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Huang H, Wan P, Luo X, Lu Y, Li X, Xiong W, Zeng Z. Tigecycline Resistance-Associated Mutations in the MepA Efflux Pump in Staphylococcus aureus. Microbiol Spectr 2023; 11:e0063423. [PMID: 37432114 PMCID: PMC10434020 DOI: 10.1128/spectrum.00634-23] [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: 02/16/2023] [Accepted: 06/24/2023] [Indexed: 07/12/2023] Open
Abstract
Tigecycline is an important antibacterial drug for treating infection by clinical multidrug-resistant bacteria, and tigecycline-resistant Staphylococcus aureus (TRSA) has been increasingly reported in recent years. Notably, only rpsJ and mepA are associated with the tigecycline resistance of S. aureus. The mepA gene encodes MepA efflux pumps, and the overexpression of mepA has been confirmed to be directly related to tigecycline resistance. Although the mutations of MepA widely occur, the associations between TRSA and mutations of MepA are still unclear. In this study, we explored mutations in the mepA genes from various sources. Then, tigecycline resistance-associated mutations T29I, E287G, and T29I+E287G in MepA were identified, and their effects were evaluated through mutant deletion and complementation, tigecycline accumulation assay, and molecular docking experiments. Results showed that the MICs of tigecycline, gentamicin, and amikacin increased in special complementary transformants and recovered after the addition of the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). The tigecycline accumulation assay of the mepA-deleted mutant strain and its complementary transformants showed that T29I, E287G, and T29I+E287G mutations promoted tigecycline efflux, and molecular docking showed that mutations T29I, E287G, and T29I+E287G decreased the binding energy and contributed to ligand binding. Moreover, we inferred the evolutionary trajectory of S. aureus under the selective pressure of tigecycline in vitro. Overall, our study indicated that mutations in MepA play important roles in tigecycline resistance in S. aureus. IMPORTANCE Previous analysis has shown that overexpression of MepA is an exact mechanism involved in tigecycline resistance apart from the rpsJ mutation and is usually dependent on the mutant mepR. However, no research has evaluated the effects of diverse mutations discovered in TRSA in MepA. This study demonstrates that the mutations in MepA confer resistance to tigecycline without overexpression and provides genotypic references for identifying TRSA. Although tigecycline resistance-associated mutations in MepA identified in this study have not been observed in clinical isolates, the mechanism should be explored given that S. aureus strains are prevalent in the environment. Measures should be implemented to contain TRSA within the time window before tigecycline resistance-associated mutations in MepA are prevalent.
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Affiliation(s)
- Honghao Huang
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Peng Wan
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Xinyue Luo
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Yixing Lu
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Xiaoshen Li
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Wenguang Xiong
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Zhenling Zeng
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
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Hussain MA, Mohamed MS, Altayb HN, Mohamed AO, Ashour A, Osman W, Sherif AE, Ghazawi KF, Miski SF, Ibrahim SRM, Mohamed GA, Sindi IA, Alshamrani AA, Elgaml A. Comparative Genomic Analysis of Multi-Drug Resistant Pseudomonas aeruginosa Sequence Type 235 Isolated from Sudan. Microorganisms 2023; 11:1432. [PMID: 37374934 DOI: 10.3390/microorganisms11061432] [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: 04/03/2023] [Revised: 05/20/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
Pseudomonas aeruginosa (P. aeruginosa) is known to be associated with resistance to practically all known antibiotics. This is a cross-sectional, descriptive, laboratory-based analytical study in which 200 P. aeruginosa clinical isolates were involved. The DNA of the most resistant isolate was extracted and its whole genome was sequenced, assembled, annotated, and announced, strain typing was ascribed, and it was subjected to comparative genomic analysis with two susceptible strains. The rate of resistance was 77.89%, 25.13%, 21.61%, 18.09%, 5.53%, and 4.52% for piperacillin, gentamicin, ciprofloxacin, ceftazidime, meropenem, and polymyxin B, respectively. Eighteen percent (36) of the tested isolates exhibited a MDR phenotype. The most MDR strain belonged to epidemic sequence type 235. Comparative genomic analysis of the MDR strain (GenBank: MVDK00000000) with two susceptible strains revealed that the core genes were shared by the three genomes but there were accessory genes that were strain-specific, and this MDR genome had a low CG% (64.6%) content. A prophage sequence and one plasmid were detected in the MDR genome, but amazingly, it contained no resistant genes for drugs with antipseudomonal activity and there was no resistant island. In addition, 67 resistant genes were detected, 19 of them were found only in the MDR genome and 48 genes were efflux pumps, and a novel deleterious point mutation (D87G) was detected in the gyrA gene. The novel deleterious mutation in the gyrA gene (D87G) is a known position behind quinolone resistance. Our findings emphasize the importance of adoption of infection control strategies to prevent dissemination of MDR isolates.
