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Alvarado Obando M, Rey-Varela D, Cava F, Dörr T. Genetic interaction mapping reveals functional relationships between peptidoglycan endopeptidases and carboxypeptidases. PLoS Genet 2024; 20:e1011234. [PMID: 38598601 PMCID: PMC11034669 DOI: 10.1371/journal.pgen.1011234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 04/22/2024] [Accepted: 03/25/2024] [Indexed: 04/12/2024] Open
Abstract
Peptidoglycan (PG) is the main component of the bacterial cell wall; it maintains cell shape while protecting the cell from internal osmotic pressure and external environmental challenges. PG synthesis is essential for bacterial growth and survival, and a series of PG modifications are required to allow expansion of the sacculus. Endopeptidases (EPs), for example, cleave the crosslinks between adjacent PG strands to allow the incorporation of newly synthesized PG. EPs are collectively essential for bacterial growth and must likely be carefully regulated to prevent sacculus degradation and cell death. However, EP regulation mechanisms are poorly understood. Here, we used TnSeq to uncover novel EP regulators in Vibrio cholerae. This screen revealed that the carboxypeptidase DacA1 (PBP5) alleviates EP toxicity. dacA1 is essential for viability on LB medium, and this essentiality was suppressed by EP overexpression, revealing that EP toxicity both mitigates, and is mitigated by, a defect in dacA1. A subsequent suppressor screen to restore viability of ΔdacA1 in LB medium identified hypomorphic mutants in the PG synthesis pathway, as well as mutations that promote EP activation. Our data thus reveal a more complex role of DacA1 in maintaining PG homeostasis than previously assumed.
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Affiliation(s)
- Manuela Alvarado Obando
- Department of Microbiology, Cornell University, Ithaca, New York, United States of America
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, United States of America
| | - Diego Rey-Varela
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Center for Microbial Research (UCMR), Science for Life Laboratory (SciLifeLab), Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Felipe Cava
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Center for Microbial Research (UCMR), Science for Life Laboratory (SciLifeLab), Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Tobias Dörr
- Department of Microbiology, Cornell University, Ithaca, New York, United States of America
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, United States of America
- Cornell Institute for Host-Microbe Interactions and Disease (CIHMID), Ithaca, New York, United States of America
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Obando MA, Dörr T. Novel role for peptidoglycan carboxypeptidases in maintaining the balance between bacterial cell wall synthesis and degradation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.12.548665. [PMID: 37503280 PMCID: PMC10369974 DOI: 10.1101/2023.07.12.548665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Peptidoglycan (PG) is the main component of the bacterial cell wall; it maintains cell shape while protecting the cell from internal osmotic pressure and external environmental challenges. PG synthesis is essential for bacterial growth and survival, and a series of PG modifications are required to allow expansion of the sacculus. Endopeptidases (EPs), for example, cleave the crosslinks between adjacent PG strands to allow the incorporation of newly synthesized PG. EPs are collectively essential for bacterial growth and must likely be carefully regulated to prevent sacculus degradation and cell death. However, EP regulation mechanisms are poorly understood. Here, we used TnSeq to uncover novel EP regulation factors in Vibrio cholerae. This screen revealed that the carboxypeptidase DacA1 (PBP5) alleviates EP toxicity. dacA1 is essential for viability on LB medium, and this essentiality was suppressed by EP overexpression, revealing that EP toxicity both mitigates, and is mitigated by, a defect in dacA1. A subsequent suppressor screen to restore viability of ΔdacA1 in LB medium was answered by hypomorphic mutants in the PG synthesis pathway, as well as mutations that promote PG degradation. Our data thus reveal a key role of DacA1 in maintaining the balance between PG synthesis and degradation.
