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      Site- and strand-specific nicking of DNA by fusion proteins derived from MutH and I-SceI or TALE repeats

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          Abstract

          Targeted genome engineering requires nucleases that introduce a highly specific double-strand break in the genome that is either processed by homology-directed repair in the presence of a homologous repair template or by non-homologous end-joining (NHEJ) that usually results in insertions or deletions. The error-prone NHEJ can be efficiently suppressed by ‘nickases’ that produce a single-strand break rather than a double-strand break. Highly specific nickases have been produced by engineering of homing endonucleases and more recently by modifying zinc finger nucleases (ZFNs) composed of a zinc finger array and the catalytic domain of the restriction endonuclease FokI. These ZF-nickases work as heterodimers in which one subunit has a catalytically inactive FokI domain. We present two different approaches to engineer highly specific nickases; both rely on the sequence-specific nicking activity of the DNA mismatch repair endonuclease MutH which we fused to a DNA-binding module, either a catalytically inactive variant of the homing endonuclease I-SceI or the DNA-binding domain of the TALE protein AvrBs4. The fusion proteins nick strand specifically a bipartite recognition sequence consisting of the MutH and the I-SceI or TALE recognition sequences, respectively, with a more than 1000-fold preference over a stand-alone MutH site. TALE–MutH is a programmable nickase.

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          Most cited references50

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          A TALE nuclease architecture for efficient genome editing.

          Nucleases that cleave unique genomic sequences in living cells can be used for targeted gene editing and mutagenesis. Here we develop a strategy for generating such reagents based on transcription activator-like effector (TALE) proteins from Xanthomonas. We identify TALE truncation variants that efficiently cleave DNA when linked to the catalytic domain of FokI and use these nucleases to generate discrete edits or small deletions within endogenous human NTF3 and CCR5 genes at efficiencies of up to 25%. We further show that designed TALEs can regulate endogenous mammalian genes. These studies demonstrate the effective application of designed TALE transcription factors and nucleases for the targeted regulation and modification of endogenous genes.
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            Targeting DNA double-strand breaks with TAL effector nucleases.

            Engineered nucleases that cleave specific DNA sequences in vivo are valuable reagents for targeted mutagenesis. Here we report a new class of sequence-specific nucleases created by fusing transcription activator-like effectors (TALEs) to the catalytic domain of the FokI endonuclease. Both native and custom TALE-nuclease fusions direct DNA double-strand breaks to specific, targeted sites.
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              An improved zinc-finger nuclease architecture for highly specific genome editing.

              Genome editing driven by zinc-finger nucleases (ZFNs) yields high gene-modification efficiencies (>10%) by introducing a recombinogenic double-strand break into the targeted gene. The cleavage event is induced using two custom-designed ZFNs that heterodimerize upon binding DNA to form a catalytically active nuclease complex. Using the current ZFN architecture, however, cleavage-competent homodimers may also form that can limit safety or efficacy via off-target cleavage. Here we develop an improved ZFN architecture that eliminates this problem. Using structure-based design, we engineer two variant ZFNs that efficiently cleave DNA only when paired as a heterodimer. These ZFNs modify a native endogenous locus as efficiently as the parental architecture, but with a >40-fold reduction in homodimer function and much lower levels of genome-wide cleavage. This architecture provides a general means for improving the specificity of ZFNs as gene modification reagents.
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                Author and article information

                Journal
                Nucleic Acids Res
                Nucleic Acids Res
                nar
                nar
                Nucleic Acids Research
                Oxford University Press
                0305-1048
                1362-4962
                April 2013
                12 February 2013
                12 February 2013
                : 41
                : 7
                : e83
                Affiliations
                Institute for Biochemistry, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany
                Author notes
                *To whom correspondence should be addressed. Tel: +49 641 35407; Fax: +49 641 35409; Email: wolfgang.wende@ 123456chemie.bio.uni-giessen.de
                Article
                gkt080
                10.1093/nar/gkt080
                3627573
                23408850
                9513a441-2f6c-45c2-a78d-6e08164b4998
                © The Author(s) 2013. Published by Oxford University Press.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 10 October 2012
                : 14 January 2013
                : 22 January 2013
                Page count
                Pages: 11
                Categories
                Methods Online

                Genetics
                Genetics

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