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Nugent PJ, Park H, Wladyka CL, Chen KY, Bynum C, Quarterman G, Hsieh AC, Subramaniam AR. Decoding RNA Metabolism by RNA-linked CRISPR Screening in Human Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.25.605204. [PMID: 39091804 PMCID: PMC11291135 DOI: 10.1101/2024.07.25.605204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
RNAs undergo a complex choreography of metabolic processes in human cells that are regulated by thousands of RNA-associated proteins. While the effects of individual RNA-associated proteins on RNA metabolism have been extensively characterized, the full complement of regulators for most RNA metabolic events remain unknown. Here we present a massively parallel RNA-linked CRISPR (ReLiC) screening approach to measure the responses of diverse RNA metabolic events to knockout of 2,092 human genes encoding all known RNA-associated proteins. ReLiC screens highlight modular interactions between gene networks regulating splicing, translation, and decay of mRNAs. When combined with biochemical fractionation of polysomes, ReLiC reveals striking pathway-specific coupling between growth fitness and mRNA translation. Perturbing different components of the translation and proteostasis machineries have distinct effects on ribosome occupancy, while perturbing mRNA transcription leaves ribosome occupancy largely intact. Isoform-selective ReLiC screens capture differential regulation of intron retention and exon skipping by SF3b complex subunits. Chemogenomic screens using ReLiC decipher translational regulators upstream of mRNA decay and uncover a role for the ribosome collision sensor GCN1 during treatment with the anti-leukemic drug homoharringtonine. Our work demonstrates ReLiC as a versatile platform for discovering and dissecting regulatory principles of human RNA metabolism.
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2
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Liu X, Hu J, Wang W, Yang H, Tao E, Ma Y, Sha S. Mycobacterial Biofilm: Mechanisms, Clinical Problems, and Treatments. Int J Mol Sci 2024; 25:7771. [PMID: 39063012 PMCID: PMC11277187 DOI: 10.3390/ijms25147771] [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: 06/02/2024] [Revised: 07/12/2024] [Accepted: 07/13/2024] [Indexed: 07/28/2024] Open
Abstract
Tuberculosis (TB) remains a threat to human health worldwide. Mycobacterium tuberculosis (Mtb) and other nontuberculous mycobacteria (NTM) can form biofilms, and in vitro and animal experiments have shown that biofilms cause serious drug resistance and mycobacterial persistence. Deeper investigations into the mechanisms of mycobacterial biofilm formation and, consequently, the exploration of appropriate antibiofilm treatments to improve the efficiency of current anti-TB drugs will be useful for curing TB. In this review, the genes and molecules that have been recently reported to be involved in mycobacterial biofilm development, such as ABC transporter, Pks1, PpiB, GroEL1, MprB, (p)ppGpp, poly(P), and c-di-GMP, are summarized. Biofilm-induced clinical problems, including biofilm-related infections and enhanced virulence, as well as their possible mechanisms, are also discussed in detail. Moreover, we also illustrate newly synthesized anti-TB agents that target mycobacterial biofilm, as well as some assistant methods with high efficiency in reducing biofilms in hosts, such as the use of nanoparticles.
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Affiliation(s)
- Xining Liu
- Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, China; (X.L.); (J.H.); (W.W.); (E.T.)
| | - Junxing Hu
- Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, China; (X.L.); (J.H.); (W.W.); (E.T.)
| | - Wenzhen Wang
- Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, China; (X.L.); (J.H.); (W.W.); (E.T.)
| | - Hanyu Yang
- The Queen’s University of Belfast Joint College, China Medical University, Shenyang 110122, China;
| | - Erning Tao
- Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, China; (X.L.); (J.H.); (W.W.); (E.T.)
| | - Yufang Ma
- Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, China; (X.L.); (J.H.); (W.W.); (E.T.)
| | - Shanshan Sha
- Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, China; (X.L.); (J.H.); (W.W.); (E.T.)
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3
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Žedaveinytė R, Meers C, Le HC, Mortman EE, Tang S, Lampe GD, Pesari SR, Gelsinger DR, Wiegand T, Sternberg SH. Antagonistic conflict between transposon-encoded introns and guide RNAs. Science 2024; 385:eadm8189. [PMID: 38991068 DOI: 10.1126/science.adm8189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 05/08/2024] [Indexed: 07/13/2024]
Abstract
TnpB nucleases represent the evolutionary precursors to CRISPR-Cas12 and are widespread in all domains of life. IS605-family TnpB homologs function as programmable RNA-guided homing endonucleases in bacteria, driving transposon maintenance through DNA double-strand break-stimulated homologous recombination. In this work, we uncovered molecular mechanisms of the transposition life cycle of IS607-family elements that, notably, also encode group I introns. We identified specific features for a candidate "IStron" from Clostridium botulinum that allow the element to carefully control the relative levels of spliced products versus functional guide RNAs. Our results suggest that IStron transcripts evolved an ability to balance competing and mutually exclusive activities that promote selfish transposon spread while limiting adverse fitness costs on the host. Collectively, this work highlights molecular innovation in the multifunctional utility of transposon-encoded noncoding RNAs.
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Affiliation(s)
- Rimantė Žedaveinytė
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Chance Meers
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Hoang C Le
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Edan E Mortman
- Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Stephen Tang
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - George D Lampe
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Sanjana R Pesari
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Diego R Gelsinger
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Tanner Wiegand
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Samuel H Sternberg
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
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4
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Hew BE, Gupta S, Sato R, Waller DF, Stoytchev I, Short JE, Sharek L, Tran CT, Badran AH, Owens JB. Directed evolution of hyperactive integrases for site specific insertion of transgenes. Nucleic Acids Res 2024:gkae534. [PMID: 38953167 DOI: 10.1093/nar/gkae534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 05/16/2024] [Accepted: 06/10/2024] [Indexed: 07/03/2024] Open
Abstract
The ability to deliver large transgenes to a single genomic sequence with high efficiency would accelerate biomedical interventions. Current methods suffer from low insertion efficiency and most rely on undesired double-strand DNA breaks. Serine integrases catalyze the insertion of large DNA cargos at attachment (att) sites. By targeting att sites to the genome using technologies such as prime editing, integrases can target safe loci while avoiding double-strand breaks. We developed a method of phage-assisted continuous evolution we call IntePACE, that we used to rapidly perform hundreds of rounds of mutagenesis to systematically improve activity of PhiC31 and Bxb1 serine integrases. Novel hyperactive mutants were generated by combining synergistic mutations resulting in integration of a multi-gene cargo at rates as high as 80% of target chromosomes. Hyperactive integrases inserted a 15.7 kb therapeutic DNA cargo containing von Willebrand Factor. This technology could accelerate gene delivery therapeutics and our directed evolution strategy can easily be adapted to improve novel integrases from nature.
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Affiliation(s)
- Brian E Hew
- Department of Cell and Molecular Biology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96814, USA
| | - Sabranth Gupta
- Department of Cell and Molecular Biology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96814, USA
| | - Ryuei Sato
- Department of Cell and Molecular Biology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96814, USA
| | - David F Waller
- Department of Cell and Molecular Biology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96814, USA
| | - Ilko Stoytchev
- Department of Cell and Molecular Biology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96814, USA
| | - James E Short
- Department of Cell and Molecular Biology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96814, USA
| | - Lisa Sharek
- Department of Cell and Molecular Biology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96814, USA
| | - Christopher T Tran
- Department of Cell and Molecular Biology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96814, USA
| | - Ahmed H Badran
- Department of Chemistry, Department of Integrative Structural and Computational Biology, Beckman Center for Chemical Sciences, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jesse B Owens
- Department of Cell and Molecular Biology, Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96814, USA
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5
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Huang BD, Kim D, Yu Y, Wilson CJ. Engineering intelligent chassis cells via recombinase-based MEMORY circuits. Nat Commun 2024; 15:2418. [PMID: 38499601 PMCID: PMC10948884 DOI: 10.1038/s41467-024-46755-1] [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: 10/16/2023] [Accepted: 03/08/2024] [Indexed: 03/20/2024] Open
Abstract
Synthetic biologists seek to engineer intelligent living systems capable of decision-making, communication, and memory. Separate technologies exist for each tenet of intelligence; however, the unification of all three properties in a living system has not been achieved. Here, we engineer completely intelligent Escherichia coli strains that harbor six orthogonal and inducible genome-integrated recombinases, forming Molecularly Encoded Memory via an Orthogonal Recombinase arraY (MEMORY). MEMORY chassis cells facilitate intelligence via the discrete multi-input regulation of recombinase functions enabling inheritable DNA inversions, deletions, and genomic insertions. MEMORY cells can achieve programmable and permanent gain (or loss) of functions extrachromosomally or from a specific genomic locus, without the loss or modification of the MEMORY platform - enabling the sequential programming and reprogramming of DNA circuits within the cell. We demonstrate all three tenets of intelligence via a probiotic (Nissle 1917) MEMORY strain capable of information exchange with the gastrointestinal commensal Bacteroides thetaiotaomicron.
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Affiliation(s)
- Brian D Huang
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, GA, 30332-0100, Georgia
| | - Dowan Kim
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, GA, 30332-0100, Georgia
| | - Yongjoon Yu
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, GA, 30332-0100, Georgia
| | - Corey J Wilson
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, GA, 30332-0100, Georgia.
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6
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Xu Y, Crowe KB, Lieske PL, Barnes M, Bandara K, Chu J, Wei W, Scarcelli JJ, Zhang L. A high-fidelity, dual site-specific integration system in CHO cells by a Bxb1 recombinase. Biotechnol J 2024; 19:e2300410. [PMID: 38375559 DOI: 10.1002/biot.202300410] [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: 08/14/2023] [Revised: 11/16/2023] [Accepted: 12/06/2023] [Indexed: 02/21/2024]
Abstract
Site-specific integration (SSI) via recombinase mediated cassette exchange (RMCE) has shown advantages over random integration methods for expression of biotherapeutics. As an extension of our previous work developing SSI host cells, we developed a dual-site SSI system having two independent integration sites at different genomic loci, each containing a unique landing pad (LP). This system was leveraged to generate and compare two RMCE hosts, one (dFRT) compatible with the Flp recombinase, the other (dBxb1) compatible with the Bxb1 recombinase. Our comparison demonstrated that the dBxb1 host was able to generate stable transfectant pools in a shorter time frame, and cells within the dBxb1 transfectant pools were more phenotypically and genotypically stable. We further improved process performance of the dBxb1 host, resulting in desired fed batch performance attributes. Clones derived from this improved host (referred as 41L-11) maintained stable expression profiles over extended generations. While the data represents a significant improvement in the efficiency of our cell line development process, the dual LP architecture also affords a high degree of flexibility for development of complex protein modalities.
