID: PMC10905542 DOI: 10.1002/ctm2.1600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 02/07/2024] [Indexed: 03/02/2024] Open
Affiliation(s)
- Brett N. Cain
- Department of Chemistry and Carl R. Woese Institute for Genomic BiologyUniversity of IllinoisUrbanaIllinoisUSA
| | - Paul J. Hergenrother
- Department of Chemistry and Carl R. Woese Institute for Genomic BiologyUniversity of IllinoisUrbanaIllinoisUSA
| |
Collapse
|
3
|
Johnson RM, Li K, Chen X, Morgan GL, Aubé J, Li B. The Hybrid Antibiotic Thiomarinol A Overcomes Intrinsic Resistance in Escherichia coli Using a Privileged Dithiolopyrrolone Moiety. ACS Infect Dis 2024; 10:582-593. [PMID: 38226592 DOI: 10.1021/acsinfecdis.3c00504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
An impermeable outer membrane and multidrug efflux pumps work in concert to provide Gram-negative bacteria with intrinsic resistance against many antibiotics. These resistance mechanisms reduce the intracellular concentrations of antibiotics and render them ineffective. The natural product thiomarinol A combines holothin, a dithiolopyrrolone antibiotic, with marinolic acid A, a close analogue of mupirocin. The hybridity of thiomarinol A converts the mupirocin scaffold from inhibiting Gram-positive bacteria to inhibiting both Gram-positive and -negative bacteria. We found that thiomarinol A accumulates significantly more than mupirocin within the Gram-negative bacterium Escherichia coli, likely contributing to its broad-spectrum activity. Antibiotic susceptibility testing of E. coli mutants reveals that thiomarinol A overcomes the intrinsic resistance mechanisms that render mupirocin inactive. Structure-activity relationship studies suggest that the dithiolopyrrolone is a privileged moiety for improving the accumulation and antibiotic activity of the mupirocin scaffold without compromising binding to isoleucyl-tRNA synthetase. These studies also highlight that accumulation is required but not sufficient for antibiotic activity. Our work reveals a role of the dithiolopyrrolone moiety in overcoming intrinsic mupirocin resistance in E. coli and provides a starting point for designing dual-acting and high-accumulating hybrid antibiotics.
Collapse
Affiliation(s)
- Rachel M Johnson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Kelin Li
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Xiaoyan Chen
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Gina L Morgan
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jeffrey Aubé
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Bo Li
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| |
Collapse
|
4
|
Haloi N, Huang S, Nichols AL, Fine EJ, Friesenhahn NJ, Marotta CB, Dougherty DA, Lindahl E, Howard RJ, Mayo SL, Lester HA. Interactive computational and experimental approaches improve the sensitivity of periplasmic binding protein-based nicotine biosensors for measurements in biofluids. Protein Eng Des Sel 2024; 37:gzae003. [PMID: 38302088 PMCID: PMC10896302 DOI: 10.1093/protein/gzae003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 01/17/2024] [Accepted: 01/29/2024] [Indexed: 02/03/2024] Open
Abstract
We developed fluorescent protein sensors for nicotine with improved sensitivity. For iNicSnFR12 at pH 7.4, the proportionality constant for ∆F/F0vs [nicotine] (δ-slope, 2.7 μM-1) is 6.1-fold higher than the previously reported iNicSnFR3a. The activated state of iNicSnFR12 has a fluorescence quantum yield of at least 0.6. We measured similar dose-response relations for the nicotine-induced absorbance increase and fluorescence increase, suggesting that the absorbance increase leads to the fluorescence increase via the previously described nicotine-induced conformational change, the 'candle snuffer' mechanism. Molecular dynamics (MD) simulations identified a binding pose for nicotine, previously indeterminate from experimental data. MD simulations also showed that Helix 4 of the periplasmic binding protein (PBP) domain appears tilted in iNicSnFR12 relative to iNicSnFR3a, likely altering allosteric network(s) that link the ligand binding site to the fluorophore. In thermal melt experiments, nicotine stabilized the PBP of the tested iNicSnFR variants. iNicSnFR12 resolved nicotine in diluted mouse and human serum at 100 nM, the peak [nicotine] that occurs during smoking or vaping, and possibly at the decreasing levels during intervals between sessions. NicSnFR12 was also partially activated by unidentified endogenous ligand(s) in biofluids. Improved iNicSnFR12 variants could become the molecular sensors in continuous nicotine monitors for animal and human biofluids.
