Marine cyanobacteria tune energy transfer efficiency in their light-harvesting antennae by modifying pigment coupling

Abstract

Photosynthetic organisms regulate energy transfer to fit to changes in environmental conditions. The biophysical principles underlying the flexibility and efficiency of energy transfer in the light-harvesting process are still not fully understood. Here we examine how energy transfer is regulated in-vivo. We compare different acclimation states of the photosynthetic apparatus in a marine cyanobacterial species that is well adapted to vertical mixing of the ocean water column and identify a novel acclimation strategy for photosynthetic life under low light intensities. Antennae rods extend, as expected, increasing light absorption. Surprisingly, in contrast to what was known for plants and predicted by classic calculations, these longer rods transfer energy faster i.e. more efficiently. The fluorescence lifetime and emission spectra dependence on temperature, at the range of 4-300K, suggests that energy transfer efficiency is tuned by modifying the energetic coupling strength between antennae pigments.