Generation of reactive oxygen species upon strong visible light irradiation of isolated phycobilisomes from Synechocystis PCC 6803.

@article{citeulike:2687937, abstract = {The mechanism of photodegradation of antenna system in cyanobacteria was investigated using spin trapping ESR spectroscopy, SDS-PAGE and HPLC-MS. Exposure of isolated intact phycobilisomes to illumination with strong white light (3500 mumol m(-2) s(-1) photosynthetically active radiation) gave rise to the formation of free radicals, which subsequently led to specific protein degradation as a consequence of reactive oxygen species-induced cleavage of the polypeptide backbone. The use of specific scavengers demonstrated an initial formation of both singlet oxygen ((1)O(2)) and superoxide (O(2)(-)), most likely after direct reaction of molecular oxygen with the triplet state of phycobiliproteins, generated from intersystem crossing of the excited singlet state. In a second phase carbon-based radicals, detected through the appearance of DMPO-R() adducts, were produced either via O(2)(-) or by direct (1)O(2) attack on amino acid moieties. Thus photo-induced degradation of intact phycobilisomes in cyanobacteria occurs through a complex process with two independent routes leading to protein damage: one involving superoxide and the other singlet oxygen. This is in contrast to the mechanism found in plants, where damage to the light-harvesting complex proteins has been shown to be mediated entirely by (1)O(2) generation.}, address = {Department of Environmental Sciences, University of Tuscia, Viterbo, Italy.}, author = {Rinalducci, Sara and Pedersen, Jens Z Z. and Zolla, Lello }, citeulike-article-id = {2687937}, doi = {10.1016/j.bbabio.2008.02.005}, issn = {0006-3002}, journal = {Biochimica et biophysica acta}, keywords = {phycobilisome}, month = {March}, posted-at = {2008-04-18 14:20:03}, priority = {2}, title = {Generation of reactive oxygen species upon strong visible light irradiation of isolated phycobilisomes from Synechocystis PCC 6803.}, url = {http://dx.doi.org/10.1016/j.bbabio.2008.02.005}, year = {2008} }

TY - JOUR ID - citeulike:2687937 L3 - citeulike-article-id:2687937 TI - Generation of reactive oxygen species upon strong visible light irradiation of isolated phycobilisomes from Synechocystis PCC 6803. JF - Biochimica et biophysica acta AD - Department of Environmental Sciences, University of Tuscia, Viterbo, Italy. SN - 0006-3002 N2 - The mechanism of photodegradation of antenna system in cyanobacteria was investigated using spin trapping ESR spectroscopy, SDS-PAGE and HPLC-MS. Exposure of isolated intact phycobilisomes to illumination with strong white light (3500 mumol m(-2) s(-1) photosynthetically active radiation) gave rise to the formation of free radicals, which subsequently led to specific protein degradation as a consequence of reactive oxygen species-induced cleavage of the polypeptide backbone. The use of specific scavengers demonstrated an initial formation of both singlet oxygen ((1)O(2)) and superoxide (O(2)(-)), most likely after direct reaction of molecular oxygen with the triplet state of phycobiliproteins, generated from intersystem crossing of the excited singlet state. In a second phase carbon-based radicals, detected through the appearance of DMPO-R() adducts, were produced either via O(2)(-) or by direct (1)O(2) attack on amino acid moieties. Thus photo-induced degradation of intact phycobilisomes in cyanobacteria occurs through a complex process with two independent routes leading to protein damage: one involving superoxide and the other singlet oxygen. This is in contrast to the mechanism found in plants, where damage to the light-harvesting complex proteins has been shown to be mediated entirely by (1)O(2) generation. KW - phycobilisome AU - Rinalducci, Sara AU - Pedersen, Jens Z AU - Zolla, Lello PY - 2008/03/06/ UR - http://dx.doi.org/10.1016/j.bbabio.2008.02.005 ER -