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Wang X, Dai Y, Kong N, Cao M, Zhang L, Wei Q. Screening Key Sites of Class 2 Integron Integrase that Impact Recombination Efficiency. Curr Microbiol 2024; 81:163. [PMID: 38710822 DOI: 10.1007/s00284-024-03674-0] [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: 12/12/2023] [Accepted: 03/19/2024] [Indexed: 05/08/2024]
Abstract
By capturing and expressing exogenous resistance gene cassettes through site-specific recombination, integrons play important roles in the horizontal transfer of antimicrobial resistant genes among bacteria. The characteristics of integron integrase make it to be a potential gene editing tool enzyme. In this study, a random mutation library using error-prone PCR was constructed, and amino acid residues mutants that impact on attI2 × attC or attC × attC recombination efficiency were screened and analyzed. Thirteen amino acid mutations were identified to be critical impacted on site-specific recombination of IntI2, including the predicted catalyzed site Y301. Nine of 13 mutated amino acid residues that have critically impacted on IntI2 activity were relative concentrated and near the predicted catalyzed site Y301 in the predicted three-dimensional structure indicated the importance of this area in maintain the activity of IntI2. No mutant with obviously increased recombination activity (more than four-fold as high as that of wild IntI2) was found in library screening, except P95S, R100K slightly increased (within two-fold) the excision activity of IntI2, and S243T slightly increased (within two-fold) both excision and integration activity of IntI2. These findings will provide clues for further specific modification of integron integrase to be a tool enzyme as well as establishing a new gene editing system and applied practically.
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Affiliation(s)
- Xiaotong Wang
- Department of Laboratory Medicine, Anhui University of Science and Technology Affiliated Fengxian Hospital, 6600 Nanfeng Road, Shanghai, 201499, China
- Clinical Laboratory, Songjiang Hospital Affiliated to Shanghai JiaoTong University School of Medicine, 748 Middle Zhongshan Road, Shanghai, 201602, China
| | - Yueru Dai
- Department of Laboratory Medicine, Anhui University of Science and Technology Affiliated Fengxian Hospital, 6600 Nanfeng Road, Shanghai, 201499, China
| | - Nana Kong
- Department of Laboratory Medicine, Anhui University of Science and Technology Affiliated Fengxian Hospital, 6600 Nanfeng Road, Shanghai, 201499, China
| | - Mei Cao
- Department of Laboratory Medicine, Anhui University of Science and Technology Affiliated Fengxian Hospital, 6600 Nanfeng Road, Shanghai, 201499, China
| | - Long Zhang
- Department of Laboratory Medicine, Anhui University of Science and Technology Affiliated Fengxian Hospital, 6600 Nanfeng Road, Shanghai, 201499, China
| | - Quhao Wei
- Department of Laboratory Medicine, Anhui University of Science and Technology Affiliated Fengxian Hospital, 6600 Nanfeng Road, Shanghai, 201499, China.
- Department of Laboratory Medicine, Southern Medical University Affiliated Fengxian Hospital, 6600 Nanfeng Road, Shanghai, 201499, China.
- Department of Laboratory Medicine, Shanghai University of Medicine & Health Sciences Affiliated Sixth People's Hospital South Campus, 6600 Nanfeng Road, Shanghai, 201499, China.
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Blanco P, Hipólito A, García-Pastor L, Trigo da Roza F, Toribio-Celestino L, Ortega A, Vergara E, San Millán Á, Escudero J. Identification of promoter activity in gene-less cassettes from Vibrionaceae superintegrons. Nucleic Acids Res 2024; 52:2961-2976. [PMID: 38214222 PMCID: PMC11014356 DOI: 10.1093/nar/gkad1252] [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: 04/18/2023] [Revised: 12/18/2023] [Accepted: 12/26/2023] [Indexed: 01/13/2024] Open
Abstract
Integrons are genetic platforms that acquire new genes encoded in integron cassettes (ICs), building arrays of adaptive functions. ICs generally encode promoterless genes, whose expression relies on the platform-associated Pc promoter, with the cassette array functioning as an operon-like structure regulated by the distance to the Pc. This is relevant in large sedentary chromosomal integrons (SCIs) carrying hundreds of ICs, like those in Vibrio species. We selected 29 gene-less cassettes in four Vibrio SCIs, and explored whether their function could be related to the transcription regulation of adjacent ICs. We show that most gene-less cassettes have promoter activity on the sense strand, enhancing the expression of downstream cassettes. Additionally, we identified the transcription start sites of gene-less ICs through 5'-RACE. Accordingly, we found that most of the superintegron in Vibrio cholerae is not silent. These promoter cassettes can trigger the expression of a silent dfrB9 cassette downstream, increasing trimethoprim resistance >512-fold in V. cholerae and Escherichia coli. Furthermore, one cassette with an antisense promoter can reduce trimethoprim resistance when cloned downstream. Our findings highlight the regulatory role of gene-less cassettes in the expression of adjacent cassettes, emphasizing their significance in SCIs and their clinical importance if captured by mobile integrons.
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Affiliation(s)
- Paula Blanco
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid 28040, Spain
- VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid 28040, Spain
| | - Alberto Hipólito
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid 28040, Spain
- VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid 28040, Spain
| | - Lucía García-Pastor
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid 28040, Spain
- VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid 28040, Spain
| | - Filipa Trigo da Roza
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid 28040, Spain
- VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid 28040, Spain
| | - Laura Toribio-Celestino
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid 28049, Spain
| | - Alba Cristina Ortega
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid 28040, Spain
| | - Ester Vergara
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid 28040, Spain
- VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid 28040, Spain
| | - Álvaro San Millán
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid 28049, Spain
- Centro de Investigación Biológica en Red de Epidemiología y Salud Pública (CIBERESP), Instituto de Salud Carlos III, Madrid 28222, Spain
| | - José Antonio Escudero
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid 28040, Spain
- VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid 28040, Spain
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