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Jiang S, Li Y, Bi K, Yang S, Xia H, Li S, Chen H, Li L. Characterization of a novel multi-resistant Pseudomonas juntendi strain from China with chromosomal bla VIM-2 and a megaplasmid coharboring bla IMP-1-like and bla OXA-1. BMC Genomics 2024; 25:774. [PMID: 39118048 PMCID: PMC11311922 DOI: 10.1186/s12864-024-10688-2] [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: 03/28/2024] [Accepted: 08/05/2024] [Indexed: 08/10/2024] Open
Abstract
BACKGROUND Pseudomonas juntendi is a newly identified opportunistic pathogen, of which we have limited understanding. P. juntendi strains are often multidrug resistant, which complicates clinical management of infection. METHODS A strain of Pseudomonas juntendi (strain L4326) isolated from feces was characterized by MALDI-TOF-MS and Average Nucleotide Identity BLAST. This strain was further subject to whole-genome sequencing and Maximum Likelihood phylogenetic analysis. The strain was phenotypically characterized by antimicrobial susceptibility testing and conjugation assays. RESULTS We have isolated the novel P. juntendi strain L4236, which was multidrug resistant, but retained sensitivity to amikacin. L4236 harbored a megaplasmid that encoded blaOXA-1 and a novel blaIMP-1 resistance gene variant. P. juntendi strain L4236 was phylogenetically related to P. juntendi strain SAMN30525517. CONCLUSION A rare P. juntendi strain was isolated from human feces in southern China with a megaplasmid coharboring blaIMP-1-like and blaOXA-1. Antimicrobial selection pressures may have driven acquisition of drug-resistance gene mutations and carriage of the megaplasmid.
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Affiliation(s)
- Shiman Jiang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, National Medical Center for Infectious Diseases, Zhejiang University School of Medicine, 79 Qingchun Rd, Hangzhou City, 310003, China
| | - Yaling Li
- Department Health Management Center, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Kefan Bi
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, National Medical Center for Infectious Diseases, Zhejiang University School of Medicine, 79 Qingchun Rd, Hangzhou City, 310003, China
| | - Sisi Yang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, National Medical Center for Infectious Diseases, Zhejiang University School of Medicine, 79 Qingchun Rd, Hangzhou City, 310003, China
| | - He Xia
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, National Medical Center for Infectious Diseases, Zhejiang University School of Medicine, 79 Qingchun Rd, Hangzhou City, 310003, China
| | - Shengjie Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, National Medical Center for Infectious Diseases, Zhejiang University School of Medicine, 79 Qingchun Rd, Hangzhou City, 310003, China
| | - Hui Chen
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, National Medical Center for Infectious Diseases, Zhejiang University School of Medicine, 79 Qingchun Rd, Hangzhou City, 310003, China
| | - Lanjuan Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, National Medical Center for Infectious Diseases, Zhejiang University School of Medicine, 79 Qingchun Rd, Hangzhou City, 310003, China.
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Caro-Astorga J, Meyerowitz JT, Stork DA, Nattermann U, Piszkiewicz S, Vimercati L, Schwendner P, Hocher A, Cockell C, DeBenedictis E. Polyextremophile engineering: a review of organisms that push the limits of life. Front Microbiol 2024; 15:1341701. [PMID: 38903795 PMCID: PMC11188471 DOI: 10.3389/fmicb.2024.1341701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 05/16/2024] [Indexed: 06/22/2024] Open
Abstract
Nature exhibits an enormous diversity of organisms that thrive in extreme environments. From snow algae that reproduce at sub-zero temperatures to radiotrophic fungi that thrive in nuclear radiation at Chernobyl, extreme organisms raise many questions about the limits of life. Is there any environment where life could not "find a way"? Although many individual extremophilic organisms have been identified and studied, there remain outstanding questions about the limits of life and the extent to which extreme properties can be enhanced, combined or transferred to new organisms. In this review, we compile the current knowledge on the bioengineering of extremophile microbes. We summarize what is known about the basic mechanisms of extreme adaptations, compile synthetic biology's efforts to engineer extremophile organisms beyond what is found in nature, and highlight which adaptations can be combined. The basic science of extremophiles can be applied to engineered organisms tailored to specific biomanufacturing needs, such as growth in high temperatures or in the presence of unusual solvents.
