Taking a second look: Cyanobacteria’s Automatic Sunshade

We look around and we see a wealth of scientific phenomena that govern the functioning and interaction of organisms in this world. We look again and we may unravel a much more delicate interplay and sophisticated system underlying each of these phenomena.

This may have been the experience of Prof. Noam Adir of the Technion Faculty of Chemistry who in collaboration with Dr. Diana Kirilovsky and her laboratory at I2BC-CEA, in France found an explanation to how bacteria protect their photosynthetic system from overexposure. 

Photosynthesis, which we are familiar with from the plant world, is essential to the animal kingdom – not only for organisms, but for all living things. This is because even animals that do not perform photosynthesis consume glucose (the primary product of photosynthesis).

Given the vital importance of this process, these organisms have developed mechanisms that protect them from overexposure to sunlight. Think of a film in pre-digital cameras that could be overexposed – the same way, natural photosynthetic systems are also affected by overexposure, leading to the death of the organism.

The defence mechanism was deciphered in cyanobacteria (formerly known as “blue green algae”). The main player in this mechanism is the protein OCP – a protein that modifies its structure and colour in response to intense light. This change blocks the flow of energy that reaches the centre of the photosynthetic reaction.

“In this study, we discovered how the OCP blocks the energy,” explains Prof. Adir. “In effect, the protein acts as a biological switch”. According to experiments done by the Kirilovsky lab, this defence mechanism blocks more than 90% of the sun’s radiation. As soon as the radiation diminishes, the protein returns to its normal state and the flow of energy resumes.

I commit myself to taking a second look, whenever I can. In order to advance science, questioning and exploring is crucial and I am glad that the Technion Israel Institute of Technology provides those who do, with the necessary means and equipment.