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Nicoloff H, Hjort K, Andersson DI, Wang H. Three concurrent mechanisms generate gene copy number variation and transient antibiotic heteroresistance. Nat Commun 2024; 15:3981. [PMID: 38730266 PMCID: PMC11087502 DOI: 10.1038/s41467-024-48233-0] [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: 03/06/2024] [Accepted: 04/23/2024] [Indexed: 05/12/2024] Open
Abstract
Heteroresistance is a medically relevant phenotype where small antibiotic-resistant subpopulations coexist within predominantly susceptible bacterial populations. Heteroresistance reduces treatment efficacy across diverse bacterial species and antibiotic classes, yet its genetic and physiological mechanisms remain poorly understood. Here, we investigated a multi-resistant Klebsiella pneumoniae isolate and identified three primary drivers of gene dosage-dependent heteroresistance for several antibiotic classes: tandem amplification, increased plasmid copy number, and transposition of resistance genes onto cryptic plasmids. All three mechanisms imposed fitness costs and were genetically unstable, leading to fast reversion to susceptibility in the absence of antibiotics. We used a mouse gut colonization model to show that heteroresistance due to elevated resistance-gene dosage can result in antibiotic treatment failures. Importantly, we observed that the three mechanisms are prevalent among Escherichia coli bloodstream isolates. Our findings underscore the necessity for treatment strategies that address the complex interplay between plasmids, resistance cassettes, and transposons in bacterial populations.
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Affiliation(s)
- Hervé Nicoloff
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Karin Hjort
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Dan I Andersson
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Helen Wang
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
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Lin Q, Jiang Z, Zhong B, Chen JQ, Lv ZB, Nie ZM. Unveiling the impact of cryptic plasmids curing on Escherichia coli Nissle 1917: massive increase in Ag43c expression. AMB Express 2024; 14:48. [PMID: 38678482 PMCID: PMC11056357 DOI: 10.1186/s13568-024-01681-9] [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: 02/07/2024] [Accepted: 02/16/2024] [Indexed: 05/01/2024] Open
Abstract
Escherichia coli Nissle 1917 (EcN) is an important chassis strain widely used for the development of live biotherapeutic products (LBPs). EcN strain naturally harbors two cryptic plasmids with unknown function. During the development of LBPs using EcN strain, the cryptic plasmids were cured usually to avoid plasmid incompatibility or alleviate metabolic burdens associated with these cryptic plasmids. While the cryptic plasmids curing in EcN may appear to be a routine procedure, the comprehensive impact of cryptic plasmids curing on the EcN strain remains incompletely understood. In the present study, the effects of cryptic plasmids curing on EcN were investigated using transcriptome sequencing. The results revealed that only a small number of genes showed significant changes in mRNA levels after cryptic plasmid curing (4 upregulated and 6 downregulated genes), primarily involved in amino acid metabolism. Furthermore, the flu gene showed the most significant different expression, encoding Antigen 43 (Ag43) protein, a Cah family adhesin. Mass spectrometry analysis further confirmed the significant increase in Ag43 expression. Ag43 is commonly present in Escherichia coli and mediates the bacterial autoaggregation. However, despite the upregulation of Ag43 expression, no Ag43-mediated cell self-sedimentation was observed in the cured EcN strain. These findings contribute to making informed decisions regarding the curing of the cryptic plasmids when Escherichia coli Nissle 1917 is used as the chassis strain.
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Affiliation(s)
- Qi Lin
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
- Center for Bioreactor and Protein Drug Research, Shaoxing Biomedical Research Institute of Zhejiang Sci-Tech University Co., Ltd, Shaoxing, 312075, China
| | - Zhuo Jiang
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Bo Zhong
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Jian-Qing Chen
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
- Center for Bioreactor and Protein Drug Research, Shaoxing Biomedical Research Institute of Zhejiang Sci-Tech University Co., Ltd, Shaoxing, 312075, China
| | - Zheng-Bing Lv
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
- Center for Bioreactor and Protein Drug Research, Shaoxing Biomedical Research Institute of Zhejiang Sci-Tech University Co., Ltd, Shaoxing, 312075, China
| | - Zuo-Ming Nie
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
- Center for Bioreactor and Protein Drug Research, Shaoxing Biomedical Research Institute of Zhejiang Sci-Tech University Co., Ltd, Shaoxing, 312075, China.
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Zheludev IN, Edgar RC, Lopez-Galiano MJ, de la Peña M, Babaian A, Bhatt AS, Fire AZ. Viroid-like colonists of human microbiomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.20.576352. [PMID: 38293115 PMCID: PMC10827157 DOI: 10.1101/2024.01.20.576352] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Here, we describe the "Obelisks," a previously unrecognised class of viroid-like elements that we first identified in human gut metatranscriptomic data. "Obelisks" share several properties: (i) apparently circular RNA ~1kb genome assemblies, (ii) predicted rod-like secondary structures encompassing the entire genome, and (iii) open reading frames coding for a novel protein superfamily, which we call the "Oblins". We find that Obelisks form their own distinct phylogenetic group with no detectable sequence or structural similarity to known biological agents. Further, Obelisks are prevalent in tested human microbiome metatranscriptomes with representatives detected in ~7% of analysed stool metatranscriptomes (29/440) and in ~50% of analysed oral metatranscriptomes (17/32). Obelisk compositions appear to differ between the anatomic sites and are capable of persisting in individuals, with continued presence over >300 days observed in one case. Large scale searches identified 29,959 Obelisks (clustered at 90% nucleotide identity), with examples from all seven continents and in diverse ecological niches. From this search, a subset of Obelisks are identified to code for Obelisk-specific variants of the hammerhead type-III self-cleaving ribozyme. Lastly, we identified one case of a bacterial species (Streptococcus sanguinis) in which a subset of defined laboratory strains harboured a specific Obelisk RNA population. As such, Obelisks comprise a class of diverse RNAs that have colonised, and gone unnoticed in, human, and global microbiomes.
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Affiliation(s)
- Ivan N Zheludev
- Stanford University, Department of Biochemistry, Stanford, CA, USA
| | | | - Maria Jose Lopez-Galiano
- Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-CSIC, Valencia, Spain
| | - Marcos de la Peña
- Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-CSIC, Valencia, Spain
| | - Artem Babaian
- University of Toronto, Department of Molecular Genetics, Ontario, Canada
- University of Toronto, Donnelly Centre for Cellular and Biomolecular Research, Ontario, Canada
| | - Ami S Bhatt
- Stanford University, Department of Genetics, Stanford, CA, USA
- Stanford University, Department of Medicine, Division of Hematology, Stanford, CA, USA
| | - Andrew Z Fire
- Stanford University, Department of Genetics, Stanford, CA, USA
- Stanford University, Department of Pathology, Stanford, CA, USA
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