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Affiliation(s)
- Yifeng Xu
- Cell Line Development, Bioprocess R&D, Biotherapeutics Pharmaceutical Science, Pfizer Inc, Andover, Massachusetts, USA
| | - Kerstin B Crowe
- Cell Line Development, Bioprocess R&D, Biotherapeutics Pharmaceutical Science, Pfizer Inc, Andover, Massachusetts, USA
| | - Paulena L Lieske
- Cell Line Development, Bioprocess R&D, Biotherapeutics Pharmaceutical Science, Pfizer Inc, Andover, Massachusetts, USA
| | - Michael Barnes
- Cell Line Development, Bioprocess R&D, Biotherapeutics Pharmaceutical Science, Pfizer Inc, Andover, Massachusetts, USA
| | - Kalpanie Bandara
- Cell Line Development, Bioprocess R&D, Biotherapeutics Pharmaceutical Science, Pfizer Inc, Andover, Massachusetts, USA
| | - Jianlin Chu
- Cell Line Development, Bioprocess R&D, Biotherapeutics Pharmaceutical Science, Pfizer Inc, Andover, Massachusetts, USA
| | - Wei Wei
- Cell Line Development, Bioprocess R&D, Biotherapeutics Pharmaceutical Science, Pfizer Inc, Andover, Massachusetts, USA
| | - John J Scarcelli
- Cell Line Development, Bioprocess R&D, Biotherapeutics Pharmaceutical Science, Pfizer Inc, Andover, Massachusetts, USA
| | - Lin Zhang
- Cell Line Development, Bioprocess R&D, Biotherapeutics Pharmaceutical Science, Pfizer Inc, Andover, Massachusetts, USA
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7
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Žedaveinytė R, Meers C, Le HC, Mortman EE, Tang S, Lampe GD, Pesari SR, Gelsinger DR, Wiegand T, Sternberg SH. Antagonistic conflict between transposon-encoded introns and guide RNAs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.20.567912. [PMID: 38045383 PMCID: PMC10690162 DOI: 10.1101/2023.11.20.567912] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
TnpB nucleases represent the evolutionary precursors to CRISPR-Cas12 and are widespread in all domains of life, presumably due to the critical roles they play in transposon proliferation. IS605family TnpB homologs function in bacteria as programmable homing endonucleases by exploiting transposon-encoded guide RNAs to cleave vacant genomic sites, thereby driving transposon maintenance through DSB-stimulated homologous recombination. Whether this pathway is conserved in other genetic contexts, and in association with other transposases, is unknown. Here we uncover molecular mechanisms of transposition and RNA-guided DNA cleavage by IS607-family elements that, remarkably, also encode catalytic, self-splicing group I introns. After reconstituting and systematically investigating each of these biochemical activities for a candidate 'IStron' derived from Clostridium botulinum, we discovered sequence and structural features of the transposon-encoded RNA that satisfy molecular requirements of a group I intron and TnpB guide RNA, while still retaining the ability to be faithfully mobilized at the DNA level by the TnpA transposase. Strikingly, intron splicing was strongly repressed not only by TnpB, but also by the secondary structure of ωRNA alone, allowing the element to carefully control the relative levels of spliced products versus functional guide RNAs. Our results suggest that IStron transcripts have evolved a sensitive equilibrium to balance competing and mutually exclusive activities that promote transposon maintenance while limiting adverse fitness costs on the host. Collectively, this work explains how diverse enzymatic activities emerged during the selfish spread of IS607-family elements and highlights molecular innovation in the multi-functional utility of transposon-encoded noncoding RNAs.
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Affiliation(s)
- Rimantė Žedaveinytė
- Department of Biochemistry and Molecular Biophysics, Columbia University; New York, NY 10032, USA
| | - Chance Meers
- Department of Biochemistry and Molecular Biophysics, Columbia University; New York, NY 10032, USA
| | - Hoang C. Le
- Department of Biochemistry and Molecular Biophysics, Columbia University; New York, NY 10032, USA
| | - Edan E. Mortman
- Department of Genetics and Development, Columbia University; New York, NY 10032, USA
| | - Stephen Tang
- Department of Biochemistry and Molecular Biophysics, Columbia University; New York, NY 10032, USA
| | - George D. Lampe
- Department of Biochemistry and Molecular Biophysics, Columbia University; New York, NY 10032, USA
| | - Sanjana R. Pesari
- Department of Biochemistry and Molecular Biophysics, Columbia University; New York, NY 10032, USA
- Present address: Biochemistry and Molecular Biophysics Program, University of California, San Diego, CA, USA
| | - Diego R. Gelsinger
- Department of Biochemistry and Molecular Biophysics, Columbia University; New York, NY 10032, USA
| | - Tanner Wiegand
- Department of Biochemistry and Molecular Biophysics, Columbia University; New York, NY 10032, USA
| | - Samuel H. Sternberg
- Department of Biochemistry and Molecular Biophysics, Columbia University; New York, NY 10032, USA
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8
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Roelle S, Kamath ND, Matreyek KA. Mammalian Genomic Manipulation with Orthogonal Bxb1 DNA Recombinase Sites for the Functional Characterization of Protein Variants. ACS Synth Biol 2023; 12:3352-3365. [PMID: 37922210 PMCID: PMC10661055 DOI: 10.1021/acssynbio.3c00355] [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: 06/10/2023] [Revised: 09/22/2023] [Accepted: 10/19/2023] [Indexed: 11/05/2023]
Abstract
The Bxb1 bacteriophage serine DNA recombinase is an efficient tool for engineering recombinant DNA into the genomes of cultured cells. Generally, a single engineered "landing pad" site is introduced into the cell genome, permitting the integration of transgenic circuits or libraries of transgene variants. While sufficient for many studies, the extent of genetic manipulation possible with a single recombinase site is limiting and insufficient for more complex cell-based assays. Here, we harnessed two orthogonal Bxb1 recombinase sites to enable alternative avenues for using mammalian synthetic biology to characterize transgenic protein variants. By designing plasmids flanked by a second pair of auxiliary recombination sites, we demonstrate that we can avoid the genomic integration of undesirable bacterial DNA elements using the same starting cells engineered for whole-plasmid integration. We also created "double landing pad" cells simultaneously harboring two orthogonal Bxb1 recombinase sites at separate genomic loci, allowing complex cell-based genetic assays. Integration of a genetically encoded calcium indicator allowed for the real-time monitoring of intracellular calcium signaling dynamics, including kinetic perturbations that occur upon overexpression of the wild-type or variant version of the calcium signaling relay protein STIM1. A panel of missense mutants of the HIV-1 accessory protein Vif was paired with various paralogs within the human Apobec3 innate immune protein family to identify combinations capable or incapable of interacting within cells. These cells allow transgenic protein variant libraries to be readily paired with assay-specific protein partners or biosensors, enabling new functional readouts for large-scale genetic assays for protein function.
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Affiliation(s)
- Sarah
M. Roelle
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, United States
| | - Nisha D. Kamath
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, United States
| | - Kenneth A. Matreyek
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, United States
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9
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Short AE, Kim D, Milner PT, Wilson CJ. Next generation synthetic memory via intercepting recombinase function. Nat Commun 2023; 14:5255. [PMID: 37644045 PMCID: PMC10465543 DOI: 10.1038/s41467-023-41043-w] [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: 04/19/2023] [Accepted: 08/22/2023] [Indexed: 08/31/2023] Open
Abstract
Here we present a technology to facilitate synthetic memory in a living system via repurposing Transcriptional Programming (i.e., our decision-making technology) parts, to regulate (intercept) recombinase function post-translation. We show that interception synthetic memory can facilitate programmable loss-of-function via site-specific deletion, programmable gain-of-function by way of site-specific inversion, and synthetic memory operations with nested Boolean logical operations. We can expand interception synthetic memory capacity more than 5-fold for a single recombinase, with reconfiguration specificity for multiple sites in parallel. Interception synthetic memory is ~10-times faster than previous generations of recombinase-based memory. We posit that the faster recombination speed of our next-generation memory technology is due to the post-translational regulation of recombinase function. This iteration of synthetic memory is complementary to decision-making via Transcriptional Programming - thus can be used to develop intelligent synthetic biological systems for myriad applications.
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Affiliation(s)
- Andrew E Short
- Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, Atlanta, GA, USA
| | - Dowan Kim
- Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, Atlanta, GA, USA
| | - Prasaad T Milner
- Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, Atlanta, GA, USA
| | - Corey J Wilson
- Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, Atlanta, GA, USA.
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10
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Sun S, Zhang X. Genetic characteristics and integration specificity of Salmonella enterica temperate phages. Front Microbiol 2023; 14:1199843. [PMID: 37593543 PMCID: PMC10428622 DOI: 10.3389/fmicb.2023.1199843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 07/12/2023] [Indexed: 08/19/2023] Open
Abstract
Introduction Temperate phages can engage in the horizontal transfer of functional genes to their bacterial hosts. Thus, their genetic material becomes an intimate part of bacterial genomes and plays essential roles in bacterial mutation and evolution. Specifically, temperate phages can naturally transmit genes by integrating their genomes into the bacterial host genomes via integrases. Our previous study showed that Salmonella enterica contains the largest number of temperate phages among all publicly available bacterial species. S. enterica is an important pathogen that can cause serious systemic infections and even fatalities. Methods Initially, we extracted all S. enterica temperate phages from the extensively developed temperate phage database established in our previous study. Subsequently, we conducted an in-depth analysis of the genetic characteristics and integration specificity exhibited by these S. enterica temperate phages. Results Here we identified 8,777 S. enterica temperate phages, all of which have integrases in their genomes. We found 491 non-redundant S. enterica temperate phage integrases (integrase entries). S. enterica temperate phage integrases were classified into three types: intA, intS, and phiRv2. Correlation analysis showed that the sequence lengths of S. enterica integrase and core regions of attB and attP were strongly correlated. Further phylogenetic analysis and taxonomic classification indicated that both the S. enterica temperate phage genomes and the integrase gene sequences were of high diversities. Discussion Our work provides insight into the essential integration specificity and genetic diversity of S. enterica temperate phages. This study paves the way for a better understanding of the interactions between phages and S. enterica. By analyzing a large number of S. enterica temperate phages and their integrases, we provide valuable insights into the genetic diversity and prevalence of these elements. This knowledge has important implications for developing targeted therapeutic interventions, such as phage therapy, to combat S. enterica infections. By harnessing the lytic capabilities of temperate phages, they can be engineered or utilized in phage cocktails to specifically target and eradicate S. enterica strains, offering an alternative or complementary approach to traditional antibiotic treatments. Our study has implications for public health and holds potential significance in combating clinical infections caused by S. enterica.
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Affiliation(s)
- Siqi Sun
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- Department of Life Sciences and Technology, Beijing University of Chemical Technology, Chaoyang, Beijing, China
| | - Xianglilan Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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11
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Huhtinen O, Salbo R, Lamminmäki U, Prince S. Selection of biophysically favorable antibody variants using a modified Flp-In CHO mammalian display platform. Front Bioeng Biotechnol 2023; 11:1170081. [PMID: 37229492 PMCID: PMC10203562 DOI: 10.3389/fbioe.2023.1170081] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 04/17/2023] [Indexed: 05/27/2023] Open
Abstract
Mammalian display enables the selection of biophysically favorable antibodies from a large IgG antibody library displayed on the plasma membrane of mammalian cells. We constructed and validated a novel mammalian display platform utilizing the commercially available Flp-In CHO cell line as a starting point. We introduced a single copy of a landing pad for Bxb1 integrase-driven recombinase-mediated cassette exchange into the FRT site of the Flp-In CHO line to facilitate the efficient single-copy integration of an antibody display cassette into the genome of the cell line. We then proceeded to demonstrate the ability of our platform to select biophysically favorable antibodies from a library of 1 × 106 displayed antibodies designed to improve the biophysical properties of bococizumab via randomization of problematic hydrophobic surface residues of the antibody. Enrichment of bococizumab variants via fluorescence-activated cell sorting selections was followed by next generation sequencing and thorough characterization of biophysical properties of 10 bococizumab variants that subsequently allowed attribution of the mutations to the biophysical properties of the antibody variants. The mammalian displayed variants exhibited reduced aggregation propensity and polyreactivity, while critically retaining its target binding thereby demonstrating the utility of this valuable tool.
