Abstract
Phycobilisome has been suggested to transfer energy not only to PSII but also to PSI, although little is known about the molecular mechanism. Phycobilisome rods and the core are associated with each other via rod-core linker polypeptides (CpcG). Last year, we showed that CpcG1 and CpcG2 have distinct roles in phycobilisome assembly in Synechocystis sp. PCC 6803. Here we present their physiological roles focused on energy distribution between PSII and PSI. While phycobilisomes with CpcG1 contained all the set of components, those with CpcG2 lacked major core components. Spectral analysis suggested that phycobilisome with CpcG2 retained a minor allophycocyanin component, which will be discussed in the presentation. Fluorescence spectra demonstrated a significant defect in energy transfer to PSI in ΔcpcG2 in contrast to a defect in transfer to PSII in ΔcpcG1. This indicates that CpcG2 together with the minor allophycocyanin component plays an important role in energy transfer to PSI.
