Temperature- and Hydration-Dependent Protein Dynamics in Photosystem II of Green Plants Studied by Quasielastic Neutron Scattering

Protein dynamics in hydrated and vacuum-dried photosystem II (PS II) membrane fragments from spinach has been investigated by quasielastic neutron scattering (QENS) in the temperature range between 5 and 300 K. Three distinct temperature ranges can be clearly distinguished by active type(s) of prote...

Full description

Saved in:

Bibliographic Details
Published in:	Biochemistry (Easton) Vol. 46; no. 40; pp. 11398 - 11409
Main Authors:	Pieper, Jörg, Hauss, Thomas, Buchsteiner, Alexandra, Baczyński, Krzysztof, Adamiak, Karolina, Lechner, Ruep E, Renger, Gernot
Format:	Journal Article
Language:	English
Published:	United States American Chemical Society 09-10-2007
Subjects:	Kinetics Neutrons Photosystem II Protein Complex - chemistry Plant Proteins - chemistry Scattering, Radiation Spinacia oleracea - chemistry Temperature Thermodynamics Water - chemistry
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Protein dynamics in hydrated and vacuum-dried photosystem II (PS II) membrane fragments from spinach has been investigated by quasielastic neutron scattering (QENS) in the temperature range between 5 and 300 K. Three distinct temperature ranges can be clearly distinguished by active type(s) of protein dynamics: (A) At low temperatures (T < 120 K), the protein dynamics of both dry and hydrated PS 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, is due to a partial onset of diffusive protein motions. (C) At temperatures above 240 K, the protein flexibility drastically changes because of the onset of diffusive (large-amplitude) protein motions. This dynamical transition is clearly hydration-dependent since it is strongly suppressed in dry PS II. The thermally activated onset 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) Biochemistry 37, 11399−11404). Analogously, the freezing of protein mobility by dehydration in dry PS II appears to be 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 of the water-oxidizing complex as outlined in the Discussion section.
Bibliography:	Financial support by Deutsche Forschungsgemeinschaft (SFB 429, TP A1) is gratefully acknowledged. istex:F608EE3D31728F55786F62690F5BCF4AF2C3CC2D ark:/67375/TPS-4HK4FQC9-8 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0006-2960 1520-4995
DOI:	10.1021/bi700179s