Time-resolved Fluorescence Spectroscopy Study of Energy Transfer Dynamics in Phycobilisome of Thermophilic Cyanobacterium Thermosynechococcus vulcanus NIES 2134

Abstract

Phycobilisomes (PBSs) are the largest light-harvesting complex in cyanobacteria and red algae. To understand the energy transfer dynamics in phycobilisome, the cyanobacterium, Thermosynechococcus vulcanus NIES 2134 (T. 2134), with a phycocyanin (PC) trimer PC612 linking the rod and core, was selected. The energy transfer dynamics in PBS from T. 2134 were studied via time-resolved fluorescence spectroscopy in sub-picosecond resolution. The energy transfer pathways and transfer rates were uncovered by deconvolution of the fluorescence decay curve. A fast time-component of 10 ps from PC612 trimer to the core and a slow time-component of 80 ps from rods to the core were recognized in the energy transfer in PBSs. The faster energy transfer rate of 10 ps enables PC612 trimer to modulate the energy transfer dynamics between rods and core. The findings help us understand the structure-induced energy transfer mechanisms in PBSs.