Blue light induces global and localized conformational changes in the kinase domain of full-length phototropin.
Blue light induces global and localized conformational changes in the kinase domain of full-length phototropin.
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DOI：
10.1021/bi9016044
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发表时间：
2010-02
期刊：
影响因子：
2.9
通讯作者：
Anna Pfeifer;T. Mathes;Yinghong Lu;P. Hegemann;T. Kottke
中科院分区：
文献类型：
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作者：
Anna Pfeifer;T. Mathes;Yinghong Lu;P. Hegemann;T. Kottke
蓝光光感受器向光素在优化植物光合作用中起着至关重要的作用。在向光素的两个光、氧或电压敏感（LOV）域中，光刺激被黄素发色团吸收。假设信号通过保守的J α螺旋元件的解离和解折叠转移到丝氨酸/苏氨酸激酶结构域。我们研究了全长phototropin从绿色衣藻莱茵衣藻通过傅里叶变换红外光谱揭示的信号传递内的蛋白质和结构上的激酶的响应。通过比较全长蛋白质与截短的LOV 1-LOV 2-J α和LOV 1-LOV 2的信号以及缺失突变体的信号来分配光诱导的结构变化。在LOV 1-LOV 2-J α中观察到源自J α接头螺旋的螺旋度损失，这与LOV 2-J α的先前研究一致。全长phototropin显示可逆的全球构象变化，通过几个转弯元件。这些变化在缺乏J α接头的缺失突变体中被抑制，并归因于激酶结构域。转角结构的丧失被解释为在LOV 2结构域释放时光诱导的激酶三级结构的打开。没有观察到激酶结构域中Asp或Glu残基的伴随质子化变化。光诱导的螺旋损失，观察到只有在存在的一个phototropin的特性的54-氨基酸的激酶激活环，这是预测位于除了催化裂缝的延伸。延伸的这种反应可能在向光素信号传导过程中起重要作用。
The blue-light photoreceptor phototropin plays a crucial role in optimizing photosynthesis in plants. In the two light-, oxygen-, or voltage-sensitive (LOV) domains of phototropin, the light stimulus is absorbed by the flavin chromophores. The signal is assumed to be transferred via dissociation and unfolding of a conserved J alpha helix element to the serine/threonine kinase domain. We investigated full-length phototropin from the green alga Chlamydomonas reinhardtii by Fourier transform infrared spectroscopy to shed light on the signal transfer within the protein and on the structural response of the kinase. Light-induced structural changes were assigned by comparing signals of the full-length protein with those of the truncated LOV1-LOV2-J alpha and LOV1-LOV2 and with those of deletion mutants. A loss of helicity originating from the J alpha linker helix was observed in LOV1-LOV2-J alpha in agreement with previous studies of LOV2-J alpha. Full-length phototropin showed reversible global conformational changes via several turn elements. These changes were suppressed in a deletion mutant lacking the J alpha linker and are attributed to the kinase domain. The loss of turn structure is interpreted as a light-induced opening of the kinase tertiary structure upon release of the LOV2 domain. Concomitant protonation changes of Asp or Glu residues in the kinase domain were not observed. A light-induced loss in helicity was observed only in the presence of a phototropin-characteristic 54-amino acid extension of the kinase activation loop, which is predicted to be located apart from the catalytic cleft. This response of the extension might play a significant role in the phototropin signaling process.