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Affiliation(s)
- Olli Huhtinen
- Protein and Antibody Engineering, Orion Corporation, Turku, Finland
- Department of Life Technologies, University of Turku, Turku, Finland
| | - Rune Salbo
- Protein and Antibody Engineering, Orion Corporation, Turku, Finland
| | - Urpo Lamminmäki
- Department of Life Technologies, University of Turku, Turku, Finland
| | - Stuart Prince
- MediCity Research Laboratory, University of Turku, Turku, Finland
- Institute of Biomedicine, University of Turku, Turku, Finland
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12
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Avidan N, Levy M, Daube SS, Bar-Ziv RH. Toward Memory in a DNA Brush: Site-Specific Recombination Responsive to Polymer Density, Orientation, and Conformation. J Am Chem Soc 2023; 145:9729-9736. [PMID: 37071757 PMCID: PMC10161217 DOI: 10.1021/jacs.3c01375] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
Site-specific recombination is a cellular process for the integration, inversion, and excision of DNA segments that could be tailored for memory transactions in artificial cells. Here, we demonstrate the compartmentalization of cascaded gene expression reactions in a DNA brush, starting from the cell-free synthesis of a unidirectional recombinase that exchanges information between two DNA molecules, leading to gene expression turn-on/turn-off. We show that recombination yield in the DNA brush was responsive to gene composition, density, and orientation, with kinetics faster than in a homogeneous dilute bulk solution reaction. Recombination yield scaled with a power law greater than 1 with respect to the fraction of recombining DNA polymers in a dense brush. The exponent approached either 1 or 2, depending on the intermolecular distance in the brush and the position of the recombination site along the DNA contour length, suggesting that a restricted-reach effect between the recombination sites governs the recombination yield. We further demonstrate the ability to encode the DNA recombinase in the same DNA brush with its substrate constructs, enabling multiple spatially resolved orthogonal recombination transactions within a common reaction volume. Our results highlight the DNA brush as a favorable compartment to study DNA recombination, with unique properties for encoding autonomous memory transactions in DNA-based artificial cells.
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Affiliation(s)
- Noa Avidan
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Michael Levy
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shirley S Daube
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Roy H Bar-Ziv
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, Rehovot 7610001, Israel
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13
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Durrant MG, Fanton A, Tycko J, Hinks M, Chandrasekaran SS, Perry NT, Schaepe J, Du PP, Lotfy P, Bassik MC, Bintu L, Bhatt AS, Hsu PD. Systematic discovery of recombinases for efficient integration of large DNA sequences into the human genome. Nat Biotechnol 2023; 41:488-499. [PMID: 36217031 PMCID: PMC10083194 DOI: 10.1038/s41587-022-01494-w] [Citation(s) in RCA: 51] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 09/01/2022] [Indexed: 11/09/2022]
Abstract
Large serine recombinases (LSRs) are DNA integrases that facilitate the site-specific integration of mobile genetic elements into bacterial genomes. Only a few LSRs, such as Bxb1 and PhiC31, have been characterized to date, with limited efficiency as tools for DNA integration in human cells. In this study, we developed a computational approach to identify thousands of LSRs and their DNA attachment sites, expanding known LSR diversity by >100-fold and enabling the prediction of their insertion site specificities. We tested their recombination activity in human cells, classifying them as landing pad, genome-targeting or multi-targeting LSRs. Overall, we achieved up to seven-fold higher recombination than Bxb1 and genome integration efficiencies of 40-75% with cargo sizes over 7 kb. We also demonstrate virus-free, direct integration of plasmid or amplicon libraries for improved functional genomics applications. This systematic discovery of recombinases directly from microbial sequencing data provides a resource of over 60 LSRs experimentally characterized in human cells for large-payload genome insertion without exposed DNA double-stranded breaks.
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Affiliation(s)
- Matthew G Durrant
- Arc Institute, Palo Alto, CA, USA
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, USA
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Alison Fanton
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, USA
- University of California, Berkeley-University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA, USA
| | - Josh Tycko
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Michaela Hinks
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Sita S Chandrasekaran
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, USA
- University of California, Berkeley-University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA, USA
| | - Nicholas T Perry
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, USA
- University of California, Berkeley-University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA, USA
| | - Julia Schaepe
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Peter P Du
- Department of Genetics, Stanford University, Stanford, CA, USA
- Cancer Biology Program, Stanford University, Stanford, CA, USA
| | - Peter Lotfy
- Laboratory of Molecular and Cell Biology, Salk Institute for Biological Studies, La Jolla, CA, USA
| | | | - Lacramioara Bintu
- Department of Bioengineering, Stanford University, Stanford, CA, USA.
| | - Ami S Bhatt
- Department of Genetics, Stanford University, Stanford, CA, USA.
- Department of Medicine (Hematology), Stanford University, Stanford, CA, USA.
| | - Patrick D Hsu
- Arc Institute, Palo Alto, CA, USA.
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, USA.
- Laboratory of Molecular and Cell Biology, Salk Institute for Biological Studies, La Jolla, CA, USA.
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA.
- Center for Computational Biology, University of California, Berkeley, Berkeley, CA, USA.
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14
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Yarnall MTN, Ioannidi EI, Schmitt-Ulms C, Krajeski RN, Lim J, Villiger L, Zhou W, Jiang K, Garushyants SK, Roberts N, Zhang L, Vakulskas CA, Walker JA, Kadina AP, Zepeda AE, Holden K, Ma H, Xie J, Gao G, Foquet L, Bial G, Donnelly SK, Miyata Y, Radiloff DR, Henderson JM, Ujita A, Abudayyeh OO, Gootenberg JS. Drag-and-drop genome insertion of large sequences without double-strand DNA cleavage using CRISPR-directed integrases. Nat Biotechnol 2023; 41:500-512. [PMID: 36424489 PMCID: PMC10257351 DOI: 10.1038/s41587-022-01527-4] [Citation(s) in RCA: 122] [Impact Index Per Article: 122.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 09/23/2022] [Indexed: 11/26/2022]
Abstract
Programmable genome integration of large, diverse DNA cargo without DNA repair of exposed DNA double-strand breaks remains an unsolved challenge in genome editing. We present programmable addition via site-specific targeting elements (PASTE), which uses a CRISPR-Cas9 nickase fused to both a reverse transcriptase and serine integrase for targeted genomic recruitment and integration of desired payloads. We demonstrate integration of sequences as large as ~36 kilobases at multiple genomic loci across three human cell lines, primary T cells and non-dividing primary human hepatocytes. To augment PASTE, we discovered 25,614 serine integrases and cognate attachment sites from metagenomes and engineered orthologs with higher activity and shorter recognition sequences for efficient programmable integration. PASTE has editing efficiencies similar to or exceeding those of homology-directed repair and non-homologous end joining-based methods, with activity in non-dividing cells and in vivo with fewer detectable off-target events. PASTE expands the capabilities of genome editing by allowing large, multiplexed gene insertion without reliance on DNA repair pathways.
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Affiliation(s)
- Matthew T N Yarnall
- McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Eleonora I Ioannidi
- McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA, USA
- ETH Zürich, Zürich, Switzerland
| | - Cian Schmitt-Ulms
- McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Rohan N Krajeski
- McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Justin Lim
- McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Lukas Villiger
- McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Wenyuan Zhou
- McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kaiyi Jiang
- McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sofya K Garushyants
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | | | - Liyang Zhang
- Integrated DNA Technologies, Coralville, IA, USA
| | | | | | | | | | | | - Hong Ma
- University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Jun Xie
- University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Guangping Gao
- University of Massachusetts Chan Medical School, Worcester, MA, USA
| | | | - Greg Bial
- Yecuris Corporation, Tualatin, OR, USA
| | | | | | | | | | | | - Omar O Abudayyeh
- McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Jonathan S Gootenberg
- McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA, USA.
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15
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Pandey A, Rodriguez ML, Poole W, Murray RM. Characterization of Integrase and Excisionase Activity in a Cell-Free Protein Expression System Using a Modeling and Analysis Pipeline. ACS Synth Biol 2023; 12:511-523. [PMID: 36715625 DOI: 10.1021/acssynbio.2c00534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We present a full-stack modeling, analysis, and parameter identification pipeline to guide the modeling and design of biological systems starting from specifications to circuit implementations and parametrizations. We demonstrate this pipeline by characterizing the integrase and excisionase activity in a cell-free protein expression system. We build on existing Python tools─BioCRNpyler, AutoReduce, and Bioscrape─to create this pipeline. For enzyme-mediated DNA recombination in a cell-free system, we create detailed chemical reaction network models from simple high-level descriptions of the biological circuits and their context using BioCRNpyler. We use Bioscrape to show that the output of the detailed model is sensitive to many parameters. However, parameter identification is infeasible for this high-dimensional model; hence, we use AutoReduce to automatically obtain reduced models that have fewer parameters. This results in a hierarchy of reduced models under different assumptions to finally arrive at a minimal ODE model for each circuit. Then, we run sensitivity analysis-guided Bayesian inference using Bioscrape for each circuit to identify the model parameters. This process allows us to quantify integrase and excisionase activity in cell extracts enabling complex-circuit designs that depend on accurate control over protein expression levels through DNA recombination. The automated pipeline presented in this paper opens up a new approach to complex circuit design, modeling, reduction, and parametrization.
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Affiliation(s)
- Ayush Pandey
- Control and Dynamical Systems, California Institute of Technology, Pasadena, California91125, United States
| | - Makena L Rodriguez
- Biology and Biological Engineering, California Institute of Technology, Pasadena, California91125, United States
| | - William Poole
- Altos Laboratories, Redwood City, California94065, United States
| | - Richard M Murray
- Control and Dynamical Systems, California Institute of Technology, Pasadena, California91125, United States.,Biology and Biological Engineering, California Institute of Technology, Pasadena, California91125, United States
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16
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Li R, Han Z, Yin Q, Li M, Zhang M, Li Z, Wang P, Jiang L, Ow DW. Target Lines for in Planta Gene Stacking in Japonica Rice. Int J Mol Sci 2022; 23:ijms23169385. [PMID: 36012650 PMCID: PMC9409015 DOI: 10.3390/ijms23169385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/11/2022] [Accepted: 08/11/2022] [Indexed: 12/02/2022] Open
Abstract
The clustering of transgenes at a chromosome location minimizes the number of segregating loci that needs to be introgressed to field cultivars. Transgenes could be efficiently stacked through site-specific recombination and a recombinase-mediated in planta gene stacking process was described previously in tobacco based on the Mycobacteriophage Bxb1 site-specific integration system. Since this process requires a recombination site in the genome, this work describes the generation of target sites in the Japonica rice genome. Agrobacterium-mediated gene transfer yielded ~4000 random-insertion lines. Seven lines met the criteria of being single copy, not close to a centromere, not inserted within or close to a known gene or repetitive DNA, having precise recombination site sequences on both ends, and able to express the reporter gene. Each target line tested was able to accept the site-specific integration of a new gfp-containing plasmid and in three of those lines, we regenerated fertile plants. These target lines could be used as foundation lines for stacking new traits into Japonica rice.
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Affiliation(s)
- Ruyu Li
- Plant Gene Engineering Center, Chinese Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- Correspondence: (R.L.); (D.W.O.)
| | - Zhiguo Han
- Plant Gene Engineering Center, Chinese Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Qian Yin
- Plant Gene Engineering Center, Chinese Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Meiru Li
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Mingyong Zhang
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Zhenzhen Li
- Plant Gene Engineering Center, Chinese Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Ping Wang
- Plant Gene Engineering Center, Chinese Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Li Jiang
- Plant Gene Engineering Center, Chinese Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - David W. Ow
- Plant Gene Engineering Center, Chinese Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- Correspondence: (R.L.); (D.W.O.)
