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Baothman OAS. Identifying therapeutic antibacterial peptides against Vibrio cholerae to inhibit the function of Na(+)-translocating NADH-quinone reductase. J Biomol Struct Dyn 2023:1-16. [PMID: 37850460 DOI: 10.1080/07391102.2023.2270696] [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: 07/15/2023] [Accepted: 10/07/2023] [Indexed: 10/19/2023]
Abstract
Vibrio cholerae is the bacteria responsible for cholera, which is a significant threat to many nations. Curing and treating this infection requires identification of the critical protein and development of a drug to inhibit its function. In this context, Na(+)-translocating NADH-quinone reductase was considered a potential therapeutic target. A library of antibacterial peptides with residue lengths of 50 was screened using a docking method, and the five most potent peptides were selected on the basis of a weighted score derived from solvent accessible surface area and docking score. To investigate the stability of the protein-peptide complex, a 100-ns molecular dynamics simulation was performed. These peptides targeted the native dimeric binding interface of Na(+)-transporting NADH-quinone reductase. This study evaluated the binding affinity and conformational stability of these peptides with the protein using different post-simulation metrics. A peptide, CCL28, exhibited steady RMSD characteristics; nonetheless, it modified the docked conformation but stabilized in the new conformation. This peptide also demonstrated the best performance in addressing the protein's native binding interface. It demonstrated a binding free energy of -120 kcal/mol with the protein. Principal component analysis (PCA) revealed that the first PC had the lowest conformational variation and the greatest coverage. Eventually, these peptides were also evaluated using steered molecular dynamics, and it was discovered that CCL28 had a greater maximum force than the other five peptides, at 1139.08 kJ/mol/nm. Targeting the native binding interface, we present a CCL28 peptide with a strong potential to block the biological activity of Vibrio cholerae's Na(+)-translocating NADH-quinone reductase.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Othman A S Baothman
- Biochemistry Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
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Kruth S, Nett M. Aurachins, Bacterial Antibiotics Interfering with Electron Transport Processes. Antibiotics (Basel) 2023; 12:1067. [PMID: 37370386 DOI: 10.3390/antibiotics12061067] [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: 05/31/2023] [Revised: 06/12/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023] Open
Abstract
Aurachins are farnesylated quinolone alkaloids of bacterial origin and excellent inhibitors of the respiratory chain in pro- and eukaryotes. Therefore, they have become important tool compounds for the investigation of electron transport processes and they also serve as lead structures for the development of antibacterial and antiprotozoal drugs. Especially aurachin D proved to be a valuable starting point for structure-activity relationship studies. Aurachin D is a selective inhibitor of the cytochrome bd oxidase, which has received increasing attention as a target for the treatment of infectious diseases caused by mycobacteria. Moreover, aurachin D possesses remarkable activities against Leishmania donovani, the causative agent of leishmaniasis. Aurachins are naturally produced by myxobacteria of the genus Stigmatella as well as by some Streptomyces and Rhodococcus strains. The recombinant production of these antibiotics turned out to be challenging due to their complex biosynthesis and their inherent toxicity. Recently, the biotechnological production of aurachin D was established in E. coli with a titer which is higher than previously reported from natural producer organisms.
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Affiliation(s)
- Sebastian Kruth
- Laboratory of Technical Biology, Department of Biochemical and Chemical Engineering, TU Dortmund University, 44227 Dortmund, Germany
| | - Markus Nett
- Laboratory of Technical Biology, Department of Biochemical and Chemical Engineering, TU Dortmund University, 44227 Dortmund, Germany
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Kruth S, Schibajew L, Nett M. Biocatalytic production of the antibiotic aurachin D in Escherichia coli. AMB Express 2022; 12:138. [DOI: 10.1186/s13568-022-01478-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 10/15/2022] [Indexed: 11/06/2022] Open
Abstract
Abstract
Aurachin D is a potent inhibitor of cytochrome bd oxidases, which are potential targets in the treatment of infectious diseases. In this study, our aim was to improve the biocatalytic production of aurachin D from a quinolone precursor molecule with recombinant Escherichia coli cells expressing the biosynthesis enzyme AuaA. In order to achieve a high-level production of this membrane-bound farnesyltransferase in E. coli, the expression of the auaA gene was translationally coupled to an upstream cistron in accordance with a bicistronic design (BCD) strategy. Screening of various BCD elements led to the identification of optimized auaA expression cassettes, which increased the aurachin D titer in E. coli up to 29-fold in comparison to T7-mediated expression. This titer could be further raised by codon optimization of auaA and by introducing the mevalonate pathway into the production strain. The latter measure was intended to improve the availability of farnesyl pyrophosphate, which is needed as a cosubstrate for the AuaA-catalyzed reaction. In sum, the described efforts resulted in a strain producing aurachin D with a titer that is 424 times higher than that obtained with the original, non-optimized expression host.
