Pumping iron: A multi-omics analysis of two extremophilic algae reveals iron economy management

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 120; no. 30; p. e2305495120
• Main Authors: Davidi, Lital, Gallaher, Sean D, Ben-David, Eyal, Purvine, Samuel O, Fillmore, Thomas L, Nicora, Carrie D, Craig, Rory J, Schmollinger, Stefan, Roje, Sanja, Blaby-Haas, Crysten E, Auber, Robert P, Wisecaver, Jennifer H, Merchant, Sabeeha S
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 25.07.2023; Proceedings of the National Academy of Sciences
• Subjects: Algae; BASIC BIOLOGICAL SCIENCES; Biological Sciences; Carbon sinks; Chlamydomonas reinhardtii; Chlorophyll; Combinatorial analysis; Dunaliella salina; Dunaliella tertiolecta; Ferredoxin; flavin biosynthesis; Flavodoxin; Genomes; Iron; Iron deficiency; iron homeostasis; iron starvation-induced protein (ISIP); Nutrient deficiency; Photosynthesis; Photosynthetic apparatus; phytoplankton; Proteins; Proteomics; Scavenging; Transcriptomes; Transferrins; phytoplankton; flavin biosynthesis; iron homeostasis; Chlamydomonas reinhardtii; iron starvation–induced protein (ISIP)
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2305495120

Marine algae are responsible for half of the world's primary productivity, but this critical carbon sink is often constrained by insufficient iron. One species of marine algae, , is remarkable for its ability to maintain photosynthesis and thrive in low-iron environments. A related species, Bardawil, shares this attribute but is an extremophile found in hypersaline environments. To elucidate how algae manage their iron requirements, we produced high-quality genome assemblies and transcriptomes for both species to serve as a foundation for a comparative multiomics analysis. We identified a host of iron-uptake proteins in both species, including a massive expansion of transferrins and a unique family of siderophore-iron-uptake proteins. Complementing these multiple iron-uptake routes, ferredoxin functions as a large iron reservoir that can be released by induction of flavodoxin. Proteomic analysis revealed reduced investment in the photosynthetic apparatus coupled with remodeling of antenna proteins by dramatic iron-deficiency induction of TIDI1, which is closely related but identifiably distinct from the chlorophyll binding protein, LHCA3. These combinatorial iron scavenging and sparing strategies make unique among photosynthetic organisms.