15N MAS NMR Studies of Cph1 Phytochrome: Chromophore Dynamics and Intramolecular Signal Transduction

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• 作者：Thierry Rohmer ; Holger Strauss ; Jon Hughes ; Huub de Groot ; Wolfgang G&auml ; rtner ; Peter Schmieder ; J&ouml ; rg Matysik
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：October 19, 2006
• 年：2006
• 卷：110
• 期：41
• 页码：20580 - 20585
• 全文大小：96K
• 年卷期：v.110,no.41(October 19, 2006)
• ISSN：1520-5207

文摘

Solid-state nuclear magnetic resonance (NMR) is applied for the first time to the photoreceptor phytochrome.The two stable states, Pr and Pfr, of the 59-kDa N-terminal module of the cyanobacterial phytochrome Cph1from Synechocystis sp. PCC 6803 containing a uniformly ¹⁵N-labeled phycocyanobilin cofactor are exploredby ¹⁵N cross-polarization (CP) magic-angle spinning (MAS) NMR. As recently shown by ¹⁵N solution-stateNMR using chemical shifts [Strauss, H. M.; Hughes, J.; Schmieder, P. Biochemistry 2005, 44, 8244], all fournitrogens are protonated in both states. CP/MAS NMR provides two additional independent lines of evidencefor the protonation of the nitrogens. Apparent loss of mobility during photoactivation, indicated by the decreaseof line width, demonstrates strong tension of the entire chromophore in the Pfr state, which is in clear contrastto a more relaxed Pr state. The outer rings (A and D) of the chromophore are significantly affected by thephototransformation, as indicated by both change of chemical shift and line width. On the other hand, on theinner rings (B and C) only minor changes of chemical shifts are detected, providing evidence for a conservedenvironment during phototransformation. In a mechanical model, the phototransformation is understood interms of rotations between the A-B and C-D methine bridges, allowing for intramolecular signal transductionto the protein surface by a unit composed of the central rings B and C and its tightly linked protein surroundingsduring the highly energetic Pfr state.