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17
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Abstract
Mycobacteriophages-bacteriophages infecting Mycobacterium hosts-contribute substantially to our understanding of viral diversity and evolution, provide resources for advancing Mycobacterium genetics, are the basis of high-impact science education programs, and show considerable therapeutic potential. Over 10,000 individual mycobacteriophages have been isolated by high school and undergraduate students using the model organism Mycobacterium smegmatis mc2155 and 2,100 have been completely sequenced, giving a high-resolution view of the phages that infect a single common host strain. The phage genomes are revealed to be highly diverse and architecturally mosaic and are replete with genes of unknown function. Mycobacteriophages have provided many widely used tools for Mycobacterium genetics including integration-proficient vectors and recombineering systems, as well as systems for efficient delivery of reporter genes, transposons, and allelic exchange substrates. The genomic insights and engineering tools have facilitated exploration of phages for treatment of Mycobacterium infections, although their full therapeutic potential has yet to be realized.
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18
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Zhao Y, Wang W, Yao J, Wang X, Liu D, Wang P. The HipAB Toxin-Antitoxin System Stabilizes a Composite Genomic Island in Shewanella putrefaciens CN-32. Front Microbiol 2022; 13:858857. [PMID: 35387082 PMCID: PMC8978831 DOI: 10.3389/fmicb.2022.858857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 02/24/2022] [Indexed: 11/25/2022] Open
Abstract
Composite genomic islands (GIs) are useful models for studying GI evolution if they can revert into the previous components. In this study, CGI48—a 48,135-bp native composite GI that carries GI21, whose homologies specifically integrated in the conserved yicC gene—were identified in Shewanella putrefaciens CN-32. CGI48 was integrated into the tRNATrp gene, which is a conserved gene locus for the integration of genomic islands in Shewanella. Upon expressing integrase and excisionase, CGI48 and GI21 are excised from chromosomes via site-specific recombination. The shorter attachment sites of GI21 facilitated the capture of GI21 into CGI48. Moreover, GI21 encodes a functional HipAB toxin–antitoxin system, thus contributing to the maintenance of CGI48 in the host bacteria. This study provides new insights into GI evolution by performing the excision process of the inserting GI and improves our understanding of the maintenance mechanisms of composite GI.
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Affiliation(s)
- Yi Zhao
- College of Life Sciences, Hebei Normal University, Shijiazhuang, China
| | - Weiquan Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jianyun Yao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Xiaoxue Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Dong Liu
- College of Life Sciences, Hebei Normal University, Shijiazhuang, China
| | - Pengxia Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
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19
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Jiang L, Li R, Han Z, Zhao X, Cao D, Ow DW. Target lines for recombinase-mediated gene stacking in soybean. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2022; 135:1163-1175. [PMID: 35325256 DOI: 10.1007/s00122-021-04015-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/06/2021] [Indexed: 05/10/2023]
Abstract
KEY MESSAGE Five soybean target lines with recombinase sites at suitable genomic positions were obtained and tested for site-specific gene stacking. For introgression of new transgenic traits to field cultivars, adding new DNA to an existing transgene locus would reduce the number of segregating loci to reassemble back into a breeding line. We described previously an in planta transgene stacking system using the Bxb1 integrase to direct new DNA into a genomic target, but for this system to operate, the target locus must have a preexisting recombination site for Bxb1-mediated integration. Here, we describe 5 soybean target lines from the screening of 118 Agrobacterium-mediated transgenic plants that were positive for gus expression. Each of the 5 target lines has a single copy of the transgenic DNA with precise DNA sequences of the recombinase recognition sites, located at least 1 kb away from the nearest coding region, not close to the centromere, and showed good expression of the reporter gene. We tested Bxb1 integrase-mediated integration of a gfp-containing plasmid into each of these lines and showed precise site-specific integration in bombarded calluses. For plant regeneration, we used embryonic axes of mature soybean seeds to conduct a new set of biolistic transformation with a DsRed-containing plasmid. Three integration events were regenerated into whole plants, demonstrating the principle that target lines can serve as foundation lines for the stacking of DNA to predefined locations in the soybean genome.
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Affiliation(s)
- Li Jiang
- Plant Gene Engineering Center; Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing, 100049, China
| | - Ruyu Li
- Plant Gene Engineering Center; Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
| | - Zhiguo Han
- Plant Gene Engineering Center; Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Xiaohui Zhao
- The Innovative Academy of Seed Design, Key Laboratory of Soybean Molecular Design Breeding, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081, China
| | - Dong Cao
- The Innovative Academy of Seed Design, Key Laboratory of Soybean Molecular Design Breeding, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, 150081, China
| | - David W Ow
- Plant Gene Engineering Center; Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
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20
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Efficient targeted transgenesis of large donor DNA into multiple mouse genetic backgrounds using bacteriophage Bxb1 integrase. Sci Rep 2022; 12:5424. [PMID: 35361849 PMCID: PMC8971409 DOI: 10.1038/s41598-022-09445-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 03/23/2022] [Indexed: 12/12/2022] Open
Abstract
The development of mouse models of human disease and synthetic biology research by targeted transgenesis of large DNA constructs represent a significant genetic engineering hurdle. We developed an efficient, precise, single-copy integration of large transgenes directly into zygotes using multiple mouse genetic backgrounds. We used in vivo Bxb1 mediated recombinase-mediated cassette exchange (RMCE) with a transgene “landing pad” composed of dual heterologous Bxb1 attachment (att) sites in cis, within the Gt(ROSA)26Sor safe harbor locus. RMCE of donor was achieved by microinjection of vector DNA carrying cognate attachment sites flanking the donor transgene with Bxb1-integrase mRNA. This approach achieves perfect vector-free integration of donor constructs at efficiencies > 40% with up to ~ 43 kb transgenes. Coupled with a nanopore-based Cas9-targeted sequencing (nCATS), complete verification of precise insertion sequence was achieved. As a proof-of-concept we describe the development of C57BL/6J and NSG Krt18-ACE2 models for SARS-CoV2 research with verified heterozygous N1 animals within ~ 4 months. Additionally, we created a series of mice with diverse backgrounds carrying a single att site including FVB/NJ, PWK/PhJ, NOD/ShiLtJ, CAST/EiJ and DBA/2J allowing for rapid transgene insertion. Combined, this system enables predictable, rapid development with simplified characterization of precisely targeted transgenic animals across multiple genetic backgrounds.
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21
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Li Y, Li R, Han Z, Wang H, Zhou S, Li Y, Wang Y, Qi J, Ow DW. Recombinase-mediated gene stacking in cotton. PLANT PHYSIOLOGY 2022; 188:1852-1865. [PMID: 35088863 PMCID: PMC8968315 DOI: 10.1093/plphys/kiac005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 12/08/2021] [Indexed: 05/24/2023]
Abstract
Site-specific gene stacking could reduce the number of segregating loci and expedite the introgression of transgenes from experimental lines to field lines. Recombinase-mediated site-specific gene stacking provides a flexible and efficient solution, but this approach requires a recombinase recognition site in the genome. Here, we describe several cotton (Gossypium hirsutum cv. Coker 312) target lines suitable for Mycobacteriophage Bxb1 recombinase-mediated gene stacking. Obtained through the empirical screening of random insertion events, each of these target lines contains a single intact copy of the target construct with precise sequences of RS2, lox, and attP sites that is not inserted within or close to a known gene or near a centromere and shows good expression of the reporter gene gfp. Gene stacking was tested with insertion of different combinations of three candidate genes for resistance to verticillium wilt into three cotton target lines: CTS1, CTS3, and CTS4. Nine site-specific integration events were recovered from 95 independently transformed embryogenic calluses. Southern and DNA sequence analyses of regenerated plants confirmed precise site-specific integration, and resistance to verticillium wilt was observed for plant CTS1i3, which has a single precise copy of site-specifically integrated DNA. These cotton target lines can serve as foundation lines for recombinase-mediated gene stacking to facilitate precise DNA integration and introgression to field cultivars.
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Affiliation(s)
- Yamei Li
- Plant Gene Engineering Center, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ruyu Li
- Plant Gene Engineering Center, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Zhiguo Han
- Plant Gene Engineering Center, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Haitang Wang
- Plant Gene Engineering Center, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Sixian Zhou
- Plant Gene Engineering Center, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yongqing Li
- Plant Gene Engineering Center, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Yumei Wang
- Plant Gene Engineering Center, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junsheng Qi
- Department of Plant Science, State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
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22
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Control of the Serine Integrase Reaction: Roles of the Coiled-Coil and Helix E Regions in DNA Site Synapsis and Recombination. J Bacteriol 2021; 203:e0070320. [PMID: 34060907 DOI: 10.1128/jb.00703-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Bacteriophage serine integrases catalyze highly specific recombination reactions between defined DNA segments called att sites. These reactions are reversible depending upon the presence of a second phage-encoded directionality factor. The bipartite C-terminal DNA-binding region of integrases includes a recombinase domain (RD) connected to a zinc-binding domain (ZD), which contains a long flexible coiled-coil (CC) motif that extends away from the bound DNA. We directly show that the identities of the phage A118 integrase att sites are specified by the DNA spacing between the RD and ZD DNA recognition determinants, which in turn directs the relative trajectories of the CC motifs on each subunit of the att-bound integrase dimer. Recombination between compatible dimer-bound att sites requires minimal-length CC motifs and 14 residues surrounding the tip where the pairing of CC motifs between synapsing dimers occurs. Our alanine-scanning data suggest that molecular interactions between CC motif tips may differ in integrative (attP × attB) and excisive (attL × attR) recombination reactions. We identify mutations in 5 residues within the integrase oligomerization helix that control the remodeling of dimers into tetramers during synaptic complex formation. Whereas most of these gain-of-function mutants still require the CC motifs for synapsis, one mutant efficiently, but indiscriminately, forms synaptic complexes without the CC motifs. However, the CC motifs are still required for recombination, suggesting a function for the CC motifs after the initial assembly of the integrase synaptic tetramer. IMPORTANCE The robust and exquisitely regulated site-specific recombination reactions promoted by serine integrases are integral to the life cycle of temperate bacteriophage and, in the case of the A118 prophage, are an important virulence factor of Listeria monocytogenes. The properties of these recombinases have led to their repurposing into tools for genetic engineering and synthetic biology. In this report, we identify determinants regulating synaptic complex formation between correct DNA sites, including the DNA architecture responsible for specifying the identity of recombination sites, features of the unique coiled-coil structure on the integrase that are required to initiate synapsis, and amino acid residues on the integrase oligomerization helix that control the remodeling of synapsing dimers into a tetramer active for DNA strand exchange.
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23
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Chow KHK, Budde MW, Granados AA, Cabrera M, Yoon S, Cho S, Huang TH, Koulena N, Frieda KL, Cai L, Lois C, Elowitz MB. Imaging cell lineage with a synthetic digital recording system. Science 2021; 372:eabb3099. [PMID: 33833095 DOI: 10.1126/science.abb3099] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 02/25/2021] [Indexed: 12/13/2022]
Abstract
During multicellular development, spatial position and lineage history play powerful roles in controlling cell fate decisions. Using a serine integrase-based recording system, we engineered cells to record lineage information in a format that can be read out in situ. The system, termed integrase-editable memory by engineered mutagenesis with optical in situ readout (intMEMOIR), allowed in situ reconstruction of lineage relationships in cultured mouse cells and flies. intMEMOIR uses an array of independent three-state genetic memory elements that can recombine stochastically and irreversibly, allowing up to 59,049 distinct digital states. It reconstructed lineage trees in stem cells and enabled simultaneous analysis of single-cell clonal history, spatial position, and gene expression in Drosophila brain sections. These results establish a foundation for microscopy-readable lineage recording and analysis in diverse systems.
