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Excitation pressure regulates the activation energy for recombination events in the photosystem II reaction centres of Chlamydomonas reinhardtii
Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
Responsible organisation
2007 (English)In: Biochemistry and Cell Biology, ISSN 0829-8211, E-ISSN 1208-6002, Vol. 85, no 6, 721-729 p.Article in journal (Refereed) Published
Abstract [en]

Using in vivo thermoluminescence, we examined the effects of growth irradiance and growth temperature on charge recombination events in photosystem IT reaction centres of the model green alga Chlamydomonas reinhardtii. We report that growth at increasing irradiance at either 29 or 15 degrees C resulted in comparable downward shifts in the temperature peak maxima (T-M) for S(2)Q(B)(-) charge pair recombination events, with minimal changes in S(2)Q(A)(-) recombination events. This indicates that such growth conditions decrease the activation energy required for S(2)QB(-) charge pair recombination events with no concomitant change in the activation energy for S(2)Q(A)(-) recombination events. This resulted in a decrease in the Delta T-M between S(2)Q(A)(-) and S(2)Q(B)(-) recombination events, which was reversible when shifting cells from low to high irradiance and back to low irradiance at 29 degrees C. We interpret these results to indicate that the redox potential of Q(B) was modulated independently of Q(A), which consequently narrowed the redox potential gap between Q(A) and Q(B) in photosystem II reaction centres. Since a decrease in the Delta T-M between S(2)Q(A)(-) and S(2)Q(B)(-) recombination events correlated with growth at increasing excitation pressure, we conclude that acclimation to growth under high excitation pressure narrows the redox potential gap between Q(A) and Q(B) in photosystem 11 reaction centres, enhancing the probability for reaction center quenching in C. reinhardtii. We discuss the molecular basis for the modulation of the redox state of Q(B), and suggest that the potential for reaction center quenching complements antenna quenching via the xanthophyll cycle in the photoprotection of C. reinhardtii from excess light.

Place, publisher, year, edition, pages
2007. Vol. 85, no 6, 721-729 p.
Keyword [en]
Excitation pressure, PS II, Chlamydomonas reinhardtii, activation energy
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:miun:diva-4358DOI: 10.1139/O07-144ISI: 000252316300007Scopus ID: 2-s2.0-38849102227Local ID: 5469OAI: oai:DiVA.org:miun-4358DiVA: diva2:29390
Note

vR-Medicine, Internal

Available from: 2008-12-09 Created: 2008-12-09 Last updated: 2016-09-26Bibliographically approved

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Citation style
  • apa
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