Blanco Alexandre G, Sola Maria, Gomis-Rüth F Xavier, Coll Miquel
Institut de Biologia Molecular de Barcelona, CSIC, Jordi Girona, 18-26, E-08034 Barcelona, Spain.
Structure. 2002 May;10(5):701-13. doi: 10.1016/s0969-2126(02)00761-x.
PhoB is a signal transduction response regulator that activates nearly 40 genes in phosphate depletion conditions in E. coli and closely related bacteria. The structure of the PhoB effector domain in complex with its target DNA sequence, or pho box, reveals a novel tandem arrangement in which several monomers bind head to tail to successive 11-base pair direct-repeat sequences, coating one face of a smoothly bent double helix. The protein has a winged helix fold in which the DNA recognition elements comprise helix alpha 3, penetrating the major groove, and a beta hairpin wing interacting with a compressed minor groove via Arg219, tightly sandwiched between the DNA sugar backbones. The transactivation loops protrude laterally in an appropriate orientation to interact with the RNA polymerase sigma(70) subunit, which triggers transcription initiation.
PhoB是一种信号转导应答调节因子，在大肠杆菌及密切相关细菌中，它在磷酸盐缺乏条件下可激活近40个基因。PhoB效应结构域与其靶DNA序列（即pho盒）形成的复合物结构揭示了一种新颖的串联排列方式，即几个单体首尾相连地结合到连续的11个碱基对的直接重复序列上，覆盖在一条平滑弯曲的双螺旋的一个面上。该蛋白具有带翼螺旋结构，其中DNA识别元件包括穿透大沟的α3螺旋，以及通过Arg219与压缩的小沟相互作用的β发夹翼，该β发夹翼紧密夹在DNA糖骨架之间。反式激活环以适当的方向横向突出，与RNA聚合酶σ（70）亚基相互作用，从而触发转录起始。
