A simple cipher governs DNA recognition by TAL effectors

Department of Plant Pathology and Bioinformatics and Computational Biology Program, Iowa State University, Ames, IA 50011, USA.
Science (Impact Factor: 31.48). 10/2009; 326(5959):1501. DOI: 10.1126/science.1178817
Source: PubMed

ABSTRACT TAL effectors of plant pathogenic bacteria in the genus Xanthomonas bind host DNA and activate genes that contribute to disease or turn on defense. Target specificity depends on an effector-variable number of typically 34 amino acid repeats, but the mechanism of recognition is not understood. We show that a repeat-variable pair of residues specifies the nucleotides in the target site, one pair to one nucleotide, with no apparent context dependence. Our finding represents a previously unknown mechanism for protein-DNA recognition that explains TAL effector specificity, enables target site prediction, and opens prospects for use of TAL effectors in research and biotechnology.

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Available from: Matthew J Moscou, Mar 11, 2015
    • "The effectors' binding domain consists of a variable number (13-28) of near-identical tandem repeats with each repeat comprising of 33 to 35 amino acids. The different types of these repeats feature a binding preference to one of the four nucleobases present in DNA (Boch et al., 2009; Moscou and Bogdanove, 2009). These specificities are defined by particular amino acids in positions 12 and 13, which thus have been coined as repeat variable diresidues (RVDs). "
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    • ", most of which contain 13e28 repeats and 33e35 amino acids per repeat ( Boch and Bonas , 2010 ) . Each repeat can recognize a single nucleotide in the target sequence , and the nucleotide spec - ificity is determined by a hypervariable region of two adjacent amino acids at positions 12 and 13 within each amino acid repeat , termed repeat - variable di - residue ( RVD ) ( Moscou and Bogdanove , 2009 ; Boch et al . , 2009 ; Morbitzer et al . "
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    • "bs_bs_banner (TALEs) are natural effector proteins secreted by numerous species of Xanthomonas, in order to modulate gene expression in host plants, and to facilitate bacterial colonization and survival (Boch and Bonas, 2010; Bogdanove et al., 2010). TALEs have revealed an elegant code linking the repetitive region of the TALEs with their target DNA-binding site (Boch et al., 2009; Moscou and Bogdanove, 2009). Two highly variable amino acids at positions 12 and 13, known as the repeat-variable di-residue (RVD) of mostly 33–35 amino acid tandem repeats, establish the base-recognition specificity of each unit. "
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