Pio F, Kodandapani R, Ni C Z, Shepard W, Klemsz M, McKercher S R, Maki R A, Ely K R
La Jolla Cancer Research Center, The Burnham Institute, La Jolla, California 92037, USA.
J Biol Chem. 1996 Sep 20;271(38):23329-37. doi: 10.1074/jbc.271.38.23329.
Transcription factors belonging to the ets family regulate gene expression and share a conserved ETS DNA-binding domain that binds to the core sequence 5'-(C/A)GGA(A/T)-3'. The domain is similar to alpha+beta ("winged") helix-turn-helix DNA-binding proteins. The crystal structure of the PU.1 ETS domain complexed to a 16-base pair oligonucleotide revealed a pattern for DNA recognition from a novel loop-helix-loop architecture (Kodandapani, R., Pio, F., Ni. C.-Z., Piccialli, G., Klemsz, M., McKercher, S., Maki, R. A., and Ely, K. R. (1996) Nature 380, 456-460). Correlation of this model with mutational analyses and chemical shift data on other ets proteins confirms this complex as a paradigm for ets DNA recognition. The second helix in the helix-turn-helix motif lies deep in the major groove with specific contacts with bases in both strands in the core sequence made by conserved residues in alpha3. On either side of this helix, two loops contact the phosphate backbone. The DNA is bent (8 degrees) but uniformly curved without distinct kinks. ETS domains bind DNA as a monomer yet make extensive DNA contacts over 30 A. DNA bending likely results from phosphate neutralization of the phosphate backbone in the minor groove by both loops in the loop-helix-loop motif. Contacts from these loops stabilize DNA bending and may mediate specific base interactions by inducing a bend toward the protein.
属于ETS家族的转录因子调节基因表达，并共享一个保守的ETS DNA结合结构域，该结构域与核心序列5'-(C/A)GGA(A/T)-3'结合。该结构域类似于α+β（“带翼”）螺旋-转角-螺旋DNA结合蛋白。与一个16碱基对寡核苷酸复合的PU.1 ETS结构域的晶体结构揭示了一种从新型环-螺旋-环结构识别DNA的模式（Kodandapani, R., Pio, F., Ni. C.-Z., Piccialli, G., Klemsz, M., McKercher, S., Maki, R. A., and Ely, K. R. (1996) Nature 380, 456 - 460）。该模型与其他ETS蛋白的突变分析和化学位移数据的相关性证实了这种复合物是ETS DNA识别的范例。螺旋-转角-螺旋基序中的第二个螺旋位于大沟深处，与核心序列中两条链上的碱基有特异性接触，这些接触由α3中的保守残基形成。在这个螺旋的两侧，两个环与磷酸骨架接触。DNA发生弯曲（8度），但弯曲均匀，没有明显的扭结。ETS结构域以单体形式结合DNA，但在超过30 Å的范围内与DNA有广泛接触。DNA弯曲可能是由于环-螺旋-环基序中的两个环对小沟中磷酸骨架的磷酸中和作用。这些环的接触稳定了DNA弯曲，并可能通过诱导向蛋白质的弯曲来介导特异性碱基相互作用。