Collapse
Affiliation(s)
- Nandan Haloi
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm 10044, Sweden
| | - Shan Huang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Eve J Fine
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Nicholas J Friesenhahn
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Christopher B Marotta
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Erik Lindahl
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm 10044, Sweden
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm 10691, Sweden
| | - Rebecca J Howard
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm 10691, Sweden
| | - Stephen L Mayo
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| |
Collapse
|
5
|
Haloi N, Huang S, Nichols AL, Fine EJ, Friesenhahn NJ, Marotta CB, Dougherty DA, Lindahl E, Howard RJ, Mayo SL, Lester HA. Interactive computational and experimental approaches improve the sensitivity of periplasmic binding protein-based nicotine biosensors for measurements in biofluids. bioRxiv 2024:2023.01.16.524298. [PMID: 36712031 PMCID: PMC9882114 DOI: 10.1101/2023.01.16.524298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We developed fluorescent protein sensors for nicotine with improved sensitivity. For iNicSnFR12 at pH 7.4, the proportionality constant for Δ F / F 0 vs [nicotine] (δ-slope, 2.7 μM-1) is 6.1-fold higher than the previously reported iNicSnFR3a. The activated state of iNicSnFR12 has a fluorescence quantum yield of at least 0.6. We measured similar dose-response relations for the nicotine-induced absorbance increase and fluorescence increase, suggesting that the absorbance increase leads to the fluorescence increase via the previously described nicotine-induced conformational change, the "candle snuffer" mechanism. Molecular dynamics (MD) simulations identified a binding pose for nicotine, previously indeterminate from experimental data. MD simulations also showed that Helix 4 of the periplasmic binding protein (PBP) domain appears tilted in iNicSnFR12 relative to iNicSnFR3a, likely altering allosteric network(s) that link the ligand binding site to the fluorophore. In thermal melt experiments, nicotine stabilized the PBP of the tested iNicSnFR variants. iNicSnFR12 resolved nicotine in diluted mouse and human serum at 100 nM, the peak [nicotine] that occurs during smoking or vaping, and possibly at the decreasing levels during intervals between sessions. NicSnFR12 was also partially activated by unidentified endogenous ligand(s) in biofluids. Improved iNicSnFR12 variants could become the molecular sensors in continuous nicotine monitors for animal and human biofluids.
Collapse
Affiliation(s)
- Nandan Haloi
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, 10044 Stockholm, Sweden
| | - Shan Huang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Eve J Fine
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Nicholas J Friesenhahn
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Christopher B Marotta
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Erik Lindahl
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, 10044 Stockholm, Sweden
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, 10691 Stockholm, Sweden
| | - Rebecca J Howard
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, 10691 Stockholm, Sweden
| | - Stephen L Mayo
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| |
Collapse
|
6
|
Geddes EJ, Gugger MK, Garcia A, Chavez MG, Lee MR, Perlmutter SJ, Bieniossek C, Guasch L, Hergenrother PJ. Porin-independent accumulation in Pseudomonas enables antibiotic discovery. Nature 2023; 624:145-153. [PMID: 37993720 DOI: 10.1038/s41586-023-06760-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/18/2023] [Indexed: 11/24/2023]
Abstract
Gram-negative antibiotic development has been hindered by a poor understanding of the types of compounds that can accumulate within these bacteria1,2. The presence of efflux pumps and substrate-specific outer-membrane porins in Pseudomonas aeruginosa renders this pathogen particularly challenging3. As a result, there are few antibiotic options for P. aeruginosa infections4 and its many porins have made the prospect of discovering general accumulation guidelines seem unlikely5. Here we assess the whole-cell accumulation of 345 diverse compounds in P. aeruginosa and Escherichia coli. Although certain positively charged compounds permeate both bacterial species, P. aeruginosa is more restrictive compared to E. coli. Computational analysis identified distinct physicochemical properties of small molecules that specifically correlate with P. aeruginosa accumulation, such as formal charge, positive polar surface area and hydrogen bond donor surface area. Mode of uptake studies revealed that most small molecules permeate P. aeruginosa using a porin-independent pathway, thus enabling discovery of general P. aeruginosa accumulation trends with important implications for future antibiotic development. Retrospective antibiotic examples confirmed these trends and these discoveries were then applied to expand the spectrum of activity of a gram-positive-only antibiotic, fusidic acid, into a version that demonstrates a dramatic improvement in antibacterial activity against P. aeruginosa. We anticipate that these discoveries will facilitate the design and development of high-permeating antipseudomonals.
