Structural basis for sequence-specific recognition of DNA by TAL effectors.
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.
State Key Laboratory of Bio-Membrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China.
Dong
D
Deng
Chuangye
C
Yan
Xiaojing
X
Pan
Magdy
M
Mahfouz
Jiawei
J
Wang
Jian-Kang
JK
Zhu
Yigong
Y
Shi
Nieng
N
Yan
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001483:Base Sequence; D055598:Chemical Phenomena; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D020449:Repetitive Sequences, Amino Acid; D037521:Virulence Factors / Q000737:chemistry* / Q000378:metabolism*; D014974:Xanthomonas / Q000737:chemistry / Q000472:pathogenicity
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D037521:Virulence Factors; D004247:DNA