The Tiny Giant of the Sea, Ostreococcus’s Unique Adaptations"

FORESI NOELIA; DE MARCO AGUSTINA ; DEL CASTELLO FIORELLA; RAMIREZ LEONOR; NEJAMKIN ANDRÉS; CALO GONZALO; GRIMSLEY NIGEL; CORREA ARAGUNDE NATALIA; MARTÍNEZ-NOËL GISELLE

PLANT PHYSIOLOGY AND BIOCHEMISTRY

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2024

0981-9428

Ostreococcus spp. are unicellular organisms with one of the simplest cellular organizations. The sequencingof the genomes of different Ostreococcus species has reinforced this status since Ostreococcus tauri has onemost compact nuclear genomes among eukaryotic organisms. Despite this, it has retained a number ofgenes, setting it apart from other organisms with similar small genomes. Ostreococcus spp. feature asubstantial number of selenocysteine-containing proteins, which, due to their higher catalytic activitycompared to their selenium-lacking counterparts, may require a reduced quantity of proteins. Notably, O.tauri encodes several ammonium transporter genes, that may provide it with a competitive edge foracquiring nitrogen (N). This characteristic makes it an intriguing model for studying the efficient use of N ineukaryotes. Under conditions of low N availability, O. tauri utilizes N from abundant proteins or aminoacids, such as L-arginine, similar to higher plants. However, the presence of a nitric oxide synthase (L-argsubstrate) sheds light on a new metabolic pathway for L-arg in algae. The metabolic adaptations of O. taurito day and night cycles offer valuable insights into carbon and iron metabolic configuration. O. tauri hasevolved novel strategies to optimize iron uptake, lacking the classic components of the iron absorptionmechanism. Overall, the cellular and genetic characteristics of Ostreococcus contribute to its evolutionarysuccess, making it an excellent model for studying the physiological and genetic aspects of how green algaehave adapted to the marine environment. Furthermore, given its potential for lipid accumulation and itsmarine habitat, it may represent a promising avenue for third-generation biofuels.