Collapse
Affiliation(s)
- Emily J Geddes
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, USA
| | - Morgan K Gugger
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, USA
| | - Alfredo Garcia
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, USA
| | - Martin Garcia Chavez
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, USA
| | - Myung Ryul Lee
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, USA
| | - Sarah J Perlmutter
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, USA
| | - Christoph Bieniossek
- Roche Pharma Research and Early Development, Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Laura Guasch
- Roche Pharma Research and Early Development, Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Paul J Hergenrother
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, USA.
| |
Collapse
|
7
|
Maher C, Hassan KA. The Gram-negative permeability barrier: tipping the balance of the in and the out. mBio 2023; 14:e0120523. [PMID: 37861328 PMCID: PMC10746187 DOI: 10.1128/mbio.01205-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023] Open
Abstract
Gram-negative bacteria are intrinsically resistant to many antibiotics, due in large part to the permeability barrier formed by their cell envelope. The complex and synergistic interplay of the two Gram-negative membranes and active efflux prevents the accumulation of a diverse range of compounds that are effective against Gram-positive bacteria. A lack of detailed information on how components of the cell envelope contribute to this has been identified as a key barrier to the rational development of new antibiotics with efficacy against Gram-negative species. This review describes the current understanding of the role of the different components of the Gram-negative cell envelope in preventing compound accumulation and the state of efforts to describe properties that allow compounds to overcome this barrier and apply them to the development of new broad-spectrum antibiotics.
Collapse
Affiliation(s)
- Claire Maher
- College of Engineering, Science and Environment, University of Newcastle, Newcastle, Australia
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, Australia
| | - Karl A. Hassan
- College of Engineering, Science and Environment, University of Newcastle, Newcastle, Australia
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, Australia
| |
Collapse
|
8
|
Gervasoni S, Mehla J, Bergen CR, Leus IV, Margiotta E, Malloci G, Bosin A, Vargiu AV, Lomovskaya O, Rybenkov VV, Ruggerone P, Zgurskaya HI. Molecular determinants of avoidance and inhibition of Pseudomonas aeruginosa MexB efflux pump. mBio 2023; 14:e0140323. [PMID: 37493633 PMCID: PMC10470492 DOI: 10.1128/mbio.01403-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 06/12/2023] [Indexed: 07/27/2023] Open
Abstract
Transporters of the resistance-nodulation-cell division (RND) superfamily of proteins are the dominant multidrug efflux power of Gram-negative bacteria. The major RND efflux pump of Pseudomonas aeruginosa is MexAB-OprM, in which the inner membrane transporter MexB is responsible for the recognition and binding of compounds. The high importance of this pump in clinical antibiotic resistance made it a subject of intense investigations and a promising target for the discovery of efflux pump inhibitors. This study is focused on a series of peptidomimetic compounds developed as effective inhibitors of MexAB-OprM. We performed multi-copy molecular dynamics simulations, machine-learning (ML) analyses, and site-directed mutagenesis of MexB to investigate interactions of MexB with representatives of efflux avoiders, substrates, and inhibitors. The analysis of both direct and water-mediated protein-ligand interactions revealed characteristic patterns for each class, highlighting significant differences between them. We found that efflux avoiders poorly interact with the access binding site of MexB, and inhibition engages amino acid residues that