Temperature- and Hydration-Dependent Protein Dynamics in Photosystem II of Green Plants Studied by Quasielastic Neutron Scattering
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- 作者：Jö ; rg Pieper ; Thomas Hauss ; Alexandra Buchsteiner ; Krzysztof Baczyski ; Karolina Adamiak ; Ruep E. Lechner ; Gernot Renger
- 刊名：Biochemistry
- 出版年：2007
- 出版时间：October 9, 2007
- 年：2007
- 卷：46
- 期：40
- 页码：11398 - 11409
- 全文大小：138K
- 年卷期：v.46,no.40(October 9, 2007)
- ISSN：1520-4995
文摘
Protein dynamics in hydrated and vacuum-dried photosystem II (PS II) membrane fragmentsfrom spinach has been investigated by quasielastic neutron scattering (QENS) in the temperature rangebetween 5 and 300 K. Three distinct temperature ranges can be clearly distinguished by active type(s) ofprotein dynamics: (A) At low temperatures (T < 120 K), the protein dynamics of both dry and hydratedPS II is characterized by harmonic vibrational motions. (B) In the intermediate temperature range (120 <T < 240 K), the total mean square displacement <u2>total slightly deviates from the predicted linear behavior.The QENS data indicate that this deviation, which is virtually independent of the extent of hydration, isdue to a partial onset of diffusive protein motions. (C) At temperatures above 240 K, the protein flexibilitydrastically changes because of the onset of diffusive (large-amplitude) protein motions. This dynamicaltransition is clearly hydration-dependent since it is strongly suppressed in dry PS II. The thermally activatedonset of protein flexibility as monitored by QENS is found to be strictly correlated with the temperature-dependent increase of the electron transport efficiency from to QB (Garbers et al. (1998) Biochemistry37, 11399-11404). Analogously, the freezing of protein mobility by dehydration in dry PS II appears tobe responsible for the blockage of reoxidation by QB at hydration values lower than 45% r.h.(Kaminskaya et al. (2003) Biochemistry 42, 8119-8132). Similar effects were observed for reactions ofthe water-oxidizing complex as outlined in the Discussion section.