You are here : Home > News > Things Are Heating Up in Cyanobacteria

Scientific result | Health & life sciences | Vegetal physiology

Things Are Heating Up in Cyanobacteria

​The light-collecting antennae in cyanobacteria can dissipate an overflow of light energy by fluorescence. This photoprotection mechanism remained unknown up to this point.
Published on 31 January 2017

Plants, algae and cyanobacteria use clever mechanisms to absorb light for photosynthesis, even under low-light conditions. To do so, they are equipped with light-collecting antennas, which are macromolecular assemblies containing many pigments capable of quickly adapting to variations in light intensity. In particular, when suddenly exposed to high-light conditions, they become thermal dissipators of the absorbed energy. In cyanobacteria, high-light conditions activate a soluble protein bound to a carotenoid molecule, the Orange Carotenoid Protein (OCP). The activated OCP interacts with the phycobilisomes, the main light-collecting antennae, thus inducing the dissipation of energy in the form of heat.

A study carried out by scientists at the Universities of Amsterdam, Pretoria and CEA-IBITECS showed that, on phycobilisomes isolated as a "single molecule", this dissipation of energy occurs through a process known as "fluorescence blinking". The bilins—pigments of the phycobilisomes—switch randomly and reversibly into "dark" metastable states in which the absorbed energy is thermally dissipated, independently from the OCP.

Although previous studies sought to associate this process with photoprotection, these attempts were carried out with light intensity several orders of magnitude greater than sunlight, which can potentially induce effects that would not be expected under physiological conditions. In this study, the scientists used much lower light intensity. The study provided the first evidence for the phenomenon of fluorescence blinking in phycobilisomes at physiological light intensities. The scientists suspect that other photosynthetic organisms may employ similar strategies to respond instantly to rapid solar light intensity fluctuations.

A deeper understanding of the photophysical mechanisms in light-collecting antennae is of paramount interest for the development of bio-inspired solar energy technologies.

Top page