Energetic Uncoupling and Dissociation of Cyanobacterial Antenna by Low Phosphate Concentration or Low Temperature

Abstract

Phycobilisomes (PBS) are supramolecular aggregates that serve as primary light-harvesting antenna for photosystem reaction centers in cyanobacteria and red algae. A basic model for hemidiscoidal PBS complexes, containing a trycilindrical core and six radiating rods, has been proposed for most cyanobaterial PBS (for review 1, 2). Nowadays, a new revised model to hemidiscoidal PBS from cyanobacteria and red algae has been proposed (3,4). Considering the earliest model, studies of energetic transfer and dissociation under low temperature and/or low phosphate concentration have been reported (5, 6,). The present work compares the kinetics of energetic uncoupling, and the products of PBS dissociation, promoted by exposing intact PBS to low temperatures or low phosphate concentrations. PBS used are hemidiscoidal type (1) composed by biliproteins Alophycocyanin (APC), Phycocyanin (PC) and phycoerythrocyanin (PEC).