Submitted on July 8, 2009
Accepted on September 23, 2009
Breaking the Code of DNA-Binding Specificity of TAL-Type III Effectors
Jens Boch 1*, Heidi Scholze 1, Sebastian Schornack 2, Angelika Landgraf 1, Simone Hahn 1, Sabine Kay 1, Thomas Lahaye 1, Anja Nickstadt 3, Ulla Bonas 1
1 Martin-Luther-University Halle-Wittenberg, Institute of Biology, Department of Genetics, Weinbergweg 10, D-06099 Halle (Saale) Germany.
2 Martin-Luther-University Halle-Wittenberg, Institute of Biology, Department of Genetics, Weinbergweg 10, D-06099 Halle (Saale) Germany.; Present address: Sainsbury Laboratory, John Innes Centre, Norwich, Norfolk NR4 7UH, UK.
3 Martin-Luther-University Halle-Wittenberg, Institute of Biology, Department of Genetics, Weinbergweg 10, D-06099 Halle (Saale) Germany.; Present address: Icon Genetics GmbH, Biozentrum, Weinbergweg 22, D-06120 Halle (Saale), Germany.
* To whom correspondence should be addressed.
Jens Boch , E-mail: jens.boch{at}genetik.uni-halle.de
Pathogenicity of many bacteria depends on injection of effector proteins via type III secretion into eukaryotic cells, to manipulate cellular processes. TAL (transcription activator-like effectors) from plant pathogenic Xanthomonas are important virulence factors which act as transcriptional activators in the plant cell nucleus where they directly bind to DNA via a central domain of tandem repeats. Here, we show how target DNA-specificity of TAL effectors is encoded. Two hypervariable amino acid residues in each repeat recognize one base pair in the target DNA. Recognition sequences of TAL effectors were predicted and experimentally confirmed. The modular protein architecture enabled construction of artificial effectors with new specificities. Our study describes the functionality of a unique type of DNA-binding domain and allows design of DNA-binding domains for biotechnology.
