The crystal structure of TAL effector PthXo1 bound to its DNA target.
|Title||The crystal structure of TAL effector PthXo1 bound to its DNA target.|
|Publication Type||Journal Article|
|Year of Publication||2012|
|Authors||Mak AN-S, Bradley P, Cernadas RA, Bogdanove AJ, Stoddard BL|
|Journal||Science (New York, N.Y.)|
|Date Published||2012 Feb 10|
|Keywords||Amino Acid Sequence, Bacterial Proteins, Binding Sites, Crystallography, X-Ray, DNA, Plant, DNA-Binding Proteins, High-Throughput Screening Assays, Hydrogen Bonding, Models, Molecular, Molecular Sequence Data, Physicochemical Processes, Protein Binding, Protein Conformation, Protein Folding, Protein Structure, Secondary, Repetitive Sequences, Amino Acid, Virulence Factors, Xanthomonas|
DNA recognition by TAL effectors is mediated by tandem repeats, each 33 to 35 residues in length, that specify nucleotides via unique repeat-variable diresidues (RVDs). The crystal structure of PthXo1 bound to its DNA target was determined by high-throughput computational structure prediction and validated by heavy-atom derivatization. Each repeat forms a left-handed, two-helix bundle that presents an RVD-containing loop to the DNA. The repeats self-associate to form a right-handed superhelix wrapped around the DNA major groove. The first RVD residue forms a stabilizing contact with the protein backbone, while the second makes a base-specific contact to the DNA sense strand. Two degenerate amino-terminal repeats also interact with the DNA. Containing several RVDs and noncanonical associations, the structure illustrates the basis of TAL effector-DNA recognition.