Graphical Abstract
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Cryo-EM structures of Na +-pumping NADH-ubiquinone oxidoreductase from Vibrio cholerae. Nat Commun 2022; 13:4082. [PMID: 35882843 PMCID: PMC9325719 DOI: 10.1038/s41467-022-31718-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 06/29/2022] [Indexed: 11/08/2022] Open
Abstract
The Na+-pumping NADH-ubiquinone oxidoreductase (Na+-NQR) couples electron transfer from NADH to ubiquinone with Na+-pumping, generating an electrochemical Na+ gradient that is essential for energy-consuming reactions in bacteria. Since Na+-NQR is exclusively found in prokaryotes, it is a promising target for highly selective antibiotics. However, the molecular mechanism of inhibition is not well-understood for lack of the atomic structural information about an inhibitor-bound state. Here we present cryo-electron microscopy structures of Na+-NQR from Vibrio cholerae with or without a bound inhibitor at 2.5- to 3.1-Å resolution. The structures reveal the arrangement of all six redox cofactors including a herein identified 2Fe-2S cluster located between the NqrD and NqrE subunits. A large part of the hydrophilic NqrF is barely visible in the density map, suggesting a high degree of flexibility. This flexibility may be responsible to reducing the long distance between the 2Fe-2S centers in NqrF and NqrD/E. Two different types of specific inhibitors bind to the N-terminal region of NqrB, which is disordered in the absence of inhibitors. The present study provides a foundation for understanding the function of Na+-NQR and the binding manner of specific inhibitors.
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Ishikawa M, Masuya T, Kuroda S, Uno S, Butler NL, Foreman S, Murai M, Barquera B, Miyoshi H. The side chain of ubiquinone plays a critical role in Na + translocation by the NADH-ubiquinone oxidoreductase (Na +-NQR) from Vibrio cholerae. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148547. [PMID: 35337841 DOI: 10.1016/j.bbabio.2022.148547] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/18/2022] [Accepted: 03/17/2022] [Indexed: 11/19/2022]
Abstract
The Na+-pumping NADH-ubiquinone (UQ) oxidoreductase (Na+-NQR) is an essential bacterial respiratory enzyme that generates a Na+ gradient across the cell membrane. However, the mechanism that couples the redox reactions to Na+ translocation remains unknown. To address this, we examined the relation between reduction of UQ and Na+ translocation using a series of synthetic UQs with Vibrio cholerae Na+-NQR reconstituted into liposomes. UQ0 that has no side chain and UQCH3 and UQC2H5, which have methyl and ethyl side chains, respectively, were catalytically reduced by Na+-NQR, but their reduction generated no membrane potential, indicating that the overall electron transfer and Na+ translocation are not coupled. While these UQs were partly reduced by electron leak from the cofactor(s) located upstream of riboflavin, this complete loss of Na+ translocation cannot be explained by the electron leak. Lengthening the UQ side chain to n-propyl (C3H7) or longer significantly restored Na+ translocation. It has been considered that Na+ translocation is completed when riboflavin, a terminal redox cofactor residing within the membrane, is reduced. In this view, the role of UQ is simply to accept electrons from the reduced riboflavin to regenerate the stable neutral riboflavin radical and reset the catalytic cycle. However, the present study revealed that the final UQ reduction via reduced riboflavin makes an important contribution to Na+ translocation through a critical role of its side chain. Based on the results, we discuss the critical role of the UQ side chain in Na+ translocation.
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Affiliation(s)
- Moe Ishikawa
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Takahiro Masuya
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Seina Kuroda
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Shinpei Uno
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Nicole L Butler
- Department of Biological Science, Rensselaer Polytechnic Institute, Troy, NY 12180, United States
| | - Sara Foreman
- Department of Biological Science, Rensselaer Polytechnic Institute, Troy, NY 12180, United States
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Blanca Barquera
- Department of Biological Science, Rensselaer Polytechnic Institute, Troy, NY 12180, United States; Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, United States
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
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Deka RK, Deka A, Liu WZ, Norgard MV, Brautigam CA. Inhibition of bacterial FMN transferase: A potential avenue for countering antimicrobial resistance. Protein Sci 2022; 31:545-551. [PMID: 34796555 PMCID: PMC8819833 DOI: 10.1002/pro.4241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 10/01/2021] [Accepted: 11/15/2021] [Indexed: 02/03/2023]
Abstract
Antibiotic resistance is a challenge for the control of bacterial infections. In an effort to explore unconventional avenues for antibacterial drug development, we focused on the FMN-transferase activity of the enzyme Ftp from the syphilis spirochete, Treponema pallidum (Ftp_Tp). This enzyme, which is only found in prokaryotes and trypanosomatids, post-translationally modifies proteins in the periplasm, covalently linking FMN (from FAD) to proteins that typically are important for establishing an essential electrochemical gradient across the cytoplasmic membrane. As such, Ftp inhibitors potentially represent a new class of antimicrobials. Previously, we showed that AMP is both a product of the Ftp_tp-catalyzed reaction and an inhibitor of the enzyme. As a preliminary step in exploiting this property to develop a novel Ftp_Tp inhibitor, we have used structural and solution studies to examine the inhibitory and enzyme-binding properties of several adenine-based nucleosides, with particular focus on the 2-position of the purine ring. Implications for future drug design are discussed.