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Affiliation(s)
- Ke-Huan K Chow
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Mark W Budde
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Alejandro A Granados
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Maria Cabrera
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Shinae Yoon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Soomin Cho
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Ting-Hao Huang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Noushin Koulena
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | | | - Long Cai
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Carlos Lois
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Michael B Elowitz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
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24
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Fan HF, Su BY, Ma CH, Rowley PA, Jayaram M. A bipartite thermodynamic-kinetic contribution by an activating mutation to RDF-independent excision by a phage serine integrase. Nucleic Acids Res 2020; 48:6413-6430. [PMID: 32479633 PMCID: PMC7337939 DOI: 10.1093/nar/gkaa401] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 05/02/2020] [Accepted: 05/08/2020] [Indexed: 12/11/2022] Open
Abstract
Streptomyces phage ϕC31 integrase (Int)—a large serine site-specific recombinase—is autonomous for phage integration (attP x attB recombination) but is dependent on the phage coded gp3, a recombination directionality factor (RDF), for prophage excision (attL x attR recombination). A previously described activating mutation, E449K, induces Int to perform attL x attR recombination in the absence of gp3, albeit with lower efficiency. E449K has no adverse effect on the competence of Int for attP x attB recombination. Int(E449K) resembles Int in gp3 mediated stimulation of attL x attR recombination and inhibition of attP x attB recombination. Using single-molecule analyses, we examined the mechanism by which E449K activates Int for gp3-independent attL x attR recombination. The contribution of E449K is both thermodynamic and kinetic. First, the mutation modulates the relative abundance of Int bound attL-attR site complexes, favoring pre-synaptic (PS) complexes over non-productively bound complexes. Roughly half of the synaptic complexes formed from Int(E449K) pre-synaptic complexes are recombination competent. By contrast, Int yields only inactive synapses. Second, E449K accelerates the dissociation of non-productively bound complexes and inactive synaptic complexes formed by Int. The extra opportunities afforded to Int(E499K) in reattempting synapse formation enhances the probability of success at fruitful synapsis.
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Affiliation(s)
- Hsiu-Fang Fan
- Institute of Medical Science and Technology, National Sun Yat-sen University, Sizihwan, Kaohsiung 804, Taiwan.,Department of Chemistry, National Sun Yat-sen University, Sizihwan, Kaohsiung 804, Taiwan.,Aerosol Science Research Center, National Sun Yat-sen University, Sizihwan, Kaohsiung 804, Taiwan
| | - Bo-Yu Su
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei 112, Taiwan
| | - Chien-Hui Ma
- Department of Molecular Biosciences, UT Austin, Austin, TX 78712, USA
| | - Paul A Rowley
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Makkuni Jayaram
- Department of Molecular Biosciences, UT Austin, Austin, TX 78712, USA
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25
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Gao H, Taylor G, Evans SK, Fogg PCM, Smith MCM. Application of serine integrases for secondary metabolite pathway assembly in Streptomyces. Synth Syst Biotechnol 2020; 5:111-119. [PMID: 32596521 PMCID: PMC7306541 DOI: 10.1016/j.synbio.2020.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 05/27/2020] [Accepted: 05/28/2020] [Indexed: 11/29/2022] Open
Abstract
Serine integrases have been shown to be efficient tools for metabolic pathway assembly. To further improve the flexibility and efficiency of pathway engineering via serine integrases, we explored how multiple orthogonally active serine integrases can be applied for use in vitro for the heterologous expression of complex biosynthesis pathways in Streptomyces spp., the major producers of useful bioactive natural products. The results show that multiple orthogonal serine integrases efficiently assemble the genes from a complex biosynthesis pathway in a single in vitro recombination reaction, potentially permitting a versatile combinatorial assembly approach. Furthermore, the assembly strategy also permitted the incorporation of a well-characterised promoter upstream of each gene for expression in a heterologous host. The results demonstrate how site-specific recombination based on orthogonal serine integrases can be applied in Streptomyces spp.
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Affiliation(s)
- Hong Gao
- Department of Biology, University of York, York, YO10 5DD, United Kingdom
| | - Gabrielle Taylor
- Department of Biology, University of York, York, YO10 5DD, United Kingdom
| | - Stephanie K Evans
- Department of Biology, University of York, York, YO10 5DD, United Kingdom
| | - Paul C M Fogg
- Department of Biology, University of York, York, YO10 5DD, United Kingdom
| | - Margaret C M Smith
- Department of Biology, University of York, York, YO10 5DD, United Kingdom
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26
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Borgers K, Vandewalle K, Festjens N, Callewaert N. A guide to Mycobacterium mutagenesis. FEBS J 2019; 286:3757-3774. [PMID: 31419030 DOI: 10.1111/febs.15041] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 07/05/2019] [Accepted: 08/12/2019] [Indexed: 12/18/2022]
Abstract
The genus Mycobacterium includes several pathogens that cause severe disease in humans, like Mycobacterium tuberculosis (M. tb), the infectious agent causing tuberculosis. Genetic tools to engineer mycobacterial genomes, in a targeted or random fashion, have provided opportunities to investigate M. tb infection and pathogenesis. Furthermore, they have allowed the identification and validation of potential targets for the diagnosis, prevention, and treatment of tuberculosis. This review describes the various methods that are available for the generation of mutants in Mycobacterium species, focusing specifically on tools for altering slow-growing mycobacteria from the M. tb complex. Among others, it incorporates the recent new molecular biological technologies (e.g. ORBIT) to rapidly and/or genome-wide comprehensively obtain targeted mutants in mycobacteria. As such, this review can be used as a guide to select the appropriate genetic tools to generate mycobacterial mutants of interest, which can be used as tools to aid understanding of M. tb infection or to help developing TB intervention strategies.
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Affiliation(s)
- Katlyn Borgers
- VIB-UGhent Center for Medical Biotechnology, Belgium.,Department of Biochemistry and Microbiology, Ghent University, Belgium
| | - Kristof Vandewalle
- VIB-UGhent Center for Medical Biotechnology, Belgium.,Department of Biochemistry and Microbiology, Ghent University, Belgium
| | - Nele Festjens
- VIB-UGhent Center for Medical Biotechnology, Belgium.,Department of Biochemistry and Microbiology, Ghent University, Belgium
| | - Nico Callewaert
- VIB-UGhent Center for Medical Biotechnology, Belgium.,Department of Biochemistry and Microbiology, Ghent University, Belgium
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27
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Fogg PCM, Younger E, Fernando BD, Khaleel T, Stark WM, Smith MCM. Recombination directionality factor gp3 binds ϕC31 integrase via the zinc domain, potentially affecting the trajectory of the coiled-coil motif. Nucleic Acids Res 2019; 46:1308-1320. [PMID: 29228292 PMCID: PMC5814800 DOI: 10.1093/nar/gkx1233] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 11/29/2017] [Indexed: 11/24/2022] Open
Abstract
To establish a prophage state, the genomic DNA of temperate bacteriophages normally becomes integrated into the genome of their host bacterium by integrase-mediated, site-specific DNA recombination. Serine integrases catalyse a single crossover between an attachment site in the host (attB) and a phage attachment site (attP) on the circularized phage genome to generate the integrated prophage DNA flanked by recombinant attachment sites, attL and attR. Exiting the prophage state and entry into the lytic growth cycle requires an additional phage-encoded protein, the recombination directionality factor or RDF, to mediate recombination between attL and attR and excision of the phage genome. The RDF is known to bind integrase and switch its activity from integration (attP x attB) to excision (attL x attR) but its precise mechanism is unclear. Here, we identify amino acid residues in the RDF, gp3, encoded by the Streptomyces phage ϕC31 and within the ϕC31 integrase itself that affect the gp3:Int interaction. We show that residue substitutions in integrase that reduce gp3 binding adversely affect both excision and integration reactions. The mutant integrase phenotypes are consistent with a model in which the RDF binds to a hinge region at the base of the coiled-coil motif in ϕC31 integrase.
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Affiliation(s)
- Paul C M Fogg
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Ellen Younger
- Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Booshini D Fernando
- Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Thanafez Khaleel
- Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - W Marshall Stark
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, UK
| | - Margaret C M Smith
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.,Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen AB25 2ZD, UK
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28
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Bessen JL, Afeyan LK, Dančík V, Koblan LW, Thompson DB, Leichner C, Clemons PA, Liu DR. High-resolution specificity profiling and off-target prediction for site-specific DNA recombinases. Nat Commun 2019; 10:1937. [PMID: 31028261 PMCID: PMC6486577 DOI: 10.1038/s41467-019-09987-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/05/2019] [Indexed: 12/26/2022] Open
Abstract
The development of site-specific recombinases (SSRs) as genome editing agents is limited by the difficulty of altering their native DNA specificities. Here we describe Rec-seq, a method for revealing the DNA specificity determinants and potential off-target substrates of SSRs in a comprehensive and unbiased manner. We applied Rec-seq to characterize the DNA specificity determinants of several natural and evolved SSRs including Cre, evolved variants of Cre, and other SSR family members. Rec-seq profiling of these enzymes and mutants thereof revealed previously uncharacterized SSR interactions, including specificity determinants not evident from SSR:DNA structures. Finally, we used Rec-seq specificity profiles to predict off-target substrates of Tre and Brec1 recombinases, including endogenous human genomic sequences, and confirmed their ability to recombine these off-target sequences in human cells. These findings establish Rec-seq as a high-resolution method for rapidly characterizing the DNA specificity of recombinases with single-nucleotide resolution, and for informing their further development. The development of site-specific recombinases as genome editing tools is limited by the difficulty of altering their DNA sequence specificity. Here the authors present Rec-seq, a method for identifying specificity determinants and off-target substrates of recombinases in an unbiased manner.
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Affiliation(s)
- Jeffrey L Bessen
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.,Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
| | - Lena K Afeyan
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.,Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
| | - Vlado Dančík
- Chemical Biology and Therapeutics Science Program, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA
| | - Luke W Koblan
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.,Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
| | - David B Thompson
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.,Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
| | | | - Paul A Clemons
- Chemical Biology and Therapeutics Science Program, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA
| | - David R Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA. .,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA. .,Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA.
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29
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TP901-1 Phage Recombinase Facilitates Genome Engineering in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2019; 9:983-986. [PMID: 30696702 PMCID: PMC6469406 DOI: 10.1534/g3.119.0002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Molecular biology techniques have a large impact on biomedical research and the availability of diverse tools to perform genome manipulations advances the ease of executing complicated genetic research. Here, we introduce in the fruit fly another such tool by harnessing the phage recombinase TP901-1 to perform site-directed recombination that leads to recombinase-mediated cassette exchange (RMCE). The TP901-1 system complements already existing recombination systems and enhances genome engineering in the fruit fly and other organisms.
