Primary Light Harvesting System: The Relationship of Phycobilisomes to Photosystem I and II. Progress Report, May 1985-September 1986

摘要

The energy transfer pathway from the phycobilisome to the photosystems in the photosynthetic membrane is being studied in cyanobacteria and red algae. Two independent terminal fluorescence emitters were resolved for the first time in isolated phycobilisomes. One of them was isolated and identified as the high molecular weight ''anchor polypeptide'' linking the phycobilisomes and the thylakoid. The other is assumed to be allophycocyanin-B. Location of the ''anchor polypeptide in both the phycobilisome and the thylakoid was verified by immunoprecipitation analysis. Within the phycobilisome core, energy flow from allophycocyanin seems to occur independently to the two terminal emitters. Since nearly parallel orientation of the dipole moment occurs only between allophycocyanin and the ''anchor polypeptide,'' the preferred energy transfer pathway is assumed to occur through the ''anchor polypeptide'' to the thylakoids. Regulation by light of the development of the photosynthetic apparatus is continuing. In the red algae Porphyridium cruentum, an obligate shade plant, the phycobilisome number changes while photosystem I remains relatively invariant with changes in light intensity. It appears that this organism will serve as a model system for studying intensity effects. (ERA citation 12:000299)