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Affiliation(s)
| | | | - Devon A. Stork
- Pioneer Research Laboratories, San Francisco, CA, United States
| | - Una Nattermann
- Pioneer Research Laboratories, San Francisco, CA, United States
| | | | - Lara Vimercati
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, United States
| | | | - Antoine Hocher
- London Institute of Medical Sciences, London, United Kingdom
| | - Charles Cockell
- UK Centre for Astrobiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Erika DeBenedictis
- The Francis Crick Institute, London, United Kingdom
- Pioneer Research Laboratories, San Francisco, CA, United States
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He W, Gao M, Lv L, Wang J, Cai Z, Bai Y, Gao X, Gao G, Pu W, Jiao Y, Wan M, Song Q, Chen S, Liu JH. Persistence and molecular epidemiology of bla NDM-positive Gram-negative bacteria in three broiler farms: A longitudinal study (2015-2021). JOURNAL OF HAZARDOUS MATERIALS 2023; 446:130725. [PMID: 36630875 DOI: 10.1016/j.jhazmat.2023.130725] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 11/15/2022] [Accepted: 01/03/2023] [Indexed: 06/17/2023]
Abstract
Although carbapenems have not been approved for animal use, blaNDM-positive bacteria (NPB) are increasingly being detected in farm animals. It is important to investigate the routes and underlying mechanisms of evolution and transmission of animal-borne NPB. In this study, NPB recovered from chicken feces and environmental samples in three adjacent broiler farms were investigated. We found that 13.0% of Escherichia coli strains recovered from chicken feces during the period 2015-2016 carried the blaNDM gene. In 2017-2021, however, as many as 55.8% chicken and environmental samples collected during the breeding period were found to harbor NPB. Importantly, such strains were detectable in samples from farmland (10.3%, 8/78), vegetable fields (7.3%, 3/41), and environment of chicken farms (25.6%, 41/160) which had been left vacant for a long period of time. Intriguingly, different sequence types of NPB became dominant in different years. Both clonal dissemination of NPB and horizontal transmission of blaNDM-bearing plasmids were observed among different farms and among the environment niches inside and outside the farm houses. Worryingly, transmission of NPB and blaNDM-bearing plasmids between these farms and other places was also observed. All in all, our results suggested the persistence of NPB in chickens and farm environments, presumably due to extensive contamination by exogenous materials and transmission of NPB within the farm system. These events were aggravated by the increase in antibiotic usage and poor sanitary conditions in the farm houses. Stringent control measures should be implemented to arrest transmission of animal-borne NPB to the environment and the community.
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Affiliation(s)
- Wanyun He
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Mingyi Gao
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Luchao Lv
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Jing Wang
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, China
| | - Zhongpeng Cai
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Yuman Bai
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Xun Gao
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Guolong Gao
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Wenxian Pu
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Yanxiang Jiao
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Miao Wan
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Qianhua Song
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China
| | - Sheng Chen
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong, SAR China.
| | - Jian-Hua Liu
- College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, South China Agricultural University, Guangzhou, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China.
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Endo YT, Aoki K, Hamada M, Kamura HN, Ishii Y, Tateda K. Full-length whole-genome sequencing analysis of emerged meropenem-resistant mutants during long-term in vitro exposure to meropenem for borderline meropenem-susceptible carbapenemase-producing and non-carbapenemase-producing Enterobacterales. J Antimicrob Chemother 2022; 78:209-215. [PMID: 36374518 DOI: 10.1093/jac/dkac376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 10/18/2022] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES Molecular analysis of meropenem-resistant mechanisms in mutants emerging from long-term in vitro meropenem exposure to borderline meropenem-susceptible carbapenemase-producing Enterobacterales (CPE) and non-CPE. METHODS Escherichia coli TUM13867 harbouring both blaIMP-6- and blaCTX-M-2-carrying IncN plasmid and Citrobacter koseri TUM13189 with blaCTX-M-2-carrying chromosome were used. Meropenem MIC was 1 mg/L against both strains. Each strain was cultured in the hollow-fibre infection model (HFIM) to approximately 1 × 106 colony formation unit (cfu)/mL, and meropenem 1 g q8h treatment was initiated. Then, changes in total and meropenem-resistant populations were observed for 124 h. Meropenem resistance mechanisms were analysed using full-length whole-genome sequencing (WGS), reverse-transcription quantitative PCR and digital PCR. RESULTS Meropenem reduced TUM13867 and TUM13189 to approximately 5 and 2 log10 cfu/mL, respectively, at 2 h after initiation, but regrowth was observed at 24 h. The meropenem-resistant mutant emergence frequency at 120 and 124 h was 4.4 × 10-4 for TUM13867 and 7.6 × 10-1 for TUM13189. Meropenem MIC of the mutants derived from TUM13867 (TUM20902) and TUM13189 (TUM20903) increased 4- and 16-fold, respectively. TUM20902, which harboured pMTY20902_IncN plasmid with a 27 505-bp deletion that included blaCTX-M-2, and blaIMP-6 showed 4.21-fold higher levels of transcription than the parental strain. TUM20903 had a 49 316-bp deletion that included ompC and a replicative increase of blaCTX-M-2 to three copies. CONCLUSIONS Molecular analysis including full-length WGS revealed that the resistance mechanisms of meropenem-resistant mutants that emerged during long-term in vitro meropenem exposure were increased blaIMP-6 transcripts in CPE and increased blaCTX-M-2 transcripts due to gene triplication and OmpC loss resulting from ompC deletion in non-CPE.
