Submitted on July 8, 2009
Accepted on September 23, 2009
A Simple Cipher Governs DNA Recognition by TAL Effectors
Matthew J. Moscou 1 and Adam J. Bogdanove 1*
1 Department of Plant Pathology and Bioinformatics and Computational Biology Program, Iowa State University, Ames, IA 50011, USA.
* To whom correspondence should be addressed.
Adam J. Bogdanove , E-mail: ajbog{at}iastate.edu
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 novel 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.