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Affiliation(s)
- Manuela Alvarado Obando
- Department of Microbiology, Cornell University, Ithaca, NY
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
| | - Tobias Dörr
- Department of Microbiology, Cornell University, Ithaca, NY
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
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Camus A, Espinosa E, Zapater Baras P, Singh P, Quenech’Du N, Vickridge E, Modesti M, Barre FX, Espéli O. The SMC-like RecN protein is at the crossroads of several genotoxic stress responses in Escherichia coli. Front Microbiol 2023; 14:1146496. [PMID: 37168111 PMCID: PMC10165496 DOI: 10.3389/fmicb.2023.1146496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 04/04/2023] [Indexed: 05/13/2023] Open
Abstract
Introduction DNA damage repair (DDR) is an essential process for living organisms and contributes to genome maintenance and evolution. DDR involves different pathways including Homologous recombination (HR), Nucleotide Excision Repair (NER) and Base excision repair (BER) for example. The activity of each pathway is revealed with particular drug inducing lesions, but the repair of most DNA lesions depends on concomitant or subsequent action of the multiple pathways. Methods In the present study, we used two genotoxic antibiotics, mitomycin C (MMC) and Bleomycin (BLM), to decipher the interplays between these different pathways in E. coli. We combined genomic methods (TIS and Hi-SC2) and imaging assays with genetic dissections. Results We demonstrate that only a small set of DDR proteins are common to the repair of the lesions induced by these two drugs. Among them, RecN, an SMC-like protein, plays an important role by controlling sister chromatids dynamics and genome morphology at different steps of the repair processes. We further demonstrate that RecN influence on sister chromatids dynamics is not equivalent during the processing of the lesions induced by the two drugs. We observed that RecN activity and stability requires a pre-processing of the MMC-induced lesions by the NER but not for BLM-induced lesions. Discussion Those results show that RecN plays a major role in rescuing toxic intermediates generated by the BER pathway in addition to its well-known importance to the repair of double strand breaks by HR.
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Affiliation(s)
- Adrien Camus
- CIRB, Collège de France, INSERM U1050, CNRS UMR 7241, Université PSL, Paris, France
| | - Elena Espinosa
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | | | - Parul Singh
- CIRB, Collège de France, INSERM U1050, CNRS UMR 7241, Université PSL, Paris, France
| | - Nicole Quenech’Du
- CIRB, Collège de France, INSERM U1050, CNRS UMR 7241, Université PSL, Paris, France
| | - Elise Vickridge
- CIRB, Collège de France, INSERM U1050, CNRS UMR 7241, Université PSL, Paris, France
- Goodman Cancer Research Centre, McGill University, Montreal, QC, Canada
| | - Mauro Modesti
- Cancer Research Center of Marseille, Department of Genome Integrity, CNRS UMR 7258, INSERM U1068, Institut Paoli-Calmettes, Aix Marseille University, Marseille, France
| | - François Xavier Barre
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Olivier Espéli
- CIRB, Collège de France, INSERM U1050, CNRS UMR 7241, Université PSL, Paris, France
- *Correspondence: Olivier Espéli,
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Shao S, Wei L, Xia F, Zhang Y, Wang AQ. Defined Mutant Library Sequencing (DML-Seq) for Identification of Conditional Essential Genes. Bio Protoc 2021; 11:e3943. [PMID: 33796617 DOI: 10.21769/bioprotoc.3943] [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: 10/25/2020] [Revised: 01/12/2021] [Accepted: 01/16/2021] [Indexed: 11/02/2022] Open
Abstract
Transposon insertion sequencing (TIS) is an emerging technique which utilizes a massive transposon mutant library to screen specific phenotype and determine the conditional essential genetic requirements for bacterial fitness under distinct conditions combined with high-throughput parallel sequencing technology. Compared with a massive mutant library in traditional TIS, the defined mutant library sequencing (DML-Seq) has advantages as: 1) efficient mutagenesis; 2) low bottleneck effects; 3) avoid hotpots caused by screening; 4) can be directly used in the following experiments. Here, we described an optimized procedure of DML-Seq for fitness screen to supply classical TIS using the marine pathogenic bacterium Edwardsiella piscicida as an example.