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Affiliation(s)
- Ranjit K. Deka
- Department of MicrobiologyUT Southwestern Medical CenterDallasTexasUSA
| | | | - Wei Z. Liu
- Department of MicrobiologyUT Southwestern Medical CenterDallasTexasUSA
| | | | - Chad A. Brautigam
- Department of MicrobiologyUT Southwestern Medical CenterDallasTexasUSA,Department of BiophysicsUT Southwestern Medical CenterDallasTexasUSA
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Dibrov A, Mourin M, Dibrov P, Pierce GN. Molecular dynamics modeling of the Vibrio cholera Na +-translocating NADH:quinone oxidoreductase NqrB-NqrD subunit interface. Mol Cell Biochem 2021; 477:153-165. [PMID: 34626300 PMCID: PMC8755685 DOI: 10.1007/s11010-021-04266-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 09/17/2021] [Indexed: 10/29/2022]
Abstract
The Na+-translocating NADH:quinone oxidoreductase (Na+-NQR) is the major Na+ pump in aerobic pathogens such as Vibrio cholerae. The interface between two of the NQR subunits, NqrB and NqrD, has been proposed to harbor a binding site for inhibitors of Na+-NQR. While the mechanisms underlying Na+-NQR function and inhibition remain underinvestigated, their clarification would facilitate the design of compounds suitable for clinical use against pathogens containing Na+-NQR. An in silico model of the NqrB-D interface suitable for use in molecular dynamics simulations was successfully constructed. A combination of algorithmic and manual methods was used to reconstruct portions of the two subunits unresolved in the published crystal structure and validate the resulting structure. Hardware and software optimizations that improved the efficiency of the simulation were considered and tested. The geometry of the reconstructed complex compared favorably to the published V. cholerae Na+-NQR crystal structure. Results from one 1 µs, three 150 ns and two 50 ns molecular dynamics simulations illustrated the stability of the system and defined the limitations of this model. When placed in a lipid bilayer under periodic boundary conditions, the reconstructed complex was completely stable for at least 1 µs. However, the NqrB-D interface underwent a non-physiological transition after 350 ns.
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Affiliation(s)
- Alexander Dibrov
- Department of Family Medicine, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB, Canada.
| | - Muntahi Mourin
- Department of Physiology and Pathophysiology, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.,Albrechtsen Research Centre, St. Boniface Hospital, 351 Taché Avenue, Winnipeg, MB, Canada
| | - Pavel Dibrov
- Department of Microbiology, Faculty of Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Grant N Pierce
- Department of Physiology and Pathophysiology, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.,Albrechtsen Research Centre, St. Boniface Hospital, 351 Taché Avenue, Winnipeg, MB, Canada
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Specific chemical modification explores dynamic structure of the NqrB subunit in Na +-pumping NADH-ubiquinone oxidoreductase from Vibrio cholerae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148432. [PMID: 33932367 DOI: 10.1016/j.bbabio.2021.148432] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 04/20/2021] [Indexed: 12/28/2022]
Abstract
The Na+-pumping NADH-ubiquinone oxidoreductase (Na+-NQR) is a main ion transporter in many pathogenic bacteria. We previously proposed that N-terminal stretch of the NqrB subunit plays an important role in regulating the ubiquinone reaction at the adjacent NqrA subunit in Vibrio cholerae Na+-NQR. However, since approximately three quarters of the stretch (NqrB-Met1-Pro37) was not modeled in an earlier crystallographic study, its structure and function remain unknown. If we can develop a method that enables pinpoint modification of this stretch by functional chemicals (such as spin probes), it could lead to new ways to investigate the unsettled issues. As the first step to this end, we undertook to specifically attach an alkyne group to a lysine located in the stretch via protein-ligand affinity-driven substitution using synthetic ligands NAS-K1 and NAS-K2. The alkyne, once attached, can serve as an "anchor" for connecting functional chemicals via convenient click chemistry. After a short incubation of isolated Na+-NQR with these ligands, alkyne was predominantly incorporated into NqrB. Proteomic analyses in combination with mutagenesis of predicted target lysines revealed that alkyne attaches to NqrB-Lys22 located at the nonmodeled region of the stretch. This study not only achieved the specific modification initially aimed for but also provided valuable information about positioning of the nonmodeled region. For example, the fact that hydrophobic NAS-Ks come into contact with NqrB-Lys22 suggests that the nonmodeled region may orient toward the membrane phase rather than protruding into cytoplasmic medium. This conformation may be essential for regulating the ubiquinone reaction in the adjacent NqrA.
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