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Affiliation(s)
- Yuko Tsutsumi Endo
- Department of Microbiology and Infectious Diseases, Toho University Graduate School of Medicine, Tokyo, Japan.,Infection, Vaccine Medical Group, Medical Affairs Department, Meiji Seika Pharma Co., Ltd, Tokyo, Japan
| | - Kotaro Aoki
- Department of Microbiology and Infectious Diseases, Toho University School of Medicine, Tokyo, Japan
| | - Masakaze Hamada
- Department of Microbiology and Infectious Diseases, Toho University School of Medicine, Tokyo, Japan
| | - Haruka Nakagawa Kamura
- Department of Microbiology and Infectious Diseases, Toho University School of Medicine, Tokyo, Japan
| | - Yoshikazu Ishii
- Department of Microbiology and Infectious Diseases, Toho University Graduate School of Medicine, Tokyo, Japan.,Department of Microbiology and Infectious Diseases, Toho University School of Medicine, Tokyo, Japan
| | - Kazuhiro Tateda
- Department of Microbiology and Infectious Diseases, Toho University Graduate School of Medicine, Tokyo, Japan.,Department of Microbiology and Infectious Diseases, Toho University School of Medicine, Tokyo, Japan
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Byrne RL, Cocker D, Alyayyoussi G, Mphasa M, Charles M, Mandula T, Williams CT, Rigby J, Hearn J, Feasey N, Adams ER, Edwards T. A novel, magnetic bead-based extraction method for the isolation of antimicrobial resistance genes with a case study in river water in Malawi. J Appl Microbiol 2022; 133:3191-3200. [PMID: 35946113 PMCID: PMC9804433 DOI: 10.1111/jam.15755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/13/2022] [Accepted: 07/31/2022] [Indexed: 01/07/2023]
Abstract
AIMS The environment is increasingly recognized as an important reservoir of antimicrobial resistance genes (ARGs), which can be identified using molecular platforms. Yet, environmental surveillance remains an underutilised tool as there is no agreement on the best strategy for sample processing. We aim to develop a low-cost extraction method independent to commercial kits or reagents. METHODS AND RESULTS We present a novel, magnetic bead-based method for the isolation of ARGs from river water named MagnaExtract. We present this with analytic limit of detection as well as a case study in Southern Malawi. Here we compare the DNA yield from MagnaExtract with commercially available QIAGEN kits and the crude boil and spin method, using a high-resolution melt analysis PCR panel designed for the detection of third-generation cephalosporin and carbapenem-resistant genes from 98 water samples. CONCLUSION The MagnaExtract method is comparable, and in some instance's superior to commercially available kits for the isolation of ARGs from river water samples. SIGNIFICANCE AND IMPACT OF THE STUDY The MagnaExtract approach offers a simple, affordable, high yielding extraction method that could be used for the detection of ARGs from river water samples in surveillance campaigns in East Africa.
