How photosynthetic proteins work in Antarctic environments

What is it about?

Psychrophiles are extremophiles that are permanently adapted to the cold, and survive and thrive at temperatures close to 0°C. Such organisms require unique cold-adapted enzymes that retain activity at cold temperatures that normally stop chemical reactions. Chlamydomonas sp. UWO241 is a psychrophilic green alga found in the Antarctic Lake Bonney. We purified and characterized ferredoxin from UWO241, one of the main photosynthetic enzymes found in all plants and algae. We show that this protein has characteristics typical of cold-adapted enzymes. Interestingly, we also found that ferredoxin is encoded by two genes in the UWO241 genome. This is in contrast with other plants and algae, where ferredoxin is present as a single gene. This could be a novel way for extremophilic algae, such as UWO241, to adapt to harsh cold environments.

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Why is it important?

Polar environments contribute significantly to global carbon cycles through photosynthesis, which sequesters inorganic carbon from the atmosphere and converts it to usable organic carbon compounds. Despite the importance of this process, we know very little how photosynthetic organisms function and evolve in the cold. Our work on the extremophilic cold-adapted green alga UWO241 provides a novel insight on how photosynthesis operates in cold environments.