Photosynthetic organisms need to cope with a wide range of light intensities, which can change over timescales of seconds to minutes. Too much light can damage the photosynthetic machinery and cause cell death. Scientists at the Carnegie Institution were part of a team that found that specific proteins in algae can act as a safety valve to dissipate excess absorbed light energy before it can wreak havoc in cells.
The research, performed mostly by Graham Peers in the laboratory of Krishna Niyogi from the University of California, Berkeley, included researchers at the University of Münster, Germany, and used a mutant strain of the single-celled green alga Chlamydomonas reinhardtii, originally isolated at the Carnegie Institution, to show that a specific protein of the light harvesting family of proteins plays a critical role in eliminating excess absorbed light energy. A mutant lacking this protein, designated LHCSR, suffered severely when exposed to fluctuating light conditions. “Photosynthetic organisms must be able to manage absorbed light energy,” says study co-author Arthur Grossman of Carnegie’s Department of Plant Biology, “and the LHCSR proteins appear to be critical for algae to eliminate absorbed light energy as heat as light levels in the environment fluctuate, becoming potentially toxic.”