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Affiliation(s)
- Rachel L. Byrne
- Centre for Drugs and DiagnosticsLiverpool School of Tropical MedicineLiverpoolUK
| | - Derek Cocker
- Malawi Liverpool Wellcome TrustBlantyreMalawi,Clinical SciencesLiverpool School of Tropical MedicineLiverpoolUK
| | - Ghaith Alyayyoussi
- Centre for Drugs and DiagnosticsLiverpool School of Tropical MedicineLiverpoolUK
| | | | | | | | | | - Jonathan Rigby
- Malawi Liverpool Wellcome TrustBlantyreMalawi,Clinical SciencesLiverpool School of Tropical MedicineLiverpoolUK
| | - Jack Hearn
- Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - Nicholas Feasey
- Malawi Liverpool Wellcome TrustBlantyreMalawi,Clinical SciencesLiverpool School of Tropical MedicineLiverpoolUK
| | - Emily R. Adams
- Centre for Drugs and DiagnosticsLiverpool School of Tropical MedicineLiverpoolUK
| | - Thomas Edwards
- Centre for Drugs and DiagnosticsLiverpool School of Tropical MedicineLiverpoolUK
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López C, Delmonti J, Bonomo RA, Vila AJ. Deciphering the evolution of metallo-β-lactamases: a journey from the test tube to the bacterial periplasm. J Biol Chem 2022; 298:101665. [PMID: 35120928 DOI: 10.1016/j.jbc.2022.101665] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 01/13/2022] [Accepted: 01/16/2022] [Indexed: 12/20/2022] Open
Abstract
Understanding the evolution of metallo-β-lactamases (MBLs) is fundamental to deciphering the mechanistic basis of resistance to carbapenems in pathogenic and opportunistic bacteria. Presently, these MBL producing pathogens are linked to high rates of morbidity and mortality worldwide. However, the study of the biochemical and biophysical features of MBLs in vitro provides an incomplete picture of their evolutionary potential, since this limited and artificial environment disregards the physiological context where evolution and selection take place. Herein, we describe recent efforts aimed to address the evolutionary traits acquired by different clinical variants of MBLs in conditions mimicking their native environment (the bacterial periplasm) and considering whether they are soluble or membrane-bound proteins. This includes addressing the metal content of MBLs within the cell under zinc starvation conditions, and the context provided by different bacterial hosts that result in particular resistance phenotypes. Our analysis highlights recent progress bridging the gap between in vitro and in-cell studies.
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Affiliation(s)
- Carolina López
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), S2000EXF Rosario, Argentina
| | - Juliana Delmonti
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), S2000EXF Rosario, Argentina
| | - Robert A Bonomo
- Research Service, Veterans Affairs Northeast Ohio Healthcare System, Cleveland, Ohio, USA; Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, and Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA; Medical Service and GRECC, Veterans Affairs Northeast Ohio Healthcare System, Cleveland, Ohio, USA; CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, Ohio, USA
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), S2000EXF Rosario, Argentina; CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, Ohio, USA; Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, S2002LRK Rosario, Argentina.
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The Carbapenemase BKC-1 from Klebsiella pneumoniae Is Adapted for Translocation by Both the Tat and Sec Translocons. mBio 2021; 12:e0130221. [PMID: 34154411 PMCID: PMC8262980 DOI: 10.1128/mbio.01302-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The cell envelope of Gram-negative bacteria consists of two membranes surrounding the periplasm and peptidoglycan layer. β-Lactam antibiotics target the periplasmic penicillin-binding proteins that synthesize peptidoglycan, resulting in cell death. The primary means by which bacterial species resist the effects of β-lactam drugs is to populate the periplasmic space with β-lactamases. Resistance to β-lactam drugs is spread by lateral transfer of genes encoding β-lactamases from one species of bacteria to another. However, the resistance phenotype depends in turn on these “alien” protein sequences being recognized and exported across the cytoplasmic membrane by either the Sec or Tat protein translocation machinery of the new bacterial host. Here, we examine BKC-1, a carbapenemase from an unknown bacterial source that has been identified in a single clinical isolate of Klebsiella pneumoniae. BKC-1 was shown to be located in the periplasm, and functional in both K. pneumoniae and Escherichia coli. Sequence analysis revealed the presence of an unusual signal peptide with a twin arginine motif and a duplicated hydrophobic region. Biochemical assays showed this signal peptide directs BKC-1 for translocation by both Sec and Tat translocons. This is one of the few descriptions of a periplasmic protein that is functionally translocated by both export pathways in the same organism, and we suggest it represents a snapshot of evolution for a β-lactamase adapting to functionality in a new host.
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