Here Comes the Sun

Phycobilisomes act as light-harvesting antennae for cyanobacteria and red algae – some of the oldest lifeforms on the planet. As such, these protein complexes are highly evolved and incredibly efficient at capturing light for photosynthetic processes (1).

Sem Tamara and colleagues used multimodal mass spectrometry (MS) to characterize the components of B-phycoerythrin, the major phycobiliprotein in the red algae Porphyridium creuntum, and further our understanding of how the complex operates (2). This knowledge, coinvestigator Aneika Leney says, has the potential to be used for “the innovative design of new light-harvesting machines for use in bioenergy processes”.

Tandem MS techniques allowed the complex structure of B-phycoerythrin – comprising 12 alpha and beta subunits linked by gamma chains – to be separated and fragmented. “Using our strategy, we were able to identify components of the light-harvesting machinery that stabilize the complex and join many different protein components together. These were more heterogeneous than we initially anticipated and possess multiple different chromophores that all act to transmit light effectively from one protein to another,” says Leney.

There are still gaps in our knowledge, says Leney, “We and others in the field have now characterized most of the light harvesting complex, however, questions still remain on how this complex is tethered to the membrane inside algae to complete the final energy transmission process from light to chemical energy.” The authors hope that we can eventually apply the knowledge to supercharge manmade solar cells. We certainly have a lot to learn – the light-harvesting systems of red algae operate at around 95 percent efficiency, while manmade solar panels average 10–20 percent.