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Zhou P, G. C. B, Stolte F, Wu C. Use of CRISPR interference for efficient and rapid gene inactivation in Fusobacterium nucleatum. Appl Environ Microbiol 2024; 90:e0166523. [PMID: 38185820 PMCID: PMC10880640 DOI: 10.1128/aem.01665-23] [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: 09/19/2023] [Accepted: 11/27/2023] [Indexed: 01/09/2024] Open
Abstract
Gene inactivation by creating in-frame deletion mutations in Fusobacterium nucleatum is time consuming, and most fusobacterial strains are genetically intractable. Addressing these problems, we introduced a riboswitch-based inducible CRISPR interference (CRISPRi) system. This system employs the nuclease-inactive Streptococcus pyogenes Cas9 protein (dCas9), specifically guided to the gene of interest by a constantly expressed single-guide RNA (sgRNA). Mechanistically, this dCas9-sgRNA complex serves as an insurmountable roadblock for RNA polymerase, thus repressing the target gene transcription. Leveraging this system, we first examined two non-essential genes, ftsX and radD, which are pivotal for fusobacterial cytokinesis and coaggregation. Upon adding the inducer, theophylline, ftsX suppression caused filamentous cell formation akin to chromosomal ftsX deletion, while targeting radD significantly reduced RadD protein levels, abolishing RadD-mediated coaggregation. The system was then extended to probe essential genes bamA and ftsZ, which are vital for outer membrane biogenesis and cell division. Impressively, bamA suppression disrupted membrane integrity and bacterial separation, stalling growth, while ftsZ targeting yielded elongated cells in broth with compromised agar growth. Further studies on F. nucleatum clinical strain CTI-2 and Fusobacterium periodonticum revealed reduced indole synthesis when targeting tnaA. Moreover, silencing clpB in F. periodonticum decreased ClpB, increasing thermal sensitivity. In summary, our CRISPRi system streamlines gene inactivation across various fusobacterial strains.IMPORTANCEHow can we effectively investigate the gene functions in Fusobacterium nucleatum, given the dual challenges of gene inactivation and the inherent genetic resistance of many strains? Traditional methods have been cumbersome and often inadequate. Addressing this, our work introduces a novel inducible CRISPR interference (CRISPRi) system in which dCas9 expression is controlled at the translation level by a theophylline-responsive riboswitch unit, and single-guide RNA expression is driven by the robust, constitutive rpsJ promoter. This approach simplifies gene inactivation in the model organism (ATCC 23726) and extends its application to previously considered genetically intractable strains like CTI-2 and Fusobacterium periodonticum. With CRISPRi's potential, it is a pivotal tool for in-depth genetic studies into fusobacterial pathogenesis, potentially unlocking targeted therapeutic strategies.
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Affiliation(s)
- Peng Zhou
- Department of Microbiology & Molecular Genetics, The University of Texas Health Science Center, Houston, Texas, USA
| | - Bibek G. C.
- Department of Microbiology & Molecular Genetics, The University of Texas Health Science Center, Houston, Texas, USA
| | - Flynn Stolte
- Department of Microbiology & Molecular Genetics, The University of Texas Health Science Center, Houston, Texas, USA
| | - Chenggang Wu
- Department of Microbiology & Molecular Genetics, The University of Texas Health Science Center, Houston, Texas, USA
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Zheng Y, Fu H, Chen J, Li J, Bian Y, Hu P, Lei L, Liu Y, Yang J, Peng W. Development of a counterselectable system for rapid and efficient CRISPR-based genome engineering in Zymomonas mobilis. Microb Cell Fact 2023; 22:208. [PMID: 37833755 PMCID: PMC10571335 DOI: 10.1186/s12934-023-02217-9] [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: 07/06/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
BACKGROUND Zymomonas mobilis is an important industrial bacterium ideal for biorefinery and synthetic biology studies. High-throughput CRISPR-based genome editing technologies have been developed to enable targeted engineering of genes and hence metabolic pathways in the model ZM4 strain, expediting the exploitation of this biofuel-producing strain as a cell factory for sustainable chemicals, proteins and biofuels production. As these technologies mainly take plasmid-based strategies, their applications would be impeded due to the fact that curing of the extremely stable plasmids is laborious and inefficient. Whilst counterselection markers have been proven to be efficient for plasmid curing, hitherto only very few counterselection markers have been available for Z. mobilis. RESULTS We constructed a conditional lethal mutant of the pheS gene of Z. mobilis ZM4, clmPheS, containing T263A and A318G substitutions and coding for a mutated alpha-subunit of phenylalanyl-tRNA synthetase to allow for the incorporation of a toxic analog of phenylalanine, p-chloro-phenylalanine (4-CP), into proteins, and hence leading to inhibition of cell growth. We demonstrated that expression of clmPheS driven by a strong Pgap promoter from a plasmid could render the Z. mobilis ZM4 cells sufficient sensitivity to 4-CP. The clmPheS-expressing cells were assayed to be extremely sensitive to 0.2 mM 4-CP. Subsequently, the clmPheS-assisted counterselection endowed fast curing of genome engineering plasmids immediately after obtaining the desired mutants, shortening the time of every two rounds of multiplex chromosome editing by at least 9 days, and enabled the development of a strategy for scarless modification of the native Z. mobilis ZM4 plasmids. CONCLUSIONS This study developed a strategy, coupling an endogenous CRISPR-based genome editing toolkit with a counterselection marker created here, for rapid and efficient multi-round multiplex editing of the chromosome, as well as scarless modification of the native plasmids, providing an improved genome engineering toolkit for Z. mobilis and an important reference to develope similar genetic manipulation systems in other non-model organisms.
