Proteomic view of the iron deficiency response in Dunaliella
EMSL Project ID
49840
Abstract
Algae are responsible for half of global primary productivity and have an important role in biogeochemical cycling. Algae can thrive in nutrient-rich and nutrient-depleted environments, indicating their wide plasticity. Iron-deficiency limits primary productivity on a global scale in croplands and in oceans, and algae are among the organisms so impacted. It is well established that since the photosynthetic machinery requires high amounts of iron, it is a key target of poor iron nutrition. Consequently, photosynthetic organisms that maintain metabolism in a chronic state of iron deficiency have evolved mechanisms for iron sparing and recycling. Research in the past decades has increased our understanding of iron acquisition mechanisms in plants and algae; however, the studies have focused on individual model systems, rather than on capturing biodiversity. Therefore, we aim to provide a broad cellular view of iron assimilation, sub-cellular compartmentation and metabolism, by discovering pathways and mechanisms of intracellular iron trafficking and storage for iron re-use and re-cycling in Dunaliella bardawil. Our focus is on monitoring the contribution and communication between the acidic vacuole vs. ferritin as iron storage sites and intermediates for iron acquisition and homeostasis, which are critical for survival during iron luxury vs. starvation transitions. The genus Dunaliella represents unicellular green microalgae that are well known for their high tolerance to extreme abiotic stress conditions of salinity, light, temperature and pH, but are otherwise not well studied at the molecular level. D. bardawil, has the unique property of being able to accumulate large amounts of beta-carotene when cultivated under appropriate conditions, making it the richest natural source for beta-carotene and therefore an important target for industrial production. Most importantly, a draft genome sequence for D. salina, which closely related to D. bardawil, has been published recently, which enables more detailed and genome-wide studies in this organism. D. bardawil can accommodate a reduced iron quota with only moderate chlorosis. Its iron assimilation pathway is distinct from that of Chlamydomonas reinhardtii, the more typical reference organism, intimating that transcriptomic and proteomic approaches will reveal new players in algal iron homeostasis. In conjunction with ongoing transcriptomic experiments and molecular physiology of iron nutrition in D. bardawil, we aim to 1) monitor the proteome of D. bardawil during the transition from iron replete to iron limitation conditions with dense sampling in order to track the short and long term responses, and 2) to elucidate the proteome of purified acidic vacuoles, the acidocalcisomes, which are hypothesized to serve as iron storage sites. The project will yield a more comprehensive and detailed map of environmental stress responses of green algae, which is relevant both to the basic understanding of algal metabolism, but can also be applied for finding sustainable solutions to energy and environmental challenges. The focus of this project on abiotic stress response fits well within the Biosystem Dynamics and Design Science Theme and is ideally suited for execution at EMSL where there is a strong tradition of quantitative proteomics.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2017-10-01
End Date
2019-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members