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Affiliation(s)
- Mohamed A Hussain
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, International University of Africa, Khartoum P.O. Box 2469, Sudan
| | - Malik Suliman Mohamed
- Department of Pharmaceutics, College of Pharmacy, Jouf University, Sakaka 72388, Saudi Arabia
- Department of Pharmaceutics, Faculty of Pharmacy, University of Khartoum, Khartoum 11111, Sudan
| | - Hisham N Altayb
- Department of Biochemistry, Faculty of Sciences, King Abdulaziz University, Jeddah 23589, Saudi Arabia
| | - Ahmed Osman Mohamed
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, International University of Africa, Khartoum P.O. Box 2469, Sudan
| | - Ahmed Ashour
- Department of Pharmacognosy, Faculty of Pharmacy, Prince Sattam Bin Abdulaziz University, Alkharj 11942, Saudi Arabia
- Department of Pharmacognosy, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt
| | - Wadah Osman
- Department of Pharmacognosy, Faculty of Pharmacy, Prince Sattam Bin Abdulaziz University, Alkharj 11942, Saudi Arabia
- Department of Pharmacognosy, Faculty of Pharmacy, University of Khartoum, Khartoum 11115, Sudan
| | - Asmaa E Sherif
- Department of Pharmacognosy, Faculty of Pharmacy, Prince Sattam Bin Abdulaziz University, Alkharj 11942, Saudi Arabia
- Department of Pharmacognosy, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt
| | - Kholoud F Ghazawi
- Clinical Pharmacy Department, College of Pharmacy, Umm Al-Qura University, Makkah 24382, Saudi Arabia
| | - Samar F Miski
- Department of Pharmacology and Toxicology, College of Pharmacy, Taibah University, Al-Madinah Al-Munawwarah 30078, Saudi Arabia
| | - Sabrin R M Ibrahim
- Department of Chemistry, Preparatory Year Program, Batterjee Medical College, Jeddah 21442, Saudi Arabia
- Department of Pharmacognosy, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt
| | - Gamal A Mohamed
- Department of Natural Products and Alternative Medicine, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Ikhlas A Sindi
- Department of Biology, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Ahmad A Alshamrani
- Pharmaceutical Care Department, Ministry of National Guard-Health Affairs, Jeddah 22384, Saudi Arabia
| | - Abdelaziz Elgaml
- Microbiology and Immunology Department, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt
- Microbiology and Immunology Department, Faculty of Pharmacy, Horus University, New Damietta 34511, Egypt
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Mehta J, Rolta R, Dev K. Role of medicinal plants from North Western Himalayas as an efflux pump inhibitor against MDR AcrAB-TolC Salmonella enterica serovar typhimurium: In vitro and In silico studies. JOURNAL OF ETHNOPHARMACOLOGY 2022; 282:114589. [PMID: 34492321 DOI: 10.1016/j.jep.2021.114589] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 08/20/2021] [Accepted: 08/29/2021] [Indexed: 06/13/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Zingiber officinale Roscoe has been utilized traditionally to cure various diseases like cold, cough, diarrhoea, nausea, asthma, vomiting, toothache, stomach upset, respiratory disorders, joint pain, and throat infection. It is also consumed as spices and ginger tea. AIM OF THE STUDY The current study was aimed to identify the phytocompounds of traditional medicinal plants of North-Western Himalaya that could inhibit the AcrAB-TolC efflux pump activity of Salmonella typhimurium and become sensitive to antibiotic killing at reduced dosage. MATERIAL AND METHODS Medicinal plant extracts were prepared using methanol, aqueous, and ethyl acetate and tested for efflux pump inhibitory activity of Salmonella typhimurium NKS70, NKS174, and NKS773 strains using Ethidium Bromide (EtBr)-agar cartwheel assay. Synergism was assessed by the agar well diffusion method and EPI activity by berberine uptake and EtBr efflux inhibition assays. Microdilution method and checkerboard assays were done to determine the minimum inhibitory concentration (MIC) and fractional inhibitory concentration index (FICI) respectively for a bioactive compound. To validate the phytocompound and efflux pump interaction, molecular docking with 6IE8 (RamA) and 6IE9 (RamR) targets was done using autoDock vina software. Toxicity prediction and drug-likeness were predicted by using ProTox-II and Molinspiration respectively. RESULTS Methanolic and ethyl acetate extracts of P. integerrima, O. sanctum, C. asiatica, M. charantia, Z. officinale, and W. somnifera in combination with ciprofloxacin and tetracycline showed synergistic antimicrobial activity with GIIs of 0.61-1.32 and GIIs 0.56-1.35 respectively. Methanolic extract of Z. officinal enhanced the antimicrobial potency of berberine (2 to 4-folds) and increased the EtBr accumulation. Furthermore, bioassay-guided fractionation leads to the identification of lariciresinol in ethyl acetate fraction, which decreased the MIC by 2-to 4-folds. The ΣFIC values varied from 0.30 to 0.55 with tetracycline, that indicated synergistic/additive effects. Lariciresinol also showed a good binding affinity with 6IE8 (-7.4 kcal mol-1) and 6IE9 (-8.2 kcal mol-1), which is comparable to tetracycline and chenodeoxycholic acid. Lariciresinol followed Lipinski's rule of five. CONCLUSION The data suggest that lariciresinol from Z. officinale could be a potential efflux pump inhibitor that could lead to effective killing of drug resistant Salmonella typhimurium at lower MIC. Molecular docking confirmed the antibacterial EPI mechanism of lariciresinol in Salmonella typhimurium and confirmed to be safe for future use.
