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首页> 外文期刊>Biochemistry >Blue Light Induces Global and Localized Conformational Changes in the Kinase Domain of Full-Length Phototropin
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Blue Light Induces Global and Localized Conformational Changes in the Kinase Domain of Full-Length Phototropin

机译：蓝光诱导全长光养蛋白激酶域中的全局和局部构象变化

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摘要

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 JR 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 transferwithin 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-JR and LOV1-LOV2 and with those of deletion mutants. A loss of helicity originating from the JR linker helix was observed in LOV1-LOV2-JR in agreement with previous studies of LOV2-JR. Full-length phototropin showed reversible global conformational changes via several turn elements. These changes were suppressed in a deletion mutant lacking the JR 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 ofAsp orGlu residues in the kinase domainwere not observed.Alight-induced loss in helicitywas observed only in the presence of a phototropincharacteristic 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.
机译：蓝光感受器光蛋白在优化植物的光合作用中起着至关重要的作用。在光蛋白的两个光，氧或电压敏感（LOV）域中，黄素发色团吸收了光刺激。假定该信号通过保守的JR螺旋元件的解离和解链转移到丝氨酸/苏氨酸激酶结构域上。我们通过傅立叶变换红外光谱研究了绿藻衣藻衣藻的全长光养蛋白，以阐明该蛋白内的信号传递以及该激酶的结构响应。通过比较全长蛋白的信号与截短的LOV1-LOV2-JR和LOV1-LOV2的信号以及缺失突变体的信号，确定光诱导的结构变化。与以前的LOV2-JR研究一致，在LOV1-LOV2-JR中观察到了源自JR连接子螺旋的螺旋性丧失。全长光养蛋白通过几个转向元件显示出可逆的整体构象变化。这些变化在缺少JR接头的缺失突变体中被抑制，并且归因于激酶结构域。转弯结构的丧失被解释为在LOV2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。仅在激酶激活环具有光蛋白特性的54个氨基酸延伸的情况下观察到了光诱导的螺旋度损失，预计该位置与催化裂口分开。延伸的这种响应可能在光养蛋白信号传导过程中起重要作用。

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