Periodic Reporting for period 2 - PHOTO-CY-APPs (Photosynthesis and photoprotection regulation in marine cyanobacteria and its potential applications)
Reporting period: 2020-06-01 to 2021-05-31
Cyanobacteria are the organisms that 'invented' photosynthesis, therefore they are the organisms responsible for evolution on Earth. They were the first photosynthetic microorganisms that started to increase the concentration of oxygen in the atmosphere, being the origin of the modern cells. Moreover, in the decades of the 70s and 80s, two specific genera of marine cyanobacteria (Prochlorococcus and Synechococcus) were discovered, which marked a turning point, disproving the idea that in the central areas of the oceans there were few microorganisms, due to the absence of nutrients. In addition, it is known, nowadays, that these small photosynthetic organisms are the main producers of organic matter on the planet. They have a tremendous ecological impact. Despite of all the knowledge about marine cyanobacteria, there is a mechanism that is still low explored, how marine cyanobacteria are protected themselves from the excess of solar energy, their photoprotection mechanisms. For that, this project is focused on the study of the Orange Carotenoid Protein (OCP) and their homologs in the marine cyanobacteria. Knowing how these ‘photoprotective’ proteins really work could have important implications. From the point of view of basic science, it is important to know how these organisms thrive. In addition, in a context of a climate emergency, we can predict how cyanobacterial populations in the ocean are going to vary with the increment of solar radiation. Finally, these proteins have a potential use as a tool in optogenetics, recent techniques that use proteins that response to light to biomedicine applications such as neuroscience.
During the project, we have been characterized the OCP and its homologs HCPs (Helical Carotenoid protein) and CTDHs (C-terminal domain homolog proteins) from marine cyanobacteria. The last two constitute two new families of carotenoid-binding proteins, whose principal functions remain enigmatic and poorly characterized. For that, we have been isolated those proteins in vitro and study them biochemically, from a structure point of view and some of their functions. We have confirmed that the OCP in marine cyanobacterium has the ability to photoactive and eliminate the excess of energy that can damage the organisms. We also showed the ability of those marine-proteins to bind canthaxanthin as a chromophore. We successfully purified marine HCP5 and CTDH1 with their bound carotenoid.
We also were able to get the structure of the complex OCP-Phycobilisome (PBS) using the latest structural biology technique, Cryo-Electron Microscopy. This data answered an important question where and how OCP binds to the PBS. This is an important achievement in the field, and lay the foundation for future photosynthesis bioengineering studies. Moreover, physiological studies were carried out to determine the expression of these genes under different conditions, and understand their regulation.
The results of this project are published in 4 papers, I have participated in different activities to disseminate the project, as for example, the European Researcher Night.
Overall, I gained tremendous knowledge and training to work with those proteins helping me to set up myself in a position to lead a future independent research career.
We also were able to get the structure of the complex OCP-Phycobilisome (PBS) using the latest structural biology technique, Cryo-Electron Microscopy. This data answered an important question where and how OCP binds to the PBS. This is an important achievement in the field, and lay the foundation for future photosynthesis bioengineering studies. Moreover, physiological studies were carried out to determine the expression of these genes under different conditions, and understand their regulation.
The results of this project are published in 4 papers, I have participated in different activities to disseminate the project, as for example, the European Researcher Night.
Overall, I gained tremendous knowledge and training to work with those proteins helping me to set up myself in a position to lead a future independent research career.
We expect that the biochemical, structural, and functional results obtained during this project lay the foundation for the use of those carotenoproteins as a synthetic biology tool. We believe this would be the next step, the properties of those proteins allow us to rational design OCP/HCP/CTDH-derived proteins for implementation in synthetic light-controlled systems.
Moreover, the latest results describing the structure of the complex phycobilisome-OCP provide detailed insights into the biophysical underpinnings of the control of cyanobacterial light-harvesting with implications for bioengineering its regulation in natural and artificial light-harvesting systems.
Moreover, the latest results describing the structure of the complex phycobilisome-OCP provide detailed insights into the biophysical underpinnings of the control of cyanobacterial light-harvesting with implications for bioengineering its regulation in natural and artificial light-harvesting systems.