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Affiliation(s)
- Jyoti Mehta
- Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Bajhol, PO Sultanpur, District Solan, 173229, Himachal Pradesh, India.
| | - Rajan Rolta
- Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Bajhol, PO Sultanpur, District Solan, 173229, Himachal Pradesh, India
| | - Kamal Dev
- Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Bajhol, PO Sultanpur, District Solan, 173229, Himachal Pradesh, India.
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Brown AR, Ettefagh KA, Todd DA, Cole PS, Egan JM, Foil DH, Lacey EP, Cech NB. Bacterial efflux inhibitors are widely distributed in land plants. JOURNAL OF ETHNOPHARMACOLOGY 2021; 267:113533. [PMID: 33137433 DOI: 10.1016/j.jep.2020.113533] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 10/12/2020] [Accepted: 10/28/2020] [Indexed: 06/11/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Secondary metabolites play a critical role in plant defense against disease and are of great importance to ethnomedicine. Bacterial efflux pumps are active transport proteins that bacterial cells use to protect themselves against multiple toxic compounds, including many antimicrobials. Efflux pump inhibitors from plants can block these efflux pumps, increasing the potency of antimicrobial compounds. This study demonstrates that efflux pump inhibition against the Gram-positive bacterial pathogen Staphylococcus aureus is widespread in extracts prepared from individual species throughout the land plant lineage. It therefore suggests a general mechanism by which plants used by indigenous species may be effective as a topical treatment for some bacterial infections. AIM OF THE STUDY The goal of this research was to evaluate the distribution of efflux pump inhibitors in nine plant extracts with an ethnobotanical use suggestive of an antimicrobial function for the presence of efflux pump inhibitory activity against Staphylococcus aureus. MATERIALS AND METHODS Plants were collected, dried, extracted, and vouchers submitted to the Herbarium of the University of North Carolina Chapel Hill (NCU). The extracts were analyzed by quantitative mass spectrometry (UPLC-MS) to determine the presence and concentration of flavonoids with known efflux pump inhibitory activity. A mass spectrometry-based assay was employed to measure efflux pump inhibition for all extracts against Staphylococcus aureus. The assay relies on UPLC-MS measurement of changes in ethidium concentration in the spent culture broth when extracts are incubated with bacteria. RESULTS Eight of these nine plant extracts inhibited toxic compound efflux at concentrations below the MIC (minimum inhibitory concentration) value for the same extract. The most active extracts were those prepared from Osmunda claytoniana L. and Pinus strobes L., which both demonstrated IC50 values for efflux inhibition of 19 ppm. CONCLUSIONS Our findings indicate that efflux pump inhibitors active against Staphylococcus aureus are common in land plants. By extension, this activity is likely to be important in many plant-derived antimicrobial extracts, including those used in traditional medicine, and evaluation of efflux pump inhibition may often be valuable when studying natural product efficacy.
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Affiliation(s)
- Adam R Brown
- Department of Chemistry/Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., Greensboro, NC, 27402, USA.
| | - Keivan A Ettefagh
- Department of Chemistry/Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., Greensboro, NC, 27402, USA.
| | - Daniel A Todd
- Department of Chemistry/Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., Greensboro, NC, 27402, USA.
| | - Patrick S Cole
- Department of Chemistry/Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., Greensboro, NC, 27402, USA.
| | - Joseph M Egan
- Department of Chemistry/Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., Greensboro, NC, 27402, USA.
| | - Daniel H Foil
- Department of Chemistry/Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., Greensboro, NC, 27402, USA.
| | - Elizabeth P Lacey
- Department of Biology, The University of North Carolina Greensboro, 312 Eberhart Building, Greensboro, NC, 27402, USA.
| | - Nadja B Cech
- Department of Chemistry/Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., Greensboro, NC, 27402, USA.
