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Science. 2012 Feb 10;335(6069):720-3. doi: 10.1126/science.1215670. Epub 2012 Jan 5.

Structural basis for sequence-specific recognition of DNA by TAL effectors.

Author information

1
State Key Laboratory of Bio-Membrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China.

Abstract

TAL (transcription activator-like) effectors, secreted by phytopathogenic bacteria, recognize host DNA sequences through a central domain of tandem repeats. Each repeat comprises 33 to 35 conserved amino acids and targets a specific base pair by using two hypervariable residues [known as repeat variable diresidues (RVDs)] at positions 12 and 13. Here, we report the crystal structures of an 11.5-repeat TAL effector in both DNA-free and DNA-bound states. Each TAL repeat comprises two helices connected by a short RVD-containing loop. The 11.5 repeats form a right-handed, superhelical structure that tracks along the sense strand of DNA duplex, with RVDs contacting the major groove. The 12th residue stabilizes the RVD loop, whereas the 13th residue makes a base-specific contact. Understanding DNA recognition by TAL effectors may facilitate rational design of DNA-binding proteins with biotechnological applications.

PMID:
22223738
PMCID:
PMC3586824
DOI:
10.1126/science.1215670
[Indexed for MEDLINE]
Free PMC Article

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