Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8816, USA.
Proc Natl Acad Sci U S A. 2011 Jun 7;108(23):9449-54. doi: 10.1073/pnas.1100262108. Epub 2011 May 23.
Light-oxygen-voltage (LOV) domains are blue light-activated signaling modules integral to a wide range of photosensory proteins. Upon illumination, LOV domains form internal protein-flavin adducts that generate conformational changes which control effector function. Here we advance our understanding of LOV regulation with structural, biophysical, and biochemical studies of EL222, a light-regulated DNA-binding protein. The dark-state crystal structure reveals interactions between the EL222 LOV and helix-turn-helix domains that we show inhibit DNA binding. Solution biophysical data indicate that illumination breaks these interactions, freeing the LOV and helix-turn-helix domains of each other. This conformational change has a key functional effect, allowing EL222 to bind DNA in a light-dependent manner. Our data reveal a conserved signaling mechanism among diverse LOV-containing proteins, where light-induced conformational changes trigger activation via a conserved interaction surface.
光氧电压（LOV）结构域是一系列光感受器蛋白中重要的蓝光激活信号模块。受到光照时，LOV 结构域形成内部的蛋白-黄素加合物，引发构象变化，从而控制效应器功能。本研究利用结构、生物物理和生化手段，对光调控 DNA 结合蛋白 EL222 进行了深入研究，进一步阐明了 LOV 的调控机制。在暗状态下，晶体结构揭示了 LOV 和螺旋-转角-螺旋结构域之间的相互作用，我们发现这些相互作用抑制了 DNA 的结合。溶液生物物理数据表明，光照破坏了这些相互作用，使 LOV 和螺旋-转角-螺旋结构域彼此分离。这种构象变化具有关键的功能效应，使 EL222 能够以光依赖的方式结合 DNA。我们的数据揭示了不同 LOV 蛋白之间保守的信号转导机制，其中光诱导的构象变化通过保守的相互作用表面触发激活。