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Genetic changes associated with tigecycline resistance in Staphylococcus aureus in vitro-selected mutants belonging to different lineages. Int J Antimicrob Agents 2021; 57:106304. [PMID: 33588015 DOI: 10.1016/j.ijantimicag.2021.106304] [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: 01/15/2020] [Revised: 07/30/2020] [Accepted: 02/06/2021] [Indexed: 11/22/2022]
Abstract
Tigecycline (TGC) resistance remains rare in Staphylococcus aureus worldwide. In this study, 12 TGC-resistant S. aureus mutants (TRSAm) were obtained displaying an increase in efflux activity. The isolates belonged to seven different genetic lineages, with a predominance of clonal complex 5 (CC5). Diverse genetic changes in mepA and mepR genes were found producing alterations in the amino acid sequences of the corresponding proteins (MepA and MepR, respectively). The most frequent amino acid change in MepA was Glu287Gly. All of the TRSAm exhibited different single nucleotide polymorphisms (SNPs) or insertions/deletions (InDels) in mepR causing premature stop codons or amino acid changes in MepR. Expression of mepA was significantly increased in TRSAm with different mutations in mepA and mepR. Of the 12 TRSAm, 6 also harboured mutations in rpsJ that resulted in amino acid changes in the S10 ribosomal protein, with Lys57 being the most frequently mutated site. Our findings demonstrate that these acquired mechanisms of TGC resistance are not restricted to a single type of genotypic background and that different lineages might have the same plasticity to develop TGC resistance. The impact of TGC selective pressure assessed by whole-genome sequencing in four selected strain pairs revealed mutations in other singular genes and IS256 mobilisation.
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Fang R, Sun Y, Dai W, Zheng X, Tian X, Zhang X, Wang C, Cao J, Zhou T. Mutations in the MepRAB efflux system contribute to the in vitro development of tigecycline resistance in Staphylococcus aureus. J Glob Antimicrob Resist 2020; 22:631-636. [PMID: 32590185 DOI: 10.1016/j.jgar.2020.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 03/24/2020] [Accepted: 06/01/2020] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVE To characterize the evolutionary pathways of tigecycline (TGC) resistance and alterations in the biological characteristics of hospital-derived Staphylococcus aureus isolates under selective pressure. METHODS Three clinical S. aureus strains and one standard S. aureus strain, ATCC 29213, were used for the in vitro selection of TGC-resistant S. aureus variants with gradient concentrations of TGC. Changes in drug resistance and genetic alterations in resistance-related genes (operon mepRAB and rpsJ) in mutant strains were determined. The efflux inhibitor assay for MepA and the fitness cost, determined by comparing the growth and virulence of parental and mutant strains, were also investigated. RESULTS Mutants induced in vitro showed a 64- to 128-fold increase in the minimum inhibitory concentration (MIC) of TGC. Substitution mutations were detected in the transcriptional repressor mepR and the efflux pump gene mepA. A K57M amino acid substitution occurred in the ribosomal S10 protein-encoding gene rpsJ. The MICs of TGC in the final mutants were significantly decreased in the presence of efflux pump inhibitors. It was worth noting that growth was unaffected by TGC resistance selection in vitro, with the exception of one strain, and the MICs of other antibiotics and virulence were also unaffected. CONCLUSIONS The evolution of TGC resistance in S. aureus in vitro is associated with a loss-of-function mutation in the efflux pump transcriptional repressor mepR and a missense mutation in the efflux pump-encoding gene mepA. Our work further validated the resistance mechanisms of S. aureus to TGC and reported previously undiscovered mutations.
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Affiliation(s)
- Renchi Fang
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325035, China
| | - Yao Sun
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325035, China
| | - Weisi Dai
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325035, China
| | - Xiangkuo Zheng
- School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Xuebin Tian
- School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Xiucai Zhang
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325035, China
| | - Chong Wang
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325035, China
| | - Jianming Cao
- School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.
| | - Tieli Zhou
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325035, China.
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Beggs GA, Brennan RG, Arshad M. MarR family proteins are important regulators of clinically relevant antibiotic resistance. Protein Sci 2019; 29:647-653. [PMID: 31682303 DOI: 10.1002/pro.3769] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 12/14/2022]
Abstract
There has been a rapid spread of multidrug-resistant (MDR) bacteria across the world. MDR efflux transporters are an important mechanism of antibiotic resistance in many pathogens among both Gram positive and Gram negative bacteria. These pumps can recognize a variety of chemically and structurally different compounds, including innate and clinically administered antibiotics. Intriguingly, these efflux pumps are often regulated by transcription factors that themselves bind a diverse set of substrates thereby allowing them to regulate the expression of their cognate MDR efflux pumps. One significant family of such transcription factors is the Multiple antibiotic resistance Repressor (MarR) family. Members of this family are well conserved across different bacterial species and in some cases are known to regulate vital bacterial functions. This review focusses on the role of MarR family transcriptional factors in antibiotic resistance within a select group of clinically relevant pathogens.