are not directly involved in binding and transport of substrates. In agreement, machine-learning models selected different residues predictive of MexB substrates and inhibitors. The differences in interactions were further validated by site-directed mutagenesis. We conclude that the substrate translocation and inhibition pathways of MexB split at the interface (between the main putative binding sites) and at the deep binding pocket and that interactions outside of the hydrophobic patch contribute to the inhibition of MexB. This molecular-level information could help in the rational design of new inhibitors and antibiotics less susceptible to the efflux mechanism. IMPORTANCE Multidrug transporters recognize and expel from cells a broad range of ligands including their own inhibitors. The difference between the substrate translocation and inhibition routes remains unclear. In this study, machine learning and computational and experimental approaches were used to understand dynamics of MexB interactions with its ligands. Our results show that some ligands engage a certain combination of polar and charged residues in MexB binding sites to be effectively expelled into the exit funnel, whereas others engage aromatic and hydrophobic residues that slow down or hinder the next step in the transporter cycle. These findings suggest that all MexB ligands fit into this substrate-inhibitor spectrum depending on their physico-chemical structures and properties.
Collapse
Affiliation(s)
- Silvia Gervasoni
- Department of Physics, University of Cagliari, Monserrato, Italy
| | - Jitender Mehla
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Charles R. Bergen
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Inga V. Leus
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Enrico Margiotta
- Department of Physics, University of Cagliari, Monserrato, Italy
| | - Giuliano Malloci
- Department of Physics, University of Cagliari, Monserrato, Italy
| | - Andrea Bosin
- Department of Physics, University of Cagliari, Monserrato, Italy
| | | | | | - Valentin V. Rybenkov
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Paolo Ruggerone
- Department of Physics, University of Cagliari, Monserrato, Italy
| | - Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| |
Collapse
|
9
|
Lapierre J, Hub JS. Converging PMF Calculations of Antibiotic Permeation across an Outer Membrane Porin with Subkilocalorie per Mole Accuracy. J Chem Inf Model 2023; 63:5319-5330. [PMID: 37560945 DOI: 10.1021/acs.jcim.3c00880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
The emergence of multidrug-resistant pathogens led to a critical need for new antibiotics. A key property of effective antibiotics against Gram-negative bacteria is their ability to permeate through the bacterial outer membrane via transmembrane porin proteins. Molecular dynamics (MD) simulations are, in principle, capable of modeling antibiotic permeation across outer membrane porins (OMPs). However, owing to sampling problems, it has remained challenging to obtain converged potentials of mean force (PMFs) for antibiotic permeation across OMPs. Here, we investigated the convergence of PMFs along a single collective variable aimed at quantifying the permeation of the antibiotic fosmidomycin across the OprO porin. We compared standard umbrella sampling (US) with three advanced flavors of the US technique: (i) Hamiltonian replica exchange with solute tempering in combination with US, (ii) simulated tempering-enhanced US, and (iii) replica-exchange US. To quantify the PMF convergence and to reveal hysteresis problems, we computed several independent sets of US simulations starting from pulling simulations in the outward and inward permeation directions. We find that replica-exchange US in combination with well-chosen restraints is highly successful for obtaining converged PMFs of fosmidomycin permeation through OprO, reaching PMFs converged to subkilocalorie per mole accuracy.