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30
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Jusiak B, Jagtap K, Gaidukov L, Duportet X, Bandara K, Chu J, Zhang L, Weiss R, Lu TK. Comparison of Integrases Identifies Bxb1-GA Mutant as the Most Efficient Site-Specific Integrase System in Mammalian Cells. ACS Synth Biol 2019; 8:16-24. [PMID: 30609349 DOI: 10.1021/acssynbio.8b00089] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Phage-derived integrases can catalyze irreversible, site-specific integration of transgenic payloads into a chromosomal locus, resulting in mammalian cells that stably express transgenes or circuits of interest. Previous studies have demonstrated high-efficiency integration by the Bxb1 integrase in mammalian cells. Here, we show that a point mutation (Bxb1-GA) in Bxb1 target sites significantly increases Bxb1-mediated integration efficiency at the Rosa26 locus in Chinese hamster ovary cells, resulting in the highest integration efficiency reported with a site-specific integrase in mammalian cells. Bxb1-GA point mutant sites do not cross-react with Bxb1 wild-type sites, enabling their use in applications that require orthogonal pairs of target sites. In comparison, we test the efficiency and orthogonality of ϕC31 and Wβ integrases, and show that Wβ has an integration efficiency between those of Bxb1-GA and wild-type Bxb1. Our data present a toolbox of integrases for inserting payloads such as gene circuits or therapeutic transgenes into mammalian cell lines.
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Affiliation(s)
- Barbara Jusiak
- Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kalpana Jagtap
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Leonid Gaidukov
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Xavier Duportet
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kalpanie Bandara
- Cell Line Development, Biotherapeutics Pharmaceutical Sciences, Pfizer Inc., Andover, Massachusetts 01810, United States
| | - Jianlin Chu
- Cell Line Development, Biotherapeutics Pharmaceutical Sciences, Pfizer Inc., Andover, Massachusetts 01810, United States
| | - Lin Zhang
- Cell Line Development, Biotherapeutics Pharmaceutical Sciences, Pfizer Inc., Andover, Massachusetts 01810, United States
| | - Ron Weiss
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Timothy K. Lu
- Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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31
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Murphy KC, Nelson SJ, Nambi S, Papavinasasundaram K, Baer CE, Sassetti CM. ORBIT: a New Paradigm for Genetic Engineering of Mycobacterial Chromosomes. mBio 2018; 9:e01467-18. [PMID: 30538179 PMCID: PMC6299477 DOI: 10.1128/mbio.01467-18] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/19/2018] [Indexed: 11/20/2022] Open
Abstract
Two efficient recombination systems were combined to produce a versatile method for chromosomal engineering that obviates the need to prepare double-stranded DNA (dsDNA) recombination substrates. A synthetic "targeting oligonucleotide" is incorporated into the chromosome via homologous recombination mediated by the phage Che9c RecT annealase. This oligonucleotide contains a site-specific recombination site for the directional Bxb1 integrase (Int), which allows the simultaneous integration of a "payload plasmid" that contains a cognate recombination site and a selectable marker. The targeting oligonucleotide and payload plasmid are cotransformed into a RecT- and Int-expressing strain, and drug-resistant homologous recombinants are selected in a single step. A library of reusable target-independent payload plasmids is available to generate gene knockouts, promoter replacements, or C-terminal tags. This new system is called ORBIT (for "oligonucleotide-mediated recombineering followed by Bxb1 integrase targeting") and is ideally suited for the creation of libraries consisting of large numbers of deletions, insertions, or fusions in a bacterial chromosome. We demonstrate the utility of this "drag and drop" strategy by the construction of insertions or deletions in over 100 genes in Mycobacteriumtuberculosis and M. smegmatisIMPORTANCE We sought to develop a system that could increase the usefulness of oligonucleotide-mediated recombineering of bacterial chromosomes by expanding the types of modifications generated by an oligonucleotide (i.e., insertions and deletions) and by making recombinant formation a selectable event. This paper describes such a system for use in M. smegmatis and M. tuberculosis By incorporating a single-stranded DNA (ssDNA) version of the phage Bxb1 attP site into the oligonucleotide and coelectroporating it with a nonreplicative plasmid that carries an attB site and a drug selection marker, we show both formation of a chromosomal attP site and integration of the plasmid in a single transformation. No target-specific dsDNA substrates are required. This system will allow investigators studying mycobacterial diseases, including tuberculosis, to easily generate multiple mutants for analysis of virulence factors, identification of new drug targets, and development of new vaccines.
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Affiliation(s)
- Kenan C Murphy
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Samantha J Nelson
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Subhalaxmi Nambi
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Kadamba Papavinasasundaram
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Christina E Baer
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Christopher M Sassetti
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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32
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Purcell O, Wang J, Siuti P, Lu TK. Encryption and steganography of synthetic gene circuits. Nat Commun 2018; 9:4942. [PMID: 30467337 PMCID: PMC6250736 DOI: 10.1038/s41467-018-07144-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/10/2018] [Indexed: 12/29/2022] Open
Abstract
Synthetic biologists use artificial gene circuits to control and engineer living cells. As engineered cells become increasingly commercialized, it will be desirable to protect the intellectual property contained in these circuits. Here, we introduce strategies to hide the design of synthetic gene circuits, making it more difficult for an unauthorized third party to determine circuit structure and function. We present two different approaches: the first uses encryption by overlapping uni-directional recombinase sites to scramble circuit topology and the second uses steganography by adding genes and interconnections to obscure circuit topology. We also discuss a third approach: to use synthetic genetic codes to mask the function of synthetic circuits. For each approach, we discuss relative strengths, weaknesses, and practicality of implementation, with the goal to inspire further research into this important and emerging area.
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Affiliation(s)
- Oliver Purcell
- Synthetic Biology Center, Massachusetts Institute of Technology, 500 Technology Square, Cambridge, MA, 02139, USA
| | - Jerry Wang
- Synthetic Biology Center, Massachusetts Institute of Technology, 500 Technology Square, Cambridge, MA, 02139, USA
| | - Piro Siuti
- Synthetic Biology Center, Massachusetts Institute of Technology, 500 Technology Square, Cambridge, MA, 02139, USA
| | - Timothy K Lu
- Synthetic Biology Center, Massachusetts Institute of Technology, 500 Technology Square, Cambridge, MA, 02139, USA. .,Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA. .,Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
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33
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Li H, Sharp R, Rutherford K, Gupta K, Van Duyne GD. Serine Integrase attP Binding and Specificity. J Mol Biol 2018; 430:4401-4418. [PMID: 30227134 DOI: 10.1016/j.jmb.2018.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/07/2018] [Accepted: 09/11/2018] [Indexed: 01/31/2023]
Abstract
Serine integrases catalyze the site-specific insertion of viral DNA into a host's genome. The minimal requirements and irreversible nature of this integration reaction have led to the use of serine integrases in applications ranging from bacterial memory storage devices to gene therapy. Our understanding of how the integrase proteins recognize the viral (attP) and host (attB) attachment sites is limited, with structural data available for only a Listeria integrase C-terminal domain (CTD) bound to an attP half-site. Here we report quantitative binding and saturation mutagenesis analyses for the Listeria innocua prophage attP site and a new 2.8-Å crystal structure of the CTD•attP half site. We find that Int binds with high affinity to attP (6.9 nM), but the Int CTD binds to attP half-sites with only 7- to 10-fold lower affinity, supporting the idea that free energy is expended to open an Int dimer for attP binding. Despite the 50-bp Int-attP interaction surface, only 20 residues are sensitive to mutagenesis, and of these, only 6 require a specific residue for efficient Int binding and integration activity. One of the integrase DNA-binding domains, the recombinase domain, appears to be primarily non-specific. Several substitutions result in an improved attP site, indicating that higher-efficiency attachment sites can be obtained through site engineering. These findings advance our understanding of serine integrase function and provide important data for efforts towards engineering this family of enzymes for a variety of biotechnology applications.
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Affiliation(s)
- Huiguang Li
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Robert Sharp
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Karen Rutherford
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kushol Gupta
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Gregory D Van Duyne
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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34
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Robust ΦC31-Mediated Genome Engineering in Drosophila melanogaster Using Minimal attP/attB Phage Sites. G3-GENES GENOMES GENETICS 2018. [PMID: 29523637 PMCID: PMC5940133 DOI: 10.1534/g3.118.200051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Effective genome engineering should lead to a desired locus change with minimal adverse impact to the genome itself. However, flanking loci with site-directed recombinase recognition sites, such as those of the phage ΦC31 integrase, allows for creation of platforms for cassette exchange and manipulation of genomic regions in an iterative manner, once specific loci have been targeted. Here we show that a genomic locus engineered with inverted minimal phage ΦC31 attP/attB sites can undergo efficient recombinase-mediated cassette exchange (RMCE) in the fruit fly Drosophila melanogaster.
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Lei X, Wang L, Zhao G, Ding X. Site-specificity of serine integrase demonstrated by the attB sequence preference of ɸBT1 integrase. FEBS Lett 2018. [PMID: 29512855 DOI: 10.1002/1873-3468.13023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Serine integrases mediate site-specific recombination and are extensively applied in genetic engineering and synthetic biology. However, which regions of the attachment sites determine site-specificity and how these regions function in recombination remain elusive. Here, we explored the sequence features of attB attachment sites recognized by ɸBT1 integrase, a representative serine integrase. A 34-bp DNA motif is found that displays distinct base-specific preference for every position. Further investigation of mutations at different positions within the attB sequence shows different recombination efficiencies and binding affinities. We found four conserved regions within the attB motif that coincide with the results of recombination assays, and mutations in the attB sequence that hamper recombination almost all cause reduced binding affinity.
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Affiliation(s)
- Xiaolai Lei
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, China
| | - Lu Wang
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, China
| | - Guoping Zhao
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, China.,CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.,Shanghai-MOST Key Laboratory of Disease and Health Genomics, Chinese National Human Genome Center at Shanghai, China
| | - Xiaoming Ding
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, China
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Abstract
A synthetic approach to biology is a promising technique for various applications. Recent advancements have demonstrated the feasibility of constructing synthetic two-input logic gates in Escherichia coli cells with long-term memory based on DNA inversion induced by recombinases. Moreover, recent evidences indicate that DNA inversion mediated by genome editing tools is possible. Powerful genome editing technologies, such as CRISPR-Cas9 systems, have great potential to be exploited to implement large-scale recombinase-based circuits. What remains unclear is how to construct arbitrary Boolean functions based on these emerging technologies. In this paper, we lay the theoretical foundation formalizing the connection between recombinase-based genetic circuits and Boolean functions. It enables systematic construction of any given Boolean function using recombinase-based logic gates. We further develop a methodology leveraging existing electronic design automation (EDA) tools to automate the synthesis of complex recombinase-based genetic circuits with respect to area and delay optimization. In silico experimental results demonstrate the applicability of our proposed methods as a useful tool for recombinase-based genetic circuit synthesis and optimization.