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Affiliation(s)
- Grace A Beggs
- Department of Biochemistry, Duke University, Durham, North Carolina
| | | | - Mehreen Arshad
- Department of Pediatrics, Ann and Robert H. Lurie Children's Hospital, Northwestern University, Chicago, Illinois
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Mutations at the Ribosomal S10 Gene in Clinical Strains of Staphylococcus aureus with Reduced Susceptibility to Tigecycline. Antimicrob Agents Chemother 2017; 62:AAC.01852-17. [PMID: 29084741 DOI: 10.1128/aac.01852-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 10/18/2017] [Indexed: 01/14/2023] Open
Abstract
Mutations on the tip of the extended loop of the ribosomal S10 protein have been associated to tigecycline (TGC) resistance in passaged mutants of different bacteria species. This study described the first two clinical TGC-resistant Staphylococcus aureus isolates with these mutations. One strain (TGC MIC = 2 mg/liter) had a 12-nucleotide deletion affecting residues 56 to 59 (HKYK) of the S10 protein. The second strain (TGC MIC = 1 mg/liter) had amino acid substitutions (K57M and Y58F) previously described in S. aureus passaged mutants.
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Dabul ANG, Avaca-Crusca JS, Van Tyne D, Gilmore MS, Camargo ILBC. Resistance in In Vitro Selected Tigecycline-Resistant Methicillin-Resistant Staphylococcus aureus Sequence Type 5 Is Driven by Mutations in mepR and mepA Genes. Microb Drug Resist 2017; 24:519-526. [PMID: 29039719 DOI: 10.1089/mdr.2017.0279] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A tigecycline-susceptible (TGC-S) Sequence Type (ST) 5 clinical methicillin-resistant Staphylococcus aureus (MRSA) strain was cultured in escalating levels of tigecycline, yielding mutants eightfold more resistant. Their genomes were sequenced to identify genetic alterations, resulting in resistance. Alterations in rpsJ, commonly related to tigecycline resistance, were also investigated. Tigecycline resistance was mediated by loss-of-function mutations in the transcriptional repressor mepR, resulting in derepression of the efflux pump mepA. Increased levels of resistance were obtained by successive mutations in mepA itself. No alterations in RpsJ were observed in selected strains, but we observed a K57M substitution, previously correlated with resistance, among TGC-S clinical strains. Thus, the pathway to tigecycline resistance in CC5 MRSA in vitro appears to be derepression of mep operon as the result of mepR loss-of-function mutation, followed by alterations in MepA efflux pump. This shows that other evolutionary pathways, besides mutation of rpsJ, are available for evolving tigecycline resistance in CC5 MRSA.
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Affiliation(s)
- Andrei Nicoli Gebieluca Dabul
- 1 Department of Physics and Interdisciplinary Science, São Carlos Institute of Physics, University of São Paulo , São Carlos, Brazil
| | - Juliana Sposto Avaca-Crusca
- 1 Department of Physics and Interdisciplinary Science, São Carlos Institute of Physics, University of São Paulo , São Carlos, Brazil
| | - Daria Van Tyne
- 2 Department of Ophthalmology, Harvard Medical School , Massachusetts Eye and Ear Infirmary, Boston, Massachusetts.,3 Department of Microbiology and Immunobiology, Harvard Medical School , Boston, Massachusetts
| | - Michael S Gilmore
- 2 Department of Ophthalmology, Harvard Medical School , Massachusetts Eye and Ear Infirmary, Boston, Massachusetts.,3 Department of Microbiology and Immunobiology, Harvard Medical School , Boston, Massachusetts
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10
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Lepri S, Buonerba F, Goracci L, Velilla I, Ruzziconi R, Schindler BD, Seo SM, Kaatz GW, Cruciani G. Indole Based Weapons to Fight Antibiotic Resistance: A Structure-Activity Relationship Study. J Med Chem 2016; 59:867-91. [PMID: 26757340 DOI: 10.1021/acs.jmedchem.5b01219] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Antibiotic resistance represents a worldwide concern, especially regarding the outbreak of methicillin-resistant Staphylococcus aureus, a common cause for serious skin and soft tissues infections. A major contributor to Staphylococcus aureus antibiotic resistance is the NorA efflux pump, which is able to extrude selected antibacterial drugs and biocides from the membrane, lowering their effective concentrations. Thus, the inhibition of NorA represents a promising and challenging strategy that would allow recycling of substrate antimicrobial agents. Among NorA inhibitors, the indole scaffold proved particularly effective and suitable for further optimization. In this study, some unexplored modifications on the indole scaffold are proposed. In particular, for the first time, substitutions at the C5 and N1 positions have been designed to give 48 compounds, which were synthesized and tested against norA-overexpressing S. aureus. Among them, 4 compounds have NorA IC50 values lower than 5.0 μM proving to be good efflux pump inhibitor (EPI) candidates. In addition, preliminary data on their ADME (absorption, distribution, metabolism, and excretion) profile is reported.
