Oxidative stress and metal ions effects on the cores of phycobilisomes in Synechocystis sp. PCC 6803.

Inactivation of the chlN gene in Synechocystis sp. PCC 6803 resulted in no chlorophyll and photosystems when the mutant was grown in darkness, providing an in vivo system to study the structure and function of phycobilisomes (PBSs). The effects of hydrogen peroxide (H2O2) and metal ions on the mutant PBSs in vivo were investigated by low temperature fluorescence emission measurement. H2O2 induced an obvious disassembly of the cores of PBSs and interruption of energy transfer from allophycocyanin to the terminal emitter. Among many metal ions only silver induced disassembly of the cores of PBSs. Our results demonstrated for the first time that the cores of PBSs act as targets in vivo for oxidative stress or silver induced damage.