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Affiliation(s)
- Yanli Zheng
- College of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, P. R. China
| | - Hongmei Fu
- College of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, P. R. China
| | - Jue Chen
- College of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, P. R. China
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Laboratory of Industrial Microbiology, The College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, P. R. China
| | - Jie Li
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Laboratory of Industrial Microbiology, The College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, P. R. China
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Engineering Research Center for Bio-enzyme Catalysis, Environmental Microbial Technology Center of Hubei Province, School of Life Sciences, Hubei University, Wuhan, 430062, P.R. China
| | - Yuejie Bian
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Engineering Research Center for Bio-enzyme Catalysis, Environmental Microbial Technology Center of Hubei Province, School of Life Sciences, Hubei University, Wuhan, 430062, P.R. China
| | - Ping Hu
- College of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, P. R. China
| | - Lei Lei
- College of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, P. R. China
| | - Yihan Liu
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Laboratory of Industrial Microbiology, The College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, P. R. China.
| | - Jiangke Yang
- College of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, P. R. China.
| | - Wenfang Peng
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Engineering Research Center for Bio-enzyme Catalysis, Environmental Microbial Technology Center of Hubei Province, School of Life Sciences, Hubei University, Wuhan, 430062, P.R. China.
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Zhou P, G C B, Stolte F, Wu C. Use of CRISPR interference for efficient and rapid gene inactivation in Fusobacterium nucleatum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.19.558491. [PMID: 37781593 PMCID: PMC10541141 DOI: 10.1101/2023.09.19.558491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Gene inactivation via creating in-frame deletion mutations in Fusobacterium nucleatum is time-consuming, and most fusobacterial strains are genetically intractable. Addressing these problems, we introduced a riboswitch-based inducible CRISPRi system. This system employs the nuclease-inactive Streptococcus pyogenes Cas9 protein (dCas9), specifically guided to the gene of interest by a constantly expressed single guide RNA (sgRNA). Mechanistically, this dCas9-sgRNA complex serves as an insurmountable roadblock for RNA polymerase, thus repressing the target gene transcription. Leveraging this system, we first examined two non-essential genes, ftsX, and radD , pivotal for fusobacterial cytokinesis and coaggregation. Upon adding the inducer, theophylline, ftsX suppression caused filamentous cell formation akin to chromosomal ftsX deletion, while targeting radD significantly reduced RadD protein levels, abolishing coaggregation. The system was then extended to probe essential genes bamA and ftsZ , vital for outer membrane biogenesis and cell division. Impressively, bamA suppression disrupted membrane integrity and bacterial separation, stalling growth, while ftsZ- targeting yielded elongated cells in broth with compromised agar growth. Further studies on F. nucleatum clinical strain CTI-2 and Fusobacterium periodonticum revealed reduced indole synthesis when targeting tnaA . Moreover, silencing clpB in F. periodonticum decreased ClpB, increasing thermal sensitivity. In summary, our CRISPRi system streamlines gene inactivation across various fusobacterial strains. IMPORTANCE How can we effectively investigate the gene functions in Fusobacterium nucleatum , given the dual challenges of gene inactivation and the inherent genetic resistance of many strains? Traditional methods have been cumbersome and often inadequate. Addressing this, our work introduces a novel inducible CRISPRi system in which dCas9 expression is controlled at the translation level by a theophylline-responsive riboswitch unit, and sgRNA expression is driven by the robust, constitutive rpsJ promoter. This approach simplifies gene inactivation in the model organism (ATCC 23726) and extends its application to previously considered resistant strains like CTI-2 and Fusobacterium periodontium . With CRISPRi's potential, it is a pivotal tool for in-depth genetic studies into fusobacterial pathogenesis, potentially unlocking targeted therapeutic strategies.
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