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Affiliation(s)
- Susan Lepri
- Department of Chemistry, Biology and Biotechnology, University of Perugia , 06123 Perugia, Italy
| | - Federica Buonerba
- Department of Chemistry, Biology and Biotechnology, University of Perugia , 06123 Perugia, Italy
| | - Laura Goracci
- Department of Chemistry, Biology and Biotechnology, University of Perugia , 06123 Perugia, Italy
| | - Irene Velilla
- Department of Chemistry, Biology and Biotechnology, University of Perugia , 06123 Perugia, Italy
| | - Renzo Ruzziconi
- Department of Chemistry, Biology and Biotechnology, University of Perugia , 06123 Perugia, Italy
| | - Bryan D Schindler
- The John D. Dingell Department of Veterans Affairs Medical Center , Detroit, Michigan 48201, United States
| | - Susan M Seo
- The John D. Dingell Department of Veterans Affairs Medical Center , Detroit, Michigan 48201, United States
| | - Glenn W Kaatz
- The John D. Dingell Department of Veterans Affairs Medical Center , Detroit, Michigan 48201, United States.,Department of Internal Medicine, Division of Infectious Diseases, Wayne State University School of Medicine , Detroit, Michigan 48201, United States
| | - Gabriele Cruciani
- Department of Chemistry, Biology and Biotechnology, University of Perugia , 06123 Perugia, Italy
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Cho MU, Kim MI, Hong M. Purification, crystallization and X-ray crystallographic studies of a Bacillus cereus MepR-like transcription factor, BC0657. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2015; 71:731-4. [PMID: 26057803 DOI: 10.1107/s2053230x15007074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 04/08/2015] [Indexed: 01/23/2023]
Abstract
Transcription factors of the MarR family respond to internal and external changes and regulate a variety of biological functions through ligand association with microorganisms. MepR belongs to the MarR family, and its mutations are associated with the development of multidrug resistance in Staphylococcus aureus, which has caused a growing health problem. In this study, a Bacillus cereus MepR-like transcription regulator, BC0657, was crystallized. The BC0657 crystals diffracted to 2.05 Å resolution and belonged to either space group P6(2)22 or P6(4)22, with unit-cell parameters a = 110.57, b = 110.57, c = 67.29 Å. There was one molecule per asymmetric unit. Future comparative structural studies on BC0657 would extend knowledge of ligand-induced transcriptional regulatory mechanisms in the MarR family and would make a significant contribution to the design of antibiotic drugs against multidrug-resistant bacteria.
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Affiliation(s)
- Min Uk Cho
- Division of Biological Science and Technology, Yonsei University, 1 Yonseidae-gil, Wonju-si, Ganwon-do 220-710, Republic of Korea
| | - Meong Il Kim
- Division of Biological Science and Technology, Yonsei University, 1 Yonseidae-gil, Wonju-si, Ganwon-do 220-710, Republic of Korea
| | - Minsun Hong
- Division of Biological Science and Technology, Yonsei University, 1 Yonseidae-gil, Wonju-si, Ganwon-do 220-710, Republic of Korea
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12
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A mass spectrometry-based assay for improved quantitative measurements of efflux pump inhibition. PLoS One 2015; 10:e0124814. [PMID: 25961825 PMCID: PMC4427306 DOI: 10.1371/journal.pone.0124814] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/17/2015] [Indexed: 01/17/2023] Open
Abstract
Bacterial efflux pumps are active transport proteins responsible for resistance to selected biocides and antibiotics. It has been shown that production of efflux pumps is up-regulated in a number of highly pathogenic bacteria, including methicillin resistant Staphylococcus aureus. Thus, the identification of new bacterial efflux pump inhibitors is a topic of great interest. Existing assays to evaluate efflux pump inhibitory activity rely on fluorescence by an efflux pump substrate. When employing these assays to evaluate efflux pump inhibitory activity of plant extracts and some purified compounds, we observed severe optical interference that gave rise to false negative results. To circumvent this problem, a new mass spectrometry-based method was developed for the quantitative measurement of bacterial efflux pump inhibition. The assay was employed to evaluate efflux pump inhibitory activity of a crude extract of the botanical Hydrastis Canadensis, and to compare the efflux pump inhibitory activity of several pure flavonoids. The flavonoid quercetin, which appeared to be completely inactive with a fluorescence-based method, showed an IC50 value of 75 μg/mL with the new method. The other flavonoids evaluated (apigenin, kaempferol, rhamnetin, luteolin, myricetin), were also active, with IC50 values ranging from 19 μg/mL to 75 μg/mL. The assay described herein could be useful in future screening efforts to identify efflux pump inhibitors, particularly in situations where optical interference precludes the application of methods that rely on fluorescence.
