Abstract
Carbonic anhydrases (CAs) exist in all kingdoms of life. They are metalloenzymes, often containing zinc, that catalyze the interconversion of bicarbonate and carbon dioxide—a ubiquitous reaction involved in a variety of cellular processes. So far, eight classes of apparently evolutionary unrelated CAs that are present in a large diversity of living organisms have been described. In this review, we focus on the diversity of CAs and their roles in photosynthetic microalgae. We describe their essential role in carbon dioxide-concentrating mechanisms and photosynthesis, their regulation, as well as their less studied roles in non-photosynthetic processes. We also discuss the presence in some microalgae, especially diatoms, of cambialistic CAs (i.e., CAs that can replace Zn by Co, Cd, or Fe) and, more recently, a CA that uses Mn as a metal cofactor, with potential ecological relevance in aquatic environments where trace metal concentrations are low. There has been a recent explosion of knowledge about this well-known enzyme with exciting future opportunities to answer outstanding questions using a range of different approaches.
Highlights
Microalgae are a heterogenous group of eukaryotic and prokaryotic microorganisms that are almost exclusively photosynthetic, phylogenetically distinct, and evolved at different geological periods during the Earth’s history [1]
We focus on the importance of Carbonic anhydrases (CAs) for inorganic carbon uptake in microalgae, on their role in the algal CO2 -concentrating mechanisms, on their diversity, and how these enzymes help microalgae to survive and flourish in modern aquatic environments
A biochemical concentrating mechanisms (CCMs) involves the pre-fixation of CO2 into C4 organic compounds, which is a process termed C4 photosynthesis that occurs in 3% of terrestrial higher plants (e.g., Zea mays)
Summary
Microalgae are a heterogenous group of eukaryotic and prokaryotic microorganisms that are almost exclusively photosynthetic, phylogenetically distinct, and evolved at different geological periods during the Earth’s history [1]. Eukaryotic microalgae, including red and green lineages, evolved over 1.5 billion years ago as the result of an endosymbiosis event between a photosynthetic cyanobacterium and a heterotrophic eukaryote [3]. Microalgae are important primary producers in aquatic environments Their success is in part the result of highly efficient photosynthetic. CO2 fixation, which can be 10 to 50 times higher than that of land plants [6] This high efficiency can occur even in environments where CO2 is usually limiting, because microalgae have evolved different strategies to take up and fix CO2 , all of which involve the enzyme carbonic anhydrase. We focus on the importance of CAs for inorganic carbon uptake in microalgae, on their role in the algal CO2 -concentrating mechanisms, on their diversity, and how these enzymes help microalgae to survive and flourish in modern aquatic environments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