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Control of Recombination Directionality by the Listeria Phage A118 Protein Gp44 and the Coiled-Coil Motif of Its Serine Integrase. J Bacteriol 2017; 199:JB.00019-17. [PMID: 28289084 DOI: 10.1128/jb.00019-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 03/06/2017] [Indexed: 02/04/2023] Open
Abstract
The serine integrase of phage A118 catalyzes integrative recombination between attP on the phage and a specific attB locus on the chromosome of Listeria monocytogenes, but it is unable to promote excisive recombination between the hybrid attL and attR sites found on the integrated prophage without assistance by a recombination directionality factor (RDF). We have identified and characterized the phage-encoded RDF Gp44, which activates the A118 integrase for excision and inhibits integration. Gp44 binds to the C-terminal DNA binding domain of integrase, and we have localized the primary binding site to be within the mobile coiled-coil (CC) motif but distinct from the distal tip of the CC that is required for recombination. This interaction is sufficient to inhibit integration, but a second interaction involving the N-terminal end of Gp44 is also required to activate excision. We provide evidence that these two contacts modulate the trajectory of the CC motifs as they extend out from the integrase core in a manner dependent upon the identities of the four att sites. Our results support a model whereby Gp44 shapes the Int-bound complexes to control which att sites can synapse and recombine.IMPORTANCE Serine integrases mediate directional recombination between bacteriophage and bacterial chromosomes. These highly regulated site-specific recombination reactions are integral to the life cycle of temperate phage and, in the case of Listeria monocytogenes lysogenized by A118 family phage, are an essential virulence determinant. Serine integrases are also utilized as tools for genetic engineering and synthetic biology because of their exquisite unidirectional control of the DNA exchange reaction. Here, we identify and characterize the recombination directionality factor (RDF) that activates excision and inhibits integration reactions by the phage A118 integrase. We provide evidence that the A118 RDF binds to and modulates the trajectory of the long coiled-coil motif that extends from the large carboxyl-terminal DNA binding domain and is postulated to control the early steps of recombination site synapsis.
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Inniss MC, Bandara K, Jusiak B, Lu TK, Weiss R, Wroblewska L, Zhang L. A novel Bxb1 integrase RMCE system for high fidelity site-specific integration of mAb expression cassette in CHO Cells. Biotechnol Bioeng 2017; 114:1837-1846. [DOI: 10.1002/bit.26268] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 01/30/2017] [Accepted: 02/08/2017] [Indexed: 12/31/2022]
Affiliation(s)
- Mara C. Inniss
- Cell Line Development; Biotherapeutics Pharmaceutical Science; Pfizer Inc; Andover 01810 Massachusetts
| | - Kalpanie Bandara
- Cell Line Development; Biotherapeutics Pharmaceutical Science; Pfizer Inc; Andover 01810 Massachusetts
| | - Barbara Jusiak
- Synthetic Biology Center; Department of Biological Engineering; Massachusetts Institute of Technology; Cambridge Massachusetts
| | - Timothy K. Lu
- Synthetic Biology Center; Department of Biological Engineering; Massachusetts Institute of Technology; Cambridge Massachusetts
| | - Ron Weiss
- Synthetic Biology Center; Department of Biological Engineering; Massachusetts Institute of Technology; Cambridge Massachusetts
| | | | - Lin Zhang
- Cell Line Development; Biotherapeutics Pharmaceutical Science; Pfizer Inc; Andover 01810 Massachusetts
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Bxb1 phage recombinase assists genome engineering in Drosophila melanogaster. Biotechniques 2017; 62:37-38. [PMID: 28118814 DOI: 10.2144/000114494] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 11/03/2016] [Indexed: 01/21/2023] Open
Abstract
Rapid and reliable genome modifications provide the basis for detailed in vivo functional analysis of any genomic entity (gene, regulatory DNA, non-coding RNA, etc). With the advent of CRISPR/Cas9 genome editing technology, manipulation of a particular genomic locus has become a routine undertaking in variety of model organisms, including the fruit fly Drosophila melanogaster. To further diversify the available tools for genome engineering, we successfully harnessed the phage recombinase Bxb1 to perform recombinase-mediated cassette exchange (RMCE) in D. melanogaster. We demonstrate that Bxb1 possesses highly efficient recombinase activity and could be used alone or in conjunction with other currently available recombinases for creating platforms for cassette exchange of targeted loci.
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Wang X, Tang B, Ye Y, Mao Y, Lei X, Zhao G, Ding X. Bxb1 integrase serves as a highly efficient DNA recombinase in rapid metabolite pathway assembly. Acta Biochim Biophys Sin (Shanghai) 2017; 49:44-50. [PMID: 27864282 DOI: 10.1093/abbs/gmw115] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 10/24/2016] [Indexed: 11/13/2022] Open
Abstract
Phage-encoded serine integrases are widely used in genetic engineering. They also have the potential to serve as efficient DNA assemblers, demonstrated by the method of site-specific recombination-based tandem assembly (SSRTA) that can combine biological parts into devices, pathways, and systems. Here, four serine integrases, ϕBT1, TG1, ϕRv1, and Bxb1, were investigated to ascertain their in vitro DNA assembly activities. Bxb1 integrase displayed the highest efficiency to obtain final products. Thus, we conclude that Bxb1 integrase is an excellent choice for DNA assembly in vitro Using this enzyme and its recognition sites, BioBrick standards were designed that are compatible with the SSRTA method for module addition. A rapid and efficient procedure was developed for the assembly of a multigene metabolic pathway in one step, directly from non-cutting plasmids containing the gene fragments. This technique is easy and convenient, and would be of interest to the synthetic biology community.
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Affiliation(s)
- Xianwei Wang
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Biao Tang
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai 200438, China
- CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
- Institute of Quality and Standard for Agro-Products, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Yu Ye
- Department of Microbiology and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China
| | - Yayi Mao
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Xiaolai Lei
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Guoping Zhao
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai 200438, China
- CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
- Department of Microbiology and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China
| | - Xiaoming Ding
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai 200438, China
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Fan HF, Hsieh TS, Ma CH, Jayaram M. Single-molecule analysis of ϕC31 integrase-mediated site-specific recombination by tethered particle motion. Nucleic Acids Res 2016; 44:10804-10823. [PMID: 27986956 PMCID: PMC5159548 DOI: 10.1093/nar/gkw861] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 09/11/2016] [Accepted: 09/22/2016] [Indexed: 11/14/2022] Open
Abstract
Serine and tyrosine site-specific recombinases (SRs and YRs, respectively) provide templates for understanding the chemical mechanisms and conformational dynamics of strand cleavage/exchange between DNA partners. Current evidence suggests a rather intriguing mechanism for serine recombination, in which one half of the cleaved synaptic complex undergoes a 180° rotation relative to the other. The 'small' and 'large' SRs contain a compact amino-terminal catalytic domain, but differ conspicuously in their carboxyl-terminal domains. So far, only one serine recombinase has been analyzed using single substrate molecules. We now utilized single-molecule tethered particle motion (TPM) to follow step-by-step recombination catalyzed by a large SR, phage ϕC31 integrase. The integrase promotes unidirectional DNA exchange between attB and attP sites to integrate the phage genome into the host chromosome. The recombination directionality factor (RDF; ϕC31 gp3) activates the excision reaction (attL × attR). From integrase-induced changes in TPM in the presence or absence of gp3, we delineated the individual steps of recombination and their kinetic features. The gp3 protein appears to regulate recombination directionality by selectively promoting or excluding active conformations of the synapse formed by specific att site partners. Our results support a 'gated rotation' of the synaptic complex between DNA cleavage and joining.
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Affiliation(s)
- Hsiu-Fang Fan
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, 112, Taiwan
- Biophotonics and Molecular Imaging Research Center, National Yang-Ming University, 112, Taiwan
| | - Tao-Shih Hsieh
- Institute of Cellular and Organismic Biology Academia Sinica, 115, Taiwan
| | - Chien-Hui Ma
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Makkuni Jayaram
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
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Keenholtz RA, Grindley NDF, Hatfull GF, Marko JF. Crossover-site sequence and DNA torsional stress control strand interchanges by the Bxb1 site-specific serine recombinase. Nucleic Acids Res 2016; 44:8921-8932. [PMID: 27550179 PMCID: PMC5062993 DOI: 10.1093/nar/gkw724] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 08/08/2016] [Indexed: 01/01/2023] Open
Abstract
DNA segment exchange by site-specific serine recombinases (SRs) is thought to proceed by rigid-body rotation of the two halves of the synaptic complex, following the cleavages that create the two pairs of exchangeable ends. It remains unresolved how the amount of rotation occurring between cleavage and religation is controlled. We report single-DNA experiments for Bxb1 integrase, a model SR, where dynamics of individual synapses were observed, using relaxation of supercoiling to report on cleavage and rotation events. Relaxation events often consist of multiple rotations, with the number of rotations per relaxation event and rotation velocity sensitive to DNA sequence at the center of the recombination crossover site, torsional stress and salt concentration. Bulk and single-DNA experiments indicate that the thermodynamic stability of the annealed, but cleaved, crossover sites controls ligation efficiency of recombinant and parental synaptic complexes, regulating the number of rotations during a breakage-religation cycle. The outcome is consistent with a ‘controlled rotation’ model analogous to that observed for type IB topoisomerases, with religation probability varying in accord with DNA base-pairing free energies at the crossover site. Significantly, we find no evidence for a special regulatory mechanism favoring ligation and product release after a single 180° rotation.
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Affiliation(s)
- Ross A Keenholtz
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Nigel D F Grindley
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Graham F Hatfull
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - John F Marko
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
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Abstract
The large serine recombinases (LSRs) are a family of enzymes, encoded in temperate phage genomes or on mobile elements, that precisely cut and recombine DNA in a highly controllable and predictable way. In phage integration, the LSRs act at specific sites, the attP site in the phage and the attB site in the host chromosome, where cleavage and strand exchange leads to the integrated prophage flanked by the recombinant sites attL and attR. The prophage can excise by recombination between attL and attR but this requires a phage-encoded accessory protein, the recombination directionality factor (RDF). Although the LSRs can bind specifically to all the recombination sites, only specific integrase-bound sites can pair in a synaptic complex prior to strand exchange. Recent structural information has led to a breakthrough in our understanding of the mechanism of the LSRs, notably how the LSRs bind to their substrates and how LSRs display this site-selectivity. We also understand that the RDFs exercise control over the LSRs by protein-protein interactions. Other recent work with the LSRs have contributed to our understanding of how all serine recombinases undergo strand exchange subunit rotation, facilitated by surfaces that resemble a molecular bearing.
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44
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Xu Z, Brown WRA. Comparison and optimization of ten phage encoded serine integrases for genome engineering in Saccharomyces cerevisiae. BMC Biotechnol 2016; 16:13. [PMID: 26860416 PMCID: PMC4748531 DOI: 10.1186/s12896-016-0241-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/19/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Phage-encoded serine integrases, such as ϕC31 integrase, are widely used for genome engineering but have not been optimized for use in Saccharomyces cerevisiae although this organism is a widely used organism in biotechnology. RESULTS The activities of derivatives of fourteen serine integrases that either possess or lack a nuclear localization signal were compared using a standardized recombinase mediated cassette exchange reaction. The relative activities of these integrases in S. cerevisiae and in mammalian cells suggested that the major determinant of the activity of an integrase is the enzyme itself and not the cell in which it is working. We used an inducible promoter to show that six integrases were toxic as judged by their effects upon the proliferative ability of transformed yeast. We show that in general the active phage-encoded serine integrases were an order of magnitude more efficient in promoting genome integration reactions than a simple homologous recombination. CONCLUSIONS The results of our study allow us to identify the integrases of the phage ϕBT1, TP901 ~ nls, R4, Bxb1, MR11, A118, ϕK38, ϕC31 ~ nls, Wβ and SPBC ~ nls as active in S. cerevisiae and indicate that vertebrate cells are more restricted than yeast in terms of which integrases are active.
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Affiliation(s)
- Zhengyao Xu
- School of Life Sciences, Queens Medical Centre, Nottingham University, Nottingham, NG7 2UH, UK.
| | - William R A Brown
- School of Life Sciences, Queens Medical Centre, Nottingham University, Nottingham, NG7 2UH, UK.
