Crystal structures of the PsbS protein essential for photoprotection in plants
Crystal structures of the PsbS protein essential for photoprotection in plants
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植物光保护所必需的 PsbS 蛋白的晶体结构
DOI：
10.1038/nsmb.3068
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发表时间：
2015-09-01
影响因子：
16.8
通讯作者：
Chang, Wenrui
中科院分区：
文献类型：
--
作者：
Fan, Minrui;Li, Mei;Chang, Wenrui
光系统II蛋白PSBs在QE型非光化学猝灭中起重要作用，它保护植物免受强光条件下的光伤害。QE是由低pH条件下PSB的激活启动的，但PSB的作用机制尚不清楚。在这里，我们报道了菠菜PSB的低pH晶体结构，它的游离态和与QE抑制剂N，N‘-二环己基碳二亚胺(DCCD)的络合物，揭示了PSB采用独特的折叠模式，并且与捕光复合体超家族的其他成员不同，它是一种非规范的色素结合蛋白。结构和生化证据表明，活性和非活性PSB都在类囊体膜上形成同源二聚体，DCCD结合破坏了活性PSB二聚体的腔内分子间氢键。在QE过程中，低pH激活PSB可能涉及与PSBS二聚体的腔内分子间相互作用改变相关的构象变化。
The photosystem II protein PsbS has an essential role in qE-type nonphotochemical quenching, which protects plants from photodamage under excess light conditions. qE is initiated by activation of PsbS by low pH, but the mechanism of PsbS action remains elusive. Here we report the low-pH crystal structures of PsbS from spinach in its free form and in complex with the qE inhibitorN,N′-dicyclohexylcarbodiimide (DCCD), revealing that PsbS adopts a unique folding pattern, and, unlike other members of the light-harvesting-complex superfamily, it is a noncanonical pigment-binding protein. Structural and biochemical evidence shows that both active and inactive PsbS form homodimers in the thylakoid membranes, and DCCD binding disrupts the lumenal intermolecular hydrogen bonds of the active PsbS dimer. Activation of PsbS by low pH during qE may involve a conformational change associated with altered lumenal intermolecular interactions of the PsbS dimer.