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Photoinhibition in vivo and in vitro Involves Weakly Coupled Chlorophyll–Protein Complexes † ¶
Author(s) -
Santabarbara Stefano,
Cazzalini Ilaria,
Rivadossi Andrea,
Garlaschi Flavio M.,
Zucchelli Giuseppe,
Jennings Robert C.
Publication year - 2002
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2002)0750613pivaiv2.0.co2
Subject(s) - photoinhibition , thylakoid , photosystem ii , biophysics , population , photochemistry , biology , non photochemical quenching , chemistry , photosynthesis , botany , biochemistry , chloroplast , demography , sociology , gene
In the present study the analysis of the relation between the excited state population in the photosystem II (PSII) antenna and photoinactivation has been extended from an in vitro system, isolated thylakoids, to an in vivo system, Chlamydomonas reinhardtii cells. The results indicate that the excited state quenching by an added singlet quencher induces maximal protection against photoinhibition of about 30% of that expected on the basis of the observed light intensity–treatment time reciprocity rule. Similar results, obtained previously with thylakoids, have been interpreted in terms of damaged or incorrectly assembled complexes that play an important role in photoinhibition in the thylakoid membranes (Santabarbara, S., K. Neverov, F. M. Garlaschi, G. Zucchelli and R. C. Jennings [2001] Involvement of uncoupled antenna chlorophylls in photoinhibition in thylakoids. FEBS Lett. 491 , 109–113.). In an attempt to better define this aspect, the photoinhibition action spectra were determined for mutant barley thylakoids, lacking the chlorophyll (Chl) a – b complexes of the outer antenna, and for its wild type. The results indicate that in both systems the action spectra are significantly blueshifted (2–4 nm) and are broader than the PSII absorption in the membranes. These data are interpreted in terms of a heterogeneous population of outer and inner antenna pigment–protein complexes that contain significant levels of uncoupled Chl.