Allosteric action in real time: Time-resolved crystallographic studies of a cooperative dimeric hemoglobin
Allosteric action in real time: Time-resolved crystallographic studies of a cooperative dimeric hemoglobin
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DOI：
10.1073/pnas.0509411103
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发表时间：
2006-05-16
影响因子：
11.1
通讯作者：
Royer, William E., Jr.
中科院分区：
文献类型：
--
作者：
Knapp, James E.;Pahl, Reinhard;Royer, William E., Jr.
蛋白质变构提供了在分子水平上调节生物学功能的机制。我们在这里提出了一个全球性的，配体诱导的蛋白质变构转变的时间分辨x射线衍射的调查。这项研究提供了一个视图的结构变化，在单晶体的Scapharca二聚血红蛋白，因为他们进行真实的时间，从5 ns到80 μ s后配体光解。当蛋白质对每个R状态蛋白质亚基内的未配体血红素的存在做出响应时，三级中间结构迅速形成（< 5 ns），在血红素基团、相邻残基和界面水分子中观察到关键的结构变化。这种中间体为发生在微秒时间尺度上的协调的三级和四级结构变化奠定了基础，并且与向低亲和力T状态结构的过渡相关。这些变化的恢复显示了相当大的滞后，因为T样结构在配体重新结合后仍然存在，这表明T到R的过渡很慢。
Protein allostery provides mechanisms for regulation of biological function at the molecular level. We present here an investigation of global, ligand-induced allosteric transition in a protein by time-resolved x-ray diffraction. The study provides a view of structural changes in single crystals of Scapharca dimeric hemoglobin as they proceed in real time, from 5 ns to 80 mu s after ligand photodissociation. A tertiary intermediate structure forms rapidly (< 5 ns) as the protein responds to the presence of an unliganded heme within each R-state protein subunit, with key structural changes observed in the heme groups, neighboring residues, and interface water molecules. This intermediate lays a foundation for the concerted tertiary and quaternary structural changes that occur on a microsecond time scale and are associated with the transition to a low-affinity T-state structure. Reversal of these changes shows a considerable lag as a T-like structure persists well after ligand rebinding, suggesting a slow T-to-R transition.