Format

Send to

Choose Destination
Philos Trans R Soc Lond B Biol Sci. 2017 Sep 26;372(1730). pii: 20160378. doi: 10.1098/rstb.2016.0378.

Photoprotection through ultrafast charge recombination in photochemical reaction centres under oxidizing conditions.

Author information

1
Department of Biophysics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands fma@iccas.ac.cn.
2
School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK.
3
Department of Biophysics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.

Abstract

Engineering natural photosynthesis to address predicted shortfalls in food and energy supply requires a detailed understanding of its molecular basis and the intrinsic photoprotective mechanisms that operate under fluctuating environmental conditions. Long-lived triplet or singlet excited electronic states have the potential to cause photodamage, particularly in the presence of oxygen, and so a variety of mechanisms exist to prevent formation of such states or safely dissipate their energy. Here, we report a dramatic difference in spectral evolution in fully reduced and partially oxidized Rhodobacter sphaeroides reaction centres (RCs) following excitation of the monomeric bacteriochlorophyll (BChl) cofactors at 805 nm. Three types of preparation were studied, including RCs purified as protein/lipid nanodiscs using the copolymer styrene maleic acid. In fully reduced RCs such excitation produces membrane-spanning charge separation. In preparations of partially oxidized RCs the spectroscopic signature of this charge separation is replaced by that of an energy dissipation process, including in the majority sub-population of reduced RCs. This process, which appears to take place on both cofactor branches, involves formation of a BChl+/bacteriopheophytin- radical pair that dissipates energy via recombination to a vibrationally hot ground state. The possible physiological role of this dissipative process under mildly oxidizing conditions is considered.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'.

KEYWORDS:

charge recombination; photoprotection; reaction centre; styrene maleic acid; ultrafast spectroscopy

PMID:
28808097
PMCID:
PMC5566878
DOI:
10.1098/rstb.2016.0378
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Atypon Icon for PubMed Central
Loading ...
Support Center