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Liang Z, Huang C, Xia Y, Ye Z, Fan S, Zeng J, Guo S, Ma X, Sun L, Huo YX. Identification of functional sgRNA mutants lacking canonical secondary structure using high-throughput FACS screening. Cell Rep 2024; 43:114290. [PMID: 38823012 DOI: 10.1016/j.celrep.2024.114290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 04/22/2024] [Accepted: 05/13/2024] [Indexed: 06/03/2024] Open
Abstract
Coexpressing multiple identical single guide RNAs (sgRNAs) in CRISPR-dependent engineering triggers genetic instability and phenotype loss. To provide sgRNA derivatives for efficient DNA digestion, we design a high-throughput digestion-activity-dependent positive screening strategy and astonishingly obtain functional nonrepetitive sgRNA mutants with up to 48 out of the 61 nucleotides mutated, and these nonrepetitive mutants completely lose canonical secondary sgRNA structure in simulation. Cas9-sgRNA complexes containing these noncanonical sgRNAs maintain wild-type level of digestion activities in vivo, indicating that the Cas9 protein is compatible with or is able to adjust the secondary structure of sgRNAs. Using these noncanonical sgRNAs, we achieve multiplex genetic engineering for gene knockout and base editing in microbial cell factories. Libraries of strains with rewired metabolism are constructed, and overproducers of isobutanol or 1,3-propanediol are identified by biosensor-based fluorescence-activated cell sorting (FACS). This work sheds light on the remarkable flexibility of the secondary structure of functional sgRNA.
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Affiliation(s)
- Zeyu Liang
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Chaoyong Huang
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Yan Xia
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Zhaojin Ye
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Shunhua Fan
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Junwei Zeng
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Shuyuan Guo
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Xiaoyan Ma
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China; Beijing Institute of Technology (Tangshan) Translational Research Center, Hebei 063611, China
| | - Lichao Sun
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China; Beijing Institute of Technology (Tangshan) Translational Research Center, Hebei 063611, China
| | - Yi-Xin Huo
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China; Beijing Institute of Technology (Tangshan) Translational Research Center, Hebei 063611, China.
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Ma S, Su T, Lu X, Qi Q. Bacterial genome reduction for optimal chassis of synthetic biology: a review. Crit Rev Biotechnol 2024; 44:660-673. [PMID: 37380345 DOI: 10.1080/07388551.2023.2208285] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/13/2022] [Accepted: 02/20/2023] [Indexed: 06/30/2023]
Abstract
Bacteria with streamlined genomes, that harbor full functional genes for essential metabolic networks, are able to synthesize the desired products more effectively and thus have advantages as production platforms in industrial applications. To obtain streamlined chassis genomes, a large amount of effort has been made to reduce existing bacterial genomes. This work falls into two categories: rational and random reduction. The identification of essential gene sets and the emergence of various genome-deletion techniques have greatly promoted genome reduction in many bacteria over the past few decades. Some of the constructed genomes possessed desirable properties for industrial applications, such as: increased genome stability, transformation capacity, cell growth, and biomaterial productivity. The decreased growth and perturbations in physiological phenotype of some genome-reduced strains may limit their applications as optimized cell factories. This review presents an assessment of the advancements made to date in bacterial genome reduction to construct optimal chassis for synthetic biology, including: the identification of essential gene sets, the genome-deletion techniques, the properties and industrial applications of artificially streamlined genomes, the obstacles encountered in constructing reduced genomes, and the future perspectives.
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Affiliation(s)
- Shuai Ma
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, P. R. China
| | - Tianyuan Su
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, P. R. China
| | - Xuemei Lu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, P. R. China
| | - Qingsheng Qi
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, P. R. China
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Aida H, Ying BW. Efforts to Minimise the Bacterial Genome as a Free-Living Growing System. BIOLOGY 2023; 12:1170. [PMID: 37759570 PMCID: PMC10525146 DOI: 10.3390/biology12091170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/17/2023] [Accepted: 08/24/2023] [Indexed: 09/29/2023]
Abstract
Exploring the minimal genetic requirements for cells to maintain free living is an exciting topic in biology. Multiple approaches are employed to address the question of the minimal genome. In addition to constructing the synthetic genome in the test tube, reducing the size of the wild-type genome is a practical approach for obtaining the essential genomic sequence for living cells. The well-studied Escherichia coli has been used as a model organism for genome reduction owing to its fast growth and easy manipulation. Extensive studies have reported how to reduce the bacterial genome and the collections of genomic disturbed strains acquired, which were sufficiently reviewed previously. However, the common issue of growth decrease caused by genetic disturbance remains largely unaddressed. This mini-review discusses the considerable efforts made to improve growth fitness, which was decreased due to genome reduction. The proposal and perspective are clarified for further accumulated genetic deletion to minimise the Escherichia coli genome in terms of genome reduction, experimental evolution, medium optimization, and machine learning.
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Affiliation(s)
| | - Bei-Wen Ying
- School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Ibaraki, Japan
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Alejaldre L, Anhel AM, Goñi-Moreno Á. pBLAM1-x: standardized transposon tools for high-throughput screening. Synth Biol (Oxf) 2023; 8:ysad012. [PMID: 37388964 PMCID: PMC10306358 DOI: 10.1093/synbio/ysad012] [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: 05/23/2023] [Revised: 06/15/2023] [Accepted: 06/20/2023] [Indexed: 07/01/2023] Open
Abstract
The engineering of pre-defined functions in living cells requires increasingly accurate tools as synthetic biology efforts become more ambitious. Moreover, the characterization of the phenotypic performance of genetic constructs demands meticulous measurements and extensive data acquisition for the sake of feeding mathematical models and matching predictions along the design-build-test lifecycle. Here, we developed a genetic tool that eases high-throughput transposon insertion sequencing (TnSeq): the pBLAM1-x plasmid vectors carrying the Himar1 Mariner transposase system. These plasmids were derived from the mini-Tn5 transposon vector pBAMD1-2 and built following modular criteria of the Standard European Vector Architecture (SEVA) format. To showcase their function, we analyzed sequencing results of 60 clones of the soil bacterium Pseudomonas putida KT2440. The new pBLAM1-x tool has already been included in the latest SEVA database release, and here we describe its performance using laboratory automation workflows. Graphical Abstract.
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Affiliation(s)
- Lorea Alejaldre
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Madrid, Spain
| | - Ana-Mariya Anhel
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Madrid, Spain
| | - Ángel Goñi-Moreno
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Madrid, Spain
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Past, Present, and Future of Genome Modification in Escherichia coli. Microorganisms 2022; 10:microorganisms10091835. [PMID: 36144436 PMCID: PMC9504249 DOI: 10.3390/microorganisms10091835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 09/05/2022] [Accepted: 09/05/2022] [Indexed: 12/04/2022] Open
Abstract
Escherichia coli K-12 is one of the most well-studied species of bacteria. This species, however, is much more difficult to modify by homologous recombination (HR) than other model microorganisms. Research on HR in E. coli has led to a better understanding of the molecular mechanisms of HR, resulting in technical improvements and rapid progress in genome research, and allowing whole-genome mutagenesis and large-scale genome modifications. Developments using λ Red (exo, bet, and gam) and CRISPR-Cas have made E. coli as amenable to genome modification as other model microorganisms, such as Saccharomyces cerevisiae and Bacillus subtilis. This review describes the history of recombination research in E. coli, as well as improvements in techniques for genome modification by HR. This review also describes the results of large-scale genome modification of E. coli using these technologies, including DNA synthesis and assembly. In addition, this article reviews recent advances in genome modification, considers future directions, and describes problems associated with the creation of cells by design.
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Genomic landscapes of bacterial transposons and their applications in strain improvement. Appl Microbiol Biotechnol 2022; 106:6383-6396. [PMID: 36094654 DOI: 10.1007/s00253-022-12170-z] [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: 05/19/2022] [Revised: 08/19/2022] [Accepted: 09/01/2022] [Indexed: 11/02/2022]
Abstract
Transposons are mobile genetic elements that can give rise to gene mutation and genome rearrangement. Due to their mobility, transposons have been exploited as genetic tools for modification of plants, animals, and microbes. Although a plethora of reviews have summarized families of transposons, the transposons from fermentation bacteria have not been systematically documented, which thereby constrain the exploitation for metabolic engineering and synthetic biology purposes. In this review, we summarize the transposons from the most used fermentation bacteria including Escherichia coli, Bacillus subtilis, Lactococcus lactis, Corynebacterium glutamicum, Klebsiella pneumoniae, and Zymomonas mobilis by literature retrieval and data mining from GenBank and KEGG. We also outline the state-of-the-art advances in basic research and industrial applications especially when allied with other genetic tools. Overall, this review aims to provide valuable insights for transposon-mediated strain improvement. KEY POINTS: • The transposons from the most-used fermentation bacteria are systematically summarized. • The applications of transposons in strain improvement are comprehensively reviewed.
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Ma S, Su T, Liu J, Wang Q, Liang Q, Lu X, Qi Q. Random genome reduction coupled with polyhydroxybutyrate biosynthesis to facilitate its accumulation in Escherichia coli. Front Bioeng Biotechnol 2022; 10:978211. [PMID: 36105609 PMCID: PMC9465206 DOI: 10.3389/fbioe.2022.978211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
Genome reduction has been emerged as a powerful tool to construct ideal chassis for synthetic biology. Random genome reduction couple genomic deletion with growth and has the potential to construct optimum genome for a given environment. Recently, we developed a transposon-mediated random deletion (TMRD) method that allows the random and continuous reduction of Escherichia coli genome. Here, to prove its ability in constructing optimal cell factories, we coupled polyhydroxybutyrate (PHB) accumulation with random genome reduction and proceeded to reduce the E. coli genome. Five mutants showed high biomass and PHB yields were selected from 18 candidates after ten rounds of genome reduction. And eight or nine genomic fragments (totally 230.1–270.0 Kb) were deleted in their genomes, encompassing 4.95%–5.82% of the parental MG1655 genome. Most mutants displayed better growth, glucose utilization, protein expression, and significant increase of electroporation efficiency compared with MG1655. The PHB content and concentration enhanced up to 13.3%–37.2% and 60.2%–102.9% when batch fermentation was performed in M9-glucose medium using the five mutants. Particularly, in mutant H16, lacking 5.28% of its genome, the increase of biomass and PHB concentration were more than 50% and 100% compared with MG1655, respectively. This work expands the strategy for creating streamlined chassis to improve the production of high value-added products.
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Affiliation(s)
| | | | | | | | | | - Xuemei Lu
- *Correspondence: Xuemei Lu, ; Qingsheng Qi,
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