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13
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Structure analysis of Bacillus cereus MepR-like transcription regulator, BC0657, in complex with pseudo-ligand molecules. Biochem Biophys Res Commun 2015; 458:644-649. [DOI: 10.1016/j.bbrc.2015.02.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 02/04/2015] [Indexed: 11/22/2022]
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14
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Schindler BD, Jacinto PL, Buensalido JAL, Seo SM, Kaatz GW. Clonal relatedness is a predictor of spontaneous multidrug efflux pump gene overexpression in Staphylococcus aureus. Int J Antimicrob Agents 2014; 45:464-70. [PMID: 25548027 DOI: 10.1016/j.ijantimicag.2014.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 09/22/2014] [Accepted: 11/07/2014] [Indexed: 10/24/2022]
Abstract
Increased expression of genes encoding multidrug resistance efflux pumps (MDR-EPs) contributes to antimicrobial agent and biocide resistance in Staphylococcus aureus. Previously identified associations between norA overexpression and spa type t002 meticillin-resistant S. aureus (MRSA), and a similar yet weaker association between mepA overexpression and type t008 meticillin-susceptible S. aureus (MSSA), in clinical isolates are suggestive of clonal dissemination. It is also possible that related strains are prone to mutations resulting in overexpression of specific MDR-EP genes. Exposure of non-MDR-EP-overexpressing clinical isolates to biocides and dyes can select for MDR-EP-overexpressing mutants. spa types t002 and t008 isolates are predominated by multilocus sequencing typing sequence types (STs) 5 and 8, respectively. In this study, non-MDR-EP gene-overexpressing clinical isolates (MRSA and MSSA) representing ST5 and ST8 were subjected to single exposures of ethidium bromide (EtBr) to select for EtBr-resistant mutants. Measurements of active EtBr transport among mutants were used to demonstrate an efflux-proficient phenotype. Using quantitative reverse-transcription PCR, it was found that EtBr-resistant mutants of ST5 and ST8 parental strains predominantly overexpressed mepA (100%) and mdeA (83%), respectively, regardless of meticillin sensitivity. Associations between clonal lineage and MDR-EP gene overexpression differed from those previously observed and suggest the latter is due to clonal spread of efflux-proficient strains. The predilection of in vitro-selected mutants of related strains to overexpress the same MDR-EP gene indicates the presence of a consistent mutational process.
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Affiliation(s)
- Bryan D Schindler
- The John D. Dingell Department of Veterans Affairs Medical Center, Detroit, MI 48201, USA
| | - Pauline L Jacinto
- Department of Internal Medicine, Division of Infectious Diseases, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Joseph Adrian L Buensalido
- Department of Internal Medicine, Division of Infectious Diseases, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Susan M Seo
- The John D. Dingell Department of Veterans Affairs Medical Center, Detroit, MI 48201, USA
| | - Glenn W Kaatz
- The John D. Dingell Department of Veterans Affairs Medical Center, Detroit, MI 48201, USA; Department of Internal Medicine, Division of Infectious Diseases, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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15
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Abstract
Antibiotic-resistant bacteria that are difficult or impossible to treat are becoming increasingly common and are causing a global health crisis. Antibiotic resistance is encoded by several genes, many of which can transfer between bacteria. New resistance mechanisms are constantly being described, and new genes and vectors of transmission are identified on a regular basis. This article reviews recent advances in our understanding of the mechanisms by which bacteria are either intrinsically resistant or acquire resistance to antibiotics, including the prevention of access to drug targets, changes in the structure and protection of antibiotic targets and the direct modification or inactivation of antibiotics.
