Molecular mechanism of photoactivation of a light-regulated adenylate cyclase
Molecular mechanism of photoactivation of a light-regulated adenylate cyclase
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DOI：
10.1073/pnas.1704391114
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发表时间：
2017-08-08
影响因子：
11.1
通讯作者：
Park, Sam-Yong
中科院分区：
文献类型：
--
作者：
Ohki, Mio;Sato-Tomita, Ayana;Park, Sam-Yong
光活化腺苷酸环化酶（PAC）从光合蓝藻Oscillatoria acuminata（OaPAC）检测光通过N-末端BLUF结构域内的黄素生色团。BLUF结构域已经在许多不同的光激活蛋白中被发现，但是具有不同的相对取向。发现OaPAC的两个BLUF结构域彼此紧密接触，在它们的界面处形成卷曲螺旋。结晶不会阻碍酶的活性转换，但将晶体快速冷却至低温可防止光活化/失活时发生的特征光谱变化。高分辨率的晶体学分析OaPAC在完全激活状态下已实现的低温冷却后立即曝光的晶体。同晶光和暗态结构的比较表明，活性位点经历最小的变化，但酶活性可能增加高达50倍，这取决于条件。OaPAC模型将有助于开发简单、直接的方法，通过光和其他光遗传学工具来提高活细胞的环AMP水平。
The photoactivated adenylate cyclase (PAC) from the photosynthetic cyanobacterium Oscillatoria acuminata (OaPAC) detects light through a flavin chromophore within the N-terminal BLUF domain. BLUF domains have been found in a number of different light-activated proteins, but with different relative orientations. The two BLUF domains of OaPAC are found in close contact with each other, forming a coiled coil at their interface. Crystallization does not impede the activity switching of the enzyme, but flash cooling the crystals to cryogenic temperatures prevents the signature spectral changes that occur on photoactivation/deactivation. High-resolution crystallographic analysis of OaPAC in the fully activated state has been achieved by cryocooling the crystals immediately after light exposure. Comparison of the isomorphous light-and dark-state structures shows that the active site undergoes minimal changes, yet enzyme activity may increase up to 50-fold, depending on conditions. The OaPAC models will assist the development of simple, direct means to raise the cyclic AMP levels of living cells by light, and other tools for optogenetics.