Engineering Designer Transcription Activator‐‐Like Effector Nucleases (TALENs) by REAL or REAL‐Fast Assembly

Deepak Reyon1, Cyd Khayter2, Maureen R. Regan2, J. Keith Joung1, Jeffry D. Sander1

1 Department of Pathology, Harvard Medical School, Boston, Massachusetts, 2 Molecular Pathology Unit, Center for Computational and Integrative Biology and Center for Cancer Research, Massachusetts General Hospital, Charlestown, Massachusetts
Publication Name:  Current Protocols in Molecular Biology
Unit Number:  Unit 12.15
DOI:  10.1002/0471142727.mb1215s100
Online Posting Date:  October, 2012
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Engineered transcription activator–like effector nucleases (TALENs) are broadly useful tools for performing targeted genome editing in a wide variety of organisms and cell types including plants, zebrafish, C. elegans, rat, human somatic cells, and human pluripotent stem cells. Here we describe detailed protocols for the serial, hierarchical assembly of TALENs that require neither PCR nor specialized multi‐fragment ligations and that can be implemented by any laboratory. These restriction enzyme and ligation (REAL)–based protocols can be practiced using plasmid libraries and user‐friendly, Web‐based software that both identifies target sites in sequences of interest and generates printable graphical guides that facilitate assembly of TALENs. With the described platform of reagents, protocols, and software, researchers can easily engineer multiple TALENs within 2 weeks using standard cloning techniques. Curr. Protoc. Mol. Biol. 100:12.15.1‐12.15.14. © 2012 by John Wiley & Sons, Inc.

Keywords: TALEN; TALENs; engineered TAL effector nucleases; engineered TALE nucleases; REAL; REAL‐Fast; protein engineering; DNA‐binding domains; FLASH

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Table of Contents

  • Introduction
  • Strategic Planning
  • Basic Protocol 1: Engineering Customized TALENs
  • Commentary
  • Literature Cited
  • Figures
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Basic Protocol 1: Engineering Customized TALENs

  • Genomic sequence of interest
  • Plasmids encoding individual TALE repeats (available through Addgene,
  • Restriction enzymes from New England Biolabs:
    • BamHI (cat. no. R0136S)
    • BbsI (cat. no. R0539L)
    • BsaI (cat, no. R0535L)
    • BsmBI (cat. no. R0580L)
    • KpnI‐HF (cat. no. R3142L)
  • 10× restriction enzyme buffers included with enzymes from New England Biolabs:
    • NEBuffer 2
    • NEBuffer 3
    • NEBuffer 4
  • 10 µg/ml bovine serum albumin (included with enzymes from New England Biolabs)
  • Nuclease‐free H 2O (unit 4.1)
  • 5% nondenaturing polyacrylamide gel (unit 2.7)
  • Quick Ligation Kit (New England Biolabs, cat. No. M2200L)
  • Chemically competent bacterial strain XL‐1 Blue (recA1 endA1 gyrA96 thi‐1 hsdR17 supE44 relA1 lac [F' proAB lacIq lacZDM15 Tn 10 (TetR)]; Stratagene, cat no. 200249)
  • LB liquid medium and agar plates (unit 1.1). with and without 100 µg/ml carbenicillin (Sigma, cat. no C1389)
  • TALEN Expression Vectors (available through Addgene:
  • Archive of preassembled TALE arrays for practicing REAL‐Fast (available through the Joung lab; see
  • Sequencing primers (optional):
    • Sequencing primer OK163: 5′ CGCCAGGGTTTTCCCAGTCACGAC 3′
    • Sequencing primer JDS2978: 5′ TTGAGGCGCTGCTGACTG 3′
    • Sequencing primer JDS2980: 5′ TTAATTCAATATATTCATGAGGCAC 3′
    • Sequencing primer JDS2778: 5′ CTGGCGCAATGCGCTCAC 3′
    • Sequencing primer JDS2979: 5′ AAGCAATGGCGACCACCTGTTC 3′
  • 42°C water bath
  • Sterile bacterial culture tubes
  • Orbital platform shaker with adjustable speed
  • Additional reagents and equipment for nondenaturing polyacrylamide gel electrophoresis (unit 2.7) and transformation of bacteria (unit 1.8)
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Key References
   Sander et al., 2011. See above.
  Describes the plasmids required to practice REAL and the efficacy of TALENs produced by this architecture in zebrafish.
   Reyon et al., 2012. See above.
  Describes archive of plasmids encoding pre‐assembled TALE repeat arrays that is required to practice REAL‐Fast and demonstrates that TALENs constructed on the same architecture as those made by REAL and REAL‐Fast function robustly and have high rate of success in human cells.
Internet Resources
  Provides access to the ZiFiT Targeter software program for engineering TALENs.
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