Trehalose matrix effects on charge-recombination kinetics in Photosystem I of oxygenic photosynthesis at different dehydration levels

Malferrari, M.; Savitsky, A.; Mamedov, M.D.; Milanovsky, G.E.; Lubitz, W.; Möbius, K.; Semenov, A.Y.; Venturoli, G.

Авторы: Malferrari Marco, Savitsky Anton, Mamedov Mahir D., Milanovsky Georgy E., Lubitz Wolfgang, Möbius Klaus, Semenov Alexey Yu, Venturoli Giovanni
Журнал: Biochimica et Biophysica Acta - Bioenergetics
Том: 1857
Номер: 9
Год издания: 2016
Издательство: Elsevier BV
Местоположение издательства: Netherlands
Первая страница: 1440
Последняя страница: 1454
DOI: 10.1016/j.bbabio.2016.05.001
Аннотация: Matrix effects on long-range electron transfer were studied in cyanobacterial Photosystem I (PS I) complexes, embedded into trehalose glasses at different hydration levels. W-band EPR studies demonstrated, via nitroxide spin probes, structural homogeneity of the dry PS I-trehalose matrix and no alteration of cofactors’ distance and relative orientation under temperature and matrix variation. In dry trehalose glasses at room temperature (RT), PS I was stable for months. Flash-induced charge recombination kinetics were examined by high-field time-resolved EPR and optical spectroscopies. The kinetics in hydrated PS I-trehalose glasses mostly reflected the reduction of the photooxidized primary donor P700•+ by the reduced terminal iron-sulfur clusters. Upon dehydration, the P700•+ decay accelerated and became more distributed. Continuous distributions of lifetimes τ were extracted from the kinetics by two numerical approaches: a maximum entropy method (MemExp program) and a constrained regularization method (CONTIN program). Both analyses revealed that upon dehydration the contribution of the two slowest components (lifetimes τ ~ 300 ms and ~ 60 ms), attributed to P700•+[FA/FB]•- recombination, decreased in parallel with the increase of the fastest component (τ ~ 150 μs), and of additional distributed phases with intermediate lifetimes. Dehydration at RT mimicked the effects of freezing water-glycerol PS I systems, suggesting an impairment of PS I protein dynamics in the dry trehalose glass. Similar effects were observed previously in bacterial reaction centers. The work presented for PS I provides new insights into the crucial issue of protein-matrix interactions for protein functionality as controlled by hydrogen-bond networks of the hydration shell.
Добавил в систему: Милановский Георгий Евгеньевич

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Trehalose matrix effects on charge-recombination kinetics in Photosystem I of oxygenic photosynthesis at different dehydration levelsстатья

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