Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot, Israel.
Angew Chem Int Ed Engl. 2016 Jun 6;55(24):6901-5. doi: 10.1002/anie.201512001. Epub 2016 Apr 21.
The ability to tune the light-absorption properties of chlorophylls by their protein environment is the key to the robustness and high efficiency of photosynthetic light-harvesting proteins. Unfortunately, the intricacy of the natural complexes makes it very difficult to identify and isolate specific protein-pigment interactions that underlie the spectral-tuning mechanisms. Herein we identify and demonstrate the tuning mechanism of chlorophyll spectra in type II water-soluble chlorophyll binding proteins from Brassicaceae (WSCPs). By comparing the molecular structures of two natural WSCPs we correlate a shift in the chlorophyll red absorption band with deformation of its tetrapyrrole macrocycle that is induced by changing the position of a nearby tryptophan residue. We show by a set of reciprocal point mutations that this change accounts for up to 2/3 of the observed spectral shift between the two natural variants.
通过蛋白质环境来调节叶绿素的吸光特性的能力是光合光捕获蛋白稳健性和高效率的关键。不幸的是，天然复合物的复杂性使得很难识别和分离出光谱调谐机制背后的特定蛋白-色素相互作用。在此，我们鉴定并证明了类黄酮（WSCPs）中 II 型水溶性叶绿素结合蛋白中叶绿素光谱的调谐机制。通过比较两种天然 WSCP 的分子结构，我们将叶绿素红光吸收带的位移与四吡咯大环的变形相关联，这种变形是由附近色氨酸残基位置的变化引起的。通过一组相互的点突变实验，我们表明这种变化解释了两个天然变体之间观察到的光谱位移的 2/3 左右。