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16
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Birukou I, Seo SM, Schindler BD, Kaatz GW, Brennan RG. Structural mechanism of transcription regulation of the Staphylococcus aureus multidrug efflux operon mepRA by the MarR family repressor MepR. Nucleic Acids Res 2013; 42:2774-88. [PMID: 24293644 PMCID: PMC3936728 DOI: 10.1093/nar/gkt1215] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The multidrug efflux pump MepA is a major contributor to multidrug resistance in Staphylococcus aureus. MepR, a member of the multiple antibiotic resistance regulator (MarR) family, represses mepA and its own gene. Here, we report the structure of a MepR–mepR operator complex. Structural comparison of DNA-bound MepR with ‘induced’ apoMepR reveals the large conformational changes needed to allow the DNA-binding winged helix-turn-helix motifs to interact with the consecutive major and minor grooves of the GTTAG signature sequence. Intriguingly, MepR makes no hydrogen bonds to major groove nucleobases. Rather, recognition-helix residues Thr60, Gly61, Pro62 and Thr63 make sequence-specifying van der Waals contacts with the TTAG bases. Removing these contacts dramatically affects MepR–DNA binding activity. The wings insert into the flanking minor grooves, whereby residue Arg87, buttressed by Asp85, interacts with the O2 of T4 and O4′ ribosyl oxygens of A23 and T4. Mutating Asp85 and Arg87, both conserved throughout the MarR family, markedly affects MepR repressor activity. The His14′:Arg59 and Arg10′:His35:Phe108 interaction networks stabilize the DNA-binding conformation of MepR thereby contributing significantly to its high affinity binding. A structure-guided model of the MepR–mepA operator complex suggests that MepR dimers do not interact directly and cooperative binding is likely achieved by DNA-mediated allosteric effects.
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Affiliation(s)
- Ivan Birukou
- Department of Biochemistry, Duke University School of Medicine, 307 Research Drive, Durham, NC 27710, USA, The John D. Dingell Department of Veterans Affairs Medical Center, B4333 JD Dingel VA Medical Center, 4646 John R, Detroit, MI 48201, USA and Department of Internal Medicine, Division of Infectious Diseases, Wayne State University School of Medicine, 5 Hudson, Harper University Hospital, 3990 John R, Detroit, MI 48201, USA
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The molecular mechanisms of allosteric mutations impairing MepR repressor function in multidrug-resistant strains of Staphylococcus aureus. mBio 2013; 4:e00528-13. [PMID: 23982071 PMCID: PMC3760248 DOI: 10.1128/mbio.00528-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Overexpression of the Staphylococcus aureus multidrug efflux pump MepA confers resistance to a wide variety of antimicrobials. mepA expression is controlled by MarR family member MepR, which represses mepA and autorepresses its own production. Mutations in mepR are a primary cause of mepA overexpression in clinical isolates of multidrug-resistant S. aureus. Here, we report crystal structures of three multidrug-resistant MepR variants, which contain the single-amino-acid substitution A103V, F27L, or Q18P, and wild-type MepR in its DNA-bound conformation. Although each mutation impairs MepR function by decreasing its DNA binding affinity, none is located in the DNA binding domain. Rather, all are found in the linker region connecting the dimerization and DNA binding domains. Specifically, the A103V substitution impinges on F27, which resolves potential steric clashes via displacement of the DNA binding winged-helix-turn-helix motifs that lead to a 27-fold reduction in DNA binding affinity. The F27L substitution forces F104 into an alternative rotamer, which kinks helix 5, thereby interfering with the positioning of the DNA binding domains and decreasing mepR operator affinity by 35-fold. The Q18P mutation affects the MepR structure and function most significantly by either creating kinks in the middle of helix 1 or completely unfolding its C terminus. In addition, helix 5 of Q18P is either bent or completely dissected into two smaller helices. Consequently, DNA binding is diminished by 2,000-fold. Our structural studies reveal heretofore-unobserved allosteric mechanisms that affect repressor function of a MarR family member and result in multidrug-resistant Staphylococcus aureus. Staphylococcus aureus is a major health threat to immunocompromised patients. S. aureus multidrug-resistant variants that overexpress the multidrug efflux pump mepA emerge frequently due to point mutations in MarR family member MepR, the mepA transcription repressor. Significantly, the majority of MepR mutations identified in these S. aureus clinical isolates are found not in the DNA binding domain but rather in a linker region, connecting the dimerization and DNA binding domains. The location of these mutants underscores the critical importance of a properly functioning allosteric mechanism that regulates MepR function. Understanding the dysregulation of such allosteric MepR mutants underlies this study. The high-resolution structures of three such allosteric MepR mutants reveal unpredictable conformational consequences, all of which preclude cognate DNA binding, while biochemical studies emphasize their debilitating effects on DNA binding affinity. Hence, mutations in the linker region of MepR and their structural consequences are key generators of multidrug-resistant Staphylococcus aureus.
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