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Affiliation(s)
- Shuai Shao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Lifan Wei
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.,Department of Endodontics and Operative Dentistry, Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Feng Xia
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yuanxing Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 130 Meilong Road, Shanghai 200237, China.,Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
| | - And Qiyao Wang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 130 Meilong Road, Shanghai 200237, China.,Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
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Kazi MI, Schargel RD, Boll JM. Generating Transposon Insertion Libraries in Gram-Negative Bacteria for High-Throughput Sequencing. J Vis Exp 2020. [PMID: 32716393 DOI: 10.3791/61612] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Transposon sequencing (Tn-seq) is a powerful method that combines transposon mutagenesis and massive parallel sequencing to identify genes and pathways that contribute to bacterial fitness under a wide range of environmental conditions. Tn-seq applications are extensive and have not only enabled examination of genotype-phenotype relationships at an organism level but also at the population, community and systems levels. Gram-negative bacteria are highly associated with antimicrobial resistance phenotypes, which has increased incidents of antibiotic treatment failure. Antimicrobial resistance is defined as bacterial growth in the presence of otherwise lethal antibiotics. The "last-line" antimicrobial colistin is used to treat Gram-negative bacterial infections. However, several Gram-negative pathogens, including Acinetobacter baumannii can develop colistin resistance through a range of molecular mechanisms, some of which were characterized using Tn-seq. Furthermore, signal transduction pathways that regulate colistin resistance vary within Gram-negative bacteria. Here we propose an efficient method of transposon mutagenesis in A. baumannii that streamlines generation of a saturating transposon insertion library and amplicon library construction by eliminating the need for restriction enzymes, adapter ligation, and gel purification. The methods described herein will enable in-depth analysis of molecular determinants that contribute to A. baumannii fitness when challenged with colistin. The protocol is also applicable to other Gram-negative ESKAPE pathogens, which are primarily associated with drug resistant hospital-acquired infections.
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Affiliation(s)
- Misha I Kazi
- Department of Biology, University of Texas at Arlington
| | | | - Joseph M Boll
- Department of Biology, University of Texas at Arlington;
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Genetic Determinants of Penicillin Tolerance in Vibrio cholerae. Antimicrob Agents Chemother 2018; 62:AAC.01326-18. [PMID: 30061291 DOI: 10.1128/aac.01326-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 07/26/2018] [Indexed: 12/25/2022] Open
Abstract
Many bacteria are resistant to killing (tolerant) by typically bactericidal antibiotics due to their ability to counteract drug-induced cell damage. Vibrio cholerae, the cholera agent, displays an unusually high tolerance to diverse inhibitors of cell wall synthesis. Exposure to these agents, which in other bacteria leads to lysis and death, results in a breakdown of the cell wall and subsequent sphere formation in V. cholerae Spheres readily recover to rod-shaped cells upon antibiotic removal, but the mechanisms mediating the recovery process are not well characterized. Here, we found that the mechanisms of recovery are dependent on environmental conditions. Interestingly, on agarose pads, spheres undergo characteristic stages during the restoration of rod shape. Drug inhibition and microscopy experiments suggest that class A penicillin binding proteins (aPBPs) play a more active role than the Rod system, especially early in sphere recovery. Transposon insertion sequencing (TnSeq) analyses revealed that lipopolysaccharide (LPS) and cell wall biogenesis genes, as well as the sigma E cell envelope stress response, were particularly critical for recovery. LPS core and O-antigen appear to be more critical for sphere formation/integrity and viability than lipid A modifications. Overall, our findings demonstrate that the outer membrane is a key contributor to beta lactam tolerance and suggest a role for aPBPs in cell wall biogenesis in the absence of rod-shape cues. Factors required for postantibiotic recovery could serve as targets for antibiotic adjuvants that enhance the efficacy of antibiotics that inhibit cell wall biogenesis.
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