Structure and Dynamics of the N-terminal Loop Region of PsbQ from Photosystem II of Spinacia oleracea studied by the Means of Molecular Modeling and Vibrational Spectroscopy

J. Ristvejová¹, V. Kopecký, Jr.², Ž. Sovová¹, M. Balsera³, J. B. Arellano³, M. Green⁴ and R. Ettrich¹

¹Laboratory of High Performance Computing, Institute of Physical Biology of USB and Institute of Systems Biology and Ecology of AS CR, Zámek 136, 37333 Nové Hrady, Czech Republic; ettrich@greentech.cz

²Institute of Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic

³Instituto de Recursos Naturales y Agrobiología (CSIC), Salamanca, Spain

⁴The College of New Jersey, Ewing NJ, United States of America

Email: sovova@greentech.cz

A combination of homology and energetic modeling combined with vibrational spectroscopy was used for the determination of the 20 amino acids loop between two b-sheets of the N-terminus of the PsbQ protein of the oxygen evolving complex bound to Photosystem II of Spinacia oleracea. Recombinant PsbQ protein was overexpressed in Escherichia coli BL21(DE3)pLysS transformed by JR2592 vector (B96 cells). Restraint-based homolgy modeling was used to create a series of initial model structures. Further restraints determined by FTIR and Raman spectroscopy were applied to identify which the initial models were best for molecular dynamics in solution. Initial results from a 20ns molecular dynamics simulation have shown a stable fold of the loop that is in accordance with the spectroscopic data.

This research was supported by the Ministry of Education, Youth and Sports of the Czech Republic (MSM6007665808, MSM0021620835, LC06010), by the Academy of Sciences of the Czech Republic (Institutional research concept AVOZ60870520) and the Grant Agency of the Czech Republic (grant No. 206/03/D082)