Hendriks Johnny, Hellingwerf Klaas J
Laboratory for Microbiology, Swammerdam Institute for Life Sciences and Netherlands Institute for Systems Biology, University of Amsterdam, 1018 WV Amsterdam, The Netherlands.
J Biol Chem. 2009 Feb 20;284(8):5277-88. doi: 10.1074/jbc.M805904200. Epub 2008 Dec 17.
The recovery reaction of the signaling state of photoactive yellow protein includes the following: (i) deprotonation of the p-coumaryl chromophore, (ii) refolding of the protein, and (iii) chromophore re-isomerization from the cis to the trans configuration. Through analysis of the pH dependence of this recovery reaction, we were able to provide proof for the existence of an additional photocycle intermediate. The spectral similarity between this new intermediate and the dark state indicates that the new intermediate has a deprotonated chromophore, which may facilitate chromophore re-isomerization. This spectral similarity also explains why this new intermediate has not been noticed in earlier studies. For our data analysis we introduce a photocycle model that takes into account the effect of the specific light regime selected, a model that was also used for simulations.
(i) 对香豆酰发色团的去质子化,(ii) 蛋白质的重新折叠,以及(iii) 发色团从顺式构型到反式构型的重新异构化。通过分析该恢复反应对pH的依赖性,我们能够为一种额外的光循环中间体的存在提供证据。这种新中间体与暗态之间的光谱相似性表明,新中间体具有去质子化的发色团,这可能有助于发色团的重新异构化。这种光谱相似性也解释了为什么在早期研究中没有注意到这种新中间体。为了进行数据分析,我们引入了一个光循环模型,该模型考虑了所选特定光照条件的影响,该模型也用于模拟。