Collapse
Affiliation(s)
- Jeremy Lapierre
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken 66123, Germany
| | - Jochen S Hub
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken 66123, Germany
| |
Collapse
|
10
|
Acharya A, Ghai I, Piselli C, Prajapati JD, Benz R, Winterhalter M, Kleinekathöfer U. Conformational Dynamics of Loop L3 in OmpF: Implications toward Antibiotic Translocation and Voltage Gating. J Chem Inf Model 2023; 63:910-927. [PMID: 36525563 DOI: 10.1021/acs.jcim.2c01108] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In the present work, we delineate the molecular mechanism of a bulky antibiotic permeating through a bacterial channel and uncover the role of conformational dynamics of the constriction loop in this process. Using the temperature accelerated sliced sampling approach, we shed light onto the dynamics of the L3 loop, in particular the F118 to S125 segment, at the constriction regions of the OmpF porin. We complement the findings with single channel electrophysiology experiments and applied-field simulations, and we demonstrate the role of hydrogen-bond stabilization in the conformational dynamics of the L3 loop. A molecular mechanism of permeation is put forward wherein charged antibiotics perturb the network of stabilizing hydrogen-bond interactions and induce conformational changes in the L3 segment, thereby aiding the accommodation and permeation of bulky antibiotic molecules across the constriction region. We complement the findings with single channel electrophysiology experiments and demonstrate the importance of the hydrogen-bond stabilization in the conformational dynamics of the L3 loop. The generality of the present observations and experimental results regarding the L3 dynamics enables us to identify this L3 segment as the source of gating. We propose a mechanism of OmpF gating that is in agreement with previous experimental data that showed the noninfluence of cysteine double mutants that tethered the L3 tip to the barrel wall on the OmpF gating behavior. The presence of similar loop stabilization networks in porins of other clinically relevant pathogens suggests that the conformational dynamics of the constriction loop is possibly of general importance in the context of antibiotic permeation through porins.
Collapse
Affiliation(s)
- Abhishek Acharya
- Department of Physics and Earth Sciences, Jacobs University Bremen, Bremen 28759, Germany
| | - Ishan Ghai
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen 28759, Germany
| | - Claudio Piselli
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen 28759, Germany
| | | | - Roland Benz
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen 28759, Germany
| | - Mathias Winterhalter
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen 28759, Germany
| | - Ulrich Kleinekathöfer
- Department of Physics and Earth Sciences, Jacobs University Bremen, Bremen 28759, Germany
| |
Collapse
|
11
|
Acharya A, Prajapati JD, Kleinekathöfer U. Atomistic Simulation of Molecules Interacting with Biological Nanopores: From Current Understanding to Future Directions. J Phys Chem B 2022; 126:3995-4008. [PMID: 35616602 DOI: 10.1021/acs.jpcb.2c01173] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biological nanopores have been at the focus of numerous studies due to their role in many biological processes as well as their (prospective) technological applications. Among many other topics, recent studies on nanopores have addressed two key areas: antibiotic permeation through bacterial channels and sensing of analytes. Although the two areas are quite far apart in terms of their objectives, in both cases atomistic simulations attempt to understand the solute dynamics and the solute-protein interactions within the channel lumen. While decades of studies on various channels have culminated in an improved understanding of the key molecular factors and led to practical applications in some cases, successful utilization is limited. In this Perspective we summarize recent progress in understanding key issues in molecular simulations of antibiotic translocation and in the development of nanopore sensors. Moreover, we comment on possible advancements in computational algorithms that can potentially resolve some of the issues.
Collapse
Affiliation(s)
- Abhishek Acharya
- Department of Physics and Earth Sciences, Jacobs University Bremen, 28759 Bremen, Germany
| | | | - Ulrich Kleinekathöfer
- Department of Physics and Earth Sciences, Jacobs University Bremen, 28759 Bremen, Germany
| |
Collapse
|
12
|
Gervasoni S, Malloci G, Bosin A, Vargiu AV, Zgurskaya HI, Ruggerone P. AB-DB: Force-Field parameters, MD trajectories, QM-based data, and Descriptors of Antimicrobials. Sci Data 2022; 9:148. [PMID: 35365662 PMCID: PMC8976083 DOI: 10.1038/s41597-022-01261-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 03/11/2022] [Indexed: 12/13/2022] Open
Abstract
Antibiotic resistance is a major threat to public health. The development of chemo-informatic tools to guide medicinal chemistry campaigns in the efficint design of antibacterial libraries is urgently needed. We present AB-DB, an open database of all-atom force-field parameters, molecular dynamics trajectories, quantum-mechanical properties, and curated physico-chemical descriptors of antimicrobial compounds. We considered more than 300 molecules belonging to 25 families that include the most relevant antibiotic classes in clinical use, such as β-lactams and (fluoro)quinolones, as well as inhibitors of key bacterial proteins. We provide traditional descriptors together with properties obtained with Density Functional Theory calculations. Noteworthy, AB-DB contains less conventional descriptors extracted from μs-long molecular dynamics simulations in explicit solvent. In addition, for each compound we make available force-field parameters for the major micro-species at physiological pH. With the rise of multi-drug-resistant pathogens and the consequent need for novel antibiotics, inhibitors, and drug re-purposing strategies, curated databases containing reliable and not straightforward properties facilitate the integration of data mining and statistics into the discovery of new antimicrobials. Measurement(s) | molecular physical property analysis objective | Technology Type(s) | Computer Modeling |
Collapse
Affiliation(s)
- Silvia Gervasoni
- University of Cagliari, Department of Physics, I-09042, Monserrato (Cagliari), Italy
| | - Giuliano Malloci
- University of Cagliari, Department of Physics, I-09042, Monserrato (Cagliari), Italy.
| | - Andrea Bosin
- University of Cagliari, Department of Physics, I-09042, Monserrato (Cagliari), Italy
| | - Attilio V Vargiu
- University of Cagliari, Department of Physics, I-09042, Monserrato (Cagliari), Italy
| | - Helen I Zgurskaya
- University of Oklahoma, Department of Chemistry and Biochemistry, Norman, OK, 73072, United States
| | - Paolo Ruggerone
- University of Cagliari, Department of Physics, I-09042, Monserrato (Cagliari), Italy
| |
Collapse
|
13
|
Vasan AK, Haloi N, Ulrich RJ, Metcalf ME, Wen PC, Metcalf WW, Hergenrother PJ, Shukla D, Tajkhorshid E. Role of internal loop dynamics in antibiotic permeability of outer membrane porins. Proc Natl Acad Sci U S A 2022; 119:e2117009119. [PMID: 35193963 DOI: 10.1073/pnas.2117009119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2022] [Indexed: 12/26/2022] Open
Abstract
Antibiotic resistance in Gram-negative pathogens has been identified as an urgent threat to human health by the World Health Organization. The major challenge with treating infections by these pathogens is developing antibiotics that can traverse the dense bacterial outer membrane (OM) formed by a mesh of lipopolysaccharides. Effective antibiotics permeate through OM porins, which have evolved for nutrient diffusion; however, the conformational states of these porins regulating permeation are still unclear. Here, we used molecular dynamics simulations, free energy calculations, Markov-state modeling, and whole-cell accumulation assays to provide mechanistic insight on how a porin shifts between open and closed states. We provide a mechanism of how Gram-negative bacteria confer resistance to antibiotics. Gram-negative bacteria pose a serious public health concern due to resistance to many antibiotics, caused by the low permeability of their outer membrane (OM). Effective antibiotics use porins in the OM to reach the interior of the cell; thus, understanding permeation properties of OM porins is instrumental to rationally develop broad-spectrum antibiotics. A functionally important feature of OM porins is undergoing open–closed transitions that modulate their transport properties. To characterize the molecular basis of these transitions, we performed an extensive set of molecular dynamics (MD) simulations of Escherichia coli OM porin OmpF. Markov-state analysis revealed that large-scale motion of an internal loop, L3, underlies the transition between energetically stable open and closed states. The conformation of L3 is controlled by H bonds between highly conserved acidic residues on the loop and basic residues on the OmpF β-barrel. Mutation of key residues important for the loop’s conformation shifts the equilibrium between open and closed states and regulates translocation of permeants (ions and antibiotics), as observed in the simulations and validated by our whole-cell accumulation assay. Notably, one mutant system G119D, which we find to favor the closed state, has been reported in clinically resistant bacterial strains. Overall, our accumulated ∼200 µs of simulation data (the wild type and mutants) along with experimental assays suggest the involvement of internal loop dynamics in permeability of OM porins and antibiotic resistance in Gram-negative bacteria.
Collapse
|