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Li R, Han Z, Hou L, Kaur G, Yin Q, Ow DW. Method for Biolistic Site-Specific Integration in Plants Catalyzed by Bxb1 Integrase. Methods Mol Biol 2016; 1469:15-30. [PMID: 27557683 DOI: 10.1007/978-1-4939-4931-1_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Crop improvement is a never ending process. With a transgenesis approach, it is not inconceivable to envision a continuous addition of new transgenes to existing cultivars. Previously, we described a recombinase-directed gene stacking method in tobacco (Hou et al., Mol Plant 7:1756-1765, 2014). Being able to stack DNA to a previous location ensures that the number of genetic loci does not increase with each new round of transgene addition. Whereas the previous demonstration was conducted through polyethylene glycol to mediate uptake of DNA into tobacco protoplasts, we now describe protocols for using biolistic transformation to stack DNA in tobacco and rice.
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Affiliation(s)
- Ruyu Li
- Plant Gene Engineering Center, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou, 510650, China
| | - Zhiguo Han
- Plant Gene Engineering Center, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou, 510650, China
| | - Lili Hou
- Plant Gene Engineering Center, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou, 510650, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Gurminder Kaur
- Plant Gene Engineering Center, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou, 510650, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qian Yin
- Plant Gene Engineering Center, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou, 510650, China
- University of Chinese Academy of Sciences, Beijing, China
| | - David W Ow
- Plant Gene Engineering Center, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou, 510650, China.
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Nandy S, Zhao S, Pathak BP, Manoharan M, Srivastava V. Gene stacking in plant cell using recombinases for gene integration and nucleases for marker gene deletion. BMC Biotechnol 2015; 15:93. [PMID: 26452472 PMCID: PMC4600305 DOI: 10.1186/s12896-015-0212-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/01/2015] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Practical approaches for multigene transformation and gene stacking are extremely important for engineering complex traits and adding new traits in transgenic crops. Trait deployment by gene stacking would greatly simplify downstream plant breeding and trait introgression into cultivars. Gene stacking into pre-determined genomic sites depends on mechanisms of targeted DNA integration and recycling of selectable marker genes. Targeted integrations into chromosomal breaks, created by nucleases, require large transformation efforts. Recombinases such as Cre-lox, on the other hand, efficiently drive site-specific integrations in plants. However, the reversibility of Cre-lox recombination, due to the incorporation of two cis-positioned lox sites, presents a major bottleneck in its application in gene stacking. Here, we describe a strategy of resolving this bottleneck through excision of one of the cis-positioned lox, embedded in the marker gene, by nuclease activity. METHODS All transgenic lines were developed by particle bombardment of rice callus with plasmid constructs. Standard molecular approach was used for building the constructs. Transgene loci were analyzed by PCR, Southern hybridization, and DNA sequencing. RESULTS We developed a highly efficient gene stacking method by utilizing powerful recombinases such as Cre-lox and FLP-FRT, for site-specific gene integrations, and nucleases for marker gene excisions. We generated Cre-mediated site-specific integration locus in rice and showed excision of marker gene by I-SceI at ~20 % efficiency, seamlessly connecting genes in the locus. Next, we showed ZFN could be used for marker excision, and the locus can be targeted again by recombinases. Hence, we extended the power of recombinases to gene stacking application in plants. Finally, we show that heat-inducible I-SceI is also suitable for marker excision, and therefore could serve as an important tool in streamlining this gene stacking platform. CONCLUSIONS A practical approach for gene stacking in plant cell was developed that allows targeted gene insertions through rounds of transformation, a method needed for introducing new traits into transgenic lines for their rapid deployment in the field. By using Cre-lox, a powerful site-specific recombination system, this method greatly improves gene stacking efficiency, and through the application of nucleases develops marker-free, seamless stack of genes at pre-determined chromosomal sites.
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Affiliation(s)
- Soumen Nandy
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Shan Zhao
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Bhuvan P Pathak
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Muthusamy Manoharan
- Department of Agriculture, 144 Woodard Hall, University of Arkansas at Pine Bluff, Pine Bluff, AR, 71601, USA.
| | - Vibha Srivastava
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
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Abstract
Reversible site-specific DNA inversion reactions are widely distributed in bacteria and their viruses. They control a range of biological reactions that most often involve alterations of molecules on the surface of cells or phage. These programmed DNA rearrangements usually occur at a low frequency, thereby preadapting a small subset of the population to a change in environmental conditions, or in the case of phages, an expanded host range. A dedicated recombinase, sometimes with the aid of additional regulatory or DNA architectural proteins, catalyzes the inversion of DNA. RecA or other components of the general recombination-repair machinery are not involved. This chapter discusses site-specific DNA inversion reactions mediated by the serine recombinase family of enzymes and focuses on the extensively studied serine DNA invertases that are stringently controlled by the Fis-bound enhancer regulatory system. The first section summarizes biological features and general properties of inversion reactions by the Fis/enhancer-dependent serine invertases and the recently described serine DNA invertases in Bacteroides. Mechanistic studies of reactions catalyzed by the Hin and Gin invertases are then discussed in more depth, particularly with regards to recent advances in our understanding of the function of the Fis/enhancer regulatory system, the assembly of the active recombination complex (invertasome) containing the Fis/enhancer, and the process of DNA strand exchange by rotation of synapsed subunit pairs within the invertasome. The role of DNA topological forces that function in concert with the Fis/enhancer controlling element in specifying the overwhelming bias for DNA inversion over deletion and intermolecular recombination is emphasized.
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Affiliation(s)
- Reid C. Johnson
- Department of Biological Chemistry, UCLA School of Medicine, Los Angeles, CA 90095-1737, Phone: 310 825-7800, Fax: 310 206-5272
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48
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Hou L, Yau YY, Wei J, Han Z, Dong Z, Ow DW. An open-source system for in planta gene stacking by Bxb1 and Cre recombinases. MOLECULAR PLANT 2014; 7:1756-65. [PMID: 25281665 DOI: 10.1093/mp/ssu107] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The rapid development of crops with multiple transgenic traits arouses the need for an efficient system for creating stacked cultivars. Most major crops rely on classical breeding to introgress the transgene from a laboratory variety to the numerous cultivars adapted to different growing regions. Even with vegetative propagated crops, genetic crosses are conducted during varietal improvement prior to vegetative cloning. The probability to assort the 'x' number of transgenic loci into a single genome may seem trivial, (¼) (x) for a diploid species, but given the 'y' number of other nontransgenic traits that breeders also need to assemble into the same genome, the (¼) (x+y) probability for a 'breeding stack' could quickly make the line conversion process unmanageable. Adding new transgenes onto existing transgenic varieties without creating a new segregating locus would require site-specific integration of new DNA at the existing transgenic locus. Here, we tested a recombinase-mediated gene-stacking scheme in tobacco. Sequential site-specific integration was mediated by the mycobacteriophage Bxb1 integrase-catalyzed recombination between attP and attB sites. Transgenic DNA no longer needed after integration was excised by Cre recombinase-mediated recombination of lox sites. Site-specific integration occurred in ~10% of the integration events, with half of those events usable as substrates for a next round of gene stacking. Among the site-specific integrants, however, a third experienced gene silencing. Overall, precise structure and reproducible expression of the sequentially added triple traits were obtained at an overall rate of ~3% of the transformed clones--a workable frequency for the development of commercial cultivars. Moreover, since neither the Bxb1-att nor the Cre-lox system is under patent, there is freedom to operate.
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Affiliation(s)
- Lili Hou
- Plant Gene Engineering Center, South China Agricultural Plant Molecular Analysis and Genetic Improvement Key Laboratory, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou 510650, China University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Yuan-Yeu Yau
- Plant Gene Engineering Center, South China Agricultural Plant Molecular Analysis and Genetic Improvement Key Laboratory, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou 510650, China Former Affiliation, Plant Gene Expression Center, USDA-ARS & Plant & Microbial Biology, University of California-Berkeley, 800 Buchanan St., Albany, CA 94710, USA
| | - Junjie Wei
- Plant Gene Engineering Center, South China Agricultural Plant Molecular Analysis and Genetic Improvement Key Laboratory, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou 510650, China University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Zhiguo Han
- Plant Gene Engineering Center, South China Agricultural Plant Molecular Analysis and Genetic Improvement Key Laboratory, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou 510650, China
| | - Zhicheng Dong
- Plant Gene Engineering Center, South China Agricultural Plant Molecular Analysis and Genetic Improvement Key Laboratory, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou 510650, China
| | - David W Ow
- Plant Gene Engineering Center, South China Agricultural Plant Molecular Analysis and Genetic Improvement Key Laboratory, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Guangzhou 510650, China Former Affiliation, Plant Gene Expression Center, USDA-ARS & Plant & Microbial Biology, University of California-Berkeley, 800 Buchanan St., Albany, CA 94710, USA
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Abstract
ABSTRACT
In site-specific recombination, two short DNA sequences (‘sites’) are each cut at specific points in both strands, and the cut ends are rejoined to new partners. The enzymes that mediate recognition of the sites and the subsequent cutting and rejoining steps are called recombinases. Most recombinases fall into one of two families according to similarities of their protein sequences and mechanisms; these families are known as the tyrosine recombinases and the serine recombinases, the names referring to the conserved amino acid residue that attacks the DNA phosphodiester and becomes covalently linked to a DNA strand end during catalysis. This chapter gives an overview of our current understanding of the serine recombinases, their types, biological roles, structures, catalytic mechanisms, mechanisms of regulation, and applications.
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Somleva MN, Xu CA, Ryan KP, Thilmony R, Peoples O, Snell KD, Thomson J. Transgene autoexcision in switchgrass pollen mediated by the Bxb1 recombinase. BMC Biotechnol 2014; 14:79. [PMID: 25148894 PMCID: PMC4148497 DOI: 10.1186/1472-6750-14-79] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 08/18/2014] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Switchgrass (Panicum virgatum L.) has a great potential as a platform for the production of biobased plastics, chemicals and energy mainly because of its high biomass yield on marginal land and low agricultural inputs. During the last decade, there has been increased interest in the genetic improvement of this crop through transgenic approaches. Since switchgrass, like most perennial grasses, is exclusively cross pollinating and poorly domesticated, preventing the dispersal of transgenic pollen into the environment is a critical requisite for the commercial deployment of this important biomass crop. In this study, the feasibility of controlling pollen-mediated gene flow in transgenic switchgrass using the large serine site-specific recombinase Bxb1 has been investigated. RESULTS A novel approach utilizing co-transformation of two separate vectors was used to test the functionality of the Bxb1/att recombination system in switchgrass. In addition, two promoters with high pollen-specific activity were identified and thoroughly characterized prior to their introduction into a test vector explicitly designed for both autoexcision and quantitative analyses of recombination events. Our strategy for developmentally programmed precise excision of the recombinase and marker genes in switchgrass pollen resulted in the generation of transgene-excised progeny. The autoexcision efficiencies were in the range of 22-42% depending on the transformation event and assay used. CONCLUSION The results presented here mark an important milestone towards the establishment of a reliable biocontainment system for switchgrass which will facilitate the development of this crop as a biorefinery feedstock through advanced biotechnological approaches.
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Affiliation(s)
| | - Chang Ai Xu
- Metabolix, Inc., 21 Erie St., Cambridge, MA 02139, USA
| | - Kieran P Ryan
- Metabolix, Inc., 21 Erie St., Cambridge, MA 02139, USA
| | | | | | | | - James Thomson
- USDA-ARS-CIU, 800 Buchanan